Sikorsky S-92: From Design to Operations

[immaengineer]

Cefoskey, You seem to know alot about whats going on with the S-92, Can you tell me what going on with the Gearbox Problems and fixes that are coming up?

[Horror box]

Having read the HSS3 report, there is most definitely no Sikorsky bashing going on. IN fact quite the opposite - the report conclusively attributes the S92 to being a part of the overall safety in Norwegian operations.

The helicopter operators on the Norwegian Shelf have in recent years put new helicopter types
into use, in particular Sikorsky S-92A (in use since 2005) and Eurocopter EC225 (in use since
2008). These helicopters have become dominant on the Norwegian Shelf. This is the newest
generation in helicopters and they have improved the operability on every level, also in relation
to safety. There have however, been a few issues with getting the technical bugs out, e.g. with
the Rotor Icing Protection System (RIPS). Nevertheless, the problems have not been any more
substantial than what is common with the phase-in of new helicopter types.

[immaengineer]

Wow... Well put Gents...

[squib66]

They seem pretty clear that the accident in Canada would not have happened to an EC225 because that CAN operate for 30 min without oil pressure.
They also cite FEMCA analysis by OEMs as the most cost effective safety improvement (Sikorsky have a history of suddenly discovering MRGB problems in service with the S92). .

[riff_raff]

Originally Posted by CEFOSKEY

Well then why do you suppose they dont specifically and overtly state that all helicopters should be equipped with ALS in HSS-3?

If we arent performing those analyses you posit are being omitted, then I work with quite a few people who are being severely overpaid.

Besides, the exact same sentiment could be made for the 332/225, as I do believe the Bond helo lost the entire rotorhead in flight due to catastrophic failure of the MRGB. Not to mention the EH101 and its 5+ year mystery tail rotor hub cracking issues.

Bottom line is that these are complicated machines. FMEA+FEA isnt perfect and unexpected failures happen to all makes and models. In the end these are all very safe helicopters. But alas, you troll away.

I'd agree that FEA may not be perfect, but it can be very good. Like many other things, the precision and accuracy of FEA results can vary widely depending upon the quality of the FEM and the guy that created it. FEA results also must be interpreted carefully. FEA is a well understood and accepted process in the aircraft world for validating structural design. Sometimes FEA is further validated by structural test, but this is becoming the exception as FEA techniques and codes improve.

As for FMEA, these techniques have been a fundamental part of aircraft systems design for decades. In fact, preparing a FMEA fault tree and CIL is one of the primary engineering tasks when designing any new system architecture (like an MRGB). Since it will provide guidance on the level of fault tolerance that each component or subsystem (like a lube circuit) must have. Preparing a FMEA/CIL is straightforward logic and is not difficult or complex. It just takes time, patience and thoroughness. As I'm sure you're aware, the real difficulty lies in producing a design that ensures adequate fault tolerance.

Thanks for linking that HSS report. I'll definitely read through it.

riff_raff

[Shell Management]

Originally Posted by CEFOSKEY

A friend of mine who works out at Boeing Seattle on the 747-8 and 787 flight test has told me that the FAA is just now beginning to qualify some of their parts based on FEA results for flight test. Both he and I agree its because the government inherently trusts Boeing's FEA and simulation code, as its used as a bargaining chip with other countries during trade (an interesting story there in itself). But I digress.

We arent so lucky, the FAA and DoD want to see NDT+destructive testing to validate our FEA. Im sitting here designing flaws into blades we are going to test to failure under the watchful eye of the FAA, because they wont have it any other way. And I think thats a good thing for everyone (except maybe whoever is paying for 5+ soon-to-be-splintered test blades).

Is that the defence Sikorsky will use in the latest Cougar court case?

[squib66]

Only one mount cracked worldwide last month.
Pity Sikorsky did not apply flaw tolerance to the gearbox mounts.

Still SM, when you are at your IHSS love-in, next week you can ask Sikorsky what their defintion of extremly remote is.

[Shell Management]

I think you will find that at Shell Aircraft's direction Sikorsky have made a solution to this (minor) cracking problem their top priority in the same way that the gearbox churning problem was prioritised at Shell's insistance over other failure modes.

Squibb 66 There is no need to ask sikorsky "extremely remote" is defined in FAR29.1309 and as the S-92 is certified to the latest certification standards in accordance with Shell's 7/7=1 safety strategy, it (and its MGRB) meet that.

[[email protected]]

http://rgl.faa.gov/Regulatory_and_Gu...meset?OpenPage

In the above link (search for Sikorsky) there is a list of the Sikorsky S92A Equivalent Level of Safety certificates which, I believe, have to be completed in cases where the design of the aircraft does not meet the FAR standard. The manufacturer then has to produce evidence that the proposed design meets and equivalent level of safety; the FAA then issue a certficate to confirm this.

