Helicopter crash off the coast of Newfoundland - 18 aboard, March 2009
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Interesting article.
Can anyone explain this?:
AFAIK the MM change simply banned reusing the nuts.
Nice to see ex TC officials understand the problem of the indaequate certification (even if Broome was not a crash):
and
Its clear Sikorsky have failed to communicate clearly, based on the experience of the TSB man who arrange the lab tests on the Broome studs:
Of more explosive note is that the FAA claims that after Broome its:
Does his mean the FAA, while failing to issue an AD before Cougar 491, had to have a debate over wether the aircraft actual meets it certification basis?
Can anyone explain this?:
On Oct. 8, 2008, the company issued an advisory calling for "enhanced inspections" of the oil filter bowl studs and threads, and on Nov. 5 made changes to the maintenance manual
Paul Jackson, a spokesman for Sikorsky, said the changes "would have allowed customers to detect discrepancies in the stud threads and thus prevent a fatigue fracture of the stud."
Paul Jackson, a spokesman for Sikorsky, said the changes "would have allowed customers to detect discrepancies in the stud threads and thus prevent a fatigue fracture of the stud."
Nice to see ex TC officials understand the problem of the indaequate certification (even if Broome was not a crash):
Alan Stewart, a former Transport Canada employee who oversaw the Canadian certification of the S-92, said after the Australian crash, the assumptions of the original certification for "30-minute run dry" were no longer valid.
"The whole premise that the (main gearbox) case could not break and leak out every drop of oil had been proven wrong before the Newfoundland crash. That's the point where the certification assumptions were proven wrong," said Stewart, who now works in the private sector.
"The whole premise that the (main gearbox) case could not break and leak out every drop of oil had been proven wrong before the Newfoundland crash. That's the point where the certification assumptions were proven wrong," said Stewart, who now works in the private sector.
Shawn Coyle, a former employee of Transport Canada's air worthiness division, contends regulators should have quickly ordered repairs and given clear instructions to pilots.
"It should have been weeks, at the most," he said.
Coyle, a 60-year-old test pilot, also said Transport Canada's certification system needs to improve the way it reacts to key assumptions used in certification if a failure is exposed.
"It should have been weeks, at the most," he said.
Coyle, a 60-year-old test pilot, also said Transport Canada's certification system needs to improve the way it reacts to key assumptions used in certification if a failure is exposed.
"I still question what Sikorsky and the FAA knew (about) how close that transmission was to failure. ... That was what I was hoping to hear when I sent the email saying, 'We look forward to hearing what you find because we have these aircraft operating in Canada,' " he said in a recent telephone interview from his office in Vancouver.
"And I still haven't heard."
"And I still haven't heard."
...response was appropriate after the incident in Broome, Australia, because it, "prompted discussions among many FAA specialists about the relationship of the Broome failure to the certification basis of the aircraft."
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Use of the word "drained" is surely indicative of losing all the oil?
Since this is a test of the capability of the residual oil in the transmission to provide limited lubrication, a critical entry condition for the test should be established.
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How about putting in a Sea State 6, wind blowing about 45 knots, OAT of -10, and water temp of say....+5.....assume no one gets into the raft, and SAR response time of one hour to the scene, 15 minute search to the first survivor....and 14 people in the water.....at night!
How does that play out?
How does that play out?
My last couple of SLF trips in the Grand Banks have been right on the flying limits, sometimes after 3 days hanging around the heliport waiting for a "window". Vessel transfer is not really an option with our current season and big oil still wants that black stuff out of the ground and sent to market. The NL economy would be crippled without it as well, so we all carry on accepting the risks, just the same as the fisherman who goes out at 3 in the morning for days at a time with an under-funded SAR coverage. That's just the hard facts right now up here on the Rock.
Although it's nice to experience systems such as the RIPS working well I do ask myself these days what are our odds of survival if for some god-forsaken reason we have to go into the drink? Is our survival equipment and training really up to snuff? Will a 1-metre wave machine in a pool really prepare us for a full-blown capsize in 3-4 metre seas, I don't think so.
Should the A/C be more robust with run-dry capability, yes of course, well then when are we going to get that and what will it take before SAC will provide this capability in the S92?
Going forward we have to learn from mistakes, and IMHO SAC/FAA are 100% at fault here for 491 via a myriad of reasons and hopefully one day soon they will be found guilty and held accountable for their grave mistakes and do their utmost to make amends. We owe that not just to those we have lost but to all of us who still work in this industry, be it engineer, pilot or PAX.
