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Twice bitten?
Its clear that some people would lkike to see Sikorsky have their day in open court to justify their design decisions.
Here is a thoughtful editorial from the local St Johns paper: Once, there was a helicopter known as the Sikorsky S-92A. In this province, we're well familiar with it: it's the type of helicopter that crashed into the North Atlantic just over a year ago, killing 17 passengers and crew. The helicopter crashed because studs broke in its main gearbox, causing oil to leak out and the gearbox to seize up just 11 minutes after the oil leaked. It wasn't supposed to be that way. Originally, the S-92A was supposed to be able to run with a dry gearbox for 30 minutes, and the aircraft was originally tested to do exactly that. Problem was, during the test, the gearbox seized up and flew apart - 11 minutes into the test. So instead of modifying the gearbox, Sikorsky successfully argued to U.S. regulators that a total loss of oil from the gearbox would be an extremely remote event - and, as such, the aircraft wouldn't need to worry about meeting the 30-minute standard. "Extremely remote" wasn't remote enough. Both Cougar Helicopters Flight 491 and another S-92A, working in Australia, suffered catastrophic oil pressure loss because of faulty studs. The Australian aircraft was lucky enough to be flying over land - the Cougar helicopter was not. Now, the U.S. Federal Aviation Administration (FAA) is saying existing S-92A helicopters won't have to be retrofitted with new gearboxes because the changes would neither be practical nor necessary. New helicopters of that model, however, will have to have a gearbox capable of running without oil for 30 minutes. You can understand why the FAA would suggest that forcing Sikorsky to switch out the old gearboxes in 140 operating helicopters would be impractical. There are those who might argue that the S-92A's gearbox studs have now been replaced, making the chance of a gearbox loss of oil "extremely remote" all over again. Replacing the gearboxes on all 140 aircraft would be a lengthy, taxing and expensive job. At the same time, impracticality shouldn't enter into the discussion. The FAA's actual memo on the issue says, "Furthermore, modifying these helicopters to be equipped with new main gearboxes would have a significant economic impact on the aviation community, and the costs would outweigh any improvements in safety." The clear and obvious costs of designing a new gearbox for future helicopters, on the other hand, apparently would not outweigh any improvements in safety. It is a bottom-line decision, and what it means is that there are really two classes of passengers and crew: those who deserve aircraft that meet a particular safety standard, and those who do not. Improvements to safety are never impractical - unless, of course, the practical finances of helicopter companies are actually more important than the lives of the people who fly in them. |
Logical Faux Pas
The fact that "a gearbox" lasted 11 minutes in bench test does not mean all gearboxes will last 11 minutes after loss of cooling, er, oil I mean. A different assembly may last 2, 11, 20 or 40 minutes.
If the writer of that article does not recognize reality and the fact that aircraft design is always a compromise between affordability (can a customer afford it?) and performance and people agree with him then Houston, we have a problem. :ugh: |
Hangin your hat on the FAA's concern for Safety is fraught with peril!
I do not mean to re-argue past events but I still wonder how this would have turned out if the crew had carried out a timely descent and ditching? Would this tragedy have turned out much differently? If they had....would we be discussing equally important but quite different safety issues...but would now be litigating the issues at hand now. That is not to say Sikorsky and the MGB issue should not be discussed but should we get too focused on that alone to the exclusion of the other issues that contributed to the loss of the people aboard the helicopter that day? I submit there is blame enough to go around to just about everyone and every organization involved in this tragedy as has been suggested by the investigations. I do defend Sikorsky but think fair is fair. Let's keep the finger pointing at each link of this accident chain and demand proper action to correct all the shortcomings no matter the source. |
NoBiggie,
Your point about setting a benchmark based on a single test is well made. The particular MRGB build that failed 11 minutes into the loss-of-lube test may have been a statistical anomaly. The way the current 30 minute loss-of-lube qualification test is structured, there are simply far too many variables involved to conclude that if a single example of an MRGB design lasts 30 minutes, then all conforming production units will also last at least 30 minutes under loss-of-lube conditions. Also consider that while the qual test unit is usually an MRGB with very low hours, would an MRGB in service with high hours perform as well as the qual unit under loss-of-lube conditions? Performing a thorough analysis of MRGB components under loss-of-lube conditions (heat transfer, frictions, etc.) would be extremely complex and costly. Thus the loss-of-lube qual test is usually one of the few test procedures that does not have substantial analysis for validation. Until the analysis capabilities needed for thoroughly analyzing loss-of-lube function become available and reliable, then the loss-of-lube qual test procedures should be restructured. The test parameters should be more controlled, the test duration should be 1.5 or 2 times the qualification period, and the configuration/condition of the test article should represent the "worst case condition" expected in service. riff_raff |
riff-raff
Your comments are well observed and in the context of recent history they sketch out a way forward. However, before we had the 30 minute run-dry qualification test there was....... let me think ..... nothing!!!
