Sikorsky S-92: From Design to Operations

[FH1100 Pilot]

Sox6, the answer to both of your questions is, "Yes."

[sox6]

I guess the extra weight will be bad for the mounts too.

So could the gearbox be the certification problem the Auditor General mentions?

[maxwelg2]

Sox6, IMHO that's the main issue for DND right now, but looks like they're going to accept the interim helicopters in 2012 without run-dry capability.

Quote from CBC website:

Following the March 12, 2009 crash of the S92 helicopter that killed 15 offshore oil workers and two crew off the coast of Newfoundland, questions started to arise about the Cyclone’s capabilities – specifically about it’s ability to “run dry” for half-an-hour in the event of a massive oil loss in the main gearbox. The fact that the S92 could not fly for half-an-hour after massive oil loss in the main gear box became a key issue after the Newfoundland crash.

Defence Mninister Peter MacKay assured last April that the Cyclone will have so-called “run dry” capability.

“I assure you that there will be rigorous testing, there will be rigorous examination of that helicopter before we take possession of it and it will meet the specifications that we submit to them," he said. "We won't accept a helicopter that isn't safe to fly.”

DND has told the fifth estate that “the run-dry capability specified in the maritime helicopter contract requires the CH-148 Cyclone to be capable of flying for either 30 minutes or a minimum of 60 nautical miles and then conduct a normal landing on a Halifax Class ship, following a total loss of lubricating oil in any drive system component,” and that “The Department of National Defence and the Canadian Forces (DND/CF) have not yet taken delivery of this aircraft. The DND/CF will verify that the CH-148 complies with all performance requirements – including the run-dry capability – prior to Canada's acceptance and delivery of the helicopter.”

Quote from jproc.ca website:

The CH-148 is based on Sikorsky’s civilian H-92 Superhawk and uses a lot of composite fabrication to reduce corrosion. Standard, self-sealing fuel tanks can carry up to 3,030 kg of fuel, and an in-flight refuelling probe allows in-air refueling. Emergency flotation systems under the cockpit and in the tailboom are automatically deployed and are expected to work up to Sea State 5 conditions. If they fail, or aren't practical, a 15-man life raft is installed in each sponson.
The 17 cubic meter cabin is fitted with a cargo handling system with a centerline 1,814 kg/ 4,000 pound capacity cargo winch, floor rollers, and cargo tie-down points. A 6 foot-wide aft ramp allows easy and fast loading and unloading of cargo and troops. A 272 kg/ 600 pound capacity hydraulic rescue hoist can reportedly be added to the helicopter if necessary. The CH-148 should fly for 170 minutes under extreme conditions and fly over 30 minutes with a dry gearbox

From the daily gleaner website:

Interim helicopters are defined as choppers with partial mission capabilities.

According to DND, the interim helicopters will be with "all specified flight equipment and hardware and will include a preliminary version of the mission system software that will allow the majority of the sensors and weapon systems to be operated but not in a fully integrated fashion."

As defined in the amended contract, the interim helicopters will not have final capability in four areas:

* messaging functionality of tactical data exchange capability (an automated data-link capability that provides for the exchange of tactical data between designated units, including the ships and aircraft);

* mission flight endurance (21 minute deficiency);

* single engine operation at high temperature; and

* the mission system software will be a preliminary version.

No operational or airworthiness requirements will be compromised with this approach, says DND. It is for this reason that DND's training timelines will be unaffected, further points out the backgrounder.

Does the 21-minute flight endurance deficiency suggests lack of 30 minute run-dry time based on perhaps only 9 minutes capability from DND-witnessed testing? Perhaps the loss of 2 minutes from the original FAR29 testing is due to higher loading requirement for CH-148 versus S-92a?

See post #1846 for more quotes, plenty of them about...either way it doesn't look like we'll see 30-minute run-dry capability for the S92 in the near future, so the big question now is will the FAA revoke its certification?