Safe flying
Max
The question seems to be, what constitutes "residual oil"? That remaining after the crew have activated the switch? Was the point of switch activation considered the "critical entry condition"? Questions, but no answers.
HC
Max, not being up to speed on things Canadian, does TC blindly accept FAA certification, or does someone in TC look at the certification data before accepting it? (just wondering if you can add TC to your list of those culpable).
I believe that there was some squeaking from EASA on the 92 certification, but in the end to refuse certification of something endorsed by FAA was politically too difficult.
HC
I believe that there was some squeaking from EASA on the 92 certification, but in the end to refuse certification of something endorsed by FAA was politically too difficult.
HC
Max.....it is not the Operators alone at fault. The Oil Companies are the ones that set the standards for their Operation....the Helicopter companies are held hostage to those standards to a great degree.
I appreciate the conditions that exist there....just as the Alaska operators face when working out of Dead Horse and to the Chukchi. We cannot change the climate, weather, or terrain. We just have to be willing to admit to ourselves the actual risk and do everything possible to mitigate that risk to a tolerable level. The 64 Dollar Question is what is the minimum tolerable level?
I appreciate the conditions that exist there....just as the Alaska operators face when working out of Dead Horse and to the Chukchi. We cannot change the climate, weather, or terrain. We just have to be willing to admit to ourselves the actual risk and do everything possible to mitigate that risk to a tolerable level. The 64 Dollar Question is what is the minimum tolerable level?
HC,
Most likely -
AGREEMENT BETWEEN THE GOVERNMENT OF CANADA
AND
THE GOVERNMENT OF THE UNITED STATES OF AMERICA
FOR
PROMOTION OF AVIATION SAFETY
In order to refine the type certification process and to gain maximum benefit from existing bilateral airworthiness agreements or other similar agreements, greater reliance is to be placed on the acceptance of foreign Type Certificates. Hitherto, with few exceptions, TCCA had accepted, without review, all normal, utility and aerobatic aircraft from the United States, including gliders and balloons on the basis of the Federal Aviation Administration type certification. By contrast, transport, commuter and restricted category aircraft designed and manufactured in the United States were subject to a validation process between 1970 and 1985, which was replaced by a familiarization process in 1985 as a result of a revised Canada/US Bilateral Airworthiness Agreement.
Most likely -
AGREEMENT BETWEEN THE GOVERNMENT OF CANADA
AND
THE GOVERNMENT OF THE UNITED STATES OF AMERICA
FOR
PROMOTION OF AVIATION SAFETY
In order to refine the type certification process and to gain maximum benefit from existing bilateral airworthiness agreements or other similar agreements, greater reliance is to be placed on the acceptance of foreign Type Certificates. Hitherto, with few exceptions, TCCA had accepted, without review, all normal, utility and aerobatic aircraft from the United States, including gliders and balloons on the basis of the Federal Aviation Administration type certification. By contrast, transport, commuter and restricted category aircraft designed and manufactured in the United States were subject to a validation process between 1970 and 1985, which was replaced by a familiarization process in 1985 as a result of a revised Canada/US Bilateral Airworthiness Agreement.
Last edited by RVDT; 7th Feb 2011 at 12:47.
I cannot but wait to see the UK CAA sign on to such a thing....and do so without twisting things up.
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Flaws spotted months before Cougar crash
Problems with gearbox, titanium studs reported in 2008: investigator
Last Updated: Sunday, February 6, 2011 | 7:57 The Canadian Press
A forthcoming Transportation Safety Board report is expected to focus on the gearbox of the Sikorsky aircraft involved in the fatal Cougar Helicopters crash of March 2009. (CBC) A Canadian investigator who red-flagged main gearbox problems months before a Sikorsky helicopter crashed off Newfoundland says he'll closely read a federal report on what caused the deadly accident.
The Transportation Safety Board of Canada is on Wednesday scheduled to release its final report on the March 12, 2009, crash of a Sikorsky S-92 helicopter that resulted in the deaths of 17 crew and passengers.
The board has already said that before the chopper carrying offshore oil workers plunged into the ocean, two titanium studs holding the main gearbox's oil filter broke in mid-flight.
Bill Yearwood, a veteran investigator with the TSB in British Columbia, says he'll be among the observers reading the final report on the disaster to see what the findings are on the gearbox.
