Helicopter crash off the coast of Newfoundland - 18 aboard, March 2009
The remote possibility clause requires "every" failure mode to be forecast, identified, and considered in order for it to be a valid analysis.
Just how likely is it for an engineer to accurately identify every single failure mode that would result in a run dry mode for every single part and gear of a transmission?
That to me is something that is extremely remote in itself.
The question about the oil filter problem is that it identified itself to all an sundry at Broome, Australia. As soon as the first filter housing parted and allowed the oil to leak from the system it breached the "FAA approved Extremely Remote" clause in FAR Part 29.927 under which the aircraft was certified. (IMHO anyway).
The real failure was not the Oil Filter Housing Titantium Studs but the failure of anyone to realize the fact that had happened upon the first set of studs to fail.
The FAA and Sikorsky will have to explain that at some time in the near future I hope.
When the requirement to replace the studs was made and predicated upon a one year or 1250 flight hour limit that would suppose someone had analyzed the situation and determined the actual risk was more like two years and 2500 hundred hours flight time and halved the estimated time between failures or whatever they wanted to call it.
The fact it could be a fatal flaw seemed to escape notice as evidenced by the amount of time granted to do the replacement.
On top of that decision, the Operators of the aircraft have to explain why they failed to see a more urgent need to replace the problem studs.
These will be interesting questions for the FAA, Sikorsky, and the Operators of the S-92's in service today.
Just how likely is it for an engineer to accurately identify every single failure mode that would result in a run dry mode for every single part and gear of a transmission?
That to me is something that is extremely remote in itself.
The question about the oil filter problem is that it identified itself to all an sundry at Broome, Australia. As soon as the first filter housing parted and allowed the oil to leak from the system it breached the "FAA approved Extremely Remote" clause in FAR Part 29.927 under which the aircraft was certified. (IMHO anyway).
The real failure was not the Oil Filter Housing Titantium Studs but the failure of anyone to realize the fact that had happened upon the first set of studs to fail.
The FAA and Sikorsky will have to explain that at some time in the near future I hope.
When the requirement to replace the studs was made and predicated upon a one year or 1250 flight hour limit that would suppose someone had analyzed the situation and determined the actual risk was more like two years and 2500 hundred hours flight time and halved the estimated time between failures or whatever they wanted to call it.
The fact it could be a fatal flaw seemed to escape notice as evidenced by the amount of time granted to do the replacement.
On top of that decision, the Operators of the aircraft have to explain why they failed to see a more urgent need to replace the problem studs.
These will be interesting questions for the FAA, Sikorsky, and the Operators of the S-92's in service today.
On top of that decision, the Operators of the aircraft have to explain why they failed to see a more urgent need to replace the problem studs.
Regardless of the nature of the operator, the manufacturer conducts the risk assessment and that is the assessment used when planning. To further expand on your logic - what if operators decide to implement ASBs early, how early is early? What if an operators decides to implement a 1 year ASB at the next 50 hour check, but the failure occurs 5 hours before? Should they have implemented it before the next flight? That is not how a commercial operator can function - as I'm sure you know.
The exact meaning of terms such as 'FREQUENT', 'REASONABLY PROBABLE', 'REMOTE', 'EXTREMELY REMOTE' and 'EXTREMELY IMPROBABLE' can be found in AC 29.1309.
This text also includes the definitions of failure condition classifications such as 'NO EFFECT', 'MINOR', 'MAJOR' and 'HAZARDOUS/SEVERE-MAJOR' - the last also including 'CATASTROPHIC'.
Jim
This text also includes the definitions of failure condition classifications such as 'NO EFFECT', 'MINOR', 'MAJOR' and 'HAZARDOUS/SEVERE-MAJOR' - the last also including 'CATASTROPHIC'.
Jim
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This posted yesterday in the Globe and Mail: The Globe and Mail: Sikorsky objects to claims helicopter failed to achieve certification
In particular:
'Although the investigation is ongoing, investigators have zeroed in on a problem that forced a S-92 to make an emergency landing in 2008: the studs that hold down the gearbox oil-filter assembly were broken, which would allow the oil to drain out.'