Those of us that remember the UK HARP report of the 1980s which sought to remedy a long held belief that helicopters could and should be built to higher engineering and airworthiness standards will take comfort, albeit small comfort, in the fact that airworthiness standards have improved substantially in some areas (crashworthiness, design integrity, damage tolerance) but seem to have further to go. This would seem to be the case with composite structures which appear not to be well understood (thanks BLACKMAX for your very valuable contribution to the debate), and with transmission components which have come a long way from the troublesome S61 MGB and the potentially catastrophic AS332 MGB but arguably should go further. The challenge is enormous. I remember the Westland gearbox designer telling us at lecture at Bristol Uni that if the helicopter MGB was designed using the (then current) car design philosophy, then it would be so heavy that it would consume all the disposable load even if the material used was aviation grade lightweight alloy. Clearly gearboxes must have a development pathway that is realistic and affordable but this does not mean that we cannot set hurdles for manufacturers to jump over and in doing so an ethical way of dealing with shortcomings must be found. Simply coming up with a convenient probability calculation ignores the realities of our world. INTEGRITY - Integrity is a keyword and I mean it should be applied to the structure AND the people involved in certification. G. :ok: |
Originally Posted by NoBiggie
(Post 6590466)
The fact that "a gearbox" lasted 11 minutes in bench test does not mean all gearboxes will last 11 minutes after loss of cooling, er, oil I mean. A different assembly may last 2, 11, 20 or 40 minutes.
If the writer of that article does not recognize reality and the fact that aircraft design is always a compromise between affordability (can a customer afford it?) and performance and people agree with him then Houston, we have a problem. :ugh: coincidentally the MRGB in the Cougar 491 lasted pretty exactly these 10 or 11 minutes. This was not a one off bad luck failure. This was systematic. And in other Helo's the same manufacturer is able to make it last 30 minutes in the same test. Go figure.... Where I do agree is that the test will not be representative of all real world cases. There you will see much more variation due to environmental conditions. |
"And in other Helo's the same manufacturer is able to make it last 30 minutes in the same test."
Would be interested in the design differences in the 2 boxes +.expected loadings. The 30 min is at least a yardstick to start with. That 3 boxes failed around 11 min (I beleive the test box failed at aprox same run time) would suggest there was a trend. Has there been any change to flight Manuels or Co. SOP regarding the way to deal with oil loss |
The RFM states that less than 5psi MGB oil pressure - Land Immediately - same as before the accident.
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js Please read the thread, the inadequacies of the RFM have been covered.
Today the Phase 2 Public Inquiry report was issued. More stinging criticism of Sikorsky and the weaknesses of the S-92. C-NLOPB || Offshore Helicopter Safety Inquiry |
Zalt,
js is entitled to express his opinion just as much as you are. I'm with js on this one though. |
How much is this going to cost Sikorsky overall to cover the 17 unfortunate individuals? 17, 27 or 37 million dollars is much cheaper than rectifiying their current fleet, I would suggest.
I recall the same sort of issue with the 737 rudder screwthread jack (1980's)that failed in the past on several occasions. The US safety board agreed with industry and the FAA that the projected costs of paying off the deceased estates was infinitely smaller than finding and fitting a fix. In fact the maths worked out to show each passenger in a 737 over its life time was worth only $820....dead := |
TC - Good point. I am surprised that today we are still having the arguments about modification and safety improvements being made regardless of cost..
If you were Jeff Pino, would you sink every last penny into designing and building a helicopter that was as safe as humanly possible, knowing that the selling price of your aircraft would be x% higher than your competitors? Would you take the moral initiative and hope your competitors follow suit, whilst risking financial catastrophe? Please note I refer to any new flight safety developments here, not purely the dry gearbox argument in isolation. This is simple risk analysis.. cost v probability v consequence of occurence. Any business has a goal of making as much money as possible.. why is anybody surprised that certain modifications can fall into a category of "Too expensive"?? I am not defending anyone here by the way, just stating the obvious. All that said, there was a time when HUMS was considered hugely and sometimes prohibatively expensive, but it did eventually find it's way into the world.. |
There is continuous improvement with the product. There is no sign that this process is slowing or stopping.