He oversaw a brief TSB report completed on Aug. 29, 2008, almost six months before the Newfoundland crash, that concluded there were problems with the oil lubrication system on the gearbox and the titanium studs.
He forwarded his results to the Federal Aviation Administration, the U.S. agency that originally certified the aircraft, saying he hoped to hear what a deeper probe would find.
"I still question what Sikorsky and the FAA knew [about] how close that transmission was to failure. … That was what I was hoping to hear when I sent the email saying, 'We look forward to hearing what you find because we have these aircraft operating in Canada,' " he said in a recent telephone interview from his office in Vancouver.
"And I still haven't heard."
Investigation overseen in 2008
Yearwood hasn't been involved in the investigation of the Cougar Flight 491 crash.
However, he hired an engineering team six months before the crash to look at why several mounting bolts holding an oil filter assembly broke and oil leaked out in 2008 during a flight carrying Australian offshore oil workers. His office was asked to look into the Australian incident by CHC Helicopter of Richmond, B.C., which operated the S-92, as the firm attempted to understand why the studs had failed.
They found the fracture of the studs was caused by problems with the oil filter system rather than a mechanic's installation error, said Yearwood.
In a memo released by the TSB, Yearwood wrote: "There appears to be several unresolved issues with the oil system ... on this particular aircraft. It seems likely that these issues are related to the stud failures."
Yearwood said he's wondered what follow-up occurred.
"All we know is they got the information that they should look further, but whether they did I don't know. And I've been anxious to see if in our (TSB) investigation they got down to the nitty-gritty and said, 'What did you learn when you looked at that first transmission?' "
No obligation to share documents
A spokesman for the U.S. agency says that the memo was received, and the agency wrote back to the investigator to thank him for his work.
Les Dorr said the agency didn't send any follow-up research it did to Yearwood because it wasn't under any obligation to do so under international agreements.
In an email, he said the agency's response was appropriate after the incident in Broome, Australia, because it, "prompted discussions among many FAA specialists about the relationship of the Broome failure to the certification basis of the aircraft."
Sikorsky issued an alert service bulletin six seeks before the Cougar crash telling S-92 operators to replace the titanium studs with steel parts. The Jan. 28, 2009, bulletin made compliance essential after one year or 1,250 flight hours.
The company also said in an email on Friday that it evaluated the studs "immediately after receipt" of Yearwood's memo.
On Oct. 8, 2008, the company issued an advisory calling for "enhanced inspections" of the oil filter bowl studs and threads, and on Nov. 5 made changes to the maintenance manual
Paul Jackson, a spokesman for Sikorsky, said the changes "would have allowed customers to detect discrepancies in the stud threads and thus prevent a fatigue fracture of the stud."
Significance not quickly grasped
At the time, Yearwood said he didn't realize the significance of what he touched on.
After the Cougar crash off Newfoundland, the ability of the gearbox to operate for 30 minutes after losing oil became an issue.
A lawsuit filed this September by St. John's-based Cougar Helicopters alleges in a statement of claim that Sikorsky's "analysis was flawed" in claiming the aircraft could fly 30 minutes after losing oil from the gearbox.
The statement of claim contends the pilots of Cougar Flight 491 were attempting to fly back to land, when they reported a loss of pressure in the chopper's main gearbox about 11 minutes before plunging into the North Atlantic.
Sikorsky has not filed a statement of defence yet.
'Extremely remote'
The FAA granted Sikorsky the "30-minute" certification in 2004, basing it on an assumption that the chances of an oil leak were "extremely remote," say documents obtained from the FAA through freedom of information legislation. The agency defines "extremely remote" as only once in every 10 million flight hours."
Alan Stewart, a former Transport Canada employee who oversaw the Canadian certification of the S-92, said after the Australian crash, the assumptions of the original certification for "30-minute run dry" were no longer valid.
"The whole premise that the (main gearbox) case could not break and leak out every drop of oil had been proven wrong before the Newfoundland crash. That's the point where the certification assumptions were proven wrong," said Stewart, who now works in the private sector.
Dorr said the FAA took into account the Australian incident and started working on a fix for the gearbox studs.
"The FAA ... worked with Sikorsky to develop and qualify improved attachment hardware to reduce the likelihood of future failures," he wrote in the email.
He said there were still questions at the time about whether the incident in Australia definitely showed that the original certification assumptions were flawed.
The agency had noted, Dorr said, that the operators of the S-92 in Australia, which was CHC helicopters, had "deviated" from the usual aircraft maintenance instructions when they did previous oil filter replacements.
Dorr also said the FAA stands by its original decision to certify the gearbox.
Since the crash, two separate air worthiness directives were issued by the agency to address concerns over possible leakage from the oil filter bowl, he added.
The first directive was issued in early 2009 to require installation of the improved studs that attach the filter bowl to the gearbox. A follow-up directive was issued in 2010 that required installation of a two-piece filter bowl featuring additional, stronger bolts with significantly improved protection against maintenance errors.
Faster response needed: test pilot
Shawn Coyle, a former employee of Transport Canada's air worthiness division, contends regulators should have quickly ordered repairs and given clear instructions to pilots.
"It should have been weeks, at the most," he said.
Coyle, a 60-year-old test pilot, also said Transport Canada's certification system needs to improve the way it reacts to key assumptions used in certification if a failure is exposed.
"There doesn't seem to be any regular review with the people doing the original approvals to see the assumption made in the approval are still valid," he said in an interview.
A spokeswoman from Transport Canada would not comment on how it handled Yearwood's memo.
Maryse Durette, a spokeswoman for the agency, says in an email the matter was the FAA's responsibility and Transport Canada would wait for the original certifier to make recommendations before acting.
"When an unsafe condition that could impact the safe operation of an aircraft is identified, the state of design (in this case, the United States FAA) issues an airworthiness directive to mandate appropriate corrective action," she wrote.
Read more: CBC News - Nfld. & Labrador - Flaws spotted months before Cougar crash
Problems with gearbox, titanium studs reported in 2008: investigator
Last Updated: Sunday, February 6, 2011 | 7:57 The Canadian Press
A forthcoming Transportation Safety Board report is expected to focus on the gearbox of the Sikorsky aircraft involved in the fatal Cougar Helicopters crash of March 2009. (CBC) A Canadian investigator who red-flagged main gearbox problems months before a Sikorsky helicopter crashed off Newfoundland says he'll closely read a federal report on what caused the deadly accident.The Transportation Safety Board of Canada is on Wednesday scheduled to release its final report on the March 12, 2009, crash of a Sikorsky S-92 helicopter that resulted in the deaths of 17 crew and passengers.
The board has already said that before the chopper carrying offshore oil workers plunged into the ocean, two titanium studs holding the main gearbox's oil filter broke in mid-flight.
Bill Yearwood, a veteran investigator with the TSB in British Columbia, says he'll be among the observers reading the final report on the disaster to see what the findings are on the gearbox.
He oversaw a brief TSB report completed on Aug. 29, 2008, almost six months before the Newfoundland crash, that concluded there were problems with the oil lubrication system on the gearbox and the titanium studs.
He forwarded his results to the Federal Aviation Administration, the U.S. agency that originally certified the aircraft, saying he hoped to hear what a deeper probe would find.
"I still question what Sikorsky and the FAA knew [about] how close that transmission was to failure. … That was what I was hoping to hear when I sent the email saying, 'We look forward to hearing what you find because we have these aircraft operating in Canada,' " he said in a recent telephone interview from his office in Vancouver.
"And I still haven't heard."
Investigation overseen in 2008
Yearwood hasn't been involved in the investigation of the Cougar Flight 491 crash.
However, he hired an engineering team six months before the crash to look at why several mounting bolts holding an oil filter assembly broke and oil leaked out in 2008 during a flight carrying Australian offshore oil workers. His office was asked to look into the Australian incident by CHC Helicopter of Richmond, B.C., which operated the S-92, as the firm attempted to understand why the studs had failed.
They found the fracture of the studs was caused by problems with the oil filter system rather than a mechanic's installation error, said Yearwood.
In a memo released by the TSB, Yearwood wrote: "There appears to be several unresolved issues with the oil system ... on this particular aircraft. It seems likely that these issues are related to the stud failures."
Yearwood said he's wondered what follow-up occurred.
"All we know is they got the information that they should look further, but whether they did I don't know. And I've been anxious to see if in our (TSB) investigation they got down to the nitty-gritty and said, 'What did you learn when you looked at that first transmission?' "
No obligation to share documents
A spokesman for the U.S. agency says that the memo was received, and the agency wrote back to the investigator to thank him for his work.
Les Dorr said the agency didn't send any follow-up research it did to Yearwood because it wasn't under any obligation to do so under international agreements.