Are they referring to the Shell S-92 that made a forced landing in the Brunei jungle? Think it was a similar problem.
In particular:
'Although the investigation is ongoing, investigators have zeroed in on a problem that forced a S-92 to make an emergency landing in 2008: the studs that hold down the gearbox oil-filter assembly were broken, which would allow the oil to drain out.'
Are they referring to the Shell S-92 that made a forced landing in the Brunei jungle? Think it was a similar problem.
Are they referring to the Shell S-92 that made a forced landing in the Brunei jungle? Think it was a similar problem
For the sake of clarity and accuracy, could people stop including the Brunei incidents in the discussion about oil loss? Neither incident was a result of a leak, and indeed my incident was a result of too much oil! Admitedly, the subsequent condition of the input module resulted in some leakage, but not to any significant degree
Thanks
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St.John’s - The Telegram, Wednesday April 8th :
“ “No such “run dry” requirement, as described in media reports, exists for civil certified rotorcraft”, said Sikorsky in a statement released late Monday evening.
The U.S. Federal Aviation Authority, which certified the S-92A’s, was mystified by the company’s response. “I have no idea why they’d say that” said Les Dorr in an e-mail.””
“ “A pilot is able to throw a manual switch that isolates the leak – it captures all the oil that’s remaining and recirculates it ” said Sikorsky spokesman Paul Jackson in an interview Tuesday.”"
....oh really ?
keep going guys, the lawyers will love it.
“ “No such “run dry” requirement, as described in media reports, exists for civil certified rotorcraft”, said Sikorsky in a statement released late Monday evening.
The U.S. Federal Aviation Authority, which certified the S-92A’s, was mystified by the company’s response. “I have no idea why they’d say that” said Les Dorr in an e-mail.””
“ “A pilot is able to throw a manual switch that isolates the leak – it captures all the oil that’s remaining and recirculates it ” said Sikorsky spokesman Paul Jackson in an interview Tuesday.”"
....oh really ?
keep going guys, the lawyers will love it.
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http://frwebgate1.access.gpo.gov/cgi...ction=retrieve
Am i missing something , I did text search for oil and dry and found no reference in this document. Is there a later release ?.
Sorry I found it , after reading back through the thread.
1) Category A. Unless such failures
are extremely remote, it must be
shown by test that any failure which
results in loss of lubricant in any normal
use lubrication system will not
prevent continued safe operation, although
not necessarily without damage,
at a torque and rotational speed
prescribed by the applicant for continued
flight, for at least 30 minutes after
perception by the flightcrew of the lubrication
system failure or loss of lubricant.
(2) Category B. The requirements of
Category A apply except that the rotor
drive system need only be capable of
operating under autorotative conditions
for at least 15 minutes.
And earlier in part 29.1
(c) Rotorcraft with a maximum
weight greater than 20,000 pounds and
10 or more passenger seats must be
type certificated as Category A rotorcraft.
Should this exception have been referenced on the TCDS ?.
Am i missing something , I did text search for oil and dry and found no reference in this document. Is there a later release ?.
Sorry I found it , after reading back through the thread.
1) Category A. Unless such failures
are extremely remote, it must be
shown by test that any failure which
results in loss of lubricant in any normal
use lubrication system will not
prevent continued safe operation, although
not necessarily without damage,
at a torque and rotational speed
prescribed by the applicant for continued
flight, for at least 30 minutes after
perception by the flightcrew of the lubrication
system failure or loss of lubricant.
(2) Category B. The requirements of
Category A apply except that the rotor
drive system need only be capable of
operating under autorotative conditions
for at least 15 minutes.
And earlier in part 29.1
(c) Rotorcraft with a maximum
weight greater than 20,000 pounds and
10 or more passenger seats must be
type certificated as Category A rotorcraft.
Should this exception have been referenced on the TCDS ?.
Last edited by widgeon; 9th Apr 2009 at 19:51. Reason: didnt read far enough.