The MRGB with the lack of 'run dry' capability surely should have had such a certificate since it did not meet the FAR requirements and Sikorsky had to show that the failure was extremely improbable.

How did they get certification without a ELOS certificate for the MRGB?

[212man]

Equivalent level of safety findings are made when literal compliance with a certification regulation cannot be shown and compensating factors exist which can be shown to provide an equivalent level of safety.

Crab,
The MRGB does meet the literal interpretation of the FAR, because 29.927 has two options within it - either demonstrate that failure is "extremely remote," or demonstrate 30 minutes running following oil loss. In this case, SAC demonstrated to the FAA/EASA that "failure was extremely remote," so no ELOS was required. Sitting in our armchairs a few years later, that might be a debatable topic, but essentially you are answering your own questions without realising it.

[[email protected]]

I see what you mean but I'm still not sure that a ELOS wasn't required. In every other case there is a clear audit trail to show why the ELOS was approved. If Sikorsky were able to demonstrate that a failure was extremely remote - where is the proof?

[[email protected]]

Extremely Remote
Qualitative: Not anticipated to occur to each item during its total life. May occur a few times in the life of an entire system or fleet.
Quantitative: Probability of occurrence per operational hour is less than 1 x 10 -7 but greater than 1 x 10 -9
Extremely Improbable
Qualitative: So unlikely that it is not anticipated to occur during the entire operational life of an entire system or fleet.
Quantitative: Probability of occurrence per operational hour is less than 1 x 10 -9

So should a gearbox be allowed to fail at all? Surely the probability of failure for such a critical component should be Extremely Improbable not just Extremely Remote especially if you are going to sidestep the requirement to prove through testing that it will run for 30 mins (which it failed).

Perhaps the criteria should be based on the likely worst-case human cost - ie 18 pax and crew for a transport aircraft and see how many times that sort of loss can be accepted statisically.

[[email protected]]

Those definitions are as used by the FAA!

That report showed that when airworthiness issues became inconvenient because of cost or time pressures then they could be ignored or taken 'at risk'.

Entirely possible the same has happened here with SAC using pressure and contacts to persuade the regulators to accept their assertions that their MRGB was fit for purpose, even if it didn't strictly meet the FAR requirement.

[Shell Management]

That report covered a devastating tale of organisations that had lost their way on airworthiness. It describe a PowerPoint culture that glossed over hard questions and detailed evidence, and sacrificed safety due to incompetence, sloppiness, complacency and cynicism. The resulting catastrophe was caused as much by organisational culture as a faulty component.

Hardly the case here.

That report showed that when airworthiness issues became inconvenient because of cost or time pressures then they could be ignored or taken 'at risk'.

Entirely possible the same has happened here with SAC using pressure and contacts to persuade the regulators to accept their assertions that their MRGB was fit for purpose, even if it didn't strictly meet the FAR requirement.

If that were the case the type should be grounded. The fact that FAA have not and Shell only briefly downgraded the type to 'non-prefferred' over the MRGB churning issues, shows there is no problem.

[[email protected]]

Keep taking the loyalty pills SM. What would be the financial impact to both SAC and Shell's operation if the S 92 were to be grounded? That and the possibility that some FAA employees might have serious questions asked of them may be reasons why, when it is crystal clear to many that the MRGB was nowhere near as robust as SAC claimed, there has been no such action.

[maxwelg2]

If that were the case the type should be grounded. The fact that FAA have not and Shell only briefly downgraded the type to 'non-prefferred' over the MRGB churning issues, shows there is no problem.

IMO the S-92 should have been grounded after Broome, which would appear to have been totally covered up as the independent team in Vancouver highlighted enough issues with the titanium studs to justify complete grounding of the fleet until the studs had been changed out to steel.

There is a problem, we still do not have a robust solution applied in service for the S-92 MRGB to give us 30-minute run-dry time and no more mounting feet cracks.

IMO FAA and SAC are smoke-screening Joe public in the hope that it will "all go away". I don't think so. Cougar suing SAC and the TSB report still to be published will hopefully make sure of that.

What finally happened with the CH-148 MRGB, did it get 30-minute dry run time or are they going with the extremely remote statement?

Safe flying

Max

[zalt]

...covered a devastating tale of organisations that had lost their way on airworthiness. It describe a PowerPoint culture that glossed over hard questions and detailed evidence, and sacrificed safety due to incompetence, sloppiness, complacency and cynicism. The resulting catastrophe was caused as much by organisational culture as a faulty component.

and

What would be the financial impact to both SAC and Shell's operation if the S 92 were to be grounded? That and the possibility that some FAA employees might have serious questions asked of them may be reasons why, when it is crystal clear to many that the MRGB [sic] was nowhere near as robust as SAC claimed, there has been no such action.

These comments are pretty accurate statements and this is an accurate analysis.

FAA and SAC are smoke-screening Joe public in the hope that it will "all go away". I don't think so. Cougar suing SAC and the TSB report still to be published will hopefully make sure of that.

Clearly the Cougar accident may have not been fatal if the the crew had ditched earlier and that may have been influenced by the Sikorsky Safety Advisory published to placate Shell on the churning issue, that came out after Broome but before St Johns. It is only a surprise that Shell Aircraft were not named in the court case too for their interference, after all Shell have deep-pockets.

SM changing the studs (they are not bolts) does not really fix the flawed design and the reason they were not fitted before the Cougar accident is that they were not delivered to overseas operators at that time.

[Dan Reno]

Sikorsky S-92® Helicopter Fleet Achieves 250,000 Flight Hours at Record Pace

Sikorsky S-92® Helicopter Fleet Achieves 250,000 Flight Hours at Record Pace | webnewswire.com

[zalt]

Auditor General slams helicopter buy
Auditor General slams helicopter buy | Canada | News | Toronto Sun

Bureaucrats in charge of replacing Canada's aging helicopters didn't follow their own rules or understand how complicated the projects were, making them more expensive and delaying delivery up to 7 years, Auditor General Sheila Fraser said Tuesday.

Fraser, a watchdog who reviews federal programs to make sure taxpayers get value for their money, says National Defence and Public Works and Government Services Canada, the department in charge of purchasing, didn't tell cabinet about the extensive changes the Sikorsky Cyclone maritime helicopter and the heavy-lift Boeing Chinooks needed to meet their needs.

Both were supposed to be “off the shelf” buys. Instead, they needed significant changes that cost more and delayed delivery by up to seven years.

The 28 Cyclones were initially estimated $3 billion. The costs have since been revised to include long-term service support and are now estimated at $5.7 billion. They're due to be delivered in 2012.

CBC News - Canada - FAQ: How Canada procured new military helicopters

The purchase of the Cyclone helicopters from manufacturer Sikorsky — dubbed by Defence Minister Peter MacKay as "the worst debacle in Canadian procurement history" — has been marked by missed delivery dates and amended contracts.

From the audit report:

6.22 A pre-qualification process was undertaken in March 2003, based on detailed technical specifications, and two manufacturers were deemed technically compliant. Each subsequently submitted a full bid in response to the request for proposals. The bids were evaluated based on compliance with the technical requirements, industrial and regional benefits, and lowest overall price. In July 2004, the government announced the winner as Sikorsky International Operations Inc. and two contracts (for the acquisition and the service support) were awarded shortly thereafter. Between 2004 and 2007, National Defence had regular progress meetings with Sikorsky on the status of the project.

6.23 In early 2008, Sikorsky informed PWGSC of a 30-month delay in the planned delivery of the helicopters, citing, among other things, additional work directed by or caused by the Crown (the departments) and the challenges associated with obtaining certification for a technical component in the new helicopter. This led to a contract amendment in 2008, which allowed for a delay in the delivery of the first fully capable helicopter to June 2012, 43 months after the original contract’s delivery date. PWGSC negotiated with the contractor for delivery of up to 19 interim helicopters starting in November 2010. These interim helicopters will not fully meet all of the operational requirements, in particular the mission endurance performance of two hours and 50 minutes, and will have to be retrofitted at a later date. While the interim helicopters will be suitable for testing, evaluation, and training, they will not be deployed on operations. The amendment extended the time period for providing in-service support by two years and amended the provisions contained in the original contract that set out damages associated with late delivery to coincide with the new delivery schedule.

6.24 The amendment also provided for additional “power reserve” (more powerful engines) to meet the mission endurance performance requirement and to accommodate a potential growth in performance in the future. According to PWGSC, this increased the cost of the contracts by about $84 million for the growth potential.

6.32 The developmental nature of the Cyclone helicopter, along with its novel features, also has implications for certifying its airworthiness. The selection process required airworthiness certification of the basic commercial helicopter at the time of the contract award and certification of the new aircraft when the first one was delivered. However, the complexity of the new aircraft has led to unanticipated certification requirements and a potential unforeseen role for National Defence in undertaking certain aspects of the certification.

[riff_raff]

zalt,

It's called "requirement creep", and it's a problem that causes schedule slip and cost overruns on every defense program. Both sides (customer and supplier) usually share responsibility. The customer always wants more performance, bells and whistles. And the supplier is usually happy to oblige since they will get paid handsomely for the changes.

Here in the US, DOD programs are now subject to the Nunn-McCurdy amendment, which calls for termination of programs that exceed the original budget by 25% or more (unless, of course, that particular program is deemed "of significant national interest").