Safe flying

Max

[widgeon]

I think the 21 minute deficiency refers to the maximum total mission time . I think they have defined a mission , transit time to target , number of minutes at hover and then return to the ship. With the current engines and fuel it misses the mission profile by 21 minutes

from original requirement:

3.5.2.3.1.2 Payload/Endurance
3.5.2.3.1.2.1 [M] The MH shall launch from a HFX with 10 Kts of relative wind, at MMCW at
ISA, remain airborne for a minimum of two hours and 50 minutes and return to ship at the DELTA
HOVER ASTERN position with a 30 minute FUEL RESERVE while meeting the following
conditions:
Maritime Helicopter Project MHRS Draft Rev. 0 December 18, 2002
16
a. 60 minutes is spent in an out of ground effect (OGE) hover in zero wind condition;
b. the 60 minute hover OGE time is IAW SOI Scenario 8 with the remainder of flight completed at
Maximum Range Cruise Speed;
c. generate a minimum vertical hover ascent of 250 feet per minute or greater Vertical Rate of
Climb (VROC) from the initial OGE hover (T+20 min.); and
d. the VROC time must allow for the recovery of the full sonar cable length out of the water.

http://www.aero.polimi.it/~rolando/b...rements-mh.pdf

[Hilife]

FH1100 Pilot

Then, if the plaintiff's attorney is smart, he'll ask: "Are there NO other places that oil might leak out of the transmission? For instance, does the transmission have input seals for the engine driveshafts?"

SAC: "Yes, of course."

ATTY: "I see. And is there an oil seal up where the mast comes out of the transmission?"

SAC: "Yes, of course."

ATTY: "Is there an oil seal where the tail rotor drive shaft comes out of the transmission?"

SAC: "Yes, of course."

ATTY: "So that's four oil seals so far...which are used when you want to keep oil *inside* something, is that correct?"

SAC: "Yes, of course."

ATTY: "And there's no way on God's green earth that oil under pressure could even possibly leak out from those locations?"

SAC: "No. No way. Those seals would never fail. Seals don't fail."

ATTY: "Oh, they don't, huh? Well, humour me for a moment, please. IF a seal did fail, could all of the transmission oil be pumped overboard and lost?"

SAC: "Well...yes...theoretically...if you want to split hairs."

ATTY: "Well that is what we attorneys do best, sir! But thank you. But we'll come back to your seals-that-never-fail in a bit. Meantime, does the S-92 have an externally-mounted oil filter"

SAC: "Yes, yes of course."

ATTY: "And tell the court, please, how is that filter attached to the main structure of the gearbox?"

SAC: "Well, we use studs to secure the filter housing to the transmission."

ATTY: "Ah yes, the infamous studs. And is there an oil seal of some sort there as well?"

SAC: "Yes, of course."

And the jury will see that there are PLENTY of places where oil might possibly leak out of an S-92 transmission, not just the oil cooler lines as Sikorsky claimed. The jury will likely conclude that the manufacturer was either negligent in their thinking, OR the FAA was "in bed" with them on this issue. How or why the FAA allowed Sikorsky to get away with that wacky (and insufficient IMHO) isolate-the-lines-to-the-cooler system is something they're probably worried about right now. I can imagine the FAA Administrator at his desk, cradling his head in his hands and going, "Holy Geez, did we REALLY approve that cockamamie setup? Why...WHY?!"

Using your courtroom scenario above, you could of course remove SAC and insert Eurocopter, AW, Bell, MDHi etc., as all transmissions have seals and oil filter bowls/access covers and no OEM would be able to offer a 100% guarantee that oil could not leak out of their transmissions under any circumstances......EVER!

So we come back to acceptable risk and probability and a certification process for ALL OEM’s based on data submission and in-service experience, which is surely how the S-92 and every other platform flying PAX was certified.

The world’s Offshore O&G helicopter fleet clocks up around 1.5 million flight hours per annum and as each helicopter main transmission has a multitude of oil seals, that’s a gargantuan amount of oil seal and static filter bowl hours being clocked up every year and yet with no apparent headline grabbing failures that I read of, so surely this would suggest that in the industry “such failures are extremely remote”, does it not?