Cougar helicopter crash survivor Robert Decker gives full account of crash to RCMP Breaking News print this article
The Telegram
Robert Decker, the only survivor of the tragic helicopter crash March 12 off the east coast of Newfoundland, has meet with RCMP investigators and has given a full account of the events surrounding the crash of Cougar Helicopters flight 491, the RCMP announced today.
The crash killed 17 of the 18 people onboard the helicopter, which was making its way to oil platforms on the Grand Banks.
The RCMP says the information given by Decker will be provided to Transportation Safety Board investigators for their ongoing investigation into the helicopter crash. While the TSB is ongoing, and since there are privacy concerns, the RCMP says it will not be in a position to recount Decker’s story to the public.
Officials with TSB have said a bolt in the main gearbox failed during flight and resulted in a sudden loss of oil pressure prior to the crash of the Sikorsky S-92 A in the Atlantic Ocean.
The TSB said its investigation has found that the flight data recorder indicated oil pressure in the gear box had dropped to zero. There was also a power interruption prior to the crash that caused the flight data recorder and cockpit voice recorder to shut off.
The flight crew radioed they were preparing to ditch, and radar indicates the aircraft descended at roughly 1,000 feet per minute. Impact data indicates the helicopter hit the water with an impact 20 times the force of gravity. The helicopter crashed belly down with the tail hitting first.
Earlier today, the Canada-Newfoundland and Labrador Offshore Petroleum Board (CNLOPB) announced it is setting up an inquiry into worker safety in the wake of the crash.
“While we believe it is important to announce the inquiry at this time, we continue to work on a definition of the mandate, terms of reference, selection of a commissioner for the inquiry, and timeline for inquiry completion,” said a release.
That information will be released at a later date.
The inquiry is being set up under the Atlantic Accord Act which requires a mandatory inquiry in the event of a serious offshore incident.
The CNLOPB says its inquiry will not examine the same issues already under review by the Transportation Safety Board of Canada.
The Telegram
Robert Decker, the only survivor of the tragic helicopter crash March 12 off the east coast of Newfoundland, has meet with RCMP investigators and has given a full account of the events surrounding the crash of Cougar Helicopters flight 491, the RCMP announced today.
The crash killed 17 of the 18 people onboard the helicopter, which was making its way to oil platforms on the Grand Banks.
The RCMP says the information given by Decker will be provided to Transportation Safety Board investigators for their ongoing investigation into the helicopter crash. While the TSB is ongoing, and since there are privacy concerns, the RCMP says it will not be in a position to recount Decker’s story to the public.
Officials with TSB have said a bolt in the main gearbox failed during flight and resulted in a sudden loss of oil pressure prior to the crash of the Sikorsky S-92 A in the Atlantic Ocean.
The TSB said its investigation has found that the flight data recorder indicated oil pressure in the gear box had dropped to zero. There was also a power interruption prior to the crash that caused the flight data recorder and cockpit voice recorder to shut off.
The flight crew radioed they were preparing to ditch, and radar indicates the aircraft descended at roughly 1,000 feet per minute. Impact data indicates the helicopter hit the water with an impact 20 times the force of gravity. The helicopter crashed belly down with the tail hitting first.
Earlier today, the Canada-Newfoundland and Labrador Offshore Petroleum Board (CNLOPB) announced it is setting up an inquiry into worker safety in the wake of the crash.
“While we believe it is important to announce the inquiry at this time, we continue to work on a definition of the mandate, terms of reference, selection of a commissioner for the inquiry, and timeline for inquiry completion,” said a release.
That information will be released at a later date.
The inquiry is being set up under the Atlantic Accord Act which requires a mandatory inquiry in the event of a serious offshore incident.
The CNLOPB says its inquiry will not examine the same issues already under review by the Transportation Safety Board of Canada.
Regards
Aser
Widgeon, "run dry" is a colloquium that simply refers to continued operation following a total oil loss. It is not an official term you will find in a certification standard.
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For the sake of clarity and accuracy, could people stop including the Brunei incidents in the discussion about oil loss? Neither incident was a result of a leak, and indeed my incident was a result of too much oil! Admitedly, the subsