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

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

Old 27th Mar 2009, 15:46
  #241 (permalink)  
 
Join Date: Sep 2007
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Sultan,

while we disagree slightly on some things.. one area I'm sure you will agree on, is the fact that I find the modern design methods of using computer simulations in place of old fashioned physical testing rather uncomfortable.

Or "qualification by similarity" another well used and uncomfortable phrase..
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Old 27th Mar 2009, 16:44
  #242 (permalink)  
 
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I just want to comment on the line where you said that the end users are happy with the 92.
The end users would be the pilots,and I know a whole lot of 92 drivers that are far from pleased flying this helicopter.This has nothing to do with the above mentioned technical problems,but everything with the vibrations and crazy noise levels up in our fancy super duper cockpits.

Have a good weekend you all
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Old 27th Mar 2009, 17:27
  #243 (permalink)  
 
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Is there any theory why the CVR FDR stopped recording while the aircraft was still at 800 feet??
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Old 27th Mar 2009, 20:40
  #244 (permalink)  
 
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The report said there was an electrical interruption. I have no idea why that happened.
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Old 28th Mar 2009, 01:14
  #245 (permalink)  
 
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Alloa Akbar

We shall visit this again in a couple of years when, hopefully for the families sake, the inevitable law suit is settled.

At that time, we shall see if the courts agree with you that SAC is blameless.
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Old 28th Mar 2009, 03:17
  #246 (permalink)  
 
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First post here and let me state that I'm not a S-92 man and certainly not an electrician so this is only theory - not trying to state facts.

In regards to the CVR/FDR electrical interruption I believe there are 2 AC generators being driven by seperate input modules which are attached to the MGB. Lets say the MGB starts to slow down (failing), wouldn't this also cause the generator to slow? If so the generator control unit would sense an under frequency and shut down both generators- no more AC power!

Like I say only a theory and I would welcome enlightenment from anyone directly involved with the S-92.
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Old 28th Mar 2009, 03:34
  #247 (permalink)  
 
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Re. my last post - just read 'S-92 design to operations', page 72 #1438. Excellent description by 212man.
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Old 28th Mar 2009, 19:11
  #248 (permalink)  
 
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There is far more to be reported by this investigation and there are far more questions than answers right now despite all of the conventional wisdom that flows here at PPRuNe.

The legal questions shall be far more complex than the explanation of what caused the aircraft to crash. There are multiple layers of responsibility and multiple layers of actions along with the law and air regulations that will have to be sorted out before the full story comes to light.

Laying blame at any one's door step and saying they were the cause is very premature at this point.

Seventeen People died, one is critically injured.....let's look for lessons learned to begin with and see if we can find solutions to those problems while we wait for the official answer to how this happened.

Have we posted the Authorized Emergency Procedures (in effect at the time of the crash) for the MGB Loss of Pressure and Loss of Lubrication Fluid situation?
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Old 28th Mar 2009, 19:30
  #249 (permalink)  
 
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SASless, from post 1420 on the 'other' thread:


FWJ. I don't have the RFM in front of me so this will (hopefully) be a correct interpretation! I am sure it will be corrected by someone if I get it wrong

The drill covers both a MGB Oil Px CAUTION and an MGB Oil Px WARNING - one yellow, the other red.

1. If MGB Oil Px WARNING then select BYP (this is a MGB oil cooler bypass switch)

2. If MGB Oil Px CAUTION with px above 35 psi
Land as soon as PRACTICAL

3. If MGB Oil Px WARNING, or MGB Oil Px CAUTION with px below 35 psi
Descend MSA
Start APU
Land as soon as POSSIBLE

However if there are secondary indications, which are:
Oil px indicating below 5 psi
Smoke or fumes
Hydraulic failure
Increased power required
Unusual noise or vibration
LAND IMMEDIATELY


VL
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Old 28th Mar 2009, 19:40
  #250 (permalink)  
 
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Thanks VL,

I thought we had but got lost looking for it.

Questions:

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?

Would the AC Generators fail due to overheating as a result of loss of oil?

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?

Would the APU continue the AC system despite the loss of the AC Generators?

Also....as I look at the time line I see the following entries....

12:17:04 MGB Pressure "Zero"....(I assume it was taken from the Data Recorder or HUMS or whatever.)

28 seconds later....

12:17:42 Crew Reports by Radio "MGB Oil Pressure "0"."

4 min's and 38 seconds later...

12:22:20 Aircraft levels at 800 feet and accelerates to 133 Kts IAS

2 min's and 14 sec's later...

12:24:44 Loss of AC Generator Power Occurs

52 Seconds later....

12:25:36 Crew reports by radio "Preparing to Ditch"

3 Min's and 16 seconds after leveling off and accelerating to normal cruise speed and power setting.....the decision to ditch is announced by the crew.

Why did the crew appear to regain normal cruise flight at 800 feet if they were planning to ditch following their descent to 800 feet after having over seven minutes to complete the emergency checklist and be aware of the "Land Immediately" situation?

This is the key to the fatal outcome of the flight in my view.


Some other questions and observations I have thought about.

A lot of questions being asked could be answered by some of our more expert contributors and even some who have first hand knowledge of how some decisions were arrived at, but due to the situation following such an event like this are probably not free to post here due to legal constraints as they might be considered potential witnesses in some proceeding.

There is much confusion in this thread as to what happened and how it could have been avoided. That is because all the facts are not yet released and Instead of seeking lay blame here, we should all seek ways to be sure the mishap is never repeated.

I posted a question about "Run Dry" Times for common types of aircraft in use in the offshore oil support industry and I got some response.

As I see it, The need to address oil out was introduced as a requirement in 1988, so it is reasonable to assume that most helos certified before that date do not meet the requirement, and have never been tested for oil out. If you search the FAA archives, you'd find that the TCDS (official FAA source for certification basis) lists the below for oil failure qualification:
B412 NOT
S-76 NOT
AS-365 NOT
AW-139 YES
EC-155 YES
EC-225 YES
S-92 YES




FAR Part 29.927 amendment 26, 10/3/1988 states the following:

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

It is my understanding that the S92 meets the FAR as is (according to its type certificate data sheet) with full compliance, and does so by isolating the internal oil system from the external oil system. The S92 does that for the Tail Rotor Gear Drive and Intermediate Gear Box , as do the AW139 and the EC225 I"d bet..

I hear that the box has some natural oil out resilience, like the UH-60 from which it is derived, so that the common MGB "oil out" situation that would result in a catastrophic MGB failure in less than a minute is not apparent. Those of us who fly older aircraft without that resilience know this, and consider "Land Immediately" as a command to look in the chin bubble, and pick a spot to put the aircraft. Those who do not do this when "Land Immediately" is dictated might find out that they land in the same place, without their pilotage being needed.

I understand that the S92 emergency procedure is specific - if oil leaks as indicated by the quantity indicator, isolate the box by activating the Isolation Switch. Fly home, land as soon as possible. If it leaks completely and the oil pressure becomes nil, land immediately.

As I look at the time line of the accident and as relayed in the CBC broadcast Press Conference I see some question as to whether that was done. I have asked in the past either by PM or on the public forum what might have occurred to sway the crew from continuing on down to the sea and doing a controlled ditching much sooner. I still wonder if there were any other counter-indications or reasons why the crew might have been swayed from either deciding to ditch immediately rather than continuing to fly as they did.

I noticed the data showed the aircraft to descend at about 80 knots but then it leveled off at 800 feet and increased speed to about 133 knots. I assume that would be pretty much normal cruise power rather than a reduced power setting which would have lessened the load on the MGB.

The Press Conference avoided relating any information about the conversation between Cougar Ops and the Flight Crew. Was something said in those exchanges that would have affected the Crew's Decision re ditching immediately?

I have also questioned the lack of urgency in the Bulletin calling for the replacement of the Titanium Studs particularly following the Shell Brunei Incident which 212Man was involved with. I cannot help but think any reasonable examination of that incident by Safety, Type Captains, or Engineering Management would have shown the need for that change to be effected in a most rapid manner. Assigning a year or 1250 flight hours as a limit seems less than wise to me.

One can also ask how replacement steel studs were on the hangar shelf and not on the filter bowl. Also, why would they not be put on immediate order and be installed upon arrival.

I posted questions to others about the Conventional Wisdom of staying airborne until the very last possible time possible despite the instruction to "Land Immediately" being the proper procedure and we found way too many of us agreed with that concept which flies in the face of the checklist and emergency procedures listed for most of the aircraft we fly when it addresses loss of lubrication to gearboxes.

Do we apply the same thought to Main Gear Boxes, Intermediate Gearboxes, Tail Rotor Gear Boxes....or even Engine gear boxes?

Last edited by SASless; 28th Mar 2009 at 20:03.
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Old 28th Mar 2009, 21:10
  #251 (permalink)  
 
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I can't help feeling that the only people who will gain out of all this is the lawyers

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.
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Old 28th Mar 2009, 22:11
  #252 (permalink)  
 
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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?
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Old 29th Mar 2009, 00:32
  #253 (permalink)  
 
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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.
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Old 29th Mar 2009, 03:20
  #254 (permalink)  
 
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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



VL

Last edited by Variable Load; 29th Mar 2009 at 03:34.
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Old 29th Mar 2009, 19:42
  #255 (permalink)  
 
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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.
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Old 29th Mar 2009, 23:22
  #256 (permalink)  
 
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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....
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Old 30th Mar 2009, 00:01
  #257 (permalink)  
 
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But.....the pressure remained at "Zero" did it not?
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Old 30th Mar 2009, 02:10
  #258 (permalink)  
 
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Get Home attitude...

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!
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Old 30th Mar 2009, 03:15
  #259 (permalink)  
 
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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.
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Old 30th Mar 2009, 05:05
  #260 (permalink)  
 
Join Date: Mar 2009
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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.
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