Only last year we had a main transmission disintegrate in flight leaving the crew and PAX with no chance of survival whatsoever, but I don’t see any posts on this thread demanding the guilty OEM’s head on a plate as appears to be the case for a number of you on this thread.

Since replacing the studs, I’m not aware (I stand to be corrected) of any further incidences on this platform type whereby the MRGB oil has leaked out at the same location, so surely the AD resolved the issue. Had the S-92 been installed with steel studs from day one, then it is likely that this thread would never have been started.

Dangermouse.

I cannot speak for the AW139 and AW101, but the EC225 does not have a 30-minute Run-Dry Main Transmission. I do concede however, that it does have an alternate lubrication/cooling system in the event of total loss of oil.

By far the biggest cause of accidents in the rotary industry is CFIT/CFIT(W), but I don’t see some of the most vocal on this thread demanding of all OEM’s that each and every platform operating in the Public Transport category be fitted with an EGPWS/TAWS/AVAD type system (irrespective of their age and with immediate effect), the installation of which would save far more lives than a true 30-minute Run-Dry compliant transmission would, would it not?

As I’ve stated before, I’ve no doubt that when the final report is issued, there will be many questions and much soul searching on all sides in this tragic accident.

Safe flying.

[squib66]

The other OEMs demonstrated theycould achieve 30 mins and in the case of the 225, EC also provided an emergency cooling system (note lube) rather than play the paperwork fudging game SAC did.

SAC claimed lube loss was extremly remote. Wrong. Not only did it happen in Australia, it happened 6 months later before they could even fix that problem.

Any one like to stake their life that there are no other ways to lose oil from the MGB?

Oh yes every S-92 pilot and passenger is doing that every day! But that's not really the tag line for an SAC advert is it!

Lets just hope they have assessed the mount cracking right.

[Shell Management]

The studs have been changed so the aircraft is safe and even happening twice it will be 'etremely remote' across the entire life of the type, so that is ok. Remember in one case every survived and that is down to the RFM.

[FH1100 Pilot]

Hilife:

Using your courtroom scenario above, you could of course remove SAC and insert Eurocopter, AW, Bell, MDHi etc., as all transmissions have seals and oil filter bowls/access covers and no OEM would be able to offer a 100% guarantee that oil could not leak out of their transmissions under any circumstances......EVER!

Hilife, you are absolutely correct. By itself, this would disqualify an aircraft from being fully certified under FAR Part 29.

The Bell helicopter I fly is not required to demonstrate *any* run-dry capability as it is not certified under Part 29. If any helicopter *is* certified under FAR 29 but does not comply with 29.927(c)(1) then yes we should be taking them to task as you suggest just as seriously as we do Sikorsky and their S-92. I think the actual statistical definition and applications of "extremely remote" will be a major issue in any future court actions.

The more strict requirements of Part 29 are not trivial or inconsequential. Nor should they be summarily dismissed merely because it's inconvenient to adhere to them. Thus, I find it odd that the person who calls himself "Shell Management" is so quick to do just that.

[HeliComparator]

By far the biggest cause of accidents in the rotary industry is CFIT/CFIT(W), but I don’t see some of the most vocal on this thread demanding of all OEM’s that each and every platform operating in the Public Transport category be fitted with an EGPWS/TAWS/AVAD type system (irrespective of their age and with immediate effect), the installation of which would save far more lives than a true 30-minute Run-Dry compliant transmission would, would it not?

True that CFIT/W is probably a major cause of accidents, but where is the evidence that EGPWS/AVAD prevents it? Just because you fit a shiny blue box and read the hyped sales literature doesn't mean its actually any safer.

CFIT/W is probably far better "fixed" by good crew training, SOPs and top notch flight automation. AVAD is quite good in terms of cost/benefit if its used properly, but by no means a panacea (GBLUN). EGPWS has so many false warnings that all most pilots want to do is switch it off, and it doesn't actually stop you falling into the sea (GREDU). You can't buy flight safety with a $10k box!

But I do agree that 30 mins dry run time is not the be-all either. What is unacceptable is a manufacturer who trumpets compliance with it, when they know the reality is the opposite.

HC

[zalt]

What is unacceptable is a manufacturer who trumpets compliance with it, when they know the reality is the opposite.

The families case, settled out of court, was not so much the trumpeting, as the 30 minutes dropped off the brochures after the test failure, but the failure to come clean about the true 'capabilities' of the S-92 and thus induce false confidence.

Meanwhile the shcking news in Canada is that the Wells Inquiry has been nobbled by the TSB who don't want the Judge to analyse their involvement in the Australian incident. How may accident investigators get to see the failure they investigate 8 months in advance of the accident?

Did the TSB really protect Canadian citizens as per their charter?

TSB e-mail

Did CHC really take the action necessary in a timely and responsible manner?

CHC e-mail

See more generally: CBC News - Nfld. & Labrador - N.L. chopper's flaw known in 2008

[Brian Abraham]

Remember in one case every survived and that is down to the RFM.

In that case yes, but the RFM is not always the be all to end all. Here is a crew complying with the RFM, have incurred a FAA/manufacturer deemed "remote event". The aircraft was flyable, but compliance with the RFM was what killed them. Things are not always black or white. One of the pax lived down the street and was a work colleague.

[squib66]

Brian - I think the RFM comment of Smell's relates to the 'Land Immediate' when oil pressure is less than 5psi. It seems that is what the CHC crew did and they lived.

Zalt - One does wonder, reading those two e-mails, how urgently the Broome investigation was really taken by CHC, SAC and TSB.

HC - You can't bu flight safety for $10k - but a wonder how much cheaper the subsequent steel bolts actually are! I bet SAC paid more for the fancy titanium ones that caused the oil loss, even before the court settlements.

[maxwelg2]

The studs have been changed so the aircraft is safe and even happening twice it will be 'etremely remote' across the entire life of the type, so that is ok. Remember in one case every survived and that is down to the RFM.

SM, I disagree with your above rather bold statement. Here's my reasoning:

Extremely remote = 10 ^7 to 10 ^9 per flight hour, so how many flight hours does the S92a have to allow 2 failures and still be in compliance with FAR 29.927 (c)(1)? I would calculate at least 10^14 hours required, so IMO the type approval is not valid and wasn't after March 12, 2009.

IMO the wording of FAR 29.927 (c)(1) is too loose and ambiguous, as a minimum "loss" should be changed to "loss and/or total loss".

So how did SAC prove to the FAA that this type approval is still valid by changing out the titanium studs to steel, did they know the true cause of the low cycle fatigue and prove that this root cause was removed by using steel instead of titanium? Broome was apparently blamed on over-torquing of the stubs, 491 still has the TSB report to be issued, so for me the jury is still out on that one.

Who is not to say that there will be another as yet unknown failure path with the current S92 MRGB, as with all rotating and mechanical wearing parts there is always the unknown to deal with albeit planned maintenance routines are put in place in an attempt to provide adequate management to prevent catastrophic failure events. We can only rely on the designers to capture all aspects/scenarios as with all other AC types.

Safe flying

Max

[HeliComparator]

Max - I agree with the sentiment but not with the maths! If it is 1 failure in 10^7 hours that is 1 in 10,000,000 hrs. Two failures would be 2 in 20,000,000 hrs, not in 20,000,000,000,000 hrs - ie its 2x10^7, not 10^14.

In any case, the fleet hours are a long way below 20 million and will probably never exceed that.

Of course the statisticians will tell you that you can't reliably determine the probability of a failure by looking at 2 cases - too few to be statistically significant.

HC

[maxwelg2]

Sorry HC, the maths head is not awake up here in NL, only got 2 cups of Java in me so far today, but as you stated the fleet hours just don't cover the requirement and/or the spirit of the clause.

Dan's recent post, #1845 on this thread, highlighted 250,000 hours, a long way away from 2 x 10^7...

My point was sometimes statistics is not the best metric to use, how about good old make it super-safe and non-ambiguous?

Zalt's post got me thinking back to how quickly the TSB homed in on the studs in the first place...surely any relevant incident with this AC type should be included in the Wells inquiry, including a Canadian investigative bodies involvement?

Safe flying

Max

[squib66]

I wonder if SAC do any of this SMS stuff they are happy to lecture others on?
http://www.ihst.org/portals/54/2010i...20Brisbois.pdf

Max - Can we really rely on SAC's gearbox designers with the tragic-comedy of errors they have performed to date (vespel splines, 927c compliance, oil system failure modes, fliter studs, churing, casing cracks, foot cracks etc)?

[maxwelg2]

Squib66, speaking as a lowly PAX I have no choice.

On a personal note we can't go back in time, but surely we can take the lessons learnt and improve safety and design for the future. That's the infuriating part right now, it takes time to get things right but you have to be seen to be proactive at the same time. IMO meeting the requirements of a DND contract albeit revised seems to be taking a higher priority than correcting a civilian type certification failure.

BTW, has the increase to 3/4" mounting feet bolts and revised mounting feet design resolved the cracking issue?

Safe flying

Max

[squib66]

From what I heard the current latest mod to fix the foot cracking uses the MHP casing, but that is now seen as just an interim fix and there is another one on its way for next year.

[Shell Management]

Correct Sikorsky has committed to a series of product enhacements. This shows their true commitment to bring everyone home safe every time.

As previously mentioned, the S-92 is victim to some bad press and politically inspired comment in Canada that has resulted in some ill-informed panic amongst the non-aviation literate passengers of certain oil companies.

It remains a fine helicopter, certified top the latest requirements, ideal for offshore transport

Nick Lappos - come on and help reassure the doubters

[FH1100 Pilot]

All this talk about how safe the S-92 is gets lost on me. Yeah, I get it, it's new. And it's got some new and interesting features. But what about the design makes it safer than anything else out there, as "Shell Management" declares?

It's got the latest and greatest avionics!
Yes, but big deal. Avionics can be retrofitted to any airframe.

It's got emergency floats in the sponsons!
Yes, but in a heavy crash landing on water the sponsons can (and did) rip off, rendering those floats worthless.

Energy-absorbing crew and passenger seats.
See, to me, this is nebulous. It assumes a particular type of crash will occur, and offers protection *only* in those particular crashes. So as long as the aircraft hits the ground level, we're good. Impact in *any* other attitude and your wonderful energy-absorbing seats aren't worth much. Not to mention that energy-absorbing crew/pax seats are not exclusive to the S-92.

Better bird-strike protection.
Okay, I'll buy that! But...wait...didn't the S-76 already have that until operators started replacing the glass windscreens with plastic? Damn.

Larger (and more) emergency exits.
I wonder about this. How many helicopter accidents have EVER occured in which the pax were required to leave via the emergency exits? I mean, more and bigger emergency exits is a good thing, but has there been a real need for this up to now? Or is it a canard? At the end of the day I'd agree that having more emergency exits probably makes the S-92 "safer" to some degree. How much it's worth...ahhh, I dunno.

Composite main rotor blades with lightning protection.
Aren't the new Carson S-61 blades composite? Doesn't the Puma have composite rotor blades?

Redundant hydraulics and fatigue-tolerant flight controls??
Umm, dont ALL big helicopters have "redundant hydraulics?" And just how many flight control failures due to fatigue have there been in the S-61/Puma/BV107/CH47 class?

Rotor blade anti-icing system (RIPS).
Here we have a genuine technical advancement: anti-icing for the MRBs. But...let me ask, has icing been a problem in the past? Have we lost any aircraft in the North Sea or North Atlantic due to MRB icing? Secondly, I'm not sure I'm in love with the idea of dispatching into "known ice" IN A HELICOPTER. I guess we'd have to get "Shell Management" to weigh-in on whether his company would approve launching when "known ice" exists. So while RIPS *is* a real technical advancement, I'm not so sure that it makes the helicopter absolutely "safer." I think that's arguable. (Okay, I know icing can occur even when it's not forecast. Has this been a problem in the past?)

