Helicopter crash off the coast of Newfoundland - 18 aboard, March 2009

[Droopystop]

I can't help feeling that the only people who will gain out of all this is the lawyers :yuk:

There is much speculation and that can only be a good thing in my opinion. The more we as pilots look at the scenario and the more we use our imaginations to look at what we might have done, hopefully we might learn from this terrible disaster.

Whether or not the crew did the right thing doesn't matter. We may never know what lead them to make the decisions they made, correctly or otherwise. Nor can we sit and type, claiming we would have done differently - we simply don't know at this stage what really happened. For example, changes in speed might be down to someone mixing IAS/TAS/GS or indeed changes in wind speed.

Lets hope that the 92, great as it is already, becomes even safer than it is. And if replacing the bolts really reduces the chances of the gearbox ever emptying itself of oil/loosing pressure to negligable (from the perspective of the pilot's not accountant's/lawyer's), then who needs 30 mins of dry running time. All everyone wants is a helicopter that gets us back safe, everytime.

[heli-cal]

Whether or not the crew did the right thing doesn't matter.

Actually, it matters a great deal!

Did you not read the post made by SASless, perhaps the significance failed to register with you.

Had you not thought along the lines of what SASless wrote?

I find it inconceivable that you could actually write what you did, what were you thinking?

[newfieboy]

Tim and Matt and all the deceased on Cougar 491, Rest in peace my friends.


I hope there's a place, way up in the sky
Where pilots can go when they have to die.
A place where a guy could buy a cold beer
For a friend and a comrade whose memory is dear.
A place where no doctor or lawyer could tread,
Nor a management-type would e'er be caught dead!
Just a quaint little place, kind of dark, full of smoke,
Where they like to sing loud, and love a good joke.
The kind of a place that a lady could go
And feel safe and secure by the men she would know.

There must be a place where old pilots go,
When their wings become heavy, when their airspeed gets low,
Where the whiskey is old, and the women are young,
And songs about flying and dying are sung.
Where you'd see all the fellows who'd 'flown west' before,
And they'd call out your name, as you came through the door,
Who would buy you a drink, if your thirst should be bad,
And relate to the others, "He was quite a good lad!"

And there, through the mist, you'd spot an old guy
You had not seen in years, though he'd taught you to fly.
He'd nod his old head, and grin ear to ear
And say, "Welcome, my Son, I'm proud that you're here!
For this is the place where true flyers come
When the battles are over, and the wars have been won.
They've come here at last, to be safe and alone,
From the government clerk, and the management clone;
Politicians and lawyers, the Feds, and the noise,
Where all hours are happy, and these good ol' boys
Can relax with a cool one, and a well deserved rest!
This is Heaven, my Son. You've passed your last test!

Gods Speed.


I will never forget you,

Newfieboy.

[Variable Load]

SASless,

I hope you don't mind if I stick to the factual side of your excellent post?


If the APU was running per the checklist....would the CVR and Data Recorder continue to operate normally in the event of a loss of AC Generators?
Yes, if the APU was running and the AC's fail, then the APU is capable of supplying power to all but a few high current draw items (RIPS, windshield heat, AVC)

Would the AC Generators fail due to overheating as a result of loss of oil?
Yes, 212man's emergency landing demonstrated this. Although his event wasn't oil loss, it did result in AC gen failure due to overheating.

Would the AC Generators fail due to a low Rotor RPM situation such that the system would sense an under frequency or under voltage situation?
Under frequency protection is only enabled when the aircraft is on the ground. I do not know how slow the generator would have to turn in order to trip the under-voltage protection - certainly less than 90% Nr, probably a lot slower?

Would the APU continue the AC system despite the loss of the AC Generators?
Yes, see my earlier answer re CVR/FDR

Of course, my answers assume the systems and redundancies worked as advertised ;)


There is one factor that I do not think has been discussed so far and that is the MGB Oil Temp indications. Once the MGB has lost all of it's oil the Oil Temp indications might not show what the crew would expect i.e. mindset might have been Low Oil Px usually results in High Oil Temp? Being faced with No Oil Px and Low (ish) Oil Temp might have led to some confusion. OK, now I'm speculating :eek:



VL

[Torquelimited]

Makes sense, if there is no flow the gauge will likely indicate the ambient temperature of the enviroment where the oil temp probe is situated.

[industry insider]

Torque

I believe you are correct. I have had a total and sudden oil loss on 2 engines during my flying days (both Makila), initially the temp may go up but quickly indicates ambient within the immediate area of the probe once all the oil has exited....

[SASless]

But.....the pressure remained at "Zero" did it not?

[PilotJoe]

The technical aspects of the investigation will show some of the reasons why aircraft and it's gearbox developed this problem, but they are really an aside to the reason for the crash. For 10 minutes and 31 seconds the pilots had a problem that all their training taught them to "Land or Ditch Immediately", but they did not. They were only 45km from land, they were aiming for the parking lot of Cape Spear which was the nearest point of land, and away from the direct route to the airport. To ditch with sufficient rotor RPM is the only way they were going to have some control for landing, but somewhere between 300 asl and the ocean they lost that, the blades were intact with the wreckage, those blades don't hit the water at sufficient rpm to stay intact, as well they did not even "pop the floats", sadly, no matter what the outcome of the investigation for the "cause" of the accident, it will invariably come down to "pilot error". Any of you who fly will know what I am talking about, how many have had a chip light and second guessed it? How many of you have been afraid for your job or reputation etc. when making a go or no go decision. When was the last time your chief pilot or Manager or the company said to you in a briefing, "I don't care what the reasons are, land the machine"! The sea state and weather that day were not bad, what Matt, or Tim, needed to do was put it down immediately, get in the raft and not second guess how serious the problem was...God Speed all of you!

[Matthew Parsons]

PilotJoe,

Consider that in the wrong sea state a ditching can have low probability of survival whereas continuing to land may have a higher probability of survival. Perhaps there was more information available to the pilots that rightfully had them doubt the severity of the emergency. At this point, we just don't know.

I get the impression that you'd second guess the decisions of the pilots either way. Why not just wait for the official report before you publicly place blame.

[PilotJoe]

I am not placing blame on anyone. Everyone on that aircraft had extensive training for ditching, everyone on board was dressed for ditching. Ditching with plenty of rotor rpm, under power or not, is very survivable. The co-pilot had extensive Sea King, Sikorsky S61N, time in the navy. The problem with ditching is deciding when to do it, and obviously the time is when you have control, rotor rpm and optimally an operating engine. Trying to see how far a main gear box with 0 pressure can get you is second guessing your instinct and training. When I was young and stupid, I flew one trip for Petroleum Helicopters, 150 miles out in the Gulf of Mexico using a single engine Long Ranger, half way back during the return trip I got a transmission chip light, training said "Land as soon as Practical" I diverted and landed on a rig not serviced by PHI, pulled and cleaned the sensor, took off and circled the rig for 10 minutes watching for a repeat. When I got back to base I caught a lot of flack for that "maneuver" and was laughed at by the more seasoned pilots. At that point I knew that single engine operations offshore was not going to be for me, nor was the cavalier attitude of the company. I got my hours and experience on other jobs, but I always followed my instincts. I just have to wonder what made them think they could get back to land with probably the most serious problem they could face, a failed MGB and the resulting deterioration of rotor rpm.

[somepitch]

pilotjoe,

its misleading to say that they continued flying problem for 10 mins 31 seconds, because they began a fairly rapid descent (over 1100 fpm) from 9,000 ft, which took the vast majority of that time and probably would not have differed much whether the crew intended to ditch immediately or not. There was only a little over 2 mins after leveling off at 800 ft until the power interruption to the FDR/CVR occurs, suggesting things went sideways pretty quickly.

the time frame for making critical decisions appears to have been pretty short, and i think second guessing actions made in those couple of minutes is a bit unfair to the crew.

[gulliBell]

I would have given it go at making dry land considering the proximity and thinking I had a 30 minute run dry gear box, until it became obvious I wasn't going to make it at which point being forced to ditch. The unknown for me in this thinking is how much time, between when the gear box starts making grinding noises and the power required to maintain RRPM starts going up, do you have to get it from that point to safely landed under control on the water? I dare say a lot less time than I expected.

I'm not a 92 pilot but I am surprised by revelations that it doesn't have a 30 minute run dry gearbox. I am a 76 pilot and I always assumed I had a 30 minute run dry gear box. Obviously I don't. So in light of all this and from here on, where the checklist says land immediately, that's exactly what I'll be doing.

[CanaDriver]

truly sad times on our east coast
i hope our military is paying attention and insist changes are made before
taking delivery of their variant to replace the sea kings

good debate folks

[Old Man Rotor]

The entire spectrum of causes will eventually be published once all the various analyses are completed by the appropriate authorities and other stakeholders.
However the “experts” of the actual operation itself are indeed ourselves, the folk that daily flog these machines to various locations full up with all those faces that we quickly forget.

With this in mind, I can’t hold back my curiosity any longer.


Two questions have been nagging me since the altitudes and timings were first published.

1: Why would an Offshore machine select 9000 AMSL as its cruising level over the open ocean?

By convention, most offshore altitudes are in the lower levels not the higher ones, and the reason given by most experienced offshore pilots: “Because it’s along way down should something go wrong”.

Surely the wind was not the only element that made the Captain select that altitude?

Could this aircraft have been flying in or above “Known Icing Conditions”, based on the weather and temperature of the day?


2: Why did the aircraft level out and increase speed at 800 AMSL?

I can appreciate the logic of “driving” a potentially damaged MGB with raw power to keep the Nr within limits, however I can’t rationalise why the aircraft was levelled at 800 AMSL. Any fall from 800 ft will hurt.

An altitude of 50’ AMSL seems a far more survivable altitude should an uncontrollable reducing Nr become the compromising element.

These and many other variations of these questions will be asked by numerous lawyers seeking the slightest crack in all the defences.

[Variable Load]

The RFM S92 (so therefore Cougar checklist??) states LAND IMMEDIATELY for the scenario the pilots faced.

Unlike the EC225 RFM, which says fly for 30 minutes at Vy, then LAND IMMEDIATELY.

Guess which one has 30 minutes run dry. There is no cover up by SAC as I do not think they have ever stated "30 minutes run dry capability", of course pilot perception is a different matter.

I'm not trying to defend SAC or the S92 gearbox, just trying to keep the debate on track :\

[Pilot DAR]

Dumb pilot answer to the reasonable question: I just have to wonder what made them think they could get back to land with probably the most serious problem they could face, a failed MGB and the resulting deterioration of rotor rpm.

Perhaps they thought that they had that magical 30 run dry time. I have, on a few occasions, finding myself on the edge of the "approved" limit, counting on the actual certification requirement as my margin of safety. Perhaps these two unfortunate pilots also did!

I agree with Svenestron: But I believe what is really misleading is the information out of SAC about the 30 min run dry compliance. Judging from the posts on here, most pilots seem to have understood there was a run dry capability when there was virtually none.
You can always argue it is there in black and white. But if a majority of pilots think differently, you have failed somewhere in communication.:ugh:

I suspect that these pilots and passengers were cheated out of a margin of safety which they reasonably thought they had, which was not actually available to them. That's not right. Either the aircraft meets the design requirements, or it does not. If it does not, it flies with a limitation, and the pilots are boldly warned of the certification shortcoming.

Pilot DAR

[SASless]

Gullibell,

I too have held the idea of flying it till I "have to ditch" rather than "land immediately" as the checklists for many aircraft require.

How did so many of us arrive at that mindset?

How did we come to believe the transmission would give us plenty of warning before it made us passengers on a very terrifying but fatal thrill ride?

How did our system of training, checking, and engineering knowledge get supplanted by the existing Conventional Wisdom?

DAR,

Can you point out in any Training document or technical paper where the S-92 clearly states there is an allowable 30 minute run dry procedure?

Are there any Training Captains, Conversion Instructors out there that have stated during any training program, check flight, or tea room conversation that the S-92 has an authorized 30 minute run dry procedure when discussing the Emergency Check List?

[HeliComparator]

OMR

Its not unusual to fly modern helicopters at high altitude, for the same reason that jet airliners fly high, ie much better fuel consumption for the same TAS, better VHF radio comms, better reception of VORs, smoother air etc

It might, as you suggest, also have had something to do with favourable tailwind and/or being above cloud / icing.

Yes it is further to fall, but that "should" not be a consideration!

HC

[chester2005]

As much as i'm fairly sure i probably would have done very similar in their situation, the sad truth of it is as someone has mentioned,

If the POH states Land Immediately with the symptoms they had, and the pilots did not do it.

The chances are that Pilot Error will be applied to this case.

Sad but True

Chester:ok:

[ArmchairExpert]

Regarding loss of the CVR/FDRs on the S-92:

1) Loss of two main generators, > Correction: FDR is on the battery bus
2) G-switch was tripped,
3) Immersion switch was tripped,
4) No APU generator. > Correction: FDR is on the battery bus

#3 can be ruled out.
#1 seems likely if mains overheated, mgb slowed dramatically, or mgb siezed. >Correction: Overheated main gens should have no effect
#2 seems unlikely unless mgb siezed catastrophically.
#4 is a mystery; APU should've been turned on with loss of mgb pressure. >Correction: APU gen should have no effect

[Pilot DAR]

Can you point out in any Training document or technical paper where the S-92 clearly states there is an allowable 30 minute run dry procedure?

Are there any Training Captains, Conversion Instructors out there that have stated during any training program, check flight, or tea room conversation that the S-92 has an authorized 30 minute run dry procedure when discussing the Emergency Check List?

Nope. And I'm not an S-92 expert either.

However, two thoughts:

A 30 minute run dry time has an allowable for damage to occur to the transmission during this time. Therefore it would not be "allowable" or "authorized" for normal operations, because, of course we are not "allowing" or "authorizing" operations which are likely to cause rapid damage to the aircraft. That's "emergency only" type stuff, requiring reporting afterward.

I know that during a certification test, the engine demonstrated safe operation at 105% of maximum speed, without an imminent unsafe condition.

"33.49 (6) A 15-hour run at 105 percent rated maximum continuous power with 105 percent maximum continuous speed"

So, if during a (admittedly poorly executed) manuever, I exceeded an engine speed limit by a few percent, (yup, I did, ONCE) I would not land immediately in an unsuitable area, or dangerous circumstances, I would fly it back to the most appropriate landing site, and report the exceedance.

Perhaps those unfortunate pilots could have set themselves up a bit better for success in a bad situation, I'm not here to judge that. But, I will judge a combination of certification testing/training/risk which entices a pilot to make a decision which is less than the best one. If there is NO margin for continued operation, the pilot has a right to know. Even "land immediately" suggests that some time will be required to execute a safe landing - 30 minutes perhaps? Maybe the term "land instantly" is what was really intended....

Pilot DAR

[SASless]

How can you stretch "Immediately" to "30 minutes perhaps"?



im⋅me⋅di⋅ate⋅ly
   /ɪˈmidiɪtli/ Show Spelled Pronunciation [i-mee-dee-it-lee]

–adverb

1. without lapse of time; without delay; instantly; at once: Please telephone him immediately.
2. with no object or space intervening.
3. closely: immediately in the vicinity.
4. without intervening medium or agent; concerning or affecting directly.
–conjunction
5. Chiefly British. the moment that; as soon as.
Origin:
1375–1425; late ME; see immediate, -ly

Synonyms:
1. instantaneously, forthwith. Immediately, instantly, directly, presently were once close synonyms, all denoting complete absence of delay or any lapse of time. Immediately and instantly still almost always have that sense and usually mean at once: He got up immediately. She responded instantly to the request. Directly is usually equivalent to soon, in a little while rather than at once: You go ahead, we'll join you directly. Presently changes sense according to the tense of the verb with which it is used. With a present tense verb it usually means now, at the present time: The author presently lives in San Francisco. She is presently working on a new novel. In some contexts, especially those involving a contrast between the present and the near future, presently can mean soon or in a little while: She is at the office now but will be home presently.

Antonyms:
1. later.

[Variable Load]

So, if during a (admittedly poorly executed) manuever, I exceeded an engine speed limit by a few percent, (yup, I did, ONCE) I would not land immediately in an unsuitable area, or dangerous circumstances, I would fly it back to the most appropriate landing site, and report the exceedance.

pilotDAR. Are you saying that if you were knowingly faced with a situation that your company SOPs stated was LAND IMMEDIATELY, you would probably fly the aircraft back and mention it to someone?

If you are the you need some professional training. If you are not then your comments are at best misleading, personally I would say they are irrelevant and deserves the delete button.

Your two recent posts have me going :ugh:

[212man]

I'm curious to know where this sudden "Oh, all the pilots out there thought helicopters had a 30 minute run dry capability" came from? Is there a serious suggestion that Joe line-pilot sits and reads FAR Part 29 in the crewroom, maybe with a bit of AC29-2C for bed-time reading? Unless your RFM specifically states a period within which to have landed (like the EC-155 25 minutes I quoted earlier) assume nothing. Assume the RFM means what is says:

Land immediately — Continued flight may not be possible. Ditching or landing in hazardous terrain is preferable to continuing flight.

The moot point is the oft-quoted Fire Warning, and the sad thing about that, in this context, is that it can result from a single point failure, and is often spurious, so that tends to lead to a suspicion of the instruction to Land Immediately. Most other situations are the result of more than one indication, usually independant of each other (switches plus pressure transducer, for instance.)

Human nature and self preservation will generally dictate looking for signs to confirm that things aren't as bad as we think, and the more clues we see to confirm that, the happier we feel with continuing. It's self induced "risky shift." It's not a helpful trait, but it's a fact.

One of the by-products of improved reliabilty and reduced accident rates in the offshore sector - don't believe me? then check the UK AAIB archives for the 1980s and 1990s - is we are less exposed to either first hand accounts or writen reports. Maybe that has eroded some of the sense of danger we should all feel when confronted by these situations? A classic Catch 22!

[Pilot DAR]

Don't worry variable load,

I fly helicopters recreationally only...

Professionally, it is a part of what I do, to imagine the worst case, and choose wording for flight manual supplements, and maintenance manuals which will convey, with zero misunderstanding, to the reader, exactly what they are to do, and when.

You'd be surprised how many pilots have some familiarity with the design standards, and misuse them as over riding guidance for flying, without truly understanding the underlying meaning.

Too often in my 30 years of flying, I have found places where the instructions mislead the pilot or maintainer, and an unsafe situation existed. I make it my prime objective to get hte words right. That's often best done by understanding them wrong first....

I am probing. If the standard requires a demonstration of a 30 minute run dry time, all other things being non-factors, it should be at least plausibly possible, of why the words in the standard? If an apparent ten or so minutes (it could take that long to get down from up high) of continued operation is not safe (I'm not saying that you're not going to scrap a transmission, just get on the surface safely), more explicit wording is appropriate in Flight Manuals. "Immediately" sounds explicit, but it's true intent is apparently not being taken seriously. (by the way, I have never read an S-92 Flight Manual - just working with what I've read here).

I'm trying to figure out what works I should use in a Flight Manual Supplement, if I mean "go down from here right now, and don't stop 'till you get there"...

[maxwelg2]

As details of the TSB investigation emerge and the oil company's joint investigation starts to grow momentum, we as offshore PAX now traveling by supply vessels are being told that S-92 testing is commencing this week in St. John's (I know it already commenced last Monday as I live on the test flight paths) with the view to move forward re-enstatement if the joint operator's decide that these helos are acceptably safe to use again. There are now more questions in my mind as more information and experiences/views come to light in these forums. Here are just a few...

How can this helo be considered safe for offshore use without the FAA re-approving/confirming the MGB dry-run capability (or lack of it) now that they are surely aware of the previous failure modes in Malaysia and Australia?

The RFM stated land immediately. Did the pilots assume that low MGB lube oil temperature due to sensor location meant that their press Tx sensor was faulty? Hopefully the FDR/VDR will answer this question.

Why is there no redundancy in MGB pressure and temperature sensors for such a critical component? Has the previous history of "nuisance" alarms with the S-92s caused mis-trust with the pilots not believing their instruments?

Is it not possible to "feel" a change in MGB performance with the high background quiescent vibration present in the 92s, or are you totally reliant on increased power consumption as your main secondary indicator?

Is vibration the main issue with the titanium filter bowl bolt failures, and can the steel variants fail due to the same inherent issue?

Why did the Blackhawk have steel bolts already and this was not passed on to the 92 immediately?

How can the Blackhawk have a 30-minute dry run capability if it is indeed the same MGB?

How good are the pilot's flight suits for offshore survival capability? Could this have had an effect on their decision to head for land?

As you can imagine we as PAX are still not convinced that the S-92 is suitable for offshore use. Unless the pilot can guarantee to me that he will ditch immediately on MGB oil pressure failure I will not be flying in the S-92 again. My life is more valuable to me than an offshore trip. The problem will be if we are told that this is our normal mode of transport to work and is deemed safe by all the official regulatory bodies, then it will be a hard call for some people to give up their offshore careers or accept the additional risk, which in this day and age should not be deemed acceptable.

[212man]

I'm trying to figure out what works I should use in a Flight Manual Supplement, if I mean "go down from here right now, and don't stop 'till you get there"...

Land immediately — Continued flight may not be possible. Ditching or landing in hazardous terrain is preferable to continuing flight.

Seems pretty clear to me and is more or less the same for all the types I've flown.

Maxwel,
all I can say is that we as pilots DO climb into this aircraft, and fly it several hours per day, and that should be your re-assurance. To put it in context, would you fly in a Boeing 777, after all there are 220 of them in current service with a known engine roll back problem that will take over a year to fix? If you flew in an MD-11 would you ask the pilot to fly not above 20,000 ft, as the Swissair could never have descended to safety from their cruise altitude following their fire? and so the list goes on.

For the sake of clarity/accuracy, there was not a similar incident in Malaysia, only Australia.

[maxwelg2]

212man, I accept a degree of risk in any mode of transport I use and most certainly you as a pilot accept an even greater degree via the additional flying hours spent in these helos, but as a PAX and using this transport as my only regular mode of transport to working offshore (weather-permitting) it is up to the operator and client (oil company) to ensure that this helo is as safe as is reasonably practical. IMHO if it is proven that the S-92a does not comply with FAR29/CS29 then this breaches this requirement. I'm quite sure that the impending lawsuits by the bereaved families will view this in a similar manner...

Wrt. the Malaysian MGB failure I accept that this event was not the same as Broome or flight 491, but the same issue of MGB reliablility is still valid. I did not mean to imply that it was the same common mode of failure. I appreciate that you have real first-hand experience of that particular incident and know only too well the limitations of the S-92 MGB design. I'm just not confident that SAR and the FAA are being proactive enough with this helo to iron out it's weaknesses and make it legally compliant with the applicable safety standards.

It is everybody's decision what they choose to accept as safe or unsafe, at present I'm on the fence with the S-92a. I would fly in a S-61 or Super Puma Mk2 any day, as I have done over the past 18 years with no qualms. I trust the pilots first and the aircraft second, always have.

[Variable Load]

I would fly in a S-61 or Super Puma Mk2 any day

maxwelg2, whilst I fully understand the emotion and associated apprehension with the S-92 in St Johns, I hope you do not object to me mentioning that neither of those aircraft have any certified run dry capability either.

I fact the S61 has a known MGB failure mode that has resulted in two aircraft burning to the keel in a couple of minutes. :eek:

Sometimes things aren't as simple as we like to make them..... :sad:

[maxwelg2]

That may be the case, but statistically and IMO they stay in the air a lot better and have some level of MGB lube oil redundancy i.e. AS332L Glycol cooling, S61 DC aux lube oil pump from lower sump.

I can remember the old Tigers and Mk1 Pumas having gearbox chewing issues in the early 90s in the North Sea and having the odd drip of oil from the chip detector access panel on my survival suit, I'd like to think that in the 21st century helos were being built with a higher safety factor.

I recall reading on one of the posts of the 30-minute dry run capability being a requirement from 1988, are we still to believe that the S-92 still avoids this requirement on the "extremely remote" wording?

[madrock]

What is the intent of putting in place Regulations like FAR29 (specifically Section 29.927) that set minimum standards other than to ensure a certain (sometimes critical in the case of MGB) redundancy is there when needed ? Surely we aren’t saying well it’s there because it says so on this piece of paper, but don’t expect to ever depend on it if you really need it ?
Is not one of the reasons these types of aircraft are chosen for offshore transportation in the first place that that they do offer that additional critical redundancy according to their FAR29 Certification, so if something bad happens really fast (e.g. you lose your MGB oil in a matter of minutes), there is that built-in additional time to get the aircraft down in a controlled manner.
From the time the crew first notices a loss of MGB lubricant, the aircraft, as Certified to FAR29.927, is to be capable of 30 minutes continued flight – it’s a design requirement, a testing requirement, and a FAR29 Certification requirement for any failure which results in loss of MGB lubricant. Aren’t these minimum standards, i.e. there may possibly even be inherent benefits over and above, but no failure below ?
I won’t second guess the flight crew’s actions relating to this tragic event and that will be determined by professional investigators who have first hand access to the many pertinent sources of information, but whatever happened after they first noticed loss of lubricant, should there have been more time available to them due to the built-in additional redundancy for the MGB as specified by the FAR29 Regulation ?
What types of redundancy systems are installed on these aircraft that protects the MGB against any of these failures ?
Are these systems designed to address multiple failure modes and are they standard equipment on all helicopters working offshore (albeit with a weight and $ cost) ?
Why only 30 minutes of continued flight – is that acceptable for hostile offshore flight times of over an hour to destination with no alternate ?
Surely the Regulations have not fallen that far behind current technology that we may be trading off potential critical redundancy for the sake of only having to meet minimum requirements which were introduced over 20 years ago ?
In an (offshore oil) industry that is cash rich, that continuously advances new technologies and has lobbying power like no other, things such as outdated regulations or a hands-off mentality are not issues that cannot be addressed ?
Lots of questions, and probably hundreds more out there – hope there are lots of answers that can help to make flying offshore safer for everybody.

[Flight Safety]

Found this on the Sikorsky website, sorry if it's been posted previously.

Sikorsky Aerospace Services and VIHAG Announce Agreement for S-92®*Helicopter Gearbox Repair and Overhaul (http://www.sikorsky.com/vgn-ext-templating-SIK/v/index.jsp?vgnextoid=00de6eb78fa78110VgnVCM1000001382000aRCRD&vgnextchannel=65f9e39d40a78110VgnVCM1000001382000aRCRD&vgnextfmt=default&pressvcmid=76afc85febdaf110VgnVCM1000004f62529fRCRD)

The press release says in part:
February 24, 2009
ANAHEIM, California - Sikorsky Aerospace Services, at Heli-Expo today announced the signing of an agreement with VIH Aviation Group (VIHAG) to authorize VIHAG's ability to repair and overhaul S-92® helicopter gearboxes. Sikorsky Aerospace Services is the aftermarket business of Sikorsky Aircraft Corp., a subsidiary of United Technologies Corp. (NYSE:UTX).

The VIH Aviation Group of companies has operations in Canada, the U.S. and other countries ranging from Taiwan to Peru. VIHAG is Canada's oldest privately owned helicopter business, and includes several helicopter operating companies as well as an aviation technical services company and regional fixed base operator companies. VIHAG subsidiary Cougar Helicopters is an acknowledged leader in all-weather, instrument flight rules (IFR) Offshore and IFR Search and Rescue services; while VIH also operates a fleet of visual flight rules (VFR) helicopters in a variety of tasks, including specialized helicopter services such as aerial crane construction, heli-logging, disaster relief, exploration, forestry and personnel transport.

I guess Cougar and VIHAG will be getting up to speed on the S-92 gearboxes faster than they originally thought.

[leading edge]

Maxwelg2

To clarify, neither the AS332L or L2 have any glycol supplementary MGB cooling or lubrication. Some S61s had an ELS but not all.

[SASless]

I have been thinking today.....a scary thing for me to do some of you might agree.


My pondering got around to the concepts of Pilot Error, Crew Error, Operational Error, and humans making errors in general as they relate to aviation.

This accident cannot be attributed to Pilot Error in the least.

The Crew was confronted with a serious mechanical problem and as it turned out....it was in fact a serious mechanical failure. That in itself rules out Pilot Error as the aircraft was lost to a mechanical failure.

The Crew were presented with unusual indications initially and those were indication abnormalities. There were no signs of smoke, fumes, fire, vapor trails, grinding noises, or other physically viewable signs of a problem. All they could see were the unusual indications of warning lights, caution lights and gauge indications.

The Crew sought and got technical assistance from their Operations. There was a back and forth discussion of some sort regarding the indications, possible causes, and options to be considered in the wake of those indications.

Thus the Crew did not act independently. That rules out Cockpit Error in my view. The Crew exercised good CRM as evidenced by taking action to descend then report the problem. It appears they consulted their Emergency Checklist, and at least initiated the proper response as indicated by the immediate descent and reduction in airspeed. They sought the counsel of their Operations and Engineering staff who provided what guidance they thought right.

That brings us to Operational Error.

If we define this to be a systemic error and not a Pilot or Crew Error and one that involves other individuals from the system including Engineering and Flight Operations then perhaps this is the category we should begin to call this accident.

Plainly Human Error played a role....a very large role in this accident.

The substantial risk of the failure of the Oil Filter Bowl retention studs was under estimated by a host of people and organizations. Perhaps the Emergency Procedures in place at the time did not adequately address the situation the crew encountered and management decisions did not effectively deal with the situation before the flight and during the actual emergency itself. If the crew had not made contact with their Operations Office, would they have been more likely to have landed the aircraft and thus avoided the result of that effort to continue flying?

Others have mentioned the NASA experiences with the loss of two Shuttles and the near loss of a third. We could add the loss of three astronauts in a launch pad fire when the capsule used an oxygen enriched atmosphere.

Was this crew not in the same situation as the astronauts aboard the shuttles? Were they not as much Victims as were the passengers?

They were professionals in the true sense of the word.

[chester2005]

SAS Let me play devil's advocate for a second,

If an aircraft manufacturer says do XYZ if ABC happens

AND

An aircraft operator does not do such XYZ, regardless of reasoning

Surely this will be deemed as "contributory negligence "
and therefore Pilot Error

Just looking at it as the Lawyers for the insurance companies will!!

Chester:ok:

[Aser]

Great post Sas, :D:D:D
Our worst enemy is ourselves when we forget we are just a piece in the system.

Regards
Aser

[Aser]

chester2005 SAS Let me play devil's advocate for a second,

If an aircraft manufacturer says do XYZ if ABC happens

AND

An aircraft operator does not do such XYZ, regardless of reasoning

Surely this will be deemed as "contributory negligence "
and therefore Pilot Error

Just looking at it as the Lawyers for the insurance companies will!!

Chester

Well , we can start by showing the lawyers Sikorsky propaganda about run-dry...

Just came to my mind that a long time ago when discussing run-dry(or other kind of tests) info, I recall someone arguing that info is better not to be known, I thought that was stupid but today I'm not so sure...

Regards
Aser

[SASless]

Chester,

Read the post carefully.

Pilot Error is when you the pilot kill a perfectly good aircraft.....one that is completely serviceable.

Cockpit Error means you contributed to the outcome by making a mistake (and I construe that to mean independently of outside involvement).

Operational Error....means you had outside help in making the error.

Human Errors are normal....they happen every day on every flight. They don't necessarily have a bad outcome. Ever miss a radio call and have to be spoke to a second time before you hear the call? Ever dial up a wrong frequency and catch yourself? Ever punch the wrong start button and think what a buffoon you are?

The Human Errors I see in this Cougar thing are some that did not get caught and wound up with a bad outcome.

The investigation should dig into every one of them along with coming up with the technical description of what broke on the aircraft and merely detailing the direct immediate actions of the crew.

Every factor that can be identified as a contributing factor should be examined to determine how it occurred and how it can be prevented from occurring again. The key is fixing what is broke before it can strke down another crew and load of passengers.

Look at the Night Offshore Approach thread.....and DB's effort to improve night flying techniques and procedures industry wide. That is the exact right response to the Bond CFIT accident. He has us all re-thinking our mindset re night flying offshore. That is a good thing!

Let's do the same with the Cougar tragedy so we can keep something like this happening again.

We need to rethink our attitudes towards gearbox failures, certification tests and standards, communication of defect reports and ensuring proper action is taken in a most timely manner. We need to review industry wide the way we train pilots, formulate emergency procedures, structure response plans, and monitor engineering standards for effective levels of safety review.

What if we find out Cougar had those very steel studs on the shelf in anticipation of an upcoming scheduled inspection and all this could have been prevented by merely installing them upon receipt? That is the kind of review we are talking about.....looking at every facet of this accident to see how the Human decision making process allowed this to happen.

This is not finger pointing....or laying blame....just being honest with ourselves on how we really do business and comparing it to how we should be doing business.

I did not know any of these folks but I have known way too many of them in the past and that is what makes me speak out as I do when these things happen.

[chester2005]

SAS I can't disagree with you on the points you raise but i am quite pragmatic and maybe a little cynical and i did say i was only playing devil's advocate.

The possibility remains that because the pilots did not follow the manufacturer's recommendations regarding this type of event i'm reasonably confident that with the right lawyer "spin" the crew will be blamed for this, at least in some way.

I don't agree with it but i am a realist and i'll be surprised if any opportunity is not fully exploited to lessen the bad PR effect this incident has on the manufacturer.

But as i said SAS i agree with you and your cause.

Chester:ok:

[What-ho Squiffy!]

Good post SASless.

But...the lawyers will ask:
"...given the same aircraft fault, was there any way a crew could have operated this aircraft to avoid the catastophic crash?"

It may not be pilot error per se.

And IF there was an "ideal sequence of events" that could have been carried out by a crew in order to avoid the eventual crash, it comes down to the degree by which this operating crew deviated from the "ideal sequence of events".

If the majority of reasonable pilots would have largely mirrored the actions of the crash crew, they should be vindicated. If the majority of resonable pilots would have done something differently, then there may be a case to answer.

It's a tough one, but ultimately the aim should be not punishment of crews, but improvement in the way things are done.

[Geoffersincornwall]

If I understand things correctly the test is carried out by running an otherwise perfect MGB on the test-bed with a fully functioning lubrication system and then stopping everything whilst the oil is drained. The test is then re-started with representative loads equal to something close to normal flight.

It is important to understand that this test is therefore one designed to experiment with a MGB that has simply lost all the oil and is otherwise undamaged.

When contructing training scenarios in the simulator I try to add a realsitic context, one that recreates the real world where you the pilot DO NOT KNOW WHAT IS GOING ON BACK THERE. You have a MGB with sensors and these, plus your eyes and ears are what guides your response.

If I have learnt anything over the years it's that the RFM is written by experts but is not read by the aircraft. The experts largely second-guess the failure modes expected based on their experience and their knowledge of the system design. There will always be failure modes that were not thought of by the experts and we, the trainers, must teach a more generic approach to this possibility thereby extracting, in the process, the very best CRM from the trainees. At the very least you come away from such exercises with an greater understanding of where the Emergency Checklist stands in the scheme of things.

Malfunctions and failures cannot be ordered up like a 'Burger-Meal-Suoer-Size-To-Go'. Many many malfunctions that I have experienced or read about are NOT per the text-book, were never contemplated.

Knowing that and with a streak of self preservation the obvious course of action if anything threatens your ability to stay airborne is to get on the surface. If the waters are rough and colour your decision making then we MUST look at THIS aspect of the equation and ask ourselves if we have it right yet. Was the survival equipment as good as it can reasonably be expected to be. Was the aircraft flying over a sea-state beyond the certification standards? How can we make a controlled landing on the water in adverse conditions as safe as possible so that the obvious decision to 'land immediately' can be taken without, or at least with as little fear as possible.

I bet the clothing worn underneath survival suits will henceforth be appropriate if it wasn't before and if it wasn't adequate why was that situation allowed to be?

I attended a Shell sponsored safety seminar many years back at which the head of IFALPA said "Ladies and gentlemen - we need accidents.......". He went on to explain that managements the world over only focus their attention and often only allocate additional resources when they are in that post-accident traumatised state. We may need that attention, may need those resources if we find there are things that need fixing, things that need further research or equipment that has to be bought. I hope that between them those associated with this unfortunate accident can find the resources to make improvements to the aircraft, to the safety equipment and to the protocols and procedures related to avoiding a repetition in the future.

G

[212man]

If I understand things correctly the test is carried out by running an otherwise perfect MGB on the test-bed with a fully functioning lubrication system and then stopping everything whilst the oil is drained. The test is then re-started with representative loads equal to something close to normal flight.


That's not quite right - this is how 29-2C describes the process:

(1) Section 29.927(c) prescribes a test which is intended to demonstrate that no hazardous failure or malfunction will occur in the event of a major rotor drive system lubrication failure. The lubrication failure should not impair the ability of the crew to continue safe operation of Category A rotorcraft for at least 30 minutes after perception of the failure by the flight crew. For Category B rotorcraft, safe operation under autorotative conditions should continue for at least 15 minutes. Near the completion of the lubrication failure test, an input torque should be applied for 15 seconds to simulate a minimum power landing following autorotation. Some damage to rotor drive system components is acceptable after completion of the lubrication system testing. The lubrication system failure modes of interest are usually limited to failure of bearings, gears, splines, clutches, etc., of pressure lubricated transmissions and/or gearboxes. A bench test (transmission test rig) is commonly used to demonstrate compliance with this
rule. Since this is a test of the capability of the residual oil in the ransmission to provide limited lubrication, a critical entry condition for the test should be established. The transmission lubricating oil should be drained while the transmission is operating at maximum normal speed and nominal cruise torque (reacted as appropriate at the main mast and tail rotor output quills). A vertical load should be applied at the mast, equal to the gross weight of the rotorcraft at 1g, and the lubricant should be at the maximum temperature limit. Upon illumination of the low oil pressure warning required by § 29.1305, reduce the input torque for Category A rotorcraft to the minimum torque necessary to sustain flight at the maximum gross weight and the most efficient flight conditions. To complete the test, apply an input torque to the transmission for approximately 25 seconds to simulate an autorotation. The last 10 seconds (of the 25 seconds) should be at the torque required for a minimum power landing. A successful demonstration may involve limited damage to the transmission, provided it is determined that the autorotative capabilities of the rotorcraft were not significantly impaired. For Category B rotorcraft, upon illumination of the low oil pressure warning light, reduce the input torque to simulate an autorotation and continue transmission operation for 15 minutes. To complete the test, apply an input torque to the transmission for approximately 15 seconds to simulate a minimum power anding. A successful demonstration may involve limited damage to the transmission provided it is determined that the autorotative capabilities of the rotorcraft were not significantly impaired. If compliance with Category A requirements is demonstrated, Category B requirements will have been met.

[Geoffersincornwall]

Many thanks for adding that detail. Fascinating as it may be the point I was making is that the test seeks to second guess the failure mode which, as we can see does not entertain any other internal damage or maybe oil contamination that may shorten bearing life or vibration which may exacerbate the possibility of gear teeth fracture.

I'm not trying to create an inventory of failure modes but simply saying that we as flight crew are not well placed to understand the exact nature of a failure when we are given some simple information via Ts and Ps and possibly accelerometers and chip detectors.

My gut feel is that we should find somewhere to put down anytime we doubt the airworthiness of the machine. This would typically be because of a fire hazard, hydraulic problems or transmission problems. Clearly we don't want to throw the aircraft into the water at the first sign of a malfunction because the chances of it ever flying again are slim but that said I would rather be embarrassed than dead. The SAR 332L2 in NL last year (or was it the year before?) is a case in point. Who cares about the airframe when everybody gets back alive. If a bunch of machines end up in Davy Jones's Locker then maybe the insurance companies will have something to say about it and we will be forced to improve things. What worries me is the angst caused by the survivability issues surrounding a ditching. We somehow have to make it a more attractive option. I can’t imagine that the Canadian crew of this S92a would have turned down the safety of a Liferaft if they had considered it a safer option.

G.

[Special 25]

Is it not the case however that the S-92 was never proven to meet these requirements ? I'm sure that was the original plan, but when testing proved that it didn't meet the spec, they were able to certify the aircraft without the dry running ability under the 'Unless such failures are extremely remote" loophole.

So whilst these definitions are clear and seemingly well thought out, the S-92 was able to get certified without meeting them.

[Beaucoup Movement]

Has anyone heard any information on the sole survivor (robert decker) & whether or not he has spoken?

regards,

BM

[NorthSeaTiger]

They are saying he has "turned the corner" and has had surgery for broken vertibrais in his back. From the news story on the link he has spoken to family and doctors and will hopefully be fit for interview at the end of the week but is still fighting serious injuries.

NST

Sole survivor may soon provide chopper crash answers: RCMP (http://www.cbc.ca/canada/newfoundland-labrador/story/2009/03/16/sole-survivor-rcmo.html)

[Pilot DAR]

It has occurred to me, and was the subject of a recent discussion I had with a recently retired jet fighter pilot, that our civilian training lacks something, which I think must be core in military training: The concept that the flying machine is paid for, who cares, save the people. This closely corresponds to; okay, I was flying one second ago, now I'm riding, I don't like it - eject! And you're out of there...

During a discussion on another thread, I offered that I doubt that I could get my head around the concept of the ballistic parachutes found on a few GA airplanes, and when to use it. Nothing in my training has ever addressed the concept of "give up flying now, and pull this handle". I've always been trained, and practiced, making the best of things, and aiming for a suitable landing area, and trying to save everything. The spectre of being harder to insure as a pilot in the future plays into this.

The difference being the concept of "save youself, forget the machine" Civilian operators really don't highlight this as much as the military - cost of crew training relative to cost of machine, I suppose. It was a shock for me a year ago, during specialized marine training, while standing at the dock, to be told by the instructor "drive it like you stole it, you don't have to pay for it, no matter what happens". You don't ever hear that on a civilian flight line! The training environment was much more relaxed, and I didn't ding the boat!

Our industry will help itself, if we draw together the currently distant elements of a machine which will really tell the pilots "okay, this is it, I'm drawing my last breath one way or the other, save yourselves now"; and pilot training which includes more reassurance that when you get that message, the boss, and insurance company, agree that the flight crew are no longer resonsible for the machine - only the people - do what you've gotta do!

In today's information age, why don't pilots have a suscinct summary of a lot of information? Instead of a chip light, and a low pressure indication, and a high oil temp indication, why does the pilot not get a message (like the soft voiced british lady some where in the spacecraft of all of those Sci-Fi movies), which urgently says: "Land now regardless of the surface under you. I'm watching 10 chip sensors, 8 temperatures, 4 pressures, 2 smoke detectors, and three torques in the main rotor transmission. 82% of the indications are outside the prescribed limits, and you should expect that the rotor will not be turning 115 seconds from now. Land now regardless of the surface under you." Once that message was written on the EFIS, and spoken to the CVR, the pilots would know that they were off the hook for the machine.

Our industry needs to take the pressure off the pilot for deciding that a flight must end before they planned it to, and include the concept that "abandon flight " is also worthy of pride.

Pilot DAR

[SASless]

As an back in my younger days on the Chinook in Uncle's Army....I had the good fortune to have been around some old helicopter pilots. One of the things we espoused was the aircraft was merely a re-usable container much akin to a metal shipping container that engines or other large components arrived in from the depot.

We taught the contents of that expendable container was what was important....and not the container.

As a civilian pilot it is the same.

Either the owner has insurance or he best have some deep pockets as the concept is the same. The boss fellah can buy you another helicopter but he cannot replace your life and limbs.

The only concern you should have for the aircraft is not using it up for no good reason.....but when you need to....save your hide first and worry about the helicopter after the fact.

[chester2005]

I was always told " any landing/ditching you can walk away from is a good one, If the aircraft can be reused as well it's a great one!!!"

If we all practised it to the letter there would probably be less machines to fly but more pilots and pax alive.

Chester:ok:

[JimL]

I’m not sure that it serves any useful purpose trying to pin the tail on the donkey in seeking a single cause to this accident. Perhaps we should move away from the use of human error and towards the less pointed human factors. The primary cause of this accident appears to be a mechanical failure; to establish all secondary causes requires that we look back and try to understand why the previous incident did not ‘raise the hackles’ and why it was felt that there was ‘room to manoeuvre’ after the first stud failure last year.

It is clear that the precursors to this accident had already been seen; on July 3rd last year malabo hinted at a transmission problem in Australia; Heli-kiwi then indicated a failure of oil filter studs; Malabo and Heli-kiwi traded quips until, after being pressed by NorthSeaTiger, Heli-kiwi gave us the essential information Day before yesterday an S92 was onroute to Broome on a return flight from an offshore rig when a main Txmsm low oil pressure was noted, shortly afterwards remaining oil pressure ceased completely and a fairly rapid decent was carried out. From time of intial low px indication at 6000ft to touchdown was 8 minutes. The oil filter housing which apparently has 3 studs fastening it to the txmsn was hanging on by one which hadn't broken and most of the oil had been pumped out. Following this report, the thread meandered on but was more engaged by the incident of a pump failure than the fact that we had seen an extremely serious incident caused by a major failure of the MGB assembly.

Within hours, it was known that all MGB oil had been lost through the filter bowl assembly. Shortly after that, it was also known that this was caused by the failure of the titanium studs. As was pointed out in an earlier post, we now had a failure mode which had not been considered during certification. In fact it must have been known quite soon after the inspection that, without a change of material for the studs, another failure was foreseeable with a likelihood of reasonably probable. Such a conclusion (if recognised, and it is not clear that it was) should have triggered a hazard analysis which should have impacted, in turn, the manufacturer, the regulator and the operator.

The manufacturer and the regulator should have conducted an assessment of whether the aircraft should be grounded until the titanium studs were replaced, against the likelihood of another failure. The fact that the aircraft was not grounded and, in the letter to operators in January, it was still not felt necessary permitting, instead, another 1250hrs or 12 months for replacement is not easily understood (in hindsight). Even with a 30 minute run-dry capability this would appear too relaxed. However, having made those decisions, all operators should have been brought into the decision making process because it was them, and their customers, who were now to take the front-line risk.

At the very least, the results of the investigation of the Broome incident should have been promulgated to all operators so that they could educate/inform their pilots, so that the likelihood and consequence of such a failure would be foremost in the minds. More, the whole notion of a 30 minute run-dry time for gearbox should have been debunked and the necessity, regardless of environment, of a ‘land immediately’ in any case of a loss of oil pressure reiterated. In view of the fact that data had been collected during the Broome incident, it would also have been possible to put the sequence of events and cockpit indications into a file, and distributed for the purpose of demonstrating the symptoms and indications.

This leads to the questions:

(1) Was the probability of another stud failure established?

(2) Was the probability of this event put to the regulator?

(3) Did the regulator accept that nothing need be done until the new stud had been sourced?

(4) When the new stud was sourced, was the rectification interval accepted by the regulator?

(5) Were the operators informed of the Broome event and the probability of another until such time as the studs had been replaced?

(6) If the operators were made aware of the situation, did they risk assess their procedures with the aim of minimising the consequences of a failure?

(7) were the operational and training departments aware of the probability of failures and did they place appropriate focus on the required actions?

The main difference between the first incident and the Cougar accident is the action of the crew following the manifestation of the same emergency. We can only speculate on why there were differences in reaction but it is probable that it was due to the operational environment: in Australia, the aircraft had coasted in and was over land; in Canada, the aircraft was over Sea State 5 and a water temperature of just above zero. Regardless of this, had the sequence of actions shown above been put into place, this accident might have been another (however, more serious) incident.

Anyone who reads this (and the S92) thread now knows that ‘land immediately’ provides no leeway. It should never have been in doubt; it might not have been if we had learnt the lessons from the Broome incident and paid less heed to those for whom such rules/procedures are seen as a challenge to their intellect.

[Pilot DAR]

Good post JimL...

[SASless]

JimL,

You are saying exactly what I have been for the past week or so.

My question to you is a bit more direct.

Why is it incumbent for someone outside the "Regulator" supposed to raise an issue.....don't the Regulators have a responsibility to monitor events as they happen and question both operators and manufacturers?

You use the singular...."Regulator" and not the plural....."Regulators".

Why did the situation you so correctly describe escape action by the Australian, American, British, and Canadian Regulators?

Why did this situation get by the Operators?

Why did this situation get by Sikorsky?

Who in the hell is supposed to be looking ahead amongst all those groups?

My answer.....every one of them!

Yet, not one person, regulator, or operator saw need to raise the flag!

There is no excuse for such a thing to happen in this day and time with all the studies, concepts, procedures, reporting venues, and communication capability we have at hand to identify such issues.

What is going to happen now.....the Regulators going to step up to the plate and admit their failure?

Will the Operators step up and admit their failure?

Will Sikorsky own up to its failure?

Or will we see the Regulators point their fingers at someone else, the Operators slink off into the bushes and hire some high dollar lawyers, and Sikorsky do the same?

I suggest there ought to be some Government Employment vacancies crop up very soon for a start. Operators need to do their soul searching as well.

Needless to say....Sikorsky is going to be given lots of assistance in finding their faults in this.

[outhouse]

Hi SaSSless
Can’t resist coming back re your post. I have one simple statement that I have used over many years seeing unfortunately continued failings in areas that should have been Red flagged. “Hindsight is a great leveller”
The ownership of this particular failing is as we know complex, will any one entity admit, answer NO, will lessons be learnt and improvements to the system be effective, unfortunately I suspect NO. Will the lobby of big business and company interests continue to have the influence they now have, answer YES.
I stand to be pilloried I know, but after over 40 odd years in the industry and seeing the so called advances in the legislation that supposedly was developed to protect, prevent and safe guard operation of helicopters the crew and passengers from predictable failings, we still see repeated events like the one in question.
At least when I started we knew the risk, the failings and lightly cause of a dramatic and spectacular meeting with our maker.
We did not have the illusion that the system gave a measure of protection; we had no WWW and the unfortunate risk of misinformation that could affect critical decisions. My own indicator was an Itch in by neck and it never let me down.
There are only old aviators; the bold seem to fade away.
Back into retirement.
Outhouse.
:ok:

[Pilot DAR]

Outhouse,

Hopefully, I can put a little reassurance back into "the system" for you...

unfortunately I suspect NO. Will the lobby of big business and company interests continue to have the influence they now have, answer YES.


I am a regulator (though nothing whatever to do with FAA, Sikorsky, or Cougar Helicopters). I am learning from this event, and will do better in the future because of it. It can be hard for a "little guy" to stand up to big business, but at the end of the day, they're asking for my signature on a recommedation for desgin approval, and I'll only sign, when I can see that compliance HAS been demonstrated, as the standard intends. Sometimes the wording of the standards are somewhat ambiguous. "Interpretation" can be a problem, though I cannot imagine how in this case!

As long as each "little guy" in the system does his or her job properly, the system works pretty well. I assure you that as every item of compliance requires the signature of a duly appointed person against it, before approval will be issued.

Everything our industry depends upon people doing their best for the next guy down the line. An "event" can serve well to remind us of how that obligation is so important...

Pilot DAR

[ericferret]

The FAA TCDS (type certificate data sheet) is a good source of performance information and in the case of the S92 there is no mention of a run dry capability. I would have assumed that if so certified then it would have warranted a line.

What it does say is (the capitals are theirs not mine).


THE HELICOPTER MUST BE OPERATED IN ACCORDANCE WITH THE OPERATING LIMITATIONS SPECIFIED IN THE FAA APPROVED ROTORCRAFT FLIGHT MANUAL.

No mention of operating it in accordance with the manufacturers sales blurb.

I am truly grateful that I have never found myself in a similar situation to this. The man who thought of the expression caught betwen a rock and a hard place must have had this crew in mind.

[widgeon]

Actually between the rock and a hard place would be ideal to describe their predicamant.

[Reflex]

As Outhouse very aptly stated - Hindsight is a wonderful thing.
I was in Aberdeen when the inclined driveshaft hinge pin fell out of TIGD (332L) on short finals for the runway.
The very same failure had happened on at least one 330J Puma and the design on that had been changed - why did the 'bad' design reappear on the newer machine?
As it was the aircraft ended up on it's side but if this had come about earlier in the flight, who knows what the outcome would have been.

[500e]

PD good post, glad you will stand up and be counted.
The 30 minute claim?? in the sales literature is very loose wording leaving you to make of it what you will.
.EF reminds us of the TCDS and says no mention of run dry yet there is a caption on sales literature pointing strongly in that direction, it would be in the back of my mind that things were not as bad as they seem.
S25s post
"Is it not the case however that the S-92 was never proven to meet these requirements ? I'm sure that was the original plan, but when testing proved that it didn't meet the spec, they were able to certify the aircraft without the dry running ability under the 'Unless such failures are extremely remote" loophole. ( there is either a requirement or not ) & as it failed to meet the requirement surely the failure in not a remote possibility
So whilst these definitions are clear and seemingly well thought out, the S-92 was able to get certified without meeting them. ".

[maxwelg2]

Perhaps the sales literature was referring to an oil cooler leak that could be isolated with the bypass switch, thus allowing continued operation for at least 30 minutes. A previous post indicated that two and a half hours had elapsed on the test machine, which obviously was not a FAR29 category "A" test. Hence no mention in the FAA TCDS...I'm quite sure that no pilot worth his salt would ever put too much faith in a manufacturer's sales pitch.

From what I've read in previous posts the RFM states land immediately on MGB pressure < 5 psi and that's what should have happened had the guys had enough time to execute that manouvere. I suspect that the MGB temp went to ambient when the guys were dropping to 800 feet as there was no lube oil to wet the sensor, they checked with flight ops and they said "probably a faulty MGB press sensor, bring it back to the hanger", the guys went to 133 knots and didn't know anything else was amiss until the pressure went to zero and the MBG failed along with the inputs for the AC gens, with not enough time to active the APU and/or arm the flotation bags (couldn't happen anyway as they were > 80 knots) hence the FDR/CVR switching off and the flotation bags not being released on water contact. This is only supposition but I can see how this hypothetical sequence of events would make sense.

Robert Decker, the sole survivor of flight 491, is now recuperating at home, and will hopefully shed some light into the actual events of the last few fatal minutes. I'm sure the TSB will glean more data from the remaining avionics components that are still being analysed by the specialists.

[SASless]

I believe this is the up to date Emergency Procedure that would have been reviewed by the Crew and the Cougar Ops folks during the conversation they held by radio during the descent to 800 feet.

I have added the bold print and underlining.

Do you 92 drivers out there concur in this is the procedure you have been taught and are expected to conform to by your operator?




MAIN GEARBOX OIL SYSTEM FAILURE

Symptom:
MGB OIL PRES or MGB OIL HOT or MGB CHIP or ACC 1 CHIP or ACC 2 CHIP or MGB OIL PRES

GEARBOX OIL PRESSURE aural alert.

Confirming:


NOTE
The confirming steps only apply to low oil pressure or high oil
temperature.

There are no confirming steps for chip indications.

Symptom:

Main gearbox oil pressure is less than 35 psi
or
Main gearbox oil temperature is greater than 130 degrees.

WARNING

BYP must be selected within 5 seconds after the MGB OIL
PRES warning has illuminated to ensure an adequate
quantity of oil remains in the gearbox.

DO NOT activate BYP
if the warning is not illuminated.


CAUTION

When the MGB BYP mode is activated by the crew, the MGB
oil temperature will increase. The temperature is expected to
increase into the red operational range, this indication
should not be considered a secondary indication for
determination of landing immediately.

CAUTION

The main AC generators are cooled by main gearbox oil. Loss
of cooling oil may result in mechanical failure of the generators
and loss of main electrical power.

NOTE

The MGB BYPASS caution will illuminate when BYP is selected. As
the MGB oil pressure stabilizes, the switch should be left in the BYP
position. The MGB BYPASS caution and MGB OIL PRES warning
will remain on until the rotor is shut down after landing.


NOTE

After MGB bypass switch is activated, MGB oil pressure should
stabilize or fluctuate in the range of 5 to 25 psi. Gearbox temperature
will slowly increase into the red zone.


NOTE

Either a massive main gearbox oil leak or the failure of a main gearbox
oil pump may cause the MGB OIL PRES warning light to illuminate.


NOTE

If the MGB OIL PRES warning illuminates, the MGB OIL PRES
caution will not be illuminated.

Action:

1. MGB OIL BYP - Select BYP only if the red MGB OIL PRES warning illuminates.
2. Descend to minimum safe altitude.
3. APU CTRL — ON.
4. APU GEN — ON.
5. Land as soon as possible.

If the MGB OIL PRES warning or the MGB OIL PRES caution and any of the following secondary indications of gearbox
failure are observed:

MGB oil pressure below 5 psi
Smoke or fumes in the cabin
Any subsequent hydraulic system failure
Progressively increasing power required to maintain flight
Unusual vibrations or noises.

6. Land immediately.

[Variable Load]

That's what the RFM states, so should be what the other operators have as well.

Just one comment on layout - I don't think it is a good idea to have so many notes, comments and warnings before you reach the actual emergency drill. Do the drill, then read the essay! Maybe that will be something Cougar will change in the near future?


VL

[212man]

VL,
that is the RFM I would suggest, not the Cougar Checklist.

Other 92 pilots, note that the 5-25 psi referred to here:

After MGB bypass switch is activated, MGB oil pressure should
stabilize or fluctuate in the range of 5 to 25 psi

will not be the case for a single pump failure, where 5-7psi can be expected with the current configuration.

[Variable Load]

212man, I was right then, when I said:

That's what the RFM states :rolleyes:

Thanks :ok: I read something into SASless's post that wasn't there :uhoh:

[Geoffersincornwall]

Looks like the designer(s) of the MGB and ancilliaries will not be getting an Oscar any day soon. It's interesting that the physical integrity of the AC gens should be dependent on the MGB oil supply.

If one takes the view that 'no oil then no AC is not your biggest problem' then maybe you can hold that up to the certification body as a reasonable analysis but if you then go on to create secondary situations with continued flight being possible with reduced flow then other, nastier, failure modes come into focus.

The only time I have had to deal with a fire in the air was on an S61 when one of the AC gens seized, the quill shaft did not break but instead ripped the AC Gen away from the gearbox and set fire to surrounding trunking and oil soaked cowlings. The only warning we got was an AC gen fail but fortunately we were on final approach when it happened. We ground taxied into dispersal oblivious of the situation until the ground crew started jumping up and down like demented go-go dancers. I hate to think what would have happened if the problem had surfaced on hour earlier over the mountains of Croatia.

Apart from reinforcing my assertion that we should not only teach malfunctions and emergencies according to the RFM but also develop generic solutions for those malfunctions that are not listed therein. We would not have found 'Transmission Deck Fire' in the S61 RFM although maybe after the Lee SAR incident it is now included.


Checklists

The degree to which the S92a checklist is being picked apart by us PPruners is an indication of the extent to which they will be reviewed by the lawyers.

We are faced with a dilemma with checklists insofar as for legal certainty they must derive from the RFM. The basic RFM covers the basic aircraft - no optional equipment is allowed for. To generate a checklist that will work properly with any particular configuration you are left to your own devices to coble together your interpretation of the inputs from maybe up to a dozen RFM Supplements. Where do you stand then? I don't know for sure is the simple answer.

What has worked in the past is that your company Operations Manual (if you are lucky enough to have one) will publish a version of the checklist that you have created and if the OM is then reviewed by the NAA and 'accepted' as meeting their requirements then you are at least in a strong situation.

Ideally the OM will contain the 'Expanded Checklist' with all the notes and cautions but the cockpit checklist needs to be a practical document that contains the minimum information required by a fully trained crew. My experience is that unworkable checklists are set aside in favour of the 'memorised' kind. Emergency Checklists may need some of the notes and cautions but the design and layout - as has been mentioned in a previous post - are critical to the effective use of them. One new type has an Emergency Drill for Hyd Fail with the No. 1 System on the right of the page and the No. 2 on the left of the page. This is completely counter intuitive and I have seen non-English speakers read out the wrong drill (oh dear - I have given the game away!). It's not the only editorial glitch that can add to your problems rather than reduce them but we're working on it.

G.

[212man]

We would not have found 'Transmission Deck Fire' in the S61 RFM although maybe after the Lee SAR incident it is now included

Geoff, as you know, nothing is new in aviation.....

http://www.aaib.gov.uk/sites/aaib/cms_resources/3-1990%20G-BEID.pdf

For those who are such ardent 61 supporters, and for another taste of life in the 70s and 80s, here's another one that happened 4 months later:

http://www.aaib.gov.uk/sites/aaib/cms_resources/1-1990%20G-BDES.pdf

I think that although both are unrelated failure modes, they illustrate the sorts of timescales we may be faced with in these kinds of emergencies, and that in reality these kinds of failures do not lend themselves well to emergency checklists....:(

[Geoffersincornwall]

You have hit the nail on the head. If we ONLY cover text book emergencies during sim training we run the risk of creating a generation incapable of thinking outside the box.

Thank God for LOFT where opportunities are available for developing decision making skills in a safe environment.

G

PS. - Have just read a bit of those two accident reports. I feel even more justified in asserting the need for developing CRM skills capable of dealing with these random failures. Case studies such as the two reports 212 has attached to his post are ideal material. I am puzzled by a lack of response to my suggestion that the ocean should be made a place of safe-haven either by lmiting the sea state for normal ops and/or improving the ability to get out of the downed helicopter and into the liferaft.

[JimL]

Geoff,

With regard to your first point; yes, but not such that existing drills can be seen as flexible.

For your second point; read the following paper which resulted from many years of research into just that subject and which was published because of: (a) the resistance to further modification of the requirements by other Authorities; and (b) the perception that the CAA no longer had the legal competence to propose rule changes and wished to pass its knowledge and recommendations to one that had - i.e. EASA.

http://www.caa.co.uk/docs/33/2005_06.PDF

I had close knowledge of the referenced paper in Appendix F because I Chaired the committee that researched and produced it.

Jim

Jim

[Geoffersincornwall]

I take your point vis a vis the established emergency protocols and would not seek to replace them but merely to give them a context. As experience with a new type grows we know that a greater understanding of the machine and its foibles will follow. I have learnt to be sceptical about text book failures and I think it is a healthy scepticism but ignoring the RFM would be throwing the baby out with the bathwater.

Will read your paper as soon as I get a quiet moment.

G

PS - I don't suppose you have an electronic copy of the HARP Report only I wanted to refresh my memory on the paragraph that highlighted the fact that gearboxes were a severe weakpoint of the (then) current designs - just before the authorities went on to certify the Boeing 234 which had 5 gearboxes in a drive train in which the failure of any one would have resulted in the total loss of the aircraft - which happened - killed 40+ people and resulted in the only time people-power has casused the withdrawal of a machine from offshore use....... in UK anyway. Makes you wonder about joined-up regulation doesn't it.

[Aser]

About the weather minima...
I don't agree but here is it:
Regulatory authorities
recognise that ditchings and crashes, though rare, do occur from time to time, and for
this reason require operators to provide a comprehensive range of safety equipment,
procedures and training. However, there are occasions when weather conditions in
offshore areas are such that a safe ditching would be impossible, survival time in the
sea would be very much reduced, and rescue would be extremely difficult or
impossible. If the safety provisions are necessary under normal conditions, it is illogical
to permit flights to take place in conditions such that they would be of no avail.
Therefore, it has been argued, flights should be prohibited in conditions that preclude
a safe ditching or would not allow survivors to be rescued.

3 The counter-argument runs as follows. There is an element of risk in all forms of
transport, but it is considered ‘safe’ when the risk is assessed as being at an acceptably
low level; occasional accidents, tragic though they are, do not invalidate this policy
unless they occur at a frequency that discredits the original risk calculations. Fixedwing
public transport flights take place globally over oceanic and mountainous areas
which would not permit a safe ditching or forced landing. Similarly, Group A public
transport helicopters routinely fly without restriction over wooded and hilly terrain, in
cloud, and over countryside covered in dense fog, where a safe autorotational landing
could not be performed. Offshore helicopter operations are not radically different
from other forms of rotary-winged public transport; such extra risks as they do carry
(related to the hostile environment and the repeated exposure of individual
passengers) are already handsomely discounted by the provision of extra safety
equipment and training. Moreover, operations over rough seas are not necessarily
more dangerous than similar flights over land; for example, if the Cormorant Alpha
accident had occurred at an airport, it is most unlikely that anyone would have
survived the impact. It would therefore be perverse to apply any restrictions to
offshore flights that are not applied to other equivalent forms of public transport.
:sad:

Regards
Aser

[SASless]

Since we have raised several new questions and ideas about how to make things better....lets return to what brought us here at this thread.

We know there was a confirmation by the Crew they were seeing "Zero Oil Pressure" an reported to ATC while on descent to 800 feet.

We know they had a two way conversation with OPS and can only assume they relayed that situation during that conversation.

If we accept the fact they did in fact continue to see "zero" oil pressure we have to question why they did not carry out the actions dictated by the checklist.

"Zero" oil pressure is one of the confirming situations that kicks off the instruction to "Land Immediately".

If the decision was made because of confusing indications....say an oil pressure that was flucuating above 5 PSI then we might suspect they might see a way out of the situation. Given the choice of ditching or continuing to fly I am sure most of us would see any indication above 5 PSI in a postive light and probably discount the fact the majority of the indications were under 5 PSI. That might not be the smart view but when confronted with ditching or not we would probably want to avoid ditching.

If the decision was an improper diagnosis by them or someone in OPS that caused them to continue flight then that would be a tragedy but seems a remote possibility.

If the decision was to avoid ditching due to the sea state and the knowledge of how cold and rough the water was and they accepted they had a very serious gearbox problem but they or someone in OPS decided it was best to try for land then that raises more questions.

[FlyingHead]

Sorry to be picky SASless but according to the report published by CBC, zero pressure has been lost at 5740 feet not 800, which in my view highlight even more your questionning:

12:17:42 CHI advises Gander ACC that they have lost all main gearbox oil pressure. CHI91 is descending through an altitude of 5,740 feet.


Back of what you say I agree, and the following months will tell us a lot more.

FH

[JimL]

Geoff,

No I do not have an electronic copy of the HARP Report (CAP 491 - 1984) but, courtesy of Adobe Acrobat and OCR, here is section 7.7 - Gear box and Transmission:
The most complex element of a helicopter, after perhaps the engine, is the transmission gearbox, taking the drive at high speed from one, two or more engines generally in a horizontal plane, and gearing it down by 80 or 100 to 1, or so, to a single vertical shaft carrying the rotor head, with another drive going rearward to a tail rotor (or another rotor head system), the engines having free Wheels, and accessory drives being taken off for generators and oil pumps.

These gearboxes are remarkable examples of the art of the mechanical engineer. Although simplicity is a good starting point in the conceptual stage, complexity is inevitable, and it is not surprising that each designer has found his own solutions. The panel has seen spur gear trains, epicyclics, bevels; it has seen normal straight teeth, 'conformal' tooth profiles; it has seen ball bearings, rollers, tapered rollers, shafts with separate ball races and shafts with rollers running direct on them; we have seen aluminium and magnesium alloy cases. The only common element noted was in the gear material, a traditional low carbon nickel-chrome case hardening steel, either carburised or nitrided, and invariably made of high purity vacuum melted stock.

Notwithstanding the exceptional facilities for gear production we were shown, and the great attention to quality control being paid we are bound to record that in our view it will never be possible to eliminate completely the possibility of failure of some part of so complex a mechanism in service, between specified inspection or overhaul periods.

Although minor surface damage to a gear or bearing is unlikely to be instantly catastrophic, and should be detectable, and although gearboxes are tested to run for a period such as 30 minutes with the oil supply failed, the possibility of a major failure within the box is ever present.

Since with present knowledge a main rotor cannot be duplicated although a tail rotor gearbox might (conceivably a helicopter may survive the failure of the latter) we now come up against the fundamental difference between normal aircraft and rotorcraft -the inability to guard against a possible defect by duplication.

The Panel believes that, while gearbox development and testing should be as stringent as practicable, other means must be introduced to monitor the condition or "health" of the gearbox, preferably in flight. Elementary condition monitoring is already practiced (e.g. oil chip detectors), but much more attention should be paid to this. We make our detail recommendations on this subject later in para. 8.5.

There have been failures of transmission systems taking the drive to the tail rotor, or coupling twin rotor heads. We believe it may be possible to achieve a degree of redundancy here, or at any rate 'damage tolerance'. On the other hand it may be simpler to have some other method of cancelling main rotor torque to use in an emergency (bleed gas jet, rudder surface •••••• )
The text in paragraph 8.5 (referred to above) contains recommendations for 'condition monitoring'; methods include: chip detectors; vibration monitoring; thermal detection or imaging in flight; oil sampling; telemetry (i.e. instantaneous download of HUMS data); and usage monitoring.

Jim

[SASless]

Geoffers,

I will have to challenge your maths on Chinook gearboxes.

I will happily accept there are three gear
boxes that if failed will end in tears...those being the Forward, Aft, and Combining gear boxes.

The Nose Boxes....Engine Gear box to some....will cause a loss of engine power and depending upon which end of the drive shaft that connects the Nose Box to the Combining Transmission should fail....it could cause some interesting damage....but a Nose box failure in itself is not that critical.

I have experienced two Nose Box failures and am still here. Those failures were treated as a single engine failure. Both were benign events mechanically although one was a bit sporty due to the phase of flight we were in at the time.

I know of only one person who survived a main gear box failure and that was the survivor of the 234 Crash in the UK.

To put it into perspective....I know of no one that survived a spindle failure on 61's.

[Geoffersincornwall]

JimL

Thanks Jim, the last paragraph is prophetic (re the sync shafts in the 234) and my bleat was just a regurgitation of a long-standing gripe about the introduction into service of that particular aircraft which IMHO had just too many suspect design features, not least the gearboxes and the sync shaft.

I haven't met a Chinook pilot yet that didn't sing the praises of this amazingly capable 'war-machine' but I was never a fan of its presence in the civvy world. The trip from chip light to catastrophic failure seemed just a bit to quick for my liking.

SAS

It's been a long time since I discussed this design in detail, maybe 25 years, and at that time I believe we could not be assured that the angle gearbox would fail in a benign way. If you are telling me that now we different then I'll take your word. Unfortunately if any of the three remaining gearboxes seize then the machine will eat itself and kill all on board. The two that survived the accident in the NS are the exceptions that prove the rule I believe. Lady luck was with those two on that day that's for sure.

G.

[SASless]

The Chinook as every new design helicopter has its problems when first fielded.

The Chinook was no different and at one time the early "A" models had as many road miles on them as they did air miles due to being flown out to the field and towed back during their introduction during the 11th Air Assault days at Fort Benning, Georgia.

We moved on through some other problems that were solved in time and now we see the Chinook as the work horse it is and will be seeing them doing the deal well towards the end of this Century.

There was a great deal of politics and resistance to introduction of the 234 on the North Sea. Alan Bristow did not want to invest such amounts of money in so few aircraft with what appeared to be a limited use.

It is interesting to note every single one of the 234's flown on the North Sea are still earning their keep daily with Columbia Helicopters hauling heavy external loads, logging, and fire fighting, all which are much harder on the aircraft than carrying passengers offshore.

But then....Columbia geared up to sustain the aircraft and drew from the vast amount of experienced Chinook people from the US Army as well as their BV-107 experience.

You are right.....I loved flying the Chinook and did so in the worst of situations and the old girls always brought me home. They gave me a few white hairs sometimes but that gives me stories to tell!

[ericferret]

I seem to remember that a KLM S61 had a spindle failure resulting in the loss of a blade with everyone surviving. Happened shortly after touchdown on a rig!!!!!!!!!!!!!

In flight however would have a been a different story.

Just being picky!!!!

[leading edge]

Not quite all of them Sas. Probably 4 out of 6 (1 crash, 1 ditch).

Bristow actually ordered 5x BV234 if you remember then cancelled. Although there were many reasons for the cancellation, there was a genuine concern regarding transmission failure and its likely catastrophic effects with the then Engineering Director and Operations Director.

A letter or memo expressing the concern was written, can't remember who the recipients were, we are talking 1979-80 era, just before the announcement of the AS332L order. I once had a copy but its long since gone.

[SASless]

Helicopter Services in Norway had two within six months or so.....in flight with no survivors....timing is of the essence.

[Geoffersincornwall]

the 234 story

SAS - There was a lot of talk at the time about the CAA being put under pressure by both the oil company and the operator as well as the manufacturer. I remember being at a 234 presentation (I was at BCALH at the time) at which they showed a video of a large model in a test tank demonstrating wonderful integral bouyancy capabilities but also demonstrating that every passing wave struck the (stationary) blade out front. I asked the Boeing bod about blade strikes after ditching and he quickly glossed over the subject. I later found out that any such blade strike is likely to result in a sync-shaft failure quickly followed by disintegration of the fuselage as the blades enmeshed above it. "So much for bouyancy" I thought. I later met the CAA Test Pilot and asked him about that and he changed the subject. Maybe he had the same thoughts as me?

G

[SASless]

Geoffers,

I cannot speak to the presentation you saw but I do know that synch shaft is actually a lot stronger than imagined as related to blade strikes. Lord knows we chopped down enough trees, power poles, PSP revetments and the like. The blades suffered but I do not know of an event that caused the airframe to tear itself apart unless it was the forward blades sweeping down through the synch shaft area and as far as half way into the cabin.

Usually that occurred after the aircraft sat down on top of an underslung load after having an engine failure and not being able to clear the load before touching down.

I am aware of one event where a ground taxi accident wound up with the forward blades chopping a twelve inch or more wooden power pole into a fence post and the only damage was to the blades and the Flight Engineer's under wear as he was stood against the thing directing the pilot. The blades cut through the pole about a foot above his head (he was a very tall rascal).

I do know she makes a fine boat and in fact I had a radio call sign one time of "Shrimp Boat" while instructing at the "other CFS".

This aircraft had an engine failure and landed on the underslung load....one fatality....guy was standing up when it all went wrong.

http://www.geronimos.org/gergallery/Page_12/IMAG0007.GIF

The end result of an unplanned EOL after running the aircraft out of fuel.

http://www.chinook-helicopter.com/history/aircraft/B_Models/67-18462/67-18462_i.jpg

[Geoffersincornwall]

SAS

I once gave a presentation at which I explained why we had chosen the MD902 for the London HEMS role. Afterwards the EC(F) rep cornered me and asked why I thought the NOTAR a better bet than the fenestron. I explained that in the crowded streets of London the fenestron still represented a theoretical threat and the NOTAR did not. Why should I take that (small) risk? He didn't answer but disappeared into the audience with a large 'thought' bubble over his head.

In the end it's all about risk management and I don't believe we should take one extra risk if we don't have to.

G.

[Flyt3est]

One small point springs to mind, with regard to an earlier post regarding the crew of the Cougar cab noting abnormal indications, but no visible or audible signs such as vapour trails, smoke, flames or noises.

This, when coupled with a difference of opinions we used to have at the CAA HUMS users and North Sea operators gatherings, "Should HUMS data be displayed instantaneously in the cockpit?" JimL you will probably recall this, there was opposition to the displays because it was felt that the systems back then were not mature or reliable enough to provide definative data.. e.g. would a pilot ditch due to a displayed warning only? The general feeling back then from NS crews (About 5/6 years ago) was a resounding "no".. However, with modern aircraft such as S-92, where the old methods such as "noisy gearbox" etc MAY not be so evident to the crew, and given that HUMS and FDR data collection is now much more reliable and comprehensive, do we have a case for perhaps reviewing attitudes towards the onboard information and indications available to the crew? I concede that this fault most probably would not have been detectable via the HUMS / FDR but thats not to say that as in the case of the Dauphin main ring gear back in 2004, monitoring could be extended to cover new failure modes.

The arguments on here about commercial gains taking priority over safety remind me of a statement I once heard Eric Clark from Shell make..

"If you think flight safety is expensive, wait until you kill somebody"

[SASless]

Geoffers,

Just a thought but as long as we are thrashing all sorts of ideas around the place....how many critical gearboxes on the 332/225/92/365/76 aircraft?

I submit they have more than one each!

Would Main Rotor blades on these aircraft have a chance of impacting waves in Sea States Five or Six?

[Geoffersincornwall]

SAS

Regret I can't agree. If any of the three critical gearboxes on the 234 seize then you exit stage left in a hundred bits but if the tail or intermediate gearboxes fail on a single rotor machine you have a fighting chance of making it to the surface. We have seen examples of both of these failure modes in the NS.

As far as the blades hitting the water is concerned a single rotor machine with the pitching centre around the position of the rotor they are a lot less likely to hit the water in equal sea states. The problem for the 234 is that a sudden stop is likely to do for the sync shaft and then it eats itself. A sudden stop on a single rotor is likely to turn it upside down - which is why we have HUET.

G.

[mickinst]

Sorry if available elsewhere......Does anyone know the total airframe hours of the accident S92?

[212man]

Fly3Test,
good point, and quite topical as the CAA ahve recently released a Research Paper that looks at the possibility of in cockpit warning of impending blade failure.

[The Sultan]

212man and Fly3,

Data for the viability of HUMS crew alerts to have assisted decision making of the Cougar crew should be available from 212's event and the Australian event (yes I know they have different causes, though same result). This information eventually should be released in any AAIB level of thoroughness report. If HUMS gave valuable/actionable data which could have been used to avoid or mitigate those events in the future it will be reported in many technical papers.

Does anyone know if any information has been published or is going to be released soon?

The Sultan

[leading edge]

In these days of MFDs and minaturisation, surely a couple of small cameras (one on the pylon facing forward and one on the cowling facing backwards, even one on each sponson facing towards the rotorhead) would be easily achievable.

If I can have sat nav and TV in my car, it must be possible to play a camera image onto an MFD.

No argument about fire etc, it would all be visible from the cockpit at the flick of a switch.

As for HUMS alerts to the crew.....that is a very complicated subject. The risk of the wrong reaction to a spurious warning (it could just be a malfunctioning sensor) is a major concern. Personally, I wouldn't like to have it but I would like a camera.

[rotorknight]

If I can have sat nav and TV in my car, it must be possible to play a camera image onto an MFD.

As I have understood at work,sikorsky tried one but it vibrates so badly that you can't see anything(welcome in 2009:})

[Aser]

About TV cameras , you can order the AW139 with them installed, as an option.
:ok:

Regards
Aser

[JimL]

As Flyt3est has indicated, the HHMAG (a group which contained the world-wide great and good of the HUMS community - what a pity the advent of EASA caused its demise) discussed cockpit indication at length.

Because the issue was so complex and in view of the lack (at that time) of the required level of reliability, and the simplicity of the systems (events only - and even those provided on a heuristic basis) - a working group was tasked to consider it in detail. This group made a finding that, for the time being, cockpit indications would only complicate the life of the pilot - not simplify it. It also reiterated that the aim of HUMS was to spot developing faults, clusters and trends in time for them to be addressed on the ground and before they could impact upon a flight.

In common with others, I still have my doubts that cockpit indications provide the answer. Perhaps the problem is believing a primary indication that appears irrational and cannot be confirmed by some other means. It could be that, in these days of digital systems and software control, more effort is required in the provision of algorithms that provide (and indicate) secondary confirmation based upon alternative diagnosis paths.

In passing I must say I was amazed at the complexity of the S92 emergency checklist - surely this information could have been better presented in the form of a flow-chart (and this provided on some diagnostic screen with all paths shown and coloured appropriately).

Jim

[ericferret]

I seem to remember Super Pumas with "wing mirrors" fitted, Bond, Bristow or HS? Low tech but they gave the crew a view of the main box and engines.

[TipCap]

You are quite right about the "wing" mirrors on the Super Puma fleets but at one company we had to fight to get them on, even though the S61N's had them fitted, as they were seen to be causing drag.:hmm:

[SASless]

JimL,

n passing I must say I was amazed at the complexity of the S92 emergency checklist - surely this information could have been better presented in the form of a flow-chart (and this provided on some diagnostic screen with all paths shown and coloured appropriately).

Are you referring to the one I posted previously or the actual Sikorsky Checklist?

If you have access to a Bell 412 checklist you will see it is just as elaborate as the 92 checklist.

We have to remember the Factory Check List is written for all cases, generic operations, and thus will not necessarily be in the best layout for use in every cockpit.

Does not the CAA allow the operator to write their own version of the aircraft checklist?

The FAA in Part 135 requires the operator to do so. Most merely use the factory checklist but some operators do construct their own and submit it to the FAA for approval.

Probably the best checklist I ever used was the Bristow S-58T checklist we had in the mid-70's. The layout and content was excellent with both the Normal Procedures and Emergency Procedures contained in the same flip chart style document. When folded to the cover page....one either saw the Normal Section or turn the chart around and you had the Emergency Section and each had tabbed pages for the various procedures so you could locate what you were looking for with ease.

[USAFPAVEHAWKDRIVER]

S92 Mech,

What is the power source for the CVR and FDR? Is it powered by AC Primary Bus or DC primary bus receiving power only from main generators or APU? You may understand where I'm going here

Pave

[you want what??]

power for the CVR/FDR 1 and 2 comes from the primary busses under normal circimstances, and will run when powered by the APU. the CVR/FDR 1 is also connected to the battery bus. an imersion senson or G sensor will shut it off to prevent data loss in an accident, cant remenber the figures though, something like 18G Horizontal and 20G vertical. dont quote me on the figures though, i dont have my books open at the page right now to confirm that!

[Oldlae]

332 Wing mirrors.

As I recall, Bristow being the lead Super Puma operators had a problem with the transmission fairing (doghouse) becoming loose before the reinforced fasteners were introduced. I think the wing mirrors were installed for the crew to keep an eye on the fairings in flight, of course, I stand to be corrected, it was some time ago.

[Aberdien]

The wing mirrors are part of the fit required for a limited icing clearance. They enable the crew to monitor any ice build up on the engine intake baskets.

[fitliker]

Any updates ?

[Fareastdriver]

The wing mirrors are part of the fit required for a limited icing clearance.

Not, initially for the 332. The mirrors were originally required to monitor the snow build-up on the 330J's intake dam.
When the 332 was introduced in Aberdeen they were not fitted and were not going to be fitted because of weight until Doogal (RIP) had his double flameout.
Doogal got them both lit again and then all Bristows 332s sprouted mirrors virtually overnight.
Useful pieces of kit. No helicopter should be without them.

Same as the tail pylon hinge restraint. Just the rubber stopper until one started coming out of a 330J in 1978. They fitted a copy of the RAF 330C mod, a metal clamp. Come the 332 with a bigger rubber stopper. Had they learned? No, not until one came adrift again and the aircraft crunched in.

[Bob Beal]

Hi PPRuNe:

There is a story today, Apr. 7, (and there was another one yesterday) about the Newfoundland helicopter crash on the Globe and Mail's website. I made a couple of comments on that story, and one of the other posters directed me to this site.

I am a former (very former) journalist who did some work on aviation accidents. I have friends in the industry and military (now mostly retired). But that is the limit of my close experience with aviation.

I thought The Globe's reporters did a particularly good job with this story. But I wonder what people who post here, who know a great deal more about all this than I do, think of it.

[SASless]

The problem with news stories as you reference is they are far from detailed enough and suffer the problem of limited length to be able to fairly discuss the topics and allow a reader to form an opinon based upon sufficient facts to be accurate.

The story was well written and seemed fairly objective but due to reasons I cite it raises more questions than it answers.

The situation is far more complex than can be addressed in a couple of thousand word article.

If they were to start a series and devote weeks worth of space they might do a much better job of describing the situation but they would have to do a lot of research and interview a great number of people to do so effectively.

Are they willing to devote those kinds of assets to the project?

[carholme]

I don't think the story was fair at all for the following reasons:

From a post I made on another forum:

With all of the hype and media crap arguing about the "30 min run dry capability", I would suggest that everybody use caution in their interpretation of what is being discussed.

Remember one important fact. The present S92A Flight Manual does not state anywhere in the Emergency Procedures that continued 30 min flight is allowed for the type of indications this crew were faced with. This was not a BYP (Bypass) problem

From the flight manual:

If the MGB OIL PRES warning or the MGB OIL PRES caution and any of the following secondary indications of gearbox
failure are observed:

MGB oil pressure below 5 psi
Smoke or fumes in the cabin
Any subsequent hydraulic system failure
Progressively increasing power required to maintain flight
Unusual vibrations or noises.

6. Land immediately.

Therefore if the crew reports are correct that they did report a complete loss of MGB oil pressure, LAND IMMEDIATELY was their option

There seems to be statements from certain areas that the crew was possibly under the idea that the gearbox did have a run dry capability and therefore proceeded under this assumption. I don't think it serves the crew very well for this kind of conjecture to be running rampant. I would find it hard to believe, that with their knowledge of the aircraft they would continue flight, thinking that they had 30 mins remaining, especially with the return distance to a shore point.

I just think that we should give them the benefit of the doubt until proven wrong.

carholme

[topendtorque]

There has been at least one reference to the Oil Temperature indication, "almost certainly registering ambient' was I think the statement.

It might just be worth mentioning that the temp sensors that are used in vehicles I.E. a bulb which must be wetted with the coolant will show a reduction in temperature as the coolant runs dry and is not therefore wetting the bulb.

ambient (indicated) temp will then be much less than that which might be being generated in a major bearing, or cylinder head, that is running dry and located some distance from the bulb.

It is illogical to assume that anyone or everyone who drives a modern helicopter has had the experience of driving a water cooled vehicle which has had a hole in the radiator and exhibited this characteristic, or, indeed been briefed of the idea.

Therefore it is logical that, if the temp sensor needs to be wetted with the coolant oil to register the temp inside the xmon in this aircraft, that the crew may have seen a low temp indication and thus been fooled into thinking that indeed there must still be oil there because it is now showing a cooler temperature.

Even the investigators of the voice comments on the CVR may not be aware of this characteristic and if not it may help them understand comments that may seem out of place. Like "look at that, ok, power up".
If that were the case a simultaneous recorded lower oil temp on the data recorder may be the nub of an explanation.

May be?
all the best tet.

[Mulligan]

I haven't read the preceding 18 or so pages so forgive me if this has already been answered.
If the S92 was certified with an exception to the 30 minute rule because the "likleyhood" of a failure was "extremely remote" then my question is this:
Since there have been two failures (That I'm aware of) in five years it would seem that the "extremely remote" condition is no longer met. If this is the case then are there not grounds for suspending the type certificate or at least restricting it. No overwater flight, for instance.
I live in St.John's and saw a Cougar S92 flying a couple of days ago. Nice to see them back at it but I can't help wondering just how comfortable the pilots are at this point. Also, of course, the rig workers.

[Mulligan]

Hmmmm...just got this from our local newspaper.

Sikorsky Aircraft Corp. says no “run dry” requirement is necessary for certifying civilian helicopters “as described in media reports.”

Sikorsky spokesman Paul Jackson said in an e-mail that the S-92A is “fully compliant with the lubrication system failure requirement” of the U.S. Federal Aviation Regulations (FAR).

The Globe and Mail reported Monday that the S-92A — the same model helicopter that crashed off Newfoundland March 12 killing 17 people — failed a key safety test.

That test, known as a run-dry requirement, determines whether the aircraft can keep flying if the oil in its main gearbox leaks out.

Sikorsky says a bypass switch in the S-92A allows pilots to capture the remaining oil if there is a leak.
It must be switched on within five seconds of noticing a drop in oil pressure.

“The aircraft has a bypass system that isolates leaks and re-circulates oil in the main gearbox once activated by the crew,” Jackson said in an e-mail.

“This system was certified by the (U.S.) Federal Aviation Authority as meeting the lubrication system failure requirements and was accepted by Transport Canada and EASA.”
EASA is the European Aviation Safety Agency.

“While the investigation into the Cougar S-92A accident continues, we cannot disclose any details that may be pertinent to the investigation. Sikorsky, however, takes exception to the characterization that the helicopter failed to meet any FAR 29 requirement,” continued Jackson.


So: Is the "run dry requirement" not a requirement after all? And how does the crew "notice" a drop in oil pressure? Aural warning, master caution? 5 seconds doesn't seem like a long time when it could be an indication problem, for instance.

[madrock]

hubris :

Overbearing pride or presumption; arrogance: “There is no safety in unlimited technological hubris” (McGeorge Bundy).

[Hilife]

BB

If you are referring to the Peter Cheney article, "Doomed helicopter failed vital safety test, files reveal", then I’d have to say that I found it generally misleading.

Sikorsky won the Canadian Maritime Helicopter Project (MHP) bidding the MH-92 (Formally H-92) NOT the S-92. The Canadian Military CH-148 Cyclone (MH-92) and its systems - including the main transmission oil system – are a far cry from those certified on the Civil S-92, but hey, that wouldn’t make for a great story would it.

There have been 4 Puma accidents in only the first 3-months of this year (three of which crashed into the sea and 3 of which resulted in fatalities), but in spite of this and without a completed Air Accident Investigation Report as to the reasons for any of these or the one in question on this thread, some seem intent solely on demonising this manufacturer prior to the conclusion of any detailed investigation of all the events that led up to the final moments.

Whatever blame is attributed to this tragic accident, I’ve no doubt that there will be some serious soul searching going on within the industry and we can only hope that changes for the better will come as a result.

[Bob Beal]

Hi Hilife: Thanks for responding to my query. (And thanks to other posters here. I am learning a few things.)

The story you refer to was yesterday's Globe story. You should look also at today's. The reporters certainly believe the gearboxes on the two machines are at least similar, and they quote a company spokesman today who leaves that impression. If you know that they are substantially different, you might want to email Peter Cheney. Reporters appreciate that kind of input. As a reporter, you often have to pick up expertise as you go along. You do your best, but sometimes it is a scramble, more so now than when I was in the business because of declining resources.

[Ian Corrigible]

There have been 4 Puma accidents in only the first 3-months of this year (three of which crashed into the sea and 3 of which resulted in fatalities)
Without wanting to cause thread drift, are you sure that is correct?

I/C

[maxwelg2]

Local news here in St. John's today followed up from the Globe's article and re-enforced a few points:

PAX over here have no confidence flying in S-92a until 30-minute dry-run capability is proven available. Question, why not just retro-fit a mil-spec MGB if this variant does indeed have this capability? If this is not practically possible then we're back to the statistics game to justify running with the current design and enforcing the current RFM. This won't fly (excuse the pun) with the PAX.

Why would SAR sell a helo without this capability when they know it will be primarily used offshore? Cost difference, secondary type approval costs?

FAR29 extremely remote clause is non-applicable now, so the type certification should be revoked. In a nutshell this should ground the S-92a for offshore use...period. How does this apply to the search and rescue S-92a units in the UK?

We just don't fancy our survival odds with the current safety equipment available. We could insist on adding a HUBA to help some more PAX survive cold-water shock, assuming we still have a high possibility of a controlled ditch. Sea state limits restricting flight operations is normally tied to whether or not a FRC can be launched, do we now need a new limit based on the buoyancy of the S-92a?

We now have the local worker's union and members of parliament wanting answers and in essence an alternative to the S-92a for the Grand Banks. If all the PAX refuse to fly in these helos, the oil companies will have no choice but to continue vessel transfers until a solution is found.

In true oil industry style the solution will end up being a combination of addressing the understandable safety concerns in conjunction with justification of the cost of continuing vessel transfers versus replacement MGBs/helos for the S-92s. Worst-case scenario is that most/all of the workers refuse to fly and bring the offshore installations to either a standstill or reduced operations/efficiency. Now we're taking big bucks if production is impacted.

We want this industry to succeed over here, but want the safety risks present to be reduced to as low as reasonably practicable. If this can only now be achieved via helo change-out/re-design, then so be it.

[maxwelg2]

Sikorsky won the Canadian Maritime Helicopter Project (MHP) bidding the MH-92 (Formally H-92) NOT the S-92. The Canadian Military CH-148 Cyclone (MH-92) and its systems - including the main transmission oil system – are a far cry from those certified on the Civil S-92, but hey, that wouldn’t make for a great story would it

Hilife et al, see the latest blurb from the Globe & Mail today (link below).

globeandmail.com: Helicopter company rushes to fix safety glitch for Canada's military fleet (http://www.theglobeandmail.com/servlet/story/RTGAM.20090407.wcopter07/BNStory/National/home)

So who do we believe now? Assuming that Paul Jackson has not been mis-quoted we apparently have no solution for the military or civvies right now...

[FH1100 Pilot]

Well. Now I'm thoroughly confused.

1) First we were told that the S-92 has basically the same powertrain as the H-60. And we were told that the H-60 MGB definitely has 30-minute "run dry" capability. In our minds, we make the obvious link.

2) But then Sikorsky media handouts proclaim that the S-92 does indeed have such "run-dry" capability, reinforcing the assumption leapt to in #1.

3) Sikorsky touts an oil-loss test they did in which they ran an S-92 trans nearly to destruction: 3 hours! But they also acknowlege that it was more a test of the "oil protection system" than of a transmission without any oil in it. So the trans lasted three hours with slightly diminished oil level and no cooling of it. (In which case, I'm surprised it lasted as long as it did!)

4) Cougar S-92 crashes off Newfoundland about ten minutes after the crew reports "zero oil pressure" in the MGB. The crew reports that they were diverting for the nearest land despite RFM procedures to the contrary, perhaps believing that the transmission had some sort of run-dry capability.

5) We subsequently find out that the external oil filter had broken off, which caused the trans to pump all of its juice overboard, most likely resulting in zero quantity. And although we don't yet have any official cause of accident, the strong indication is that the real-world, not-in-a-test-cell "run-dry" time of an S-92 MGB is...umm...well...ten or eleven minutes. Offshore oil workers freak out.

6) A Canadian newspaper alleges that Sikorsky's S-92 transmission failed the run-dry specification required by certification, and that Sikorsky installed a "work-around" in the form of the emergency lube system whereby the pilots can isolate the oil cooler which, presumably is the only place that they thought could/would possibly spring a leak. The newspaper questions the status of the Canadian military version of the S-92. Sikorsky vehemently denies that there was any "run-dry" requirement for the S-92. Others allege that the S-92, MH-92, and CH-148 Cyclone have different transmission lubrication systems. Subsequently, Sikorsky admits that yes, the transmissions in all of the above will have to be modified. In some way. Yet to be determined.

Hoo-boy, what a mess.

I think we can safely conclude that the S-92 and all of its variants do *not* have any sort of "run-dry" capability. Any such claim is just marketing crap.

So my question (the one nobody is asking) is: Does the H-60 really have 30-minute run-dry capability? Or is that all crap too? I mean, H-60 and S-92 have the "same" transmission, no? Or did Sikorsky completely redesign the MGB of the S-92?



(And hey, if I got any of the above wrong, please feel free to correct me. After wading through 19 pages in this thread, and 76 pages in the other thread, one is bound to be confused.)

[Pilot DAR]

I am by no means an S92 or H60 expert, but the day after the Cougar accident, I had a very interesting conversation with a former H60 pilot. He related to me an offshore flight he had, during which he had a main transmission run dry. Though I do not recall how long he told me that he flew it dry, he did continue to a suitable on shore landing site, carrying lots of additional torque to overcome the friction of the failing transmisson. After landing the failed transmission was apparently very evident. It would appear that the H60 demostrated for this pilot, run dry capability far superior to that of the S92.

[madrock]

Quote :
So my question (the one nobody is asking) is: Does the H-60 really have 30-minute run-dry capability? Or is that all crap too?

FH1100Pilot - I'll betcha' US$1 there'll be one very influential group asking the question........you know......the people who live in the 5-sided house.......if the sky suddenly darkens you'll know what the answer is.........
Rule #1 - better not to p:mad: off the one group that's got more power than Big Oil ! :eek:
(although it wouldn't be the first time).

[500e]

The Globe and Mail revealed yesterday that the Sikorsky civilian S-92 lacks the mechanism to fly for 30 minutes in a "run-dry" emergency. Documents filed with the Joint Aviation Authorities, a European certification body, show the S-92 couldn't meet the capability, but won an exemption by establishing that the chances of gearbox oil loss are "extremely remote."
Sikorsky spokesman Paul Jackson said yesterday that the company is still working on a design that would allow the Canadian Forces' militarized version of the same helicopter to cope with a gearbox oil leak.
"We are designing a system to meet the program requirements and will test and enhance it as necessary," Mr. Jackson said in an e-mail.
So there it is it does not have 30 min run dry & never managed to comply with this requirement, so they fudged the words like a lot of others to make the product seem better than it is, along with suggestions in sales literature to give at least an impression that it had this capability.

[TalkSpike]

FH1100 Pilot

"I think we can safely conclude that the S-92 and all of its variants do *not* have any sort of "run-dry" capability. Any such claim is just marketing crap."

While all your data seems reasonable you have missed the mark with your conclusion above. "Any sort" might be a bit over the top when on two occasions in a real world, non test bed type emergency the S92 demonstrated approx a 10 min run dry capability. On one occasion the acft was landed safely when the RFM was followed, albeit in a lot less benign conditions than in the latest incident where it appears the RFM may not have been followed.

I think what any reasonable S92 pilot will take from the latest incident (unfortunately hindsight was not available to the cougar crew) is that if in future he/she has a problem the acft is on the ground/water ASAP. With haste, although I would not like be the one to try, the acft could theoretically land safely from 10 000 feet in less than 10 min.

I would suggest that even a 30 min run dry capability does not give anyone a license to push the envelope in the case of total loss of oil in the MGB. This incident should remind all helicopter pilots that a helo is replaceable and you and your pax are not, land ASAP should be the only responsible action. I cannot think of any helicopter type or variant that has repeatedly flown over an extended time in the real world with no oil in the MGB, therefore no one should be over confident with any stated run dry capability. Anyone who chooses to add to the data in this regard is simply tempting fate!

TalkSpike.

[FH1100 Pilot]

TalkSpike, well...yeah, of course. I absolutely, 100% agree with you. Helicopter transmissions don't run without oil. Period.

The problem is, we dumb pilots get to thinking that they can. And that's a problem right there - when pilots think.

In the other thread on the S-92, the transmission and associated emergency procedures are discussed at length. To me, the whole setup seems goofy. To wit: there are two transmission oil pumps, but neither can supply full pressure on their own. In fact, if one of the pumps fails, then the xmsn oil pressure will go down to...get this...5 psi...and Sikorsky says that's okay to continue flight. Say whaaaat? And let's remember, the crew has no way to determine just what kind of failure they've had that caused the xmsn pressure to drop. All they know is that it did.

Now, to this dumb ol' pilot, 5 psi seems in the realm of gauge or needle error. 5 psi is nothing. Yet with 5 psi you're good-to-go. Okay, that's my first beef with the S-92, that we drivers willingly accept this bit of lunacy as normal. "Oh yeah, 5 psi is okay." Not for this guy. Then again, I don't fly Supercopter, so my judgment hasn't yet been clouded by marketing hype.

But if the needle subsequently drops to 0 psi you're supposed to land RIGHT NOW! Which means of course, that one pilot must fly the helicopter and the other must keep his eyeballs glued to the transmission pressure gauge.

Transmission failure is without a doubt a helicopter pilot's worst nightmare. You're up there, desperately seeking to be down here before the thing seizes up completely, leaving you with little skinny, flexible glider wings that won't have much effect on your rate of descent, which will probably be terminal velocity at the bottom where the smoking hole is.

So manufacturers have come up with this magical phrase, "run-dry capability." They say that such-and-such model can fly around the world! with absolutely nothing in the transmission case but WD-40 fumes. Then we dumb pilots get to thinking (there's that problem again) that "most" modern transmissions have at least "some" run-dry capability. This is often compounded by misleading adverts by the manufacturer, even if no such capability is mentioned in the official certification documents or RFM.

And what happens is that some poor crew gets way out over water and their transmission pressure goes to zero. What the...? They know what the EP in the RFM says: "Land immediately. LAND NOW if you wanna kiss momma tonight." They look down - the water is icy-cold and the waves are so high that they'd be breaking over the top of their rotor. The prospect of putting themselves (not to mention the 16 other people in the cheap seats) down there is not very pretty. Landing down there means that the chances of everyone onboard kissing momma tonight or ever again will not be good.

But *real* land is not that far away. They head for that land, believing in their hearts that the transmission has got to be able run without oil. Come on! It's a Sikorsky S-92, which the manufacturer has bragged about as being the safest helicopter in the air...maybe the safest helicopter ever designed, past, present or future! They get down low (well, 800 feet seems low compared to 9,000 feet). "Come on, girl, hold it together for us just until we see the beach. Just a few minutes longer, baby." They vow...they promise each other to set her down at the very first sign that the trans is not holding up. One of them really does have his eyes glued to the panel now. They hope and pray that Sikorsky has given them at least 30 minutes of flight with no oil pressure. Sadly, they apparently only got eleven.

TalkSpike, you say:I would suggest that even a 30 min run dry capability does not give anyone a license to push the envelope in the case of total loss of oil in the MGB.

I agree. So why even mention it? Why even give pilots the impression...the merest hint that there is any kind of emergency capability available in the event of total loss of transmission oil? It's wrong. Because when real emergencies happen, the good pilot will use every tool at his disposal. Trouble is, that particular tool may not be in the bag.

[unstable load]

I would have thought that the possibility of jeapordising a multi billion dollar deal to fit something that has been left out of the deal when it should have been included could cause a minor scramble.

[Flyt3est]

Unstable Load - You think??

Customer fails to include items in a deal, then decides to change the deal to include said item further down the line.. I'd say the problem is the customers, not the supplier.

You wouldn't buy a car without telling the dealer what trim level and colour you want up front.

Thats what variation requests are for, and they are damn expensive too.. again, customer problem.

Harsh, and as trifle over-simplistic example.. but true.

[YHZChick]

Flyt3est, I can assume then that you are familiar with the original specifications that were agreed to between DND and Sikorsky?

You are making the assumption now that the government did not intially require dry-run capability.

[maxwelg2]

Tonight Norwegian media reports that a Norsk/Bristow S-92 made a precautionary landing on the Tor rig due to oil leak during a flight from Ekofisk to Sola. (Does not mention which system that was leaking oil)

A/C stuck on helideck pending repairs

Saw this on the main S-92 thread. Here's the web-link for those who speak Norwegian.

Helikopter måtte nødlande på Tor - Stavanger Aftenblad (http://www.aftenbladet.no/energi/olje/1012531/Helikopter_maatte_noedlande_paa_Tor.html)

For those who speak the Queen's English, here's Google's version (not the best but you'll get the gist of it).

The helicopter had nødlande on Tor
Easter holiday is postponed to the 19 passengers, but no one was injured when a 92-Sikorsky helicopter had technical problems and had to nødlande instead to go to land Wednesday afternoon.

There was a 92-Sikorsky helicopter that had nødlande. (Photo: Norsk Helikopter)
Published 08.04.2009 15:50 - Updated 08.04.2009 17:36 Ellen Kong scored

Emergency landing took place on the Tor-platform: (Photo: Conoco Phillips)
92-Sikorsky helicopter, owned by Norsk Helikopter, which now has changed its name to Bristow, was on its way to land with the 19 passengers who had finished his shift at Ekofisk.

92-Sikorsky helicopters on the Norwegian continental shelf was put on the ground after the crash in Newfoundland that claimed 17 lives, but 22. March was the helicopters back in the air.

See also:

Now, helicopters fly again (22.03.09)

Therefore, the helicopter crashed with 17 people killed (19.03.09)

A helicopter with 19 passengers from Conoco-Phillips had to make a controlled landing on the platform Tor south of the North Sea shortly after at 14 today, Wednesday.

The drama takes place just 16 days after the 15 Norwegian helicopter types of Sirkorsky S-92 was put on the ground after the fatal accident outside of Canada.

The 12. March this year, crashed a helicopter of the type of Sikorsky S-92 off Newfoundland and 17 people died.

Need to change the machine

The investigation revealed findings that made the Canadian authorities Friday afterwards sent out instructions that all Sikorsky S-92 had to replace a machine immediately.

This had 15 helicopters from Norsk Helikopter / Bristow and CHC Helicopter Services to the park was changed.

The helicopters were in the air again 23. March.

But 16 days later - today - it almost went wrong again:

A helicopter with 19 passengers from Conoco-Phillips had to make a controlled landing on the platform Tor south of the North Sea shortly after at 14 today, Wednesday.

Oil leak

The helicopter of typet Sikorsky 92 had an undefined oil leak under the flight and had to instead land on the platform Tor where passengers will now be seated.

- We hope everyone can be flown in to land tonight, but we are not sure, "says Torgeir Throndsen, operations coordinator in Bristow.

It is unclear what caused the oil leak and it is not clear where it comes from, according Throndsen.

Currently, passengers seated firmly out in the ocean and must wait for the technical people come out to find the error by helicopter.

- We must first remove the helicopter from the helipad before we can send out a new, "says Throndsen.

He can not guarantee that it will be tonight.

Main Redningssentralen the sun was notified and was in readiness when they came to innflygingen platform. HRS describes the incident as "a controlled landing," and Nødsignaler were not sent out.

The helicopter kept a low altitude over the last 15 minutes in to the platform and controlled the country, the HRS.

Here's the S-92a MGB reliability to date wrt. MGB lube oil loss events from what I've seen over the threads:

January 2008, Shell Brunei, MGB lube oil loss from superheated seals (input 1 module fail to be confirmed as the root cause). Helo landed OK.

July 2008, Broome Australia, 2 MGB titanium studs failed, total loss of MGB oil, running time from low pressure to landing 8 minutes, descent 6000 ft.

March 2009, CGR 491, 2 MGB titanium studs failed, descent from 9000 ft to 800 ft, then rapid descent to sea water impact, total estimated running time from initial MGB low oil pressure to MGB failure 10 minutes.

April 2009, Norway, Ekofisk to Sola, MGB leak (amount/cause unknown), emergency landing on Tor platform, running time 15 minutes from identification of leak (low MGB oil pressure). Was it an oil leak or vespel spline failure? Were the MGB studs confirmed as changed out?

This is not doing anything to help the S-92a resumption case...now the local regulator (C-NLOPB) is also starting their own inquiry into worker safety on helos.

Simple solution, land immediately in event of ANY MGB lube oil system compromise that ends up with no pressure? Not so easy if you don't have an acceptable landing zone. I agree with the previous comment on do not assume that you have any dry run capability, unless you're in a hot zone you should LAND IMMEDIATELY. If you cannot safely survive such a landing then the equipment is not suitable for the job and should not be flying.

[Oldlae]

As regards the MGB oil pressure indications and the crew watching the oil presure guage surely there must be a master caution panel warning light for this purpose?

[FH1100 Pilot]

Oldlae:
As regards the MGB oil pressure indications and the crew watching the oil presure guage surely there must be a master caution panel warning light for this purpose?

Oldlae, while one would assume that there most certainly *is* a caption that illuminates when the MGP pressure drops below a certain threshhold, I don't believe there would be any additional visual (or audio, for that matter) warning that the pressure has dropped from the miniscule 5 psi to zero, unless it was caught by one of the pilots' eyeballs.

I could be wrong (and often am).

[SASless]

The ramifications of 5 PSI or more....and less than 5 PSI would seem to suggest I would be keeping a very sharp eye on the pressure indication and not just looking for pretty orange and red lights on the panel.:uhoh:

[Arnie Madsen]

One of our TV news stations just reported that the one survivor of the ditching is now able to tell investigators his story.

He is talking to NSTB staff but his statement is not being made public at this time.

[212man]

You make a very good point svenestron, and one which I have talked about privately. If a new aircraft starts having failures, everyone assumes it has a problem, whereas if an old established aircraft has failures everyone says "ah yes, but generally it's a very safe aircraft". The fact is the number of failures per 100,000 flying hours may be the same!

Personally, I think this particular failure mode was proven to be no longer extremely remote, following the Broome incident. Particularly when tied to the fact that frequent oil filter bypass pop out indicators 'popping' has required an unexpected number of filter housing removals.

For the sake of clarity and accuracy, could people stop including the Brunei incidents in the discussion about oil loss? Neither incident was a result of a leak, and indeed my incident was a result of too much oil! Admitedly, the subsequent condition of the input module resulted in some leakage, but not to any significant degree.

[snotcicles]

Please forgive my ignorance if this has been mentioned somewhere previously in this post however is it correct that the "30 dry run" is passed with oil in the MRGB but with the oil pump not functioning. Is a 30 minute test with no oil whatsoever in the system a different test that most gear sets of any sort under full load cannot pass?

[madrock]

"This obviously leads to the question of how remote this occurrence might be. To my knowledge, only Sikorsky and the certifying authority can answer this question."

God I hope not !!

Hopefully when the risk equations are re-done it's taken into account not only occurrence which is a straight calculation, but take another look at consequence based on area of operations - how far offshore and what percentage of total flight time is spent there.

One thing I can absolutely guarantee you is extremely remote is the Flemish Pass - 450k east of St. John's.

[212man]

Please forgive my ignorance if this has been mentioned somewhere previously in this post however is it correct that the "30 dry run" is passed with oil in the MRGB but with the oil pump not functioning. Is a 30 minute test with no oil whatsoever in the system a different test that most gear sets of any sort under full load cannot pass?

The test is for NO OIL, not pump failure:

it must be shown by test that any failure which results in loss of lubricant

The description of the test initiation is (my bold):

...With the transmission operating at maximum normal speed, with
lubricant as described above, with nominal cruise torque applied (reacted as
appropriate at main mast and tail rotor output quills), and with a vertical load at the mastequal to gross weight of the rotorcraft at 1g, disconnect or cause a leak in an external oil plumbing device...

[SASless]

The remote possibility clause requires "every" failure mode to be forecast, identified, and considered in order for it to be a valid analysis.

Just how likely is it for an engineer to accurately identify every single failure mode that would result in a run dry mode for every single part and gear of a transmission?

That to me is something that is extremely remote in itself.

The question about the oil filter problem is that it identified itself to all an sundry at Broome, Australia. As soon as the first filter housing parted and allowed the oil to leak from the system it breached the "FAA approved Extremely Remote" clause in FAR Part 29.927 under which the aircraft was certified. (IMHO anyway).

The real failure was not the Oil Filter Housing Titantium Studs but the failure of anyone to realize the fact that had happened upon the first set of studs to fail.

The FAA and Sikorsky will have to explain that at some time in the near future I hope.

When the requirement to replace the studs was made and predicated upon a one year or 1250 flight hour limit that would suppose someone had analyzed the situation and determined the actual risk was more like two years and 2500 hundred hours flight time and halved the estimated time between failures or whatever they wanted to call it.

The fact it could be a fatal flaw seemed to escape notice as evidenced by the amount of time granted to do the replacement.

On top of that decision, the Operators of the aircraft have to explain why they failed to see a more urgent need to replace the problem studs.

These will be interesting questions for the FAA, Sikorsky, and the Operators of the S-92's in service today.

[212man]

On top of that decision, the Operators of the aircraft have to explain why they failed to see a more urgent need to replace the problem studs.

No they don't - the operators' role is not to second guess every decision made by a manufacturer regarding urgency of implementation. Quite apart from anything, they will not have the big picture on in service experience, certification test data and engineering design rationale. Some operators are very large with huge amounts of inhouse expertise (including approved design 'houses' and flight test personnel) others are very small and are constrained by resources.

Regardless of the nature of the operator, the manufacturer conducts the risk assessment and that is the assessment used when planning. To further expand on your logic - what if operators decide to implement ASBs early, how early is early? What if an operators decides to implement a 1 year ASB at the next 50 hour check, but the failure occurs 5 hours before? Should they have implemented it before the next flight? That is not how a commercial operator can function - as I'm sure you know.

[JimL]

The exact meaning of terms such as 'FREQUENT', 'REASONABLY PROBABLE', 'REMOTE', 'EXTREMELY REMOTE' and 'EXTREMELY IMPROBABLE' can be found in AC 29.1309.

This text also includes the definitions of failure condition classifications such as 'NO EFFECT', 'MINOR', 'MAJOR' and 'HAZARDOUS/SEVERE-MAJOR' - the last also including 'CATASTROPHIC'.

Jim

[De Regulator]

This posted yesterday in the Globe and Mail: The Globe and Mail: Sikorsky objects to claims helicopter failed to achieve certification (http://www.theglobeandmail.com/servlet/ArticleNews/freeheadlines/LAC/20090408/COPTER08ART2237/national/National)

In particular:
'Although the investigation is ongoing, investigators have zeroed in on a problem that forced a S-92 to make an emergency landing in 2008: the studs that hold down the gearbox oil-filter assembly were broken, which would allow the oil to drain out.'

Are they referring to the Shell S-92 that made a forced landing in the Brunei jungle? Think it was a similar problem.

[212man]

Are they referring to the Shell S-92 that made a forced landing in the Brunei jungle? Think it was a similar problem

Whilst I appreciate that not every reader of this thread has read every post, I would at least expect the last few pages to have been read before posting, let alone 7 posts before, where the following was requested:

For the sake of clarity and accuracy, could people stop including the Brunei incidents in the discussion about oil loss? Neither incident was a result of a leak, and indeed my incident was a result of too much oil! Admitedly, the subsequent condition of the input module resulted in some leakage, but not to any significant degree

I find it insulting to the memory of those who have perished, to see continuous reference to the Brunei incident. It was in no way related to either the Broome incident or the Cougar accident. Any reference to it should be limited to the 'S-92 Design to Operations' thread, if at all, and not on this one.

Thanks

[madrock]

St.John’s - The Telegram, Wednesday April 8th :
“ “No such “run dry” requirement, as described in media reports, exists for civil certified rotorcraft”, said Sikorsky in a statement released late Monday evening.
The U.S. Federal Aviation Authority, which certified the S-92A’s, was mystified by the company’s response. “I have no idea why they’d say that” said Les Dorr in an e-mail.””
“ “A pilot is able to throw a manual switch that isolates the leak – it captures all the oil that’s remaining and recirculates it ” said Sikorsky spokesman Paul Jackson in an interview Tuesday.”"
....oh really ?
keep going guys, the lawyers will love it.

[widgeon]

http://frwebgate1.access.gpo.gov/cgi-bin/PDFgate.cgi?WAISdocID=305129189184+2+2+0&WAISaction=retrieve

Am i missing something , I did text search for oil and dry and found no reference in this document. Is there a later release ?.

Sorry I found it , after reading back through the thread.



1) Category A. Unless such failures
are extremely remote, it must be
shown by test that any failure which
results in loss of lubricant in any normal
use lubrication system will not
prevent continued safe operation, although
not necessarily without damage,
at a torque and rotational speed
prescribed by the applicant for continued
flight, for at least 30 minutes after
perception by the flightcrew of the lubrication
system failure or loss of lubricant.
(2) Category B. The requirements of
Category A apply except that the rotor
drive system need only be capable of
operating under autorotative conditions
for at least 15 minutes.

And earlier in part 29.1

(c) Rotorcraft with a maximum
weight greater than 20,000 pounds and
10 or more passenger seats must be
type certificated as Category A rotorcraft.

Should this exception have been referenced on the TCDS ?.

[Aser]

Cougar helicopter crash survivor Robert Decker gives full account of crash to RCMP Breaking News print this article
The Telegram

Robert Decker, the only survivor of the tragic helicopter crash March 12 off the east coast of Newfoundland, has meet with RCMP investigators and has given a full account of the events surrounding the crash of Cougar Helicopters flight 491, the RCMP announced today.
The crash killed 17 of the 18 people onboard the helicopter, which was making its way to oil platforms on the Grand Banks.
The RCMP says the information given by Decker will be provided to Transportation Safety Board investigators for their ongoing investigation into the helicopter crash. While the TSB is ongoing, and since there are privacy concerns, the RCMP says it will not be in a position to recount Decker’s story to the public.
Officials with TSB have said a bolt in the main gearbox failed during flight and resulted in a sudden loss of oil pressure prior to the crash of the Sikorsky S-92 A in the Atlantic Ocean.
The TSB said its investigation has found that the flight data recorder indicated oil pressure in the gear box had dropped to zero. There was also a power interruption prior to the crash that caused the flight data recorder and cockpit voice recorder to shut off.
The flight crew radioed they were preparing to ditch, and radar indicates the aircraft descended at roughly 1,000 feet per minute. Impact data indicates the helicopter hit the water with an impact 20 times the force of gravity. The helicopter crashed belly down with the tail hitting first.
Earlier today, the Canada-Newfoundland and Labrador Offshore Petroleum Board (CNLOPB) announced it is setting up an inquiry into worker safety in the wake of the crash.
“While we believe it is important to announce the inquiry at this time, we continue to work on a definition of the mandate, terms of reference, selection of a commissioner for the inquiry, and timeline for inquiry completion,” said a release.
That information will be released at a later date.
The inquiry is being set up under the Atlantic Accord Act which requires a mandatory inquiry in the event of a serious offshore incident.
The CNLOPB says its inquiry will not examine the same issues already under review by the Transportation Safety Board of Canada.


The Telegram - St. John?s, NL: Local News | Cougar helicopter crash survivor Robert Decker gives full account of crash to RCMP (http://www.thetelegram.com/index.cfm?sid=240586&sc=79)

Regards
Aser

[212man]

Widgeon, "run dry" is a colloquium that simply refers to continued operation following a total oil loss. It is not an official term you will find in a certification standard.

[maxwelg2]

For the sake of clarity and accuracy, could people stop including the Brunei incidents in the discussion about oil loss? Neither incident was a result of a leak, and indeed my incident was a result of too much oil! Admitedly, the subsequent condition of the input module resulted in some leakage, but not to any significant degree

212man, thanks for clarifying, first time I've heard it mentioned that the Brunei incident was over-filling of MGB lube oil. Obviously not a design/certification issue. Ever tried running your car with too much oil, excessive pressure build-up = gasket blow or pressure sensor blowout.

Whilst I'm in clarification mode, the main S-92a thread has mentioned that the latest S-92a incident over in Norway is believed to be a hydraulic fluid leak. This brought back to memory my own personal recollection of a similar incident. I had the unfortunate pleasure of experiencing a similar hydraulic leak issue back in Nov 15, 2006. Luckily we had just landed on the Henry Goodrich and I spied the drip-drip as we got off for refuelling. We then were told that it was a minor leak and not to worry, took off and promptly landed again. The helo had to be fixed by Cougar in situ which meant a wee boat trip and crane transfer for the techs and us PAX who were going to Terra Nova. No mention in CADORS on that one...Kudos to the Cougar pilots for immediately grounding that helo, probably saved us getting our feet wet or even worse.

The point I'm trying to make is that this didn't stop me from flying in the 92 after the event, we were well de-briefed on the problem and again trusted the whole team to keep us flying safely. This will hopefully be the case in the future.

The only positive thing that can come out of 491 is that we're hopefully going to have safer operations and a greater understanding of the inherent risks in helo flying. The big question now is will the S-92a type 'A' certification be pulled in light of the now well-known facts?

[Arnie Madsen]

Survivor of N.L. chopper crash tells tale of escape

By THE CANADIAN PRESS http://www.canoe.ca/CanoeGlobalnav/invisible.gif

ST. JOHN'S, N.L. - Robert Decker escaped through the window of a helicopter that crashed in the North Atlantic, killing 17 people, and remained calm throughout the ordeal until he was rescued, he said Thursday.
In a statement provided by a family friend, Decker offered his first public account of how he survived last month's tragedy at sea.
"I escaped through a window after I released my seatbelt shortly after impact," said Decker, the sole survivor of the crash. "I reached the surface and managed to remain calm until I was rescued."
Decker said he didn't know how Allison Maher, the only other person who managed to get out of the helicopter, escaped. She died and her body was recovered on the surface.
"Things happened extremely fast," he said. "There was no time for panic. There were no words spoken. There was no time for suffering."
Decker said he spoke with the RCMP in an effort to help out with the Transportation Safety Board's investigation into the crash. He said he won't speak further publicly until the federal agency's final report is released, or until he's certain his comments won't hinder its probe.
Decker was released from a hospital in St. John's last week after suffering lung injuries and multiple fractures. He continues his recovery at home.
"I will continue to work really hard at resuming a normal life," he said. "I continue to appreciate your support and patience with this, and the untold kindness of the public."
Cougar Flight 491 crashed March 12, about 65 kilometres southeast of St. John's, as it was ferrying workers to two of the province's offshore oil platforms.
The Transportation Safety Board has said that titanium mounting studs that attach an oil filter bowl assembly to the main gearbox broke during the flight. The board says the pilots indicated there was a problem with the main gearbox oil pressure before the crash.
The board said it remains unclear precisely what caused the crash, but less than 10 minutes after the oil pressure loss, the transport chopper slammed at high speed into the Atlantic.


from : Survivor of N.L. chopper crash tells tale of escape- Politics - Canoe.ca (http://cnews.canoe.ca/CNEWS/Politics/2009/04/09/9071616-cp.html)

[maxwelg2]

I'm totally amazed that Robert survived the impact, to me this is nothing short of a miracle. I know the S-92a seats are designed to reduce impact, but if the helo did indeed hit the water with a 20g force this is unbelievable.

I'm really glad that some of the real facts are coming out now, there's been so many rumours e.g. that Robert jumped out before impact.

Does anyone know what the maximum survivable impact force is supposed to be for this helo? How do we safeguard to ensure that the landing is soft enough to survive and the helo stays upright long enough to get into the life-rafts? Shear-pin type main rotor bearing to allow auto-rotate with complete MGB failure? Improved flotation devices to cope with Grand Banks sea states? Will HUBA's become mandatory now to cope with cold-water shock?

Robert, here's to your continuing recovery and hopefully more recollections to help the TSB work this one out.

[Brian Abraham]

Re 20g an article in Aviation Weeks "Business and Commercial Aviation", February 2002, on the 92 has,
The airframe itself is designed to withstand a 21 foot/second vertical crash (20g downward momentum).
“ “No such “run dry” requirement, as described in media reports, exists for civil certified rotorcraft”, said Sikorsky in a statement released late Monday evening.
Article also says,
The main gearbox is designed to go 6,000 hours between overhauls and can run completely dry for up to 30 minutes. The case is made out of WE-43A magnesium alloy, which is resistant to saltwater corrosion.
Sikorsky can't have been ignorant of the claims being printed in the press and certainly did nothing to refute what had been published.

[[email protected]]

If memory serves, the maximum g the human body can absorb (and certainly not without serious damage) is 25g - Robert Decker was very lucky indeed that his injuries allowed him sufficient mobility to escape from the fuselage and I hope he makes a full recovery.

[HeliComparator]

Crab

Yes, but the stroking seats would reduce the peak g. If the airframe suffered a peak of 20g, the occupants of the seats would suffer somewhat less. Still very lucky though!

I wonder if this is the first time a crashworthy helicopter seat has saved a passenger's life?

HC

[Brian Abraham]

Broadly speaking the human tolerance with harness and lap belt are given as,
Longitudinal
45 G (0.1 second)
25 G (0.2 seconds)
Vertical
25 G (0.1 second)
Lateral
20 G (0.1 second)

Of interest the lap belt only figures are,
Longitudinal
15 G (0.002 second)
Vertical
4 G (injured)
Lateral
11 G (0.1 second)

The latest seat standards if I recall correctly, is 16 G Forward, 8 G Lateral, 20 G Downwards and 4 G Upwards.

For bedtime reading see www.everyspec.com/MIL-STD/MIL-STD+(1100+-+1299)/download.php?spec=MIL_STD_1290A.860.pdf and http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980228043_1998394351.pdf

[maxwelg2]

Seeing as we're now talking about the helo's safety capabilities, what's the maximum allowable force that the fuel tanks can cope with? It was mentioned earlier in the media that Robert Decker had fuel in his lungs as well as salt water. I thought that these tanks were designed to withstand a crash scenario.

In our HUET training we wear goggles to prevent eye damage from fuel etc. in the water during a ditching. The HUBA would potentially have saved Robert's lungs from chemical damage, plus given perhaps some other poor souls the chance to escape.

One thing with HUBA or rebreathers, they shouldn't be used until post-impact as the mouthpieces can do more damage than good on impact.

I am assuming that the RCMP know now exactly where Robert was sitting, that may or may not have had a contributory factor to his survival.

[madrock]

The Black Hawk refers to run dry for 30 minutes at cruise power (in the RFM), the S-92 transmission is bigger and better, and will be fitted as-is onto the Hawks as future upgrades but has no run dry, the S-92’s FBY military variant CH-148 for Canada under a 2004 contract that called for run dry (according to the Globe & Mail) had first flight last year, but SAC are now saying the MGB for the CH-148 is still in the design stage?
Will someone with big boots now tell SAC to put ELS systems in place and not allow them to invoke any clause that excludes them from testing to confirm MGB run dry redundancy ?
If the S-92/Blackhawk MGB is a bolt-on transplant it would happen sooner rather than later ?
Would be real nice to see the 20 year old “30 minute” figure improved on as well ?

[NorthSeaTiger]

Any update on Robert Decker the sole suvivor ?

NST

[gwillie]

Any update on Robert Decker the sole suvivor ?

From April 9... (http://www.cbc.ca/canada/newfoundland-labrador/story/2009/04/09/cougar-crash-decker-survivor009.html)

[Aser]

Newfoundland company orders S-92 pilots to remain below 7,000 feet

globeandmail.com: Newfoundland company orders S-92 pilots to remain below 7,000 feet (http://www.theglobeandmail.com/servlet/story/RTGAM.20090514.wxcopter14art2237/BNStory/National/home?cid=al_gam_mostview)

Regards
Aser

[Special 25]

Not sure what the above complaints are about. That looks like a fairly well researched and balanced article. Maybe over-stressed the Norsk incident a bit, but generally was fair and accurate.

Sikorski's claim that they "take exception to the characterization that the helicopter failed to meet any FAR 29 requirement" just continues to annoy me.

We have the same debate going on here in the UK at the moment - Whilst it may have fallen within the rules, was it within the 'Spirit of the Rules' ??

[js0987]

It's my understanding that the reason behind the main gear oil bypass system was because the transmission could not run 30 minutes with no oil. It was thought that any loss of oil would occur in the external oil cooling system, so if you stop oil from being pumped to the cooler and trap it inside the case you have your 30 minutes. Apparently the transmission was run with a small amount of oil for a long time, enough to satisfy both the FAA and CAA, but with the caveat that below 5psi you land immdiately.

The tragedy of the irony on this forum is the spirited debate between the 225 and 92 groups and that both types suffered catastrophic transmission failures. Aviation always learns from its mistakes, often at a terrible price, so, hopefully, positive things will happen in these cases.

[Special 25]

Just to correct the above ..........

The aircraft that crashed with a catastrophic gear box failure was in fact a 332L2, and not a 225.

The cause of this crash has still not been determined and whilst it is fair to say that both types have a similar gear box, they are not the same. The 225 has a basically identical layout to the L2 but has been 'beefed up' for want of a better phrase.

And with regard to the certification of the S92, I refer to previous responses within this thread that questioned, How do you qualify 'Remote Possibility' on a brand new aircraft type ??

[maxwelg2]

Correct me if I'm wrong as I've not been following these threads for a while, but the Globe & Mail article implies 4 MGB oil loss cases. I only recall 3, Broome Australia and Cougar 491 were due to filter housing titanium stud failures, and the Shell Brunei was an over-filled MGB lube oil reservoir causing seal failure.

The Norsk incident was MGB oil pressure drop due to vespel spline failure. I don't recall lube oil leaking in that case.

I still don't agree with the S92 FAR29 compliance, but I'm sure the manufacturer's lawyers will win their case regardless.

[SASless]

Interim Report due to be released today by Canadian Authorities.

Lawsuit filed against Sikorsky by families of the passengers aboard the Cougar Aircraft.

http://www.cbc.ca/news/pdf/nl-helicopter-suit-200906.pdf

[js0987]

Maybe I missed it, but I didn't see any mention of the RFM's requirement to "land immediately" if oil pressure falls below 5psi.

[TLB]

The Transportation Safety Board of Canada issues an investigation update into the Sikorsky S-92A helicopter accident (A09A0016)

GATINEAU, QC, June 18 /CNW Telbec/ - The Transportation Safety Board of Canada (TSB) is well into a comprehensive investigation of the accident of a Sikorsky S-92A helicopter, Cougar Helicopters Flight 491, which occurred 30 nautical miles east of St. John's, Newfoundland and Labrador, on March 12, 2009.

A thorough, unbiased investigation is necessary to understand as completely as possible all the contributing factors involved in this accident. To this end, a dedicated team of TSB investigators and several TSB Engineering Laboratory specialists is working towards completing the investigation. A number of other specialists and observers from Cougar Helicopters, Transport Canada, Sikorsky, and the Federal Aviation Administration (FAA), along with the accredited representative of the United States National Transportation Safety Board (NTSB), continue to provide valuable contributions to the TSB investigation.

Work Completed to Date

A significant amount of work has been completed so far, but much remains to be done. Dozens of interviews have been conducted with individuals from various organizations. The latest interviews were conducted in May, including a follow-up interview with the sole survivor. More interviews remain to be conducted in the coming weeks. Hundreds of technical and operational documents, weather reports, air traffic control communications, incident reports, studies, and research papers have been gathered, and the review of this material continues. The TSB has examined the main gearbox (MGB), the tail rotor drive shaft, the flight data recorder (FDR), and cockpit voice recorder (CVR). As reported previously, the FDR stopped recording at approximately 1225:17, (1) while the helicopter was about 800 feet above sea level (asl). The reason the recorder stopped remains under investigation. The TSB Engineering Laboratory, in concert with manufacturer's specialists, has been able to successfully retrieve additional data from the aircraft's Health and Usage Monitoring System (HUMS) and flight control computer (FCC) to be able to piece together most of Cougar Helicopters Flight 491's flight profile below 800 feet. While this portion of the flight profile is still in a preliminary stage, and further analysis is required, the following additional factual information can be released at this time.

Factual Information

Examination of the MGB indicates that there was no loss of main rotor drive and that the main rotor blades were rotating at the time of the impact. The examination of the MGB also revealed that the tail rotor drive gears had been severely damaged, resulting in a loss of drive, causing it to stop producing thrust. Further examination is being carried out by the TSB Engineering Laboratory to determine the cause and sequence of this loss of tail rotor drive.

The metallurgical examination of the titanium oil filter attachment studs revealed fatigue cracking in the studs as well as evidence of thread damage. A detailed metallurgical examination of the studs, nuts, and filter bowl is under way to identify the origin of the fatigue cracks and to determine the fracture mechanism.

Just before the recorder stopped, engine power was reduced, a descent from 800 feet was initiated, and the speed of Flight 491 began to decrease from 133 knots. The helicopter continued to descend and to slow down in a controlled manner, until about 1225:44, at which time driving power to the tail rotor was lost. At this time, Flight 491 was heading 290 degrees magnetic (M) at 85 knots and was descending through approximately 500 feet. At 1225:47, a shut-down of both engines was initiated, which is consistent with a tail rotor drive failure emergency.

Subsequently, the aircraft experienced a number of large and rapid attitude changes. At 1225:54, Flight 491's pitch attitude increased from approximately 10 degrees nose down to about 16 degrees nose up, which is consistent with a flare for an engines-off landing. The helicopter struck the water at approximately 1226 in a slight right-banked, nose-high attitude at an approximate location of 47 degrees 26'03" N, 051 degrees 56'34.8" W, with moderate speed and a high rate of descent. The wreckage was found at a depth of 165 metres on a bearing of 283 degrees from the surface position.

The Sikorsky S-92A flotation system activation switch was found in the armed position after recovery. The helicopter experienced significant forces during the impact with the water, and examination of the inflation bottles indicates that they had not released their compressed gas to inflate the flotation collars. The reason the collars failed to inflate is still under investigation.

Investigation Activities in Progress

Continued investigation activities being finalized include evaluations of the Flight 491 flight profile in an S-92A simulator. Investigators from the TSB and other agency specialists will recreate as closely as possible the accident flight profile to add to the understanding of the challenges encountered by the pilots of Flight 491. In addition, pilot training, human performance aspects, crew resource management, and cockpit ergonomics will be evaluated.

Oil filter bowl studs on all Sikorsky S-92A aircraft have been replaced with new steel studs in accordance with a Sikorsky Aircraft Alert Service Bulletin (ASB). Compliance with the Sikorsky Aircraft ASB was subsequently mandated by an FAA Airworthiness Directive (AD).
The investigation has revealed that, even though the Sikorsky S-92A MGB was certificated to meet requirements of Part 29 of the Federal Aviation Regulations (FAR 29) of the United States FAA, there is a perception in some areas of the aviation community that the MGB can be run in a dry state-that is, without lubricating oil-for 30 minutes. FAR 29 does not require run-dry operation of a gearbox to meet the 30-minute "continued safe operation." Based on the applicable guidance material at the time of certification, the lubrication failure modes of interest were limited to the failure of external lines, fittings, valves, and coolers. This practice was consistent with industry experience, which had found that loss of lubrication tended to be associated with external devices. Therefore, the possibility of a failure at the oil filter was considered to be extremely remote. As a result of the fracture of the filter bowl mounting studs, resulting in the loss of a large quantity of oil, the certification guidance material is being reviewed. Additionally, the FAA and Sikorsky Aircraft are working to identify all the modes of failure that might lead to Sikorsky S-92A MGB oil loss, determining their probability of occurrence, and developing appropriate mitigation strategies.

The Sikorsky S-92A Rotorcraft Flight Manual (RFM) has been reviewed regarding MGB oil pressure loss below 5 pounds per square inch (psi) and the need for pilots to land immediately. An RFM revision has been approved by the FAA and Transport Canada.

A number of issues regarding survivability such as passenger immersion suit and crew flight suit effectiveness, use of underwater breathing devices, adequacy of survival training, adequacy of general ditching procedures, personal locator beacons, weather/sea state flight limitations, and Sikorsky S-92A flotation system are currently under investigation.

Safety Action

As the TSB investigation progresses, the team continues to work closely with the other agencies involved. Safety concerns have been communicated directly to these change agents and have resulted in safety action taken by Cougar Helicopters, Sikorsky Aircraft, and the various regulatory bodies.

Cooperation with Other Agencies

The TSB is working in cooperation with other external agencies such as the Canada-Newfoundland and Labrador Offshore Petroleum Board (C-NLOPB) to ensure that the upcoming public inquiry by retired Justice Robert Wells does not impinge upon the work being done by the TSB under our mandate.

To this end, several exchanges of information have occurred and meetings have been held to coordinate activities. The general concerns of offshore workers have been passed to the TSB and those concerns appropriate to the TSB's mandate have been checked against the investigation issues already under consideration by the investigation team. The other concerns of offshore workers have been addressed by an external Helicopter Operations Task Force, a working group composed of representatives from the helicopter operator and the oil companies.

As always, the thoughts of the TSB investigation team go out first to the families who lost loved ones on board Flight 491. The investigation work of the TSB team on this accident will help all understand what happened in this accident and hopefully prevent any similar accidents from happening again in the future.

The TSB is an independent agency that investigates marine, pipeline,railway and aviation transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.

The investigation update and photos are available on the TSB website at
www.bst-tsb.gc.ca (http://www.bst-tsb.gc.ca/).

----------------------------
(1) All times are Coordinated Universal Time (UTC).

[SASless]

They gloss over the fact the FAA and other such agencies certified the aircraft as well.

You can say anything you want in a filing....proving it in court is an entirely different matter. Typical lawyer prays there will be an out of court settlement so he can claim his prize money for not much work and zero risk.

[carholme]

Here is the latest from the TSB site:

Transportation Safety Board of Canada - Featured Investigations - Aviation - 2009 - A09A0016 (http://www.tsb.gc.ca/eng/medias-media/majeures-major/aviation/a09a0016/mi-a09a0016.asp)

carholme

[SASless]

Key Point?

Examination of the MGB indicates that there was no loss of main rotor drive and that the main rotor blades were rotating at the time of the impact. The examination of the MGB also revealed that the tail rotor drive gears had been severely damaged, resulting in a loss of drive, causing it to stop producing thrust. Further examination is being carried out by the TSB Engineering Laboratory to determine the cause and sequence of this loss of tail rotor drive.

[carholme]

As it goes on to say that "the aircraft entered the water at a high rate of descent" makes you wonder just how much rotor RPM existed.
Previous TSB reports state that it impacted with 20g.

Another important question which comes to light after verifying that the floats were "armed" is why they failed to deploy?

carholme

[maxwelg2]

I'm assuming that the tail rotor drive pinion is normally lubricated by the MGB lube oil system. Is this a known weak point in this type of MGB design?

As for the flotation collars not working, I'm assuming that the rate of descent and high G forces may have played a part there. The fact that the pilots were attempting an auto-rotation due to tail rotor failure and got their speed below 85 knots to arm the flotation system just re-enforces that they were doing their best with what they could and by the book.

What's still bugging me is why were they flying at 800 feet and 133 knots when they knew that the MGB lube oil system was compromised? What height would you have to be at to ensure that an auto-rotation operation could be implemented effectively? Was the lube oil temperature reading falsely low, and until the tail rotor drive failed they had no knowledge of anything else amiss that would warrant going from land as soon as possible to land immediately? Has the RFM been fully updated to ensure that this cannot happen again?

Going forward, would it not make sense to have temperature sensors at all critical points in the MGB? These could then pick up excessive heat build-up and force a land immediately action as well as lube oil pressure < 5psi. The only other options are to have either an ELS and/or more robust MGB components to achieve a true dry-run capability. I wonder what the CH-148 new MGB design is going to be...

[widgeon]

So sad , sounds like if the TR drive had not failed at the critical moment they may have had a fighting chance. One thing I am not clear on , though it probably would not have made any difference if you are sure you are ditching would you not deploy the floats once you have reduced speed rather than just arming. Or is the SOP just to arm and allow the auto inflate to happen after you have hit the water surface ?. Does any one have the ditching procedure from the Flight Manual they could post .

[Horror box]

Or is the SOP just to arm and allow the auto inflate to happen after you have hit the water surface ?. Does any one have the ditching procedure from the Flight Manual they could post .

The RFM states that the floats are not designed to absorb the force of water impact and must only be deployed after water entry. Therefore SOP's are not to deploy the floats before hitting the water. They are armed and then the immersion switch should deal with the inflation.

[Oldlae]

Curiouser and curiouser, which came first, loss of oil from the MGB or damage to the T/R Drive? I would have thought that when the MGB lost it's oil the epicyclic gearing would have failed first because of the torque loading, but perhaps the T/R Drive gearing failed because metal particles dropping from the epicyclic contaminated the T/R Drive enough to break up the gears.
A major concern is the reported failure of the flotation system.
It is also understood that the flotation beacons did not operate, in my old company the beacons were wrapped in the liferafts so if the liferafts were not manually deployed no beacons. Automatic deployment of the beacons without the liferafts should be considered, this may also be relevant in the case of Air France 447.

[HeliComparator]

CEFOSKEY - A tail rotor drive failure from <800' would be quite difficult to deal with even when already pretty much in autorotation, though the report just says descending, not autorotating. With significant power on, the intial yaw would likely cause a serious upset. Looking at the pictures of the tail drive here,

http://www.verticalmag.com/control/news/articlefiles/11086-4.jpg



if the tail drive pinion was in such a bad state, think what the rest of the gearbox would be looking like. You state "the torque should have been almost zero", this may be true (though probably not at the time of failure) but you are assuming no increased drag from a seriously damaged main transmission. In reality once engine power was removed there would likely be significant negative torque causing the fueslage to rotate anti-clockwise. The S92 is bus-shaped at the best of times, I don't think it has much weathercocking effect without a tail rotor going round. Most likely it spun, if not immediately, then as the speed was reduced in the flare.


HC

[SASless]

HC,

Bit snippy that....after all he was asking a question seeking some enlightenment. Put a bit of sweetner in that castor oil !

[HeliComparator]

CFEOSKEY - if it truely was an open question, not a rhetorical question, then I apologise. It was the addition of the second sentence that caused my interpretation that you were really saying "so what was the problem, surely its easy enough to autorotate with no tail rotor especially when the torque was near zero". This is the problem with the written word, it can be interpreted in different ways. Only you will know what the thinking behind your question really was...

In the mean time, I have deleted the first sentence & last para.

HC

[SASless]

HC,

As there are no photos or discussion of the tear down inspection of the MGB beyond the mention of the Tail Rotor Drive failure and the photos that pertain to that.....we can make no assumptions of what the rest of the gearbox looked like. One would be flat assed guessing what it looks like.

[malabo]

Does the S92 initial and recurrent training program cover tail-rotor failures through to a successful autorotative landing? Seems to be an exercise that pilots have difficulties with on other aircraft types, to the point of reluctance on the part of some TRTO to include it in the LPC check, lest all their candidates end up failing.

Since out here in the bush we don't have the whole wide ocean, or 10,000' runway to land on, we're taught from day one to precision auto to a spot with T/R failures. One of the benefits of small helicopters I guess, but you guys have Level D sims that should allow for some pretty representative full on autos without a tailrotor.

FWIW, I feel better about the 92 now with this latest revelation than I do about the L2 coming apart at 2000'. Hazards of partial knowledge.

[js0987]

The Flight Safety school includes full touchdown tail rotor failures. I recall the entry at 1000' doing a straight in. I don't recall doing 180 tail rotor failures - full autos -yes.

It appears they were headed north, back to land, with a very stiff wind from the south. Impact was heading west. Tough to get around 180 degrees under the best of circumstances from 800ft.

One other thing to keep in mind about overwater operations. Judging your height above the water can be difficult, even for experienced pilots. There have been a number of little ships that had engine failures and misjudged the height to begin the deceleration.

Going through Naval Flight School, we were taught that when descending in your parachute, wait until you feet touched the water before letting go of your chute. That policy was adopted in WW2 as a result of the earlier policy of dropping out of your chute at 5 to 10 ft. and the resulting deaths of pilots who misjudged their height above the waves.

[JimL]

I would question the usefulness of tail rotor failure exercises for larger types in the simulator; there is little or no data and you would be reliant upon the software engineer's (or someone else's) view of the probable flight characteristics.

We used to do them in the S61 simulator in Stavanger but only as a handling exercise, not as a representative failure exercise.

The last time I heard of a tail-rotor failure (to one of these larger helicopters) and auto-rotation in the North Sea it was G-TIGK; the crew's actions were exemplary. However, they did have a number of clues that a failure was imminent.

Jim

[HeliComparator]

SAS - true, there is no info about the state of the rest of the gearbox, but with that much metal missing from the pinion, and with a gearbox that has proven it can't run for long with no oil in it, it seems likely that there would be significant degredation of the transmission drag. Not certain, just likely.

malabo - just how do you practice fulldown autos with no tail rotor drive in your aircraft? Or do you mean fulldown autos with the examiner planting his feet on the pedals so you can't move them? There is a massive difference! Or do you use a Sim?

[SASless]

When testing for competence in Emergency Procedures....is there a requirement for a "safe controlled touchdown" for every malfunction? How do we simulate "actual" failures in a safe manner in the actual aircraft particularly large complex aircraft like 61's/92's/225's/332's?

Or....are we checking for application of "procedure" with the hope of a satisfactory outcome even if not necessarily a damage free landing?

I submit we can begin to approximate some of these extreme emergencies but cannot "duplicate" them and the training point is recognition of the fault and applying the best action possible to minimize adverse consequences. That should be the pass fail point and not a pretty touchdown under "simulated" conditions.

[Geoffersincornwall]

I agree with Jim et al, tail rotor drive shaft failure is available as a malfunction in our sim but I always precede its use with a little speech that highlights the dangers of any 'lessons learnt' by developing techniques in the box.

I find it disturbing to hear folk leave us saying "well at least we now know how to handle a tail rotor failure". The reality is that simple drive failures are only 33% of all tail rotor failures (CAA data) and that complicated failures such as loss of blades, entire unit or entire gearbox can make the handling solution very different.

One thing it may teach us is that if you lose directional control you had better make your mind up pretty damn quick about reacting to the situation. The sim does at least allow you to exercise that thought process.

If the analysis is correct it seems the crew were reacting appropriately but as others have said, why no 'Land Immediately'.

Don't suppose there will be much dallying in the future.

G. :hmm:

[maeroda]

What about seizure of the hydraulic pumps and subsequently the flight controls douring the autorotation, most likely the final part of the emergency phase?
Could the loss of MGB oil have been the onset for the hydraulic pumps failure, being them normaly fitted on outputs coming from the MGB case?

:confused:

maeroda

[maeroda]

Any opinion?
:confused:

[maxwelg2]

Without the FDR/CVR running I doubt if there would be any way of knowing this, unless the TSB can perceive this somehow from the wreckage.

Remember, there was one surviving PAX, Robert Decker, who has already spoke to the TSB investigators, allthough he may not have been able to provide more details on the final stages of the crash.

I'm sure that more will come out in the next TSB update, until then we'll have to wait and see...

[491]

My brother was killed in the Cougar helicopter crash on march 12 of this year. I am trying to find the pilot of the helicopter S-92 that landed safely in aussie. My email is [email protected]

[you want what??]

i hardly think its appropriate to give out information on the Australian crew.


on a subject from the last page about the fuels tanks taking the life rafts with them. the fuel tanks will, and i believe in this case did happen, break away from the aircraft. the life raft compartment is not part of that break away section. With regard to the need for better floatation devices? well, i cant comment on the reason for not inflating, but i can tell you that there is a modification which has been around for some time called the Sea State 6 Mod. 2 extra floats fitted to the sponsons at the undercarriage mounts. UK SAR aircraft have them, as do many others in europe, but most are inhibbited waiting for something. dont know what though.

my personal opinion as a S92 type rated engineer? well, there has been about 1000 posts berating sikorsky and anyone else that can think of for the cause of this crash. while most of you guys are pilots and i understand your reluctance to do so, why cant you accept that the cause of the CRASH could just have been that the pilots didnt follow the RFM and LAND IMMEDIATLY. the failure of the oil system or the failure of the tail rotor, was only the initiation of the problem. infact does it not say in the last report that they dont know if the bolts on the oil filter bowl broke before or after the crash? they said there was signs of cracking, but didnt know when final failure occured. monitoring of the oil pressure and temperature, for those non 92 people is displayed on the EICAS screen in front of the pilot. its obvious when the pressure drops below limits as the box changes colour and the line goes from straight to having a big dip in it at the pressure read out. it also displays a numeric pressure readout, so whoever said before that you wouldnt notice a change from 5 psi to 0 psi, well you would, there is no needle to clutter things up. if either the input manifold pressure switch or the last jet pressure switch is tripped, a yellow "MGB OIL PRES" caption will appear. if both are tripped a Red "MGB OIL PRES" caption, a master caution will illuminate and a "GEARBOX PRESSURE" aural warning will sound. so there was no way to miss these things, as someone else intimated towards.

Also, if you are going to ignore the RFM and keep trying for land, knowing your gearbox could be on the way out 30 minute run dry or not, would you fly it at 130kts ??? or at 800ft???? a fall from 800ft, with no forward motion is still going to hurt, A LOT. ive spoken with s92 pilots on the matter including one who has survived a tail rotor failure of the s92. he said "30-40ft above the sea, and crawled in!" thats what the cougar guys should have done. i dont want to speak ill of the dead and they did pay with thier lives, but is this or is this not, the reason for the outcome in this case? thats not to say that lessons cant be learned, but lets stay focused.

i bet a lot of people on this thread were surprised to hear that the rotors were still turning at impact!!!!

now awaiting the backlash from angry pilots!!!

[SASless]

You,

Some of us here have said pretty much what you just did.

Early on I questioned the level off at 800 feet and the return to a near normal cruise speed. That was after the radio conversation with Cougar Ops.

I posed a question that suggested the crew made a decision to continue flight despite the last line in the checklist that instructed them to "Land Immediately!" and I queried what that decision was based upon. I still do.

These were professional pilots, well trained, dedicated to their work. They died as a result of that decision which I am sure was not made lightly or without due regard to the checklist and both their experience and training.

Asking how this chain of events occurred is certainly a valid issue to be discussed here, in future training, and in CRM venues.

One thing to remember however, is Pilots die from their decisions, Pilots also die from Engineer's decisions, Engineers get to bury the results of their bad decisions. That is why we will always be a bit demanding of those who design, build, and maintain our flyiing machines.

[you want what??]

Mixing lever,

regardless of the sea state, if you arent going to land immediatly, you should be skiming the tops of the waves and crawling!! am i wrong?

SAS,

i know some people including yourself, have asked that question, but there seems to be far to much focus on the wrong things. and as for what you said about making decisions. yes pilots can die from their decision, but think about how it affects engineers? we dont just bury it and get on with our lives. if we make a mistake and it kills the passengers and crew, how do you think that would affect us for the rest of our lives, having their ghosts haunting you till you die. i know of a number of engineers who have eventually committed suicide after making mistakes like that. not to mention that we could also go to jail. I'm not going to get into a fight over whats worse, but see it from both sides. i agree there are some technical issues that need to be adressed, and if there is wrongdoing, be accountable. but that needs to apply to everyone, not just the manufacturer. i also have dedication, extensive training, (3 years appreticeship, and 4 years to get a licence. type training on top of that. took about 10 years before i could take responsibilty for anything. how does that compare to a pilot?) and experience, but i am not allowed by law to make my own decisions. i must follow the procedures laid down, or i am liable to diciplinary action or even prosecution. i know things dont always work out that way to the letter, but you have to justify it and mitigate any potential outcomes, like if there is a bad sea state below you, keep it low and slow. not balls out at 800 ft.

no matter the circumstances, with a compromised gearbox, do you believe that was a bad decision? As someone else said earlier, sikorsky can always build you a new aircraft, thats what insurance is for isnt it?. i know hind-sight is 20-20!

on a slightly different matter, based on the reports over the families suing. if they take those arguments as reported to court, i believe they will loose.


these are the ramblings and opinions of myself and myself alone! i may not be a wise old man, but i hope im not too naive !

[madrock]

To be fair I think the TSB is focusing on the right things, according to the items being reviewed/investigated (from the last TSB report) :

The reason the recorder stopped remains under investigation.

Further examination is being carried out by the TSB Engineering Laboratory to determine the cause and sequence of this loss of tail rotor drive.

A detailed metallurgical examination of the studs, nuts, and filter bowl is under way to identify the origin of the fatigue cracks and to determine the fracture mechanism.

The reason the collars failed to inflate is still under investigation.

In addition, pilot training, human performance aspects, crew resource management, and cockpit ergonomics will be evaluated.

As a result of the fracture of the filter bowl mounting studs, resulting in the loss of a large quantity of oil, the certification guidance material is being reviewed.

Additionally, the FAA and Sikorsky Aircraft are working to identify all the modes of failure that might lead to Sikorsky S-92A MGB oil loss, determining their probability of occurrence, and developing appropriate mitigation strategies.

A number of issues regarding survivability such as passenger immersion suit and crew flight suit effectiveness, use of underwater breathing devices, adequacy of survival training, adequacy of general ditching procedures, personal locator beacons, weather/sea state flight limitations, and Sikorsky S-92A flotation system are currently under investigation.

TSB will no doubt, when considering the human factors side, look at the background as to what could influence why certain decisions were or weren't made at the time and will have access to information from many levels that has not yet been the subject of public debate.

Still wondering if the risk assessment after the Broome incident will come under further scrutiny ?

[SASless]

You,

Not suggesting engineers are a uncaring lot.....not at all. The vast majority are as you describe....are very much aware of the importance of their responsibilities.

I was trying to point out the reason why those who ride in these things have a very real interest in the non-flying half of the equation.

[Phil77]

mixing lever: What was the weather during the final moments of 491? Sea state, etc....

Myself (from first page of this thread):
Just checked the NOAA buoy data:
NDBC - Station 44251

Conditions at Station 44251 - Nickerson Bank as of
1600 GMT on 03/12/2009:

Wind Direction (WDIR): S ( 180 deg true )
Wind Speed (WSPD): 29.1 kts
Wind Gust (GST): 35.0 kts
Wave Height (WVHT): 7.9 ft
Dominant Wave Period (DPD): 7 sec
Atmospheric Pressure (PRES): 29.72 in
Pressure Tendency (PTDY): -0.20 in ( Falling Rapidly )
Air Temperature (ATMP): 36.0 °F
Water Temperature (WTMP): 32.4 °F
Wind Chill (CHILL): 22.3 °F

(maybe not the closest buoy to the scene, but close enough to get the big picture :eek:)

...I have to agree, 800 ft seems pretty high. It's a difficult call though; I can see a reason for the speed: the gearbox probably won't wait until you made it home crawling, so if you don't want to ditch, you'd have to find a compromise... and given the sea state and temperature, an intentional ditching would have almost certainly meant that somebody's gonna die - meanwhile there is always hope that it is not that bad. That's a decision I hopefully never have to make!

[[email protected]]

Phil77, I completely agree - it is a position none of us would relish - a major gearbox malfunction miles from land over a very inhospitable sea.

The decision to deliberately ditch in such conditions would come with the high probability that some of your pax wouldn't survive - think of what was probably going through the pilots mind - it is tantamount to asking him to commit murder and, when there is a perceived option (admittedly based on supposition that the gearbox has a 30 min run-dry capability) to try and get closer to land (quicker rescue) or even make landfall, one can quite understand how all the training in the world might not help make the right decision.

I have immense sympathy for the families of the pilots as no doubt they will end up taking or sharing the blame for trying to make the best of a horrendous situation which should never have arisen had the manufacturers and regulators done their jobs properly.

As for this Additionally, the FAA and Sikorsky Aircraft are working to identify all the modes of failure that might lead to Sikorsky S-92A MGB oil loss, determining their probability of occurrence, and developing appropriate mitigation strategies Isn't that what they were supposed to have done before the aircraft flew - and isn't a 'mitigation strategy' the same bullsh*t as saying there is a very remote likelihood of a failure and then allowing a sidestepping of the FARs?

[FH1100 Pilot]

Crab and Phil have it right. Let's put ourselves in the cockpit. Any of us who've flown offshore know exactly what was going through those pilots' minds as they tried to make it back to the beach with no transmission pressure.

Rock and a hard place? Oh boy! Landing on the cold, inhospitable sea would have been tantamount to murder, or just as bad, suicide. With this in the very front of their minds, they decided to press on: Surely this thing has *some* run dry capability. Surely! It's one of the big safety selling points of this new ship. I mean, everything I've read has mentioned it..."30-minute run-dry capability of the main gearbox." Well, no, not the RFM but those damn lawyers probably wouldn't let Sikorsky put that in official writing. But surely...

Slow down? Not bloody likely, not when time is of the essence and slowing down would've increased the amount of time it would take to get back to dry land. Go down? Yeah...but if you get really low, then VHF commo and being seen on radar become issues. So 800 feet probably seemed "low enough" to the crew, a good compromise altitude.

I'm also certain both of them had their hearts in their throats...because mine would have been, desperately hoping that I'd at least get some sign of impending doom before it all came apart - a little warning...something...enough to let me get the damn thing down on the water if I really, really had to, which wouldn't take me long from 800 feet. But if that was their thinking, they figured wrong.

We pilots simply have to come to grips with the fact that no helicopter transmission can be guaranteed to run for any length of time without oil, no matter what the manufacturer might say in their fancy four-color sales brochure. Of all the things that we can have more than one of (e.g. engines, generators, hydraulics...) the main transmission is the one thing that still *cannot* be redundified (or for you pedants, "made redundant").

The Cougar accident is a sad, sobering reminder of this truth.

[SASless]

given the sea state and temperature, an intentional ditching would have almost certainly meant that somebody's gonna die

Is there something about that situation that needs considering.....such as why we are flying that day at all?

Let's add in the thought the Canadian Government SAR aircraft was away for training and Cougar knew it had to provide its own SAR aircraft by established agreement with the SAR folks.

The Cougar SAR bird was not configured for that mission on a ready basis but was rigged and launched very quickly after the ditching.

There is far more to this crash than meets the eye....and all of this figures into the factors that weighed upon the crew that day.

I have worried the usual "pilot error" tag would be applied to this accident and I think if that is done then the system will have done these two pilots well and truely dirty in all regard.

What we need to do is use this tragedy to point out the very real failures in the certification system, training system, and management policies of both the oil and helicopter industry that allowed this to happen.

Otherwise, more lives are going to be lost for the same reasons.

[Winnie]

I have friends that work at Cougar, and it was an emotional time after the accident, waiting to find out if it was anyone of my friends that perished. Thankfully it was not, but that does not make it any easier.

In 1978 I lost my Godfather in an accident off Norway, in a series of accidents S-61's tossed main rotor blades. AS I was only 3 years old at the time I have no recollection of the hardships that were then, but I can certainly empathise with all who have lost someone in this tragic accident.

AS far as procedures, the only twin I am certified on, is a Twinstar, so not really relevant, only similarities are they are both helicopters, and both are twins,
Anyways, I always understood, that to reduce the impact or wear on the MRGB if you were to have any MAJOR problems, like fluid loss or excessive temps, was to slow down to "bucket" speed, and keep that, as there would be least wear and tear. This I believe is also the best rate of climbs speed, and least rate of descend in an auto. Not obviously knowing what went through the two pilot's minds during the last minutes, what made them choose to fly at this higher speed?

Reaching shore faster? as the pictures show, there was a loss of tail rotor drive, which would NOT have been as severe if they were flying at "bucket" speed...

Anyways, just my thoughts.
Cheers

[Alba T Ross]

SASless brings up a good point with SAR coverage, in the copy of the Q&A's between the rig workers, Cougar and Transport Canada I saw, the rig workers said they were not happy with the SAR time of the rescue S-92 , most people i've talked to thought it was pretty quick and Cougar should be congratulated to launch a helo so quick...... at least they had a rescue helo on standby, the UK sector of the north sea has RAF and RN Seakings and Coastguard S-92's and the Norwegian sector RNoAF Seakings and Canada has the EH-101's and backup 92's, in Australia there is practically nothing most bases do there own SAR (pretty hard with only one a/c at the base) and when you get bases hundreds of Kilometres apart help is a long way away (Karratha to Broome 650km, Broome to Truscott 615 km, Truscott to Darwin 510 km), years ago oil companies payed for SAR backup, a 214ST or S.Puma offshore machine with a 212 or 412 as SAR backup but not anymore .....cost cutting , bases may have multiple machines as tech backup or medivac backup but no hoist equiped helos for hundreds of km's, would these same Canadian oil workers who said it took to long to have a rescue helo overhead put up with the situation in Australia?

[aeronavis]

Sikorsky (KHC) installs cameras all the time on S-76 and S-92 for internal and external monitoring.

[albatross]

Search and rescue not fast enough?

I would say you would practically have needed a rescue helicopter flying formation with you to be any faster!

[SASless]

Albatross,

So may we conclude from your statement that the concern of a delayed SAR recovery of folks in the water would not be an issue in the crew's decision making that day? They were not that far offshore when the decision to return to land was made.

Remember....I am not being critical of the crew but rather am trying to narrow down the factors they would have to considered while talking to Cougar Ops about what they should do.

This is CRM at its best....pilots seeking advice from outside the cockpit.

[212man]

The crew had told ops they were preparing to ditch and requested "the boys come and get us" (or words very close to that.). There is no question that they were not planning to ditch rather than try for land - the problem is they ran out of time in the process. :(

[SASless]

What was the content of the discussion between OPS and the Crew? Anything said there that delayed the decision to ditch after the oil pressure dropped below 5PSI? As I recall the pressure dropped below the limit during the early part of the descent and well before they leveled off.

[albatross]

SASLess sorry if I was not clear:

12:26:26 St. John's radar records the last radar return of CHI91 at 300 feet.

12:26 Gander ACC advises search and rescue that CHI91 has ditched. Cougar dispatch confirms the ditching with search and rescue, and advises that they will launch Cougar 61 as a rescue helicopter.

12:42 A Provincial Airlines patrol aircraft arrives at crash site and observes two people in orange immersion suits in the water.

13:07 Cougar rescue helicopter departs St. John's.

13:25 Cougar rescue helicopter arrives at crash site and spots two people (one of whom is later confirmed dead), two rafts and helicopter debris.

13:33 Cougar rescue helicopter lowers a rescue person toward the people in the water.


A/C overhead 16 minutes after impact.

Rescue helicopter overhead 59 minutes after impact

Rescue swimmer lowered 1:07 minutes after impact.


In my opinion that is very fast crash response in Canada or the US. Big countries.

In many parts of Canada you are advised not expect rescue for at least 24 Hours. They do everything possible to get there sooner but sometimes the nearest asset is thousands of miles away.

Of course I believe the concern of a delayed SAR recovery of folks in the water would be an issue in the crew's decision.

What I am disagreeing with the rig workers saying that they were not happy with the SAR time of the rescue S-92.

To be on scene any sooner there would have had to be a SAR machine just about running on the ground.

Of course we would like to have a helicopter overhead immediately and for all to be rescued.

[maxwelg2]

What I am disagreeing with the rig workers saying that they were not happy with the SAR time of the rescue S-92.


Albatross, the reason that the offshore PAX were not happy with the SAR time is down to the fact that the current Helly Hansen E-452 immersion suits are not effective in preventing water ingress, thus reducing the survivability time greatly in our harsh environment. The only survivor Robert Decker had mild hypothermia after less than 90 minutes in the water, all because his suit let in water. We are currently flying over here with these suits after being supposedly fit-tested by Helly Hansen. The problem is mainly the face seal as there are very limited sizes. If you fail the suit fit test then some of the operators will transfer you by vessel, and you use a Fitzwright immersion suit for Frog transfer.

The issue is not the SAR response time IMO, it's the suits and the fact that this helo should have ditched immediately upon loss of MGB oil pressure below 5 psi. We need a decent survival suit and the chance to use it via a controlled landing. If this means tighter restrictions of weather/sea state conditions then so be it.

As to the events of 491, we are still waiting for the final TSB findings to explain the root cause failure of the titanium studs, and explanation on the other areas of concern raised in the report such as the activated flotation bags not inflating and the leakage of fuel, suspected to be from the sponson tanks. Still a lot of questions to be answered...

[SASless]

Alabatross,

The SAR effort was very good.....not saying anything derrogatory about the actual response time itself.

My question could have been better stated.

I will try again so you can understand where I am headed with the question.

The day of the crash, the goverment dedicated SAR machine was away for training.

That information was known ahead of time.

That required Cougar to be their own SAR unit.

That is a standard practice as I understand it.

Did Cougar have a 92, SAR equipped, manned, and on standby ready for launch?

Or....did they have an aircraft available with access to SAR qualified crews and upon callout....then prepare the aircraft for the SAR mission by outfitting the aircraft with the SAR mission equipment and removing a few seats?

That is the only interest I have by asking the question I did.

I know for a fact without any reservation.....that when told of your friends, fellows, and "family" being the reason for your SAR mission....anyone would turn Heaven and Earth to get out there and help them anyway you can. I know that was what happend that day and as it should have.

The only question is was the aircraft loaded and cocked before the call?

[albatross]

All good points both SASless and Maxwelg2

I trust the final report will address these issues.

[iceberglead]

SASless;

I think you must understand by this point in time that some people are upset with your seemingly relentless drive for intimate details in a fatal accident. Give it up numbnuts. What is done is done. All the conversation to this point has cumulative value to prevent this happening again. It really upsets me to see an old fart pusrsue details of an accident that is investigated by a national body, the safety standards of which sets precedents in the world. When Transport Canada is ready for information release they will let us know, in the meantime, curb your comments. I have faith in the system.
Now, this should give you hours of fun for rebuttal.
Personally, you remind me of a guy that had a bad career and has to somehow justify it by adding endless comments about bull**** on this forum.
I fly helicopters for a living and realize the danger as do most other guys on this forum so tell me again, what is your point??

Do you think by exposing manufacturer's weaknesses this is going to improve the economic outlook??

Hard line is boys, if you feel scared, don't fly. That goes for the pilots and the people they fly. Accept the risk and make the big money, I don't hear any hard stories about that.

Bunch of hypocrites if you ask me.

:rolleyes::ok::O

[SASless]

Iceberg,

Questionable approach to helicopter safety you seem to have.

Am I correct in assuming you feel there is no value in discussing safety issues before, during, or after flight....to include incidents, accidents, injuires, and deathes that result from them.

Is it you resent the questions, the answers, lack of answers, or the fact one must confront such issues at all when you object?

Tragedies such as this one should be mined for all the positive value we can find as otherwise it would be a real waste of money and people if we did not. It is the lessons we learn from these events that help prevent future tragedies. That can only be done by a fair, reasonable, objective discussion of all the factors and issues that pertain to the event.

As to pointing out anyone's weaknesses.....is that not what a proper safety program is all about? Does it matter whose ox gets gored if the outcome is an improvement in the operational safety for those of us who are flying the line and living with the inherent risks of our occupation.

The key is to be able to live long enough to become an old Fart and retire. I did that....with an accident/incident free career. Perhaps in time you might do so as well although the odds might be against you if you really feel the way you suggest about cowboying up and damn the risks.

The goal is to minimize risks by identifying those that exist and mitigating the ones that can be eliminated, cured, or reduced. That requires and open, free, objective discussion of the issues.

I have been criticized before for being a strong advocate for safety....but then I have seen way too many friends killed as a result of safety failures during my flying career that started in 1967. I see posing questions as a way of soliciting information or generating a discussion. If that offends you then you will have to get used to it.

[Senior Pilot]

iceberglead,

I have deleted the last 4 posts of yours, as they are not wanted on this thread. If you have an issue with SASless on a personal level, keep it outside this Forum.

[maxwelg2]

I fly helicopters for a living and realize the danger as do most other guys on this forum so tell me again, what is your point??

Iceberglead

I truly feel sorry for you, please do not attempt to comment on an industry which you do not understand/appreciate and obviously do not operate within, where we are all trying to improve helo safety and PAX confidence. Your negative comments are not appreciated.

I hope that you never have to say goodbye to personal friends and colleagues due to compromises in helo safety like we have had to.

Max

[carholme]

Families drop lawsuit, no other details.

Families of passengers on downed N.L. chopper 'voluntarily discontinue' lawsuit - Yahoo! Canada News (http://ca.news.yahoo.com/s/capress/090804/national/nl_chopper_lawsuit)


carholme

[Lonewolf_50]

Also, if you are going to ignore the RFM and keep trying for land, knowing your gearbox could be on the way out 30 minute run dry or not, would you fly it at 130kts ??? or at 800ft???? a fall from 800ft, with no forward motion is still going to hurt, A LOT. ive spoken with s92 pilots on the matter including one who has survived a tail rotor failure of the s92. he said "30-40ft above the sea, and crawled in!" thats what the cougar guys should have done. i dont want to speak ill of the dead and they did pay with thier lives, but is this or is this not, the reason for the outcome in this case? thats not to say that lessons cant be learned, but lets stay focused.
You have raised my curiosity enough to break lurk mode. I may have an answer for your question.

I realize the S-92 isn't the Seahawk/Blackhawk, but I do recall that if you are trying to make it to the ship and your MGB has chips/secondaries/out of oil, the profile you were given in the NATOPS manual was fifty feet and fifty knots. Granted, that guaranteed nothing. It put you into an envelope where the next symptom of "it all going wrong" allowed you a quick drop-flare-ditch to egress and swim away with your lives.

The discussion here on the risk management challenge the aircrew faced has been sobering.

"Yeah, I can ditch, but will likely freeze to death once I do." Thanks, I'll not sign up for a bowl of that soup, given a choice. :(

However, if that's how you read the situation, I understand why an aircrew would choose a course of action to avoid a ditch as long as practical, and hedge against possible TR thust loss.

Did the TR drive failure catch them by surprise? Likely. Might have been looking for a failure in the main and had a delayed reaction to the TR drive loss.

But back to the decision to get as close to land as soon as could be done. Something conservative like fifty-fifty gets you there slow. If the crew believes in a 30 min "mulligan" for this hole, it barely gets you where 130kt/800' does in terms of "we will likely freeze to death" as an alternate assessment.

As noted above, when the TR stops doing its work, you auto.

So, to answer your question: why choose 130 kts?

130 knots looks a little like the kind of airspeed we were taught to fly if we had a TR drive failure in a Seahawk (around 125 kts actually), hadn't lost energy/nose into the wind configuration, and were trying to keep the nose streamlined into the wind. (Can't recall if anyone ever successfully pulled that off for long enough to find a place to auto ... memory foggy)

The crew might have been anticipating a lost TR, and thus had the helicopter at an airspeed that would keep the nose from cocking/tucking right, and creating the nightmare "one quarter turn broadside to the wind that commits you to the auto." That quick tuck/massive drag problem got a guy I knew killed in San Diego, TR drive failure, back in '89.

Granted, I freely admit that I am applying a bit of apples and oranges here. I base that estimation on the S-92 being a bit of a Blackhawk/Seahawk on steroids. (yes, a gross estimate.) If any of the S-92 drivers can tell me how close my guess is, in terms of

"Can you keep xxx knots up and prevent the nose from breaking right with te TR losing drive"

I'd appreciate it.

It is very sad to read of mishaps like this, when the choices between the devil and the deep blue sea plays out so tragically for those in peril in the air.

Vaya con Dios, amigos

[212man]

The crew might have been anticipating a lost TR, and thus had the helicopter at an airspeed that would keep the nose from cocking/tucking right

I would think that was the last thing on their minds!

"Can you keep xxx knots up and prevent the nose from breaking right with te TR losing drive"

There hasn't been a TR drive failure on the S-92 (prior to this accident) and so no-one can tell you. Any reference to the simulator should clearly be ignored. The incident the other poster dramatically refers to as a "TR failure" was in fact a loss of TR pitch control - an entirely different situation (albeit very well handled by the crew concerned.)

[TalkSpike]

LW50,

While the blackhawk/seahawk has a tail rotor vertical fin with aerodynamic properties that offsets tail rotor thrust , almost completely at around 120 KIAS, the S92 does not.

In the BH/SH you do not have to enter auto if you lose tail rotor drive in forward flight because of the aerodynamic properties of the vertical fin, in the S92 you have to enter auto because the vertical pylon does not stop you from spinning.

Not sure why they did not incorporate the vertical fin into the S92, it just makes sense to me.

TalkSpike.

[JohnDixson]

Wish it were true, Tail Spike, but the S-70 family will not maintain level flight in this situation, even at a large slip angle.

The original US Army requirement was for the UTTAS to be able to accomplish this, with no more than a 20 degree slip angle at max endurance speed ( ~80 KIAS ). Thus the huge, and highly cambered, original tail that was flown on the prototypes for most of 1974. Someone will ask about why we didn't use a fenestron in order to meet this requirement ( we had already flown a large fenstron made by Hamilton Standard on the S-67 original Blackhawk ), but there were a number of factors at play:

The T-700 engines were already selected by the Army so the power available was a fixed number.
The Army had a vertical climb requirement stemming from UH-1 issues in Vietnam, and everyone knew that this requirement had to be met or exceeded.
The cabin size, crashworthy structural requirements, fuel/range requirements etc pretty much sized the machine.
The Army had strong directional control thrust requirements.Given all this, there wasn't room, from a performance standpoint, to accept the fenestron performance penalty. One can envision a fenestron that would provide the same thrust as the present 11' diameter tail rotor!

In spite of a few very elegant pieces of aerodynamic structure* , instrumentation and data analysis wizardry, and after a lot of flying, we could never satisfy ourselves ( not to mention anyone else ) that we had achieved the goal. On top of that, that original tail brought on terrible, speed related, directional control trim change requirements for the pilot and in themselves, a violation of the US Army handling requirement specification.

* The UTTAS competition had a fixed schedule, with a head to head fly-off with Boeing. So anything that was suggested to fix problems brought with it heated discussions about risk to making the fly-off on time . One of the suggested tail changes to meet this requirement/problem was an entirely new vertical tail with a triple slotted arrangement ( new tail structure from the intermediate gearbox up ). Talk about sophisticated aerodynamics! The manufacturing director told us that if this was the answer, he would have to build not one, but three, one for each of the competition aircraft. Approval was granted and he had three totally new tails built. I likened the effort to that which I've read existed at Supermarine in coming up with Spitfire advances in the middle of a war ( see the Jeffrey Quill book " Test Pilot" ). Anyhow, we finally received and installed the first one and went out and flew it.....one time. None of the aero predictions were accomplished and we stacked all three brand new tails in a corner of the hangar.

So, faced with taking possibly two spec non-compliances, and being hardly certain of the zero tail rotor thrust results with the big tail, we changed the vertical tail to its present geometry, solved the trim issue, and took the deviation on the other issue.

There was no lack of effort, though.

Thanks,
John Dixson

[TalkSpike]

JD,

Having a quick look through by BH notes, the emerg proc for insufficient tail rotor thrust in flight has two options:

1. if continued flight is not possible........
2. If continued flight is possible........

In this emerg the S92 has one option:

1. Enter autorotation.

The one flight control coupling that the BH has that the S92 does not is collective airspeed to yaw, an electrical coupling provided through the trim. Due to the camber of the tail rotor pylon (not present in the S92) trim inputs are used to counter left yaw produced due to lack of airflow over the pylon. The trim input is slowly washed out until the IAS reaches approx 120KIAS.

Could be wrong but it is my belief the reason you may still be able to maintain continued flight in the event insufficient TR thrust in the BH is due to the properties of the tail rotor pylon. Personally never tried it myself and maybe it would only work with partial loss of thrust?

Anyway I'm sure there is a good reason this coupling and the properties of the tail rotor pylon were left out of the S92, maybe someone else can answer that question.

TalkSpike.

[212man]

Talkspike,
Although the tail pylon is not cantered, the TGB is, so the effects are similar. Regarding coupling, the mixing unit does have a mechanical Collective/Yaw function, but not a trim related airspeed one that you describe.

The RFM has the following preamble to the TR malfunctions section:

With loss of tail rotor thrust, it is impossible to remain in level flight. This failure is associated with a loss in drive and characterized by a sharp, right yaw of the aircraft that requires immediate entry into autorotation (if in forward flight) or landing (if in a hover). If thrust is lost in forward flight (60 KIAS or above) roll excursions up to 10°, pitch attitude changes up to 5° and heading changes up to 50° may be experienced during the transition to autorotation. Once established in autorotation the aircraft can be flown to a stable pitch and roll attitude with an acceptable level of sideslip

[Blackhawk9]

Went back thru my old Black hawk notes (1988!) and it said that the side lift from the cambered fin helps unload the tail rotor at approx 100knts and above 100knts (approx 120) flight with loss of t/r should be possible? and that was from Sikorsky instructors ,when I saw the 92 had no camber on the fin I thought it must be
A: the loss of t/r drive was so remote it wasn't needed or
B: it wouldn't matter how big the camber or fin size was it wouldn't stop the a/c from spinning.

Thanks for your insite into the fins on BH John.

[JohnDixson]

Is it possible that your notes were in reference to the amount of tail rotor control available to the pilot after losing hydraulics to both stages of the tail rotor servos? In that instance a loss of both the No.1 Primary and the No. 3 stage ( powered by the 3rd stage electrically driven backup pump) is assumed , so only the No.2 Primary pump is running. That pressurizes the boost servos however, and so, since you still have a yaw boost servo working for you, between it and your strong legs pushing on the pedals, you can force a limited range of tail rotor control. That control range is under most circumstances good enough to fly level from about 40 kts to 120 kts, ( with the aid of some very small aerodynamic assistance from the remaining very small cambered section of vertical fin that exists ). And it is quite enough range to allow a run-on type landing.

This discussion assumes that tail rotor drive is intact.

Thanks,
John Dixson

[maxwelg2]

For those interested the inquiry into helo safety in NL commences in full tomorrow. Attached is the link to the site where you can review the transcripts and testimonials.

Offshore Helicopter Safety Inquiry : Home (http://www.oshsi.nl.ca/?Content=Home)

Hopefully some good will come out of this tragedy to improve safety in our industry...

Safe flying

Max

[Dan Reno]

Chopper instantly filled with icy water after N.L. crash, sole survivor says

1 hour, 23 minutes ago

By Sue Bailey, The Canadian Press

ST. JOHN'S, N.L. - Robert Decker clung to the seat in front of him when the pilot of Cougar Flight 491 called over the helicopter's PA: "Ditching, ditching, ditching!" moments before the helicopter crashed in the North Atlantic.

The lone survivor of the devastating disaster on March 12 described the doomed aircraft's last terrifying moments to an inquiry packed with loved ones of the 17 people who died that day.

"I guess almost as soon as they said 'Ditch' the helicopter lost control," Decker said Thursday in his first detailed public account of the tragedy.

"I was looking out my window for most of it so I knew when we were going to hit the water."

The 28-year-old said the chopper's bow came up slightly and the aircraft turned quickly to its starboard, or right side, just before it crashed about 60 kilometres east of St. John's.

"The next thing I can remember was waking up in a submerged helicopter," Decker said.

"It was instantly filled with water ... it was kind of as if it was sinking the same way it was dropping through the sky."

Decker showed little emotion throughout his testimony, except for when he thanked the rescuers who saved his life, which brought him to tears.

Since 2006, Decker has worked as a weather and ice observer with Provincial Aerospace. He had flown about 50 times to the three offshore oil sites about 300 kilometres east of St. John's before that fateful day.

Decker had been asleep in a window seat along the starboard of the Sikorsky S-92A. A passenger woke him up just as the pilot announced a mechanical problem that forced the flight to turn back toward land.

He initially didn't think much of it.

It was a cold, clear day that seemed ideal for flying, Decker said. He wasn't supposed to head out until the next day but had received a call the night before asking him to move up his trip because of ice conditions at sea.

Window seats are coveted, and people try to "muscle" to the head of pre-boarding lineups to get them, he told the inquiry.

"Everybody's looking for the most comfortable seats so you don't have to sit next to anyone or the auxiliary fuel tank," Decker said.

He stressed in later testimony that it would have been "next to impossible" for those in seats away from the windows to escape."I just can't see how this person would ever stand a chance," he said, pointing to a rear inside seat on a diagram of the chopper's layout.

There was an auxiliary fuel tank blocking windows on the port, or left side, of the helicopter.

After the crash, the helicopter was dimly lit from the glow emitted by the survival suits that each passenger had hastily zipped up in the flight's last moments.
Fighting the water pressure inside the plummeting chopper, Decker unbuckled his seatbelt, escaped through the broken window beside him and floated toward the light above.
Once he broke the surface, he managed to inflate a pillow-like flotation collar on his suit to keep his head above water. But he couldn't get to two lifeboats floating nearby nor fully use his hands because the cold water numbed his fingers.
Trying to swim with a ruptured vertebrae, dislocated ankle and broken sternum "was a losing battle," he said.
Decker remembered worrying that he was paralyzed until he realized he could move his toes. He talked and sang to himself to keep panic at bay, though the fear of internal bleeding gripped him.
Decker had also inhaled sea water, though he doesn't remember fighting for breath.
He recalled seeing a Provincial Aerospace plane flying toward him. At one point he fought panic again as the plane appeared to turn around.
He knew he'd been spotted when the aircraft flew low over him and tipped its wings.
A Cougar search and rescue helicopter arrived later and a basket was lowered. But by then, Decker was hypothermic and could hardly move because of the icy water that had seeped into his survival suit. His body temperature on arrival at a hospital was logged at 28 C, nine degrees below normal.
Rescue swimmer Ian Wheeler, the leader of Cougar's in-house search and rescue team, was lowered into the sea beside Decker, who said he was almost blind and irrational with shock by that point.
Decker thought he recalled Wheeler yelling something about needing to go back for another piece of equipment.
He remembered grabbing Wheeler, begging him: "Please don't leave me here."
Decker was hoisted into the chopper and rushed to a St. John's hospital where he remained for nearly three weeks.
He said there were long-standing concerns among passengers about survival suits that don't properly fit. And he said the five-day simulated crash training he took in 2006 was inadequate.
"A couple of days of controlled immersion in a pool every few years is not enough to allow anyone to develop the instinctive reactions that they need to have a chance of escaping a helicopter crash like Cougar 491."
He credits his survival to a childhood spent sailing the waters of Conception Bay - and sheer luck.
"Many times I've been thrown into the cold sea water from an overturned boat. I think that experience meant that when the helicopter suddenly filled with icy water I could react instinctively ... it was like a reflex to take a breath and hold it and to stay calm until I could get to the surface," he said.
"I don't think that anyone will ever know why it was that I survived this disaster and the others did not. There probably is no good reason. Just luck."
Decker said he won't fly offshore anymore. But the key to protecting workers who still board choppers everyday lies with the safety of the aircraft, he said.
"Safety starts with the helicopter and I think everything else is secondary."
The inquiry is trying to assess whether the risks of flying to the offshore are as low as is reasonably practical.
Union leader Sheldon Peddle, who represents about 700 offshore workers, said he is confident Cougar is a cautious operator. It's the Sikorsky S-92A he's not sure about.
"With all of the issues that we're seeing, I just hope we don't have another crash," he said.
Sikorsky officials were called this week to inspect the main gearbox of an S-92 to determine what caused a hairline crack on a chopper based in Halifax.
Two international aviation regulatory agencies also recently issued directives that mandate visual inspections of the mounting feet of S-92s after every 10 hours of flight.
The Transportation Safety Board is still probing the crash, but investigators have said that a mounting stud on the filter bowl assembly broke, causing a loss of oil to the main gearbox.

[Heli-Ice]

Dan

Thank you for the post.

[Dan Reno]

You're Welcome Heli-Ice
............................................................ .............
Offshore union hopes survivor's testimony brings change

Source: CBC News

Posted: 11/06/09 7:34AM

Filed Under: Canada (http://news.aol.ca/canada)

A union leader representing offshore oil industry workers in Newfoundland and Labrador says testimony from the sole survivor of the Cougar helicopter crash underscores serious problems with offshore safety.
Sheldon Peddle, who works on the Hibernia platform and is president of Local 2121 of the Communications, Energy and Paperworkers union, sat in an inquiry room Thursday and listened intently as Robert Decker told his story of what happened before and after the crash.
Decker was testifying at the inquiry into offshore helicopter safety, prompted by the March 12 crash off St. John's that killed 17 people.
Peddle said he sometimes struggled as he listened to Decker explain what he went through after the Sikorsky S-92A crashed into the ocean and sank into deep water.
"I think for Robert it was hardest of all," Peddle told CBC news following the testimony. "I noticed that for a little while he struggled a bit. I did myself actually. Yeah, It was pretty tough."
Decker told the inquiry that the training people must complete before they are allowed to travel to offshore work isn't adequate.
"As good as the training is, a couple of days of controlled emergency training in a pool [are] not enough to allow anyone to develop the instinctive reaction to survive a crash like this," he told the inquiry.
Decker escaped the helicopter as it plummeted deep into the ocean. He said that when he reached the surface, he had problems with his survival suit.
"I couldn't get the gloves on and even in the training in warm water when you have complete dexterity with your fingers, I think they're a little bit tricky to get on. And there is also a shield that you pull over from around the hood that kind of protects the spray from getting on your face and I wasn't able to access that, either," Decker said.
Peddle said he shares Decker's concern about the survival suits.
"I haven't flown in a helicopter since the spring because of survival suit issues. I don't have a suit that fits me," he said.
Peddle said he hopes Decker's testimony will have a powerful effect on the offshore industry, as the offshore workers he represents still have many questions about the Sikorsky S-92A.
He said the latest news that a crack was found in the gearbox footing of a Halifax-based Sikorsky this week has amplified their concerns.
"To know now that we are developing cracks in the gearbox is a very unsettling thought. I think a lot of members feel that the helicopter has significant safety problems."
Following Decker's testimony, the offshore helicopter inquiry adjourned until Nov. 16.

[Steve76]

There certainly is much more scope for more realistic training for offshore workers but good luck trying to get their fat arses out and into a realistic environment.
As for survival suits not fitting correctly? Perhaps they should address limiting the size of persons who are flying offshore? Lets face it - no matter if you had ejection seats in these aircraft, most of the offshore workers are tragically unfit and wouldn't survive 'realistic' conditions. Before decisions are made about safety offshore - persons should address their personal contributions to their survival.

As for all the copious discussions about what these pilots did correct and incorrectly - its totally irrelevant. There is a time and place for 'seat of the pants' flying and trying to outsmart this problem via the checklist is folly. You can apply all the numbers and end up well behind the curve. We seem to be living in an time of life where human interface is being discredited and superceeded by computerisation and this is contributing to a disassociation between the pilot and his aircraft. We don't fly airliners, we shouldn't be 'managing' our aircraft but integrating ourselves into them. I have always said "strap the aircraft on and take responsibility for it"
Never let the aircraft or environment call the play. Flying offshore decays a pilots hands on feel for his aircraft and complete simulator training exacerbates this lack of 'feel'.

Sit back and read some stories about the old timers. Some of these guys performed miracles with aircraft problems they encountered and they knew half the information we do about POF or aircraft physics. I'm humbled as I consider what problems they dealt with.

I just wonder if its time for a complete rethink of training and pilot selection. We can have all the safety systems in the world. Its a dangerous job and you get one shot at making a good decision.

[maxwelg2]

There certainly is much more scope for more realistic training for offshore workers but good luck trying to get their fat arses out and into a realistic environment.


Dear Sir

I hate to burst your bubble, but the offshore oil and gas industry is not a military regime, it's a business, and in such the oil companies and relevant authorities decide who is fit for work, not you. For your information all offshore workers have to pass a CAPP medical every 3 years, and shorter intervals the older you get e.g. 40+ is every 2 years, including a EKG. The BST-R survival refresher is not a simple walk in the park either, trust me I've done enough of them. You don't pass the course you don't go offshore, period.

Survival training is always a compromise of what is safe to do whilst emulating actual typical scenarios e.g. current limits on immersion depth when performing HUEBA training to prevent potential injury to lungs. I'm sure that what we currently do will be reviewed and revised by suitably competent organisations post-491. Continuous improvement is key in all aspects of helo operations.

How realistic do you wish things to be? Do you actually think that a more rigorous training regime such as cold-water immersion in a leaking suit every 3 years would prepare anybody for a 20G crash? We already jump off a perfectly good boat every 3 years and know what the feeling of the Grand banks sea on your face is like, but in an immersion suit that generally doesn't leak, and from a controlled escape route.

Robert Decker has made some excellent statements, especially the one regarding the helo should stay in the air, everything else is secondary.

So give us controlled landings in the drink as a last resort (SS6 for S-92 plus enough run-dry time to allow a soft and upright landing), suits that keep us dry, therefore a better chance of escaping a capsized/submerged helo (HUEBA now gives us that at least) if you really want to be proactive.

On a more personal note I'm sure you will receive similar feedback from us PAX up here who remember the loss of our fellow colleagues on a daily basis. I just hope that your comments do not get read by the families of the deceased. Shame on you for being so insensitive, especially considering what thread you have decided to post on.:=

Max

[js0987]

Max,

Everyone on this board appreciates your comments about the tragic accident. Another forum would probably be a better place for this discusion but let me offer a partial defence of Steve76. Apparently in Canada and other places, all offshore workers have to go through a complete physical and demonstate a level of fitness, but here in the Gulf of Mexico, that kind of screening is problamatic at best. We often have a problem with passengers, who to say the least, are huge. This is especially true of service hands. I'm sure any of us who have been doing this for some time have had to refuse to carry passengers because they couldn't get the life jackets on or couldn't get the seat belt around them. That's the easy part. Its the passengers that can - barely - that I worry about were an emergency ditching to happen. Frankly there should be no need for a special step for passengers who weigh over 400 pounds for the 92.

I will say that histroy has shown, in a controlled ditching, passengers can and do escape often with no training at all. The Northwest Airline ditching in the Hudson River, the Bristow Super Puma ditching several years ago in the North Sea and the Air Log 76 ditching after the Allison engine blew up and took out the DC junction box meaning no floats and the aircraft immediately began to roll over are some examples.

Perhaps as part of offshore training, having everyone demonstrate they can fit through a window frame should be required.

[maxwelg2]

Thanks js0987 for the clarification and positive feedback

After reading through some of Steve76's previous posts I appreciate that he may be inadvertently comparing NL PAX to GOM PAX, or even New Zealand PAX where I believe he was once based/originated from, however that may be highlighting a GOM PAX offshore certification issue completely unrelated to this thread. As you suggested, perhaps a new thread should be set up to assist in discussing that issue. Without knowing all the relevant facts of helo ops up here in NL and the ongoing safety inquiry it is not possible IMHO for anybody to make such statements.

Wrt. PAX being able to fit through a S-92 window, that most definitely should be one of the revised aspects of all HUET training where this type of A/C is operated, same applies for all other A/C. The NL BST and BST-R HUET does have modified windows that are meant to emulate the S-92 size, but don't quote me on the size comparison being exact or realistic. What I can say is that myself at a strapping 240 lbs can fit through the provided gap easily, even with the big clumpy E-452 flight suit boots. I recall offshore "bears" from my North Sea days that would never fit through a Tiger or Super Puma window, and we used to all avoid the middle seat at the back as everybody knew your survival chances from that spot were certainly reduced. So what's changed, well for one thing PAX confidence in helos, particularly the S92a. That's a human nature reaction and sadly only time with no further accidents will bring that confidence back. The latest scrutiny of the MGB housing mounting feet cracks, and still no official report from TSB confirming the root cause failure mode of flight 491 is definitely not helping things...

One of the other issues that Robert mentioned was the HUET exercise only being performed with 2 PAX at a time as earlier BST courses highlighted inboard PAX having issues with the window-adjacent PAX restricting their egress. So do we now go down to a no aux fuel tank configuration and/or seat reduction to remove inboard seat positions? I'm sure the operators won't be keen on that option, more flights = more risk = more cost = what's the benefit of using a S-92 now? Is the 19-seat configuration approved based on yet another extremely remote statistic?

Interesting times ahead...

Safe flying

Max

[Steve76]

Without intending to be completely obnoxious, I hardly think that the pax carried offshore in NFL are any better than those in the global offshore market. Neither physically better nor more better trained. Everyone does HUET & sea survival and as stated earlier - plenty of instances of successful HUET moments in real life.
I just don't want to see a fine aircraft blamed. We seem constantly to be looking for excuses or something to blame for what is just an accident. To infer that any aircraft out there is not built to be 100% faultless by intent is ridiculous.
What are people hoping to gain from this? The safer option is to take the boat. Go for it. The same environment sank the Titanic.

What has happened to PPRUNE. It used to be PILOTS discussing PILOTING issues. Isn't there a better place for passangers to take their complaints? Are we fuelling a debate here and informing persons with ZERO experience behind the controls and NO aviation qualifications?

How detremental is this to our industry. How many of these posts are from the media?

[riff_raff]

maxwelg2,

The MRGB in the S-92, like all other FAA certified rotorcraft MRGB's, is qualified for operating in a 30 minute loss of lube condition while maintaining power levels sufficient for level flight. Thus the pilot has a 30 minute period after the HUMS gives an indication of loss of lube circuit pressure, in which to continue at level flight and/or perform an emergency landing. So that should not be a concern to you.

Regards,
riff_raff

[Heli-Ice]

Just to make clear, I have little experience with other helicopters than the Schweizer 300C so I am not able to base my comments on matters regarding other types than on what I read about them.

From my point of view I find it worrying that in case of a TR failure in the S92, the only option is to enter autorotation.

Another worrying thing is the cracks observed in the MGB housing mounting feet. From reading about these facts, I am not sure if I would be comfortable flying these machines. One of my friends works at Cougar and he is very satisfied with flying the S92 and he tells me that Cougars' approach to all around safety in their operations is of the highest standards.

The S92 seems to be a safe machine and has accumulated lots of flight hours in harsh environments without many major problems. I am sure that Sikorsky is doing everything to make their helicopters as safe as humanly possible however, the teething problems seem to be of the bigger nature and I am not surprised that passengers are a little worried when strapping in those machines.

I agree with those who say that it is not fair to blame the aircraft if the passengers are not able to squeeze themselves out the aircraft windows because of the passengers size or fitness. HUET training, as is with all other emergency training in offshore operations, is an absolute necessity. I don't know the intervals of that training with the offshore workers but maybe that is something that needs more attention from the operators?

In Iceland, all fishermen have to undergo Maritime Survival Training before being able to take on jobs on fishing vessels. But they only have to do recurrency training every 5 years which I believe is to infrequent. I have done that training and I think it is very important, but I have to say that I would like to be able to do that at least every 2 years to be better prepared if/when things go wrong.

From my point of view as a pilot, I think that the HUET training of offshore workers should be performed at least every 2 years and at best, annually. When things go wrong out at sea, on board ships or other man made stuff that hits the sea, it is every man for himself and from that point of view, good emergency training cannot be replaced by any kind of emergency equipment. If you don't know how to operate the equipment or know how to react or where to go, you are in for trouble. We should never have to depend only on luck in emergency situations.

That being said, I am in no way saying that the emergency training was a deciding factor in survivability in the Cougar crash, nor am I saying that the unfortunate people on board the helicopter were unfit or badly trained.

Lets just make the most out of learning from this terrible tragedy to prevent it from happening to others.

[Brian Abraham]

Oh dear, cue HC. You're off the chain HC. ;)

[Geoffersincornwall]

HUET is not as universal as you make think..... or wish. There are 45,000 offshore workers in the Campos Basin, Brazil, whose (Petrobras) employers have been persuaded NOT to introduce HUET. I am not exactly sure who has persuaded who but it is not been mandated and it is a regrettable lapse.

There is a first class HUET training facility in Macae but, alas it was just ticking over last time I was there.


G. :hmm:

[HeliComparator]

Thanks for the prompt Brian, but life it too short to go round that loop yet again - maybe its your turn to clarify the point now you are enlightened!

Clearly the guy knows nothing about the S92 since he think its the HUMS system that alerts the pilots to low oil pressure. I think by now all S92 pilots understand the capabilities of the transmission in the absence of any oil, so my work here is done!

If the on-lookers still don't understand and can't read does it really matter? Moral: Never listen to your maintenance technician telling you what the aircraft can and cannot do, just follow the RFM!

A mellow HC

[Outwest]

maxwelg2,

The MRGB in the S-92, like all other FAA certified rotorcraft MRGB's, is qualified for operating in a 30 minute loss of lube condition while maintaining power levels sufficient for level flight. Thus the pilot has a 30 minute period after the HUMS gives an indication of loss of lube circuit pressure, in which to continue at level flight and/or perform an emergency landing. So that should not be a concern to you.

Regards,
riff_raff

Are you on drugs man???

[maxwelg2]

What has happened to PPRUNE. It used to be PILOTS discussing PILOTING issues. Isn't there a better place for passangers to take their complaints? Are we fuelling a debate here and informing persons with ZERO experience behind the controls and NO aviation qualifications?

Steve76, I came across this forum when initially looking for background information on the S-92 after Cougar 491 by Googling it. Perhaps if PAX were better informed of the technical abilities of the helo industry and equipment certification requirements we would all improve our mutual respect for each other's jobs. As PAX we generally assume that all equipment in use as part of our jobs and the way in which it is operated has been risk-assessed to be as low as reasonably practicable (ALARP). What do you define as ALARP, FAR 29 "extremely remote" classification? If so, then will the S-92 MRGB not exceed that definition until there is another MRGB failure? Did the RFM reflect that or was a 30-minute dry-run time assumed?

I know of quite a few PAX up here in NL who look to this forum for information either out of general interest, or whilst waiting for the TSB investigation and ongoing helicopter safety inquiry to complete their due process and provide findings as applicable. In hindsight perhaps this forum and the lack of rumour control and media usage of such outweighs the benefit to all. Personally I have a better understanding of the limitations of the S-92, in particular the current lack of MRGB run-dry time.

If you do not wish to engage PAX in a proactive and information-sharing way, then perhaps you should discuss this matter with the moderators. I for one would see this as a step backwards in collectively advancing helicopter technology awareness.

Heli-ice, you make some excellent points wrt. offshore safety training. In NL we currently do a refresher survival course every 3 years, used to be just 2 days, but may be longer now with the addition of the HUEBA training, which we did this year as a 1-day separate course. I suspect that we will see quite a few more changes in offshore survival training, and perhaps even in the offshore medical requirements. This however will not replace resolving the currently known S-92 "teething" issues.

Safe flying

Max

[madrock]

The first cracks in the MRGB mounting feet were noticed 10 months ago. Since then, it has happened not once, or twice, or six times, it's happened a lot. Tight inspection and replacement schedule of the main mounting bolts has been introduced, along with a re-designed OEM press fit process for the steel bushings, and it's still happening ?

A Sikorsky rep. was recently quoted ""Analysis shows the aircraft can operate safely for a minimum of 10 hours, even assuming a full mount fracture and resulting worst-case stresses " Jackson said.
He said the company has advised all operators worldwide to visually inspect the footings every 10 hours."

Considering the latest fleet total TIS, number of occurances, and the potential consequences, it would be interesting to find out, under the present circumstances, whether or not there is now any increased risk (and if so how much) calculated by the OEM, Regulators, Owners, Operators, Oil Companies, Aircrew and/or PAX, of an accident occurring, if the aircraft continues to be used in the offshore environment before the root cause of this problem is identified and rectified ?

(not the risk to each party, the risk of an accident occurring)

[oldgrubber]

I have looked at this thread for a while and as an engineer I am puzzled by one major point, Sikorsky designed Seakings are operated by UK armed forces with ELS fitted to the main gearboxes. This was due to need for aircrew to be able to land the thing if they lost all gearbox oil pressure and it does work, not 1/2 hour fly dry, but good enough for most situations. If the idea that the Seaking could lose all it's gearbox oil is not "remote" or "negligible" ( first hand knowledge!), why is it that, from what I've read here, by some very knowledgable people, the S92 has NO ELS? It seems to be like a car manufacturer inventing the seatbelt and then not fitting it in the latest model! If I missed the answer to my puzzle, I apologise and await your scorn! (newbie flaming)

[Phil77]

Welcome to pprune oldgrubber!

No intention of flaming a newbie, nor am I an expert in the S92.
However, my research (read: google search for "sikorsky ELS" - sometimes google is more effective finding stuff inside pprune than the build-in search function) led me to page 63 of this thread:
http://www.pprune.org/rotorheads/163206-sikorsky-s-92-design-operations-63.html

...I know, an obvious place to look for, but the fellow resident experts elaborating extensively over the emergency lube issue in particular on that very page; just follow the link.

[oldgrubber]

Cheers Phil,

I see it's been done to death. I like the "indication" "operation" argument.
Thanks for the kind welcome, I'll try to be a bit more useful in future (laugh).

[riff_raff]

Outwest,

"Are you on drugs man???"

It's not me, it's the FAA. So lighten up.

"FAR 29.927.-
[(c) Lubrication system failure. For lubrication systems required for proper operation of rotor drive systems, the following apply:
(1) Category A. Unless such failures are extremely remote, it must be shown by test that any failure which results in loss of lubricant in any normal use lubrication system will not prevent continued safe operation, although not necessarily without damage, at a torque and rotational speed prescribed by the applicant for continued flight, for at least 30 minutes after perception by the flightcrew of the lubrication system failure or loss of lubricant."

Now I've been involved in a couple of MRGB design qualifications. And there is no way to show by (FMEA) analysis and/or with a qual test validation, that a typical single-fault-tolerant lube system failure can be shown to be an "extremely remote" event. Unless the S-92 MRGB has two totally isolated, independent, and functionally redundant lube systems (which it doesn't), then it must show by qual test that it has a 30 minute loss-of-lube capability, according to FAR 29. Not my requirements, it's the FAA's.

Plus, even though I'm obviously not intimately familiar with the S-92 MRGB design itself, I do understand that it is based on the UH-60 design which does have a firm requirement for a loss-of-lube condition per MIL-T-5955:

"G.6.9 Lubrication. It shall be demonstrated, either analytically or by
testing, that lubrication is suitable for all steady-state operational attitudes
with respect to gravity."

So what do you say now?

[Brian Abraham]

riff_raff, I'm afraid you are holding the stick by the wrong end, and not your fault, as like many others you obviously believe what you read in the professional aviation press. Search this thread for posts by HeliComparator and also the thread here http://www.pprune.org/rotorheads/163206-sikorsky-s-92-design-operations-89.html for an education.

[Outwest]

So what do you say now?

I say go back and read your initial post again or refer to the section of your post that I hi-lighted in red.

like all other FAA certified rotorcraft MRGB's,

I'm pretty sure the following are FAA certified rotorcraft

BH206,204,205,212,412, MD500, AS350, etc,etc,etc.......

also pretty sure I won't be draining the oil out of any of them and expect to last 30 minutes.

Care to revise your post?

[Phil77]

[post deleted by me, since in hindsight it created more confusion than enlightenment as Brian clearly points out in the following post - Thanks Brian]

[Brian Abraham]

Phil77, perhaps not clear enough but I was referring to riff_raff's post,
The MRGB in the S-92, like all other FAA certified rotorcraft MRGB's, is qualified for operating in a 30 minute loss of lube condition while maintaining power levels sufficient for level flight. Thus the pilot has a 30 minute period after the HUMS gives an indication of loss of lube circuit pressure, in which to continue at level flight and/or perform an emergency landing. So that should not be a concern to you.
The fact is the 92 does not have a 30 minute capability as suggested by riff_raff, and as I said in my previous post he can not be blamed for having that view as it has been propagated erroneously by the professional aviation press as if it were fact. As I said, search for HeliComparator's posts on the subject.

HC, why are you leaving the job to this amateur, you're the professional?

[squib66]

I don't want to spoil a good rant but the same rule WAS introduced at the same time for Part 27 Cat A rotorcraft and has been sucessfully applied to MD900, EC135 etc.

Brian A is right that the issue has been covered extensively elsewhere.

Lets just say, there is a rule, the aircraft was certified, and as long as the heat exchanger and its pipework are the source of the leak, IF you follow the RFM action to activate the bypass in seconds AND watch the oil pressure like a hawk until it stabalises then you have time to seek a landing site. So far there have been no leaks from the external part of the system (GOOD!). There have been pump drive failures that have created similar symptoms and resulted in premature landings.

If the leak is from elsewhere then, unlike other types certified to 27/29.927, you will see the pressure drop below 5psi and you must Land Immediately. Leaks from the MGRB itself were claimed to be 'Extremely Remote' but have happened twice to date, about 1 every 100k hours (BAD). The outcome of failing to do that promptly is demonstrated by C-GZCH.

I'm sure those who voiced doubts about the certification 5 years ago will take no comfort that their worst fears have come true.

We can only hope the TSB get to the bottom of why this was allowed.

[500e]

rifaf
ch posts 384 385

[JimL]

Svenestron,

That is an extremely interesting contention!

How did you manage to establish that the event was 'extremely remote'; empirical knowledge would have been difficult to provide as it would have had to show that there had been no failure of any lines, fittings, valves, coolers, etc. over a period of 10,000,000 to 1,000,000,000 hours.

The very fact that, as squibb66 has pointed out, there were two 'loss of oil events' to the S92 type over a period of six months would indicate that making such judgements is fraught with danger.

I cannot imagine that the regulator would be sympathetic to such contentions in the future.

My interpretation of the intent of the rule would be no more accurate than yours but I would consider it to be 'unless such failures can be established to be extremely remote'. However, that was before the S92 accident; it might be difficult, since the accident, to contend that such failures are 'extremely remote'.

'Semantics' is not the way to address engineering issues:Sematics: The individual meanings of words, as opposed to the overall meaning of a passage.
Jim

[victor papa]

svenestron, that approach costs money and we all know Eurocopter parts are ridiculously expensive! Makes me wonder why?

[widgeon]

As a matter of interest is the EC135 tgb made by Zahnradfabrik Friedrichshafen. I know the 105/117 Inter and tail were ?

[tecpilot]

widgeon, yes it's made by ZF.

Svenestron,

as i believe you know some years ago a BO 105M (Army version) from ECD (MBB) killed the two persons onboard while chrashing due to a tail rotor gearbox failure. In the TRGB the oil level wasn't correct filled after maintenance work.

As i remember the crash occured within 15-20 min after take off.

[squib66]

I'm sure a few old 61/Sea King hands will remember many oil leaks from casings seals and even filter housings. I think the point of Svenestron's post is that other manufacturers would not even have dreamed (hallucinated?) of doing the test the unique and less demanding way that Sikorsky finally did (and yes a more robust gearbox does cost).

Just days after the Cougar accident EASA took action to make its opposition clear to a Sikorsky 'Safety Advisory' issued immediately after:-

EASA cautions S-92A operators over Sikorsky letter (http://www.flightglobal.com/articles/2009/03/17/323956/easa-cautions-s-92a-operators-over-sikorsky-letter.html)


The European Aviation Safety Agency (EASA) (http://ad.easa.europa.eu/ad/2009-05)today cautioned operators of Sikorsky S-92A helicopters that a recent Sikorsky all operators letter issued in the wake of the Cougar Helicopters S-92A crash on 12 March (http://www.flightglobal.com/articles/2009/03/12/323787/one-confirmed-dead-in-cougar-helicopters-sikorsky-s-92-downing.html) could appear to suggest using flight manual changes not approved by the US Federal Aviation Administration (FAA), a possibility Sikorsky denies.



Sikorsky issued the note on 14 March to update owners on recent safety bulletins related to the S-92A, but not connected with the accident. The letter, provided to Flight International by Sikorsky, reminds operators of all safety bulletins issued in the previous 90 days, including at least one dealing with the main gearbox.

EASA says a 26 September 2008 SSA (SSA-S92-08-006), not specifically called out in the 14 March letter, informed owners of impending rotorcraft flight manual (RFM) changes for the S-92A based on service difficulties with the aircraft’s main gearbox lubrication system. “This advisory document refers to RFM changes that have not yet been approved by the FAA,” the regulator continues. “In fact, the SSA specifies the ‘corrective action’ as ‘Ensure all flight crews become familiar with the RFM changes when received.’”

Flight has learned that SSA-S92-08-006 discusses methods for detecting and responding to single and multiple indications of main gearbox problems and an impending transmission failure.



EASA says it published today's information bulletin "to ensure that all owners and operators of affected rotorcraft, registered in the European Union member states or associated countries, are aware that the procedures specified (in Sikorsky's September SSA) have not been approved by the FAA or EASA. The relevant emergency procedures in the approved RFM must be observed,” EASA states.

Sikorsky officials tell Flight the 14 March letter was sent to remind operators to comply with existing rules, not proposed changes to the RHM.
"The Sikorsky Safety Advisory referred to in the EASA bulletin (SSA-S92-08-006) had been issued as notice to operators that a change might be forthcoming. Sikorsky's practice is to provide operators with transparency and to supply information as it becomes available. This bulletin was simply notice of a proposed change, with no directive to comply either then or now pending all required approvals per normal procedures," Sikorsky says.


A few days later the FAA were forced to issue a humiliating note:-

FAA: Sikorsky S-92 gearbox safety alert ?premature?-19/03/2009-Washington DC-Flightglobal.com (http://www.flightglobal.com/articles/2009/03/19/324109/faa-sikorsky-s-92-gearbox-safety-alert-premature.html)

The FAA admitted they agreed with EASA and said that:-

The information in the Sikorsky safety advisory (SSA) was premature and may not be appropriate


That information, obtained by Flight International, was relayed by Sikorsky to operators in SSA-S92-08-006 on 26 September. The SSA points out that “some of the indications for an impending gearbox failure currently listed in the rotorcraft flight manual (RFM) are not representative of the main gearbox (MGB) performance/capability during a malfunction. As such, Sikorsky will be removing these items as indications of an impending gearbox failure."

The SSA was based on Sikorsky's investigation of “recent events” involving the S-92 MGB lubrication system. It's not clear what current indications are "not representative".

Sikorsky clearly indicates in the SSA that the revised guidance was being provided “in advance” of the RFM revision. It later states that the RFM changes would be forthcoming to “formally document (the guidance).”
That guidance includes suggestions for how to handle an impending transmission failure, which Sikorsky says can be manifested by an increase in power required at a constant collective setting; yaw kicks and unusual vibrations or unusual noise. “Multiple symptoms are a very strong indication of an impending failure,” Sikorsky adds.

“If an impending failure is suspected, the primary consideration is to land the aircraft before the failure progresses to a gearbox seizure or loss of drive to the main or tail rotor,” the SSA continues. Sikorsky writes that a “single” indication of a MGB problem (pilots receive MGB temperature, pressure and chip detection system readings) dictates that the helicopter should land “as soon as practical”. Multiple indications, Sikorsky notes, “dictate that the helicopter should land as soon as possible,” while an impending transmission failure “would necessitate that the helicopter land immediately.”

In addition to descending to an “altitude from which a landing can be quickly made with minimal power changes” if pilots suspect an impendng failure, Sikorsky also recommends flying at an airspeed “for which minimum power is required”, avoiding “rapid or frequent” changes to power, and performing descents at a reduced power setting “but with enough torque to drive the transmission.”


It is believed the 'recent events' mentioned above were the emergency landings in the jungle of Brunei of two Shell S-92s in January & May 2008 (connected with the pump drive failures mentioned in my last post) and this SSA was issued after pressure for Sikorsky to respond to those two events before an aircraft ditched with a surivable pump failure. The authors of the SSA did not apparently consider the July 2008 oil loss in Australia and the need to land immediately in those cases because such failures are not protected by the bypass system. Perhaps Sikorsky was starting to believe its own hype.

Rotor and Wing have been on the S-92's case since April and showed that after 20 years of production Sikorksy were still having casting problems with the UH-60 box and that the S-92 casing had a life limit imposed by AD:-

Rotor & Wing Magazine :: Program Insider: S-92 Main Gearbox Under Scrutiny in Cougar Crash (http://www.aviationtoday.com/rw/commercial/offshore/Program-Insider-S-92-Main-Gearbox-Under-Scrutiny-in-Cougar-Crash_30850.html)


Sources in the industry said that the S-92A’s MGB was not known for its "robustness." But what does that mean? Again, facts are sketchy, but here’s what we have.

Some of the S-92A’s technology is derived from the Sikorsky UH-60 Black Hawk. In a December 17, 2006 interview with Sikorsky president Jeff Pino, the Connecticut Post reported that the Pentagon had sent Sikorsky a "Level III: Corrective Action Requests" letter after "...the Army discovered the walls were too thin on main gear box housings on Black Hawk helicopters...." Sikorsky declined to specifically comment on the Pentagon letter, but Pino defended the company’s commitment safety.

Sikorsky spokesperson Paul Jackson denied that the UH-60’s 2006 problems revealed any fundamental flaws in its MGB housing. "What really occurred is the local DCMA [Defense Contract Management Agency] did spot-checking and found some units not in conformance," he said. "We took corrective action, and no aircraft were grounded. This was not a design or engineering issue, but a manufacturing escape (sic) with some units." Note: The accident aircraft, serial number 920048, was built in 2006.

Doubts about the UH-60’s MGB are just that; doubts. But according to the FAA, there is a problem with the S-92A’s MGB housing. The proof: On July 26, 2006, the FAA issued AD 2006-15-19, which applies specifically to "Model S-92A helicopter, with main gearbox (MGB) upper main housing assembly (housing assembly), part number 92351-15110-042, installed, certificated in any category."

AD 2006-15-19 reads: "To prevent fatigue failure of the MGB housing, loss of MGB lube oil, loss of main and tail rotor drive, and subsequent loss of control of the helicopter, do the following: (a) Before further flight, replace each MGB housing with 2,700 or more hours time-in-service (TIS) with an airworthy MGB housing with less than 2,700 hours TIS. (b) This AD revises the Airworthiness Limitations section of the maintenance manual by establishing a new retirement life for the MGB housing assembly of 2,700 hours TIS."

These are not the only UH-60 gearbox problems as recounted here:-

http://www.pprune.org/rotorheads/163206-sikorsky-s-92-design-operations-52.html#post3904718

The multiple main gear box issues with the original UH-60 2800 SHP boxes which one writer referred to were traced to a ring gear failure of ring gears from a particular manufacturer. SA got rid of those gears.

There were two planetary gear carrier fatigue crack induced failures that I learned about. Neither involved a complete failure of the planetary gear, and see immediately below for the story.

The one planetary carrier failure of a 3400 SHP gear box was caused by a fatigue crack and subsequent investigation disclosed that this customer ( non US Army ) was flying a GAG ( Ground-Air-Ground ) cycle powerwise that was way beyond the power ( should have said torque ) usage that formed the basis for the main box TBO . That failure did in fact result in deformation of the carrier plate, allowing it to contact an aluminum shim, generating lots of aluminum chips and clogging the filter, eventually shutting off oil flow. A precautionary landing was made without incident. No chip detection reported. The TBO for this operator was reduced in keeping with the power/time-at-power spectrum that he was in fact flying.

I did not get the history behind the single planetary carrier failure of a UH-60 2800 SHP main box, but based on the investigation of the 3400 SHP box event, assume it was a fatigue crack initiated thru usage far beyond the power/torque/time-at-power spectrum for which that TBO was formulated.


Sikorsky boasted about the run dry capability of the S-92 gearbox just after certification, the then S-92 Program Director, Nick Lappos posted here:-

http://www.pprune.org/rotorheads/163206-sikorsky-s-92-design-operations-4.html#post1744337

In addition to its civil helicopter capabilities, the rotor system and dynamic components are designed to meet the UH-60 BLACK HAWK ballistic tolerance requirements and all gearboxes are capable of running 30 minutes after loss of oil.

He has also said:-

http://www.pprune.org/rotorheads/163206-sikorsky-s-92-design-operations-52.html#post3901911

[the S92 transmission is a true modular trannie, designed with structural partitions and independence of lube so that a section can be shot away (yes, shot away) and not compromise the ability of safe operation of the remaining sections./QUOTE]

Really? Like the filter?

[quote]The S92 trannie design is the precise opposite of the early 1960's designs where the entire box is a single entity

So more joints and leak paths?


The S92 transmission is bigger, taller, beefier and heavier that the Black Hawk transmission by almost precisely the amount of extra power that it transmits.

So more power and therefore torque than the UH-60, so therefore 'beefier'. Is it 'beefy' enough?

Just days after the Canadian Globe & Mail 'revealed' that actually the test failure (common knowledge on PPRuNe to those not blinded by the hype) and how the JAA resisted certifying the S-92 for over 18 months after the FAA certification on this and related issues:-

POLEMIC & PARADOX: S92 FAILED RUN DRY TEST (http://www.polemicandparadox.com/2009/04/s92-failed-run-dry-test.html)

Certification documents show that the S-92 couldn't meet a specification that calls for the main gearbox to run for half an hour without oil – a requirement known as “run dry.” The specification is designed to give pilots extra time to make a safe landing if the gearbox loses its oil.

This was picked up by other newspapers and a debate started in Canada on the Sikorsky Cyclone, an S-92 based naval helicopter, that apparently will have to pass the test with no oil:-

The Telegram - St. John's, NL: Local News | Specs for new chopper include crucial gearbox requirement: Defence (http://www.thetelegram.com/index.cfm?sid=240179&sc=79)


Specifications for Canada’s new naval helicopters include a requirement that the gearbox be able to run in the event of a serious oil leak, the Defence Department says.

The department says its Cyclone helicopters will have to have a “run-dry” capability before they will be accepted from Sikorsky.

“The run-dry capability requirement for the CH-148 gearboxes, as stipulated in the solicitation document, is included in the maritime helicopter contract,” a department spokesman wrote in an email.
Sikorsky won the helicopter contract in 2004. A series of delays have put off the first delivery to 2012 from 2010. The initial delivery target was 2008.

Defence says the U.S. manufacturer is still working on the gearbox system.

News reports say the civilian S-92 won an exemption from the “dry-run” requirement by submitting evidence that the likelihood of a catastrophic oil loss was extremely remote.

Then in June the lawsuit of the Cougar familes charged Sikorsky with also giving and allowing to go uncorrected what they knew to be misleading information on the robustness of the gearbox to be circulated:-

Lawsuit claims Sikorsky knew of the S-92 flaws… S-92 Facts (http://s92facts.wordpress.com/2009/06/22/lawsuit-claims-sikorsky-knew-of-the-s-92-flaws/)









Flawed mechanical design and dishonest marketing led to a helicopter crash that killed 17 people off the coast of Newfoundland this winter, according to a lawsuit filed by the families of the victims.The lawsuit charges that Sikorsky sold its $15-million S-92 as “the safest helicopter in the world,” even though it was aware of a serious problem with the machine’s all-important main gearbox – a component that has emerged as the likely cause of the March 12 crash.The lawsuit, filed in Pennsylvania, alleges that Sikorsky marketed the S-92 on the basis of its compliance with an advanced safety standard that calls for a helicopter to fly for at least 30 minutes after losing the oil in its main gearbox (also known as “MGB”), giving pilots time to make a safe landing. The lawsuit says that the S-92 did not actually meet the standard, but customers were led to believe that it did, creating a fatal misperception by pilots – including the Cougar Helicopters crew who died in the Newfoundland crash along with 15 passengers…… The lawsuit argues that the pilots would have attempted a controlled landing on the surface of the ocean almost immediately had they been aware of the S-92’s true capabilities. “Within seconds of being alerted to the rapid loss of oil pressure in the MGB, the pilots turned the aircraft towards a safe landing site, which was close enough to be reached within the purported 30-minute ‘run-dry’ capacity of an S-92 helicopter. Because of the defendants’ misrepresentations and misstatements, the pilots were not aware that complete loss of operational control was imminent, and therefore, they did not attempt to set the craft down immediately on the water while the pilots still maintained control of the helicopter.”The S-92’s run-dry capabilities have been at the centre of an ongoing dispute within the aviation community. The helicopter was certified to an advanced safety standard known as FAR Part 29, which calls for the extended run-dry time. A Globe and Mail investigation revealed that the S-92 failed the run-dry test, but was certified after Sikorsky showed that the chance of losing gearbox lubrication was “extremely remote.”Sikorsky has argued that the S-92 meets the standard, and that pilots should have been aware of the need to land immediately in case of an oil leak. But the lawsuit charges that Sikorsky completely misrepresented the gearbox’s durability in a widespread campaign. “In addition to stating in their product literature and technical bulletins that their S-92 helicopters had a ‘30 minute run-dry capacity,’ the defendants knew that aircraft references, including Jane’s All the World’s Aircraft , innocently repeated the defendants’ representations.… Pilots would detrimentally rely on these misstatements, lulling them into a false sense of safety.”The lawsuit alleges that Sikorsky “trivialized” the risks posed by oil loss, and failed to highlight it in the S-92’s flight manual, even after a series of incidents. (This week, the U.S. Federal Aviation Administration ordered changes to the S-92’s flight manual, instructing pilots to land immediately if a gearbox oil leak is detected.)

A few days after this the TSB revealled how the Cougar tail rotor take off gear (shown right as compared to a new on the left) disintegrated as the crew attempted to ditch:-

http://www.tsb.gc.ca/eng/medias-media/photos/aviation/A09A0016/A09A0016.asp

http://www.tsb.gc.ca/eng/medias-media/photos/aviation/A09A0016/images/photo_8.jpg

They added that:-


The Sikorsky S-92A Rotorcraft Flight Manual (RFM) has been reviewed regarding MGB oil pressure loss below 5 pounds per square inch (psi) and the need for pilots to land immediately. An RFM revision has been approved by the FAA and Transport Canada.


And that brings us to today and yet more cracking:-

FAA to mirror EASA S92 emergency directive (http://www.flightglobal.com/articles/2009/10/29/334092/faa-to-mirror-easa-s92-emergency-directive.html)


The US Federal Aviation Administration plans issue an airworthiness directive calling on Sikorsky S-92 operators to repetitively inspect the helicopter's main gearbox mounting feet for cracks, defects that could lead to gearbox detachment and loss of control of the helicopter.
The FAA mandate will follow an emergency airworthiness directive issued by the European Aviation Safety Agency on 23 October after reports that cracks had been found in the feet, pads and foot ribs on main gearboxes during inspections. "In one case, the mounting foot was completely severed from the gearbox," says EASA. "Other cases include cracks at the fore and aft mounting bolt location on the right-hand side of the mounting foot."


With the FAA delaying apparently because as they:-


waited for Sikorsky to submit a failure analysis for the main gearbox mounting feet and other information. The FAA says the cracking phenomenon, while seen in the North Sea, has not been experienced by operators in the USA and Gulf of Mexico.


So much for the 100,000 pages of engineering reports mentioned here:-

http://www.pprune.org/rotorheads/163206-sikorsky-s-92-design-operations-4.html#post1744342

Just a few days after the FAA made this statement about the cracking being a North Sea problem and their AD was issued:-

http://www.canadaeast.com/news/article/844479




HALIFAX, N.S. - A hairline crack has been found in the main gearbox mounting feet on a Cougar Helicopters chopper based in Halifax. The St. John's, N.L., company announced that Cougar engineers found the crack on a Sikorsky S-92 during an inspection that followed a routine training flight Monday.


It is again worth turning to the words of the Program Director just after FAA certification:-

http://www.pprune.org/rotorheads/163206-sikorsky-s-92-design-operations-4.html#post1744340

It was the fastest, cleanest certification anyone at Sikorsky can remember. The first certification data flight was made last December, the FAA got on board in September, and we were done with all flights exactly one year later, Dec 12. The data was all processed in real time, so the FAA was ready to sign on Dec 17 (Wright Brothers day!) so they did.

In many ways the S-92 gearbox saga has some echoes of the two NASA space shuttle disasters and NASA's failure to anticipate and plan for the worst, properly act on the early o-rings and tile problems promptly or listen to those who did voice concerns. The only difference is more people died on Cougar 491 than in Challenger and Columbia combined.

So what will happen next?

[HeliComparator]

squib - excellent post thankyou

Sven - yes you are missing something, the cracking thing refers to the MGB attachment feet cracking, a new phenomena since the Cougar crash and not related to it as far as we know.

HC

[squib66]

HC is correct - the newest cracks are of the big highgly loaded gearbox feet (the right hand one in particular) rather than the small fliter studs.

I forgot to mention the gearbox mounting bolts were also changed out earlier this year too (just like the filter studs the first material choice was poor) and are now a nickle based steel.

Svenestron there WAS no alternative way to pass the test until it was 'invented' by Sikorsky and I doubt anyone even thought of the meaning you did when teh words were written.

I hope no other OEM is stupid enougth to use the S-92 as a precedent to try the same thing, but I doubt any regulator would let them.

I now understand the significance of JimL's comment about semantics and missing the meaning of the whole rule by focusing on the meaning of a couple of words. However it would be good if the words 'extremely remote' were taken out of the rule.

[Shawn Coyle]

squib66:
If I understand you, by eliminating the 'except if it can be shown to be extremely improbable' you'd like all gearboxes to demonstrate 30 minute run dry capability??
Good idea!

[rjsquirrel]

squib66 said: However it would be good if the words 'extremely remote' were taken out of the rule.

It might not be obvious to ppruners, but every new helicopter takes use of that phrase for gear box design and approval in many ways. Erase that rule, and all helos will undergo major new design efforts.
That is because the same FAR/JAR paragraph is used to cover the tail and intermediate gear boxes, which are qualified by showing that they "cannot leak" and the housings are highly reliable structure.

[Mars]

It may be of interest to see when and why the words "Unless such failures are extremely remote" were inserted into the rule. Below you can see the rule as proposed in NPA 84-19, followed by the justification for the change that occurred in the final rule:Proposal 3-46. The notice proposed several amendments to Sec. 29.927. Paragraph (c) is changed by revising and extending the rotor drive system lubrication failure test requirements for Category A rotorcraft and by clarifying the corresponding test requirements for Category B rotorcraft. Category A aircraft must have significant continued flight capability after a failure in order to optimize eventual landing opportunities. However, indefinite flight following the lubrication system failure is not expected. The changes to the Category B rotorcraft drive system lubrication failure test requirements are largely for clarification and are not substantive.
In NPA 84-19, issued on 10/10/84, this was the proposal: (c) Lubrication system failure. For lubrication systems, the function of which is required for operation of the rotor drive system, the following apply:

(1) Category A. It must be shown by tests that each rotor drive system, where the probable failure of any element could result in the loss of lubricant, is capable of continued operation, although not necessarily without damage, for a period of at least 30 minutes at a torque and rotational speed prescribed by the applicant for continued flight, after indication to the flight crew of the loss of lubricant.

(2) Category B. It must be shown by tests that the rotor drive system is capable of operating under autorotative conditions, although not necessary without damage, for 15 minutes after indication to the flight crew of the loss of lubricant.
Following consultation, the Final Rules, Docket No. 24337, was issued on 08/26/88. The text had been amended with the following justification:A commenter notes that paragraph (c), as proposed, could be interpreted to preclude credit for auxiliary lubrication systems or to require consideration of lubricant failures to self-lubricated bearings. This was not intended, and the wording of paragraphs (c)(1) and (c)(2) has been revised to eliminate this possible ambiguity.
The final rule being:(c) Lubrication system failure. For lubrication systems required for proper operation of rotor drive systems, the following apply:

(1) Category A. Unless such failures are extremely remote, it must be shown by test that any failure which results in loss of lubricant in any normal use lubrication system will not prevent continued safe operation, although not necessarily without damage, at a torque and rotational speed prescribed by the applicant for continued flight, for at least 30 minutes after perception by the flight crew of the lubrication system failure or loss of lubricant.

(2) Category B. The requirements of Category A apply except that the rotor drive system need only be capable of operating under autorotative conditions for at least 15 minutes.