Sikorsky are no where near saying "Well there it is". :D |
Flyt3est
I think if you were to contact Jeff Pino at Sikorsky, he would confirm that the company is putting millions of $ into improving the S-92 MGB. The phase 3 MGB is being fielded now and the IDMGB will be fielded from 2012. There are other product improvements in the pipeline which will significantly extend the capabilities of the S-92. If you contact your regional FSR or Sikorsky sales person, I am sure you will be able to get an update on the MGB continuous improvement process. If you work for an S-92 operator, you should have already been briefed by your company or should be able to request a briefing. My company receives regular briefings and participates in 3 day maintenance and operations reviews with Sikorsky. |
Flyt3est,
Your point about cost/risk analysis is well made. I would also add that executives in the aircraft business are not the greedy, crass, heartless people some make them out to be. Upper level private-sector business executives in modern democracies are often held accountable for their actions and decisions by public regulatory agencies. In fact, private sector businessmen are held to higher standards than their counterparts in the public-sector. These public corporation executives must, as you noted, take cost into account with any decision they make. We must also consider, in view of our current litigious business environment, that for a company to unilaterally make safety-related changes to their existing product would open them up to serious civil liabilities, whether justified or not. We should try to be cautious when assigning blame (in hindsight) to any business decision that caused problems, especially one which the general public does not have full insight to all factors that influenced that particular decision. While discussing and speculating on such issues is what makes these forums interesting, there should never be a point at which the discussion becomes accusatory in nature. Improving safety and reliability in aircraft is a slow and methodical evolutionary process. Unfortunately, human nature tends to make us focus on our current shortcomings, rather than on how much substantial progress we have made in the short history of commercial rotorcraft. I am especially thankful that most of us live in open democratic societies where we have regulatory systems that promote cooperation between public agencies and private enterprises to make improvements for the public good. Our system may not yet be perfect, but it's a far sight better than those of authoritarian governments where such embarrassing issues are swept under the rug. Best regards, riff_raff |
riff_raff
It would help prevent future accidents if the people who made the decision after the loss of lubrication test failure in August 2002 to fit a simple cooler bypass valve and assessed oil loss from elsewhere as 'extremely remote' explained their logic. That might dismiss the thought that it was mere commercial expediency. I saw this today too: C-NLOPB Responds to Offshore Helicopter Safety inquiry phase II report | Shephard Group Looks like Canadian offshore workers will be told about every ASB now. |
Looks like Canadian offshore workers will be told about every ASB now. I can only see this as positive progress and long-awaited, the more focus that is placed on this key piece of operating and safety equipment that we rely on so heavily over here in the Grand Banks the better. I hope to hear of progress soon on the improved MRGB and the outcome of the recent Searose AP incident, preferably officially. Safe flying Max |
Legal process moves on
Sikorsky v Lloyd's TSB General Leasing (No 20) 2011 NLCA 49.
The Newfoundland and Labrador court of Appeal have upheld the February decision of the Newfoundland court that the trial can take place in Newfoundland, not in Connecticut as Sikorsky contended. Sikorsky therefore loses it's appeal with costs. If you are intrested in the arguments of jurisdiction of the claim, and the reasons for the answer, see Newfoundland court dismisses appeal in Sikorsky case - International Law Office |
VOCM.COM|Search and Rescue Technician to get Medal of Bravery | Article
The man who rescued the only person to survive the Cougar helicopter crash is getting the Governor General's Medal of Bravery award. Ian Wheeler is a search and rescue technician with Cougar Helicopters. Cougar Flight 491 was heading to the offshore when it crashed into the Atlantic on March 12th, 2009. Robert Decker escaped the aircraft, severely injured. He was falling in and out of consciousness as he floated in a field of debris. Wheeler was lowered from a rescue chopper and fought two-metre-high waves and the wind action from the rotor blades to reach him. The rescue basket was lowered to them, and after many attempts, Wheeler was able to place Decker inside. Wheeler remained un-tethered during the lift as he tended to Decker, who was hypothermic. Wheeler ensured he was safe and well secured. The Governor General's office says the Medal of Bravery will be presented to Wheeler at a later date. |
Originally Posted by squib66
(Post 6764542)
VOCM.COM|Search and Rescue Technician to get Medal of Bravery | Article
Would a double strop not have been quicker? |
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