In an email, he said the agency's response was appropriate after the incident in Broome, Australia, because it, "prompted discussions among many FAA specialists about the relationship of the Broome failure to the certification basis of the aircraft."
Sikorsky issued an alert service bulletin six seeks before the Cougar crash telling S-92 operators to replace the titanium studs with steel parts. The Jan. 28, 2009, bulletin made compliance essential after one year or 1,250 flight hours.
The company also said in an email on Friday that it evaluated the studs "immediately after receipt" of Yearwood's memo.
On Oct. 8, 2008, the company issued an advisory calling for "enhanced inspections" of the oil filter bowl studs and threads, and on Nov. 5 made changes to the maintenance manual
Paul Jackson, a spokesman for Sikorsky, said the changes "would have allowed customers to detect discrepancies in the stud threads and thus prevent a fatigue fracture of the stud."
Significance not quickly grasped
At the time, Yearwood said he didn't realize the significance of what he touched on.
After the Cougar crash off Newfoundland, the ability of the gearbox to operate for 30 minutes after losing oil became an issue.
A lawsuit filed this September by St. John's-based Cougar Helicopters alleges in a statement of claim that Sikorsky's "analysis was flawed" in claiming the aircraft could fly 30 minutes after losing oil from the gearbox.
The statement of claim contends the pilots of Cougar Flight 491 were attempting to fly back to land, when they reported a loss of pressure in the chopper's main gearbox about 11 minutes before plunging into the North Atlantic.
Sikorsky has not filed a statement of defence yet.
'Extremely remote'
The FAA granted Sikorsky the "30-minute" certification in 2004, basing it on an assumption that the chances of an oil leak were "extremely remote," say documents obtained from the FAA through freedom of information legislation. The agency defines "extremely remote" as only once in every 10 million flight hours."
Alan Stewart, a former Transport Canada employee who oversaw the Canadian certification of the S-92, said after the Australian crash, the assumptions of the original certification for "30-minute run dry" were no longer valid.
"The whole premise that the (main gearbox) case could not break and leak out every drop of oil had been proven wrong before the Newfoundland crash. That's the point where the certification assumptions were proven wrong," said Stewart, who now works in the private sector.
Dorr said the FAA took into account the Australian incident and started working on a fix for the gearbox studs.
"The FAA ... worked with Sikorsky to develop and qualify improved attachment hardware to reduce the likelihood of future failures," he wrote in the email.
He said there were still questions at the time about whether the incident in Australia definitely showed that the original certification assumptions were flawed.
The agency had noted, Dorr said, that the operators of the S-92 in Australia, which was CHC helicopters, had "deviated" from the usual aircraft maintenance instructions when they did previous oil filter replacements.
Dorr also said the FAA stands by its original decision to certify the gearbox.
Since the crash, two separate air worthiness directives were issued by the agency to address concerns over possible leakage from the oil filter bowl, he added.
The first directive was issued in early 2009 to require installation of the improved studs that attach the filter bowl to the gearbox. A follow-up directive was issued in 2010 that required installation of a two-piece filter bowl featuring additional, stronger bolts with significantly improved protection against maintenance errors.
Faster response needed: test pilot
Shawn Coyle, a former employee of Transport Canada's air worthiness division, contends regulators should have quickly ordered repairs and given clear instructions to pilots.
"It should have been weeks, at the most," he said.
Coyle, a 60-year-old test pilot, also said Transport Canada's certification system needs to improve the way it reacts to key assumptions used in certification if a failure is exposed.
"There doesn't seem to be any regular review with the people doing the original approvals to see the assumption made in the approval are still valid," he said in an interview.
A spokeswoman from Transport Canada would not comment on how it handled Yearwood's memo.
Maryse Durette, a spokeswoman for the agency, says in an email the matter was the FAA's responsibility and Transport Canada would wait for the original certifier to make recommendations before acting.
"When an unsafe condition that could impact the safe operation of an aircraft is identified, the state of design (in this case, the United States FAA) issues an airworthiness directive to mandate appropriate corrective action," she wrote.
Read more: CBC News - Nfld. & Labrador - Flaws spotted months before Cougar crash
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Max, not being up to speed on things Canadian, does TC blindly accept FAA certification, or does someone in TC look at the certification data before accepting it? (just wondering if you can add TC to your list of those culpable).
Should it be this way,again IMHO...no.
SASless, totally agree sir, my previous post was directed at Big Oil not the operator who I personally believe do the best job possible up here with the equipment available to them. It's all a question of what level of risk we all are willing to accept. The fact that I still fly and do not exercise my right to refuse work is my own personal decision and does not detract from the bigger issues currently present not just with the S92 but with helo ops globally in hostile environments. I've been in this industry for nearly 20 years now and have seen many safety improvements over the years, but there is always still room for improvement.
I'm hopeful that one day FAA & SAC will provide us with a more robust A/C but there will always be risk in relation to flying ops, especially in the Grand Banks. More robust safety equipment (survival suits), better and more realistic training will be steps in the right direction.
With the 2nd anniversary of 491 all too soon approaching I reflect back and look to see how we are now better off. For me there is still not enough forward progress on all the issues that we are currently aware of. Hopefully this will change soon.
Safe flying
Max
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The agency had noted, Dorr said, that the operators of the S-92 in Australia, which was CHC helicopters, had "deviated" from the usual aircraft maintenance instructions when they did previous oil filter replacements.
Brian lad.....look into the years old rift between the US NTSB and the FAA! The FAA are a bunch of round shouldered paper shuffling take no stand buinch of bureaucrats. The NTSB calls for changes, modifications, and the FAA twiddles their thumbs and initiate committes, reviews, studies, and call for testimony for Proposed Rule Changes. Glaciers move faster than the FAA!
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Brian
But remember Sikorsky did the test like every other manufacturer has done and drained the oil, just leaving the residual oil HC mentions BUT the difference is that when that test spectacularly failed, Sikorsky only then cooked up their novel interpretation and introduced the bypas system.
Quote:
Use of the word "drained" is surely indicative of losing all the oil?
HC, this is another illustration of how do you interpret AC 29-2C.
Quote:
Since this is a test of the capability of the residual oil in the transmission to provide limited lubrication, a critical entry condition for the test should be established.
The question seems to be, what constitutes "residual oil"? That remaining after the crew have activated the switch? Was the point of switch activation considered the "critical entry condition"? Questions, but no answers.
Use of the word "drained" is surely indicative of losing all the oil?
HC, this is another illustration of how do you interpret AC 29-2C.
Quote:
Since this is a test of the capability of the residual oil in the transmission to provide limited lubrication, a critical entry condition for the test should be established.
The question seems to be, what constitutes "residual oil"? That remaining after the crew have activated the switch? Was the point of switch activation considered the "critical entry condition"? Questions, but no answers.
How do you determine you have an oil leak on the 92 while in flight? How do you determine the extent of the leak once you determine a leak exists?
212man....or any of you other 92 folks care to enlighten the rest of us?
212man....or any of you other 92 folks care to enlighten the rest of us?
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maxweig2
I used to work in TC's Aircraft Certification section.
TC does not blindly accept FAA certification. There were a number of 'concern' papers raised by TC on issues related to the S-92 certification. Unfortunately, it appears that there was none raised on the loss of lubrication.
In the past, TC has been pretty good on this - the Boeing 757 thrust reverser design was changed to suit TC requirements long before the Lauda air crash (when the thrust reverser deployed in flight).
You'd have to ask TC why there wasn't such a concern paper raised on the S-92. Good luck getting any kind of sensible answer.
I used to work in TC's Aircraft Certification section.
TC does not blindly accept FAA certification. There were a number of 'concern' papers raised by TC on issues related to the S-92 certification. Unfortunately, it appears that there was none raised on the loss of lubrication.
In the past, TC has been pretty good on this - the Boeing 757 thrust reverser design was changed to suit TC requirements long before the Lauda air crash (when the thrust reverser deployed in flight).
You'd have to ask TC why there wasn't such a concern paper raised on the S-92. Good luck getting any kind of sensible answer.
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SASless
I'm not sure if this is trick question(!), but the S-92 is fairly conventional in using an indirect indication based on oil pressure (indirect because you could theoretically lose the pump funtionality but without a loss of oil). In the case of a leak, oil pressure pretty proportional to oil quantity.
55psi is normal on S-92 with a caution light as ~35/45psi
Below 5 psi the Flight Manual calls for Land Immediately.
No that might seem straightfoward when flying an armchair, confusingly that is well down a rather wordy checklist, alongside text that may have implied other physical symptoms would also have been present and without prior clear instruction to continue to monitor the relatively small gauge.
There is no warning given at the critical 5psi level.
The last press article also hints at a so-called Sikorsky Safety Advisory that came out after Broome but before St John's that implied the Flight Manual was to be changed to eliminate certain requirements to land immediately (in the case of smoke in cabin caused by another type of gearbox failure that has occurred). EASA (and then FAA) both issued safety alerts that the proposed change discussed in that Sikorsky document had not been approved and that proposal to slacken the Flight Manual has since been dropped.
An added challenge is that if one pump fails (as has happened several times on the S-92 so far promting rapid landings) the pressure can drop to 7psi (dependent on the build standard of the oil system). Remember that 2psi delta could be the difference between flying on to a landing site and ditching into an ocean. Now think about the last oil gauge you looked at, remember how small it was and wonder how well calibrated the gauge is...
IMHO Sikorsky have been very lucky to have not had prior ditchings to the various MGB dynamic system failures. BTW is you look in the new CAA CAP800 UK safety review, S-92 features 5 times in a list of recent high-severity events due to MGB foot cracks. These might be technically unrelated failures modes but they share an element in common: the same design team.
How do you determine you have an oil leak on the 92 while in flight? How do you determine the extent of the leak once you determine a leak exists?
55psi is normal on S-92 with a caution light as ~35/45psi
Below 5 psi the Flight Manual calls for Land Immediately.
No that might seem straightfoward when flying an armchair, confusingly that is well down a rather wordy checklist, alongside text that may have implied other physical symptoms would also have been present and without prior clear instruction to continue to monitor the relatively small gauge.
There is no warning given at the critical 5psi level.
The last press article also hints at a so-called Sikorsky Safety Advisory that came out after Broome but before St John's that implied the Flight Manual was to be changed to eliminate certain requirements to land immediately (in the case of smoke in cabin caused by another type of gearbox failure that has occurred). EASA (and then FAA) both issued safety alerts that the proposed change discussed in that Sikorsky document had not been approved and that proposal to slacken the Flight Manual has since been dropped.
An added challenge is that if one pump fails (as has happened several times on the S-92 so far promting rapid landings) the pressure can drop to 7psi (dependent on the build standard of the oil system). Remember that 2psi delta could be the difference between flying on to a landing site and ditching into an ocean. Now think about the last oil gauge you looked at, remember how small it was and wonder how well calibrated the gauge is...
IMHO Sikorsky have been very lucky to have not had prior ditchings to the various MGB dynamic system failures. BTW is you look in the new CAA CAP800 UK safety review, S-92 features 5 times in a list of recent high-severity events due to MGB foot cracks. These might be technically unrelated failures modes but they share an element in common: the same design team.
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Hi Shawn
I wouldn't even consider asking TC, as a lowly PAX/SLF I just trust that they do their job properly and that suitable safeguard/compliance procedures are in place via adherence to the respective standards. Sadly in this case and IMHO they did not, neither did SAC.
I'll leave it to the professionals who really know their stuff to take them to court in an attempt to prevent such a similar event happening in the future. I am still hopeful that this will happen albeit not as quickly as I would like to see.
Safe flying
Max
I wouldn't even consider asking TC, as a lowly PAX/SLF I just trust that they do their job properly and that suitable safeguard/compliance procedures are in place via adherence to the respective standards. Sadly in this case and IMHO they did not, neither did SAC.
I'll leave it to the professionals who really know their stuff to take them to court in an attempt to prevent such a similar event happening in the future. I am still hopeful that this will happen albeit not as quickly as I would like to see.
Safe flying
Max
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SASless
Good question.
Part 29 calls for catestrophic transmission failure modes to be identified and reduced as far as technically feasible and economicaly justifiable.
If changing the studs to steel is an adequate fix as Sikorsky claim, the 64 (k or million) Dollar Question seems to have a 64 cent answer - it wasn't.
The 64 Dollar Question is what is the minimum tolerable level?
Part 29 calls for catestrophic transmission failure modes to be identified and reduced as far as technically feasible and economicaly justifiable.
If changing the studs to steel is an adequate fix as Sikorsky claim, the 64 (k or million) Dollar Question seems to have a 64 cent answer - it wasn't.
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Appreciate perspectives
Appreciate comments/perspectives on article. Just a note to say that I'd be interested in being contacted by S-92 pilots regarding reaction to TSB findings on Weds., after people have read relevant portions. The Halifax bureau telephone is 1-902-422-1129.