Hey, here's something SAC can add to the S-92 that will absolutely-positively make it a safer helicopter: A transmission oil quantity gauge. For such a critical component as your one-and-only transmission, I'm surprised EVERY helicopter doesn't have one. In fact, I'm astonished that SAC left it off, if their real goal was to produce the safest helicopter ever designed. (Then again, I'm surprised by how many helicopters don't even have transmission oil pressure gauges!)

Okay, it seems to me that the S-92 does not bring all that much that's really new to the industry that makes it demonstrably or measurably "safer" than anything else out there. But like I said, it's just new, is all, and people like "new." But let's face it, the S-92 is a single-rotor (single-transmission) helicopter with all of the limitations and weaknesses inherent in the design. I'm sure it's a fun helicopter to fly, what with all the bells and whistles for pilots to play with. Because we pilots do love bells and whistles. We like flying new stuff, not old crap, no matter how reliable or "field-tested" the old crap is.

Sadly, as we've seen in reality, the S-92 is not proving to be all that much safer than anything else. Maybe less safe compared to helicopters that actually *do* have emergency lubrication systems (not that cockamamie emergency bypass system). But hey, it is fancy and new!

Now, about 29.927(c)(1): Up a bunch of posts (or back a few pages at this point), Hilife states:

all transmissions have seals and oil filter bowls/access covers and no OEM would be able to offer a 100% guarantee that oil could not leak out of their transmissions under any circumstances......EVER!

Thank you, Hilife, you kind of reinforce my point. In their infinite wisdom, the FAA actually has a statistical definition of "extremely remote." And there are simply too many potential failure points on EVERY helicopter transmission for a manufacturer to say that a leak...*any* leak...is "extremely remote." So clearly the S-92 transmission does not - and more importantly, did not at the time of certification - meet the requirements of 29.927(c)(1). Oh, did I mention IN MY HUMBLE OPINION? Obviously, a jury might feel otherwise.

How this aircraft still has Category A certification under this part is a friggin' mystery to me. It says that money talks. SAC (mostly likely backed up by the oil companies and operators) have probably convinced the FAA that revoking the Type Certificate would be economically "devastating." That's the term they always use, right? It also says that Shell has a severe double-standard when it comes to safety...which those of us who've flown for Shell have known for years.

The reality is that when you operate for-hire a helicopter over inhospitable terrain, then the transmission becomes THE SINGLE MOST IMPORTANT piece of your safety pie. Not too much else matters. And in this regard, the S-92 is absolutely no safer than anything else on the market.

Imagine, if you will, that the Cougar boys had been on their way back in, cruising at 10,000 feet when they noticed their transmission oil pressure decreasing. They're still in the same mindset of not really wanting to land on the ocean, so they communicate with base to make sure SAR is on the way, and they want to give the guys in the back time to make sure they're prepared for a ditching. They initiate a 500-700fpm rate of descent to land on the water. The descent will put them landing between 14 and 20 minutes - a long time, they think maybe too long.

Six minutes in, they get anxious and start to really want to get on the deck because that gauge really, really, really is on zero psi, dammit ("How can that be??"). But they're only down to, like, 5,500 feet. So they increase their rate of descent to 1500 fpm - almost autorotative. Now they only have 3.6 minutes to go. "Should be enough," they think. But they still have to do the landing (break the RoD, slow down, set up for the ditching, flare and set her down), which will eat up more precious seconds. Total time from the top of the descent to the water, ten minutes, maybe a little more.

In all likelihood, they still would not have made it.

Playing devil's advocate another way, let's say they really did have the mythical "30-minute run-dry capability." The crew decides to use minimum power...something that gives them around 70 knots. When Cougar 91's transmission pressure went to zero, they were still 42 miles from land. At 70 knots, it would have taken them 36 minutes to reach Cape Spear (depending on wind, of course).

In all likelihood, they still would not have made it.

Those Cougar pilots were between a big rock and a really hard place. How many of us can say with absolute certainty that we would have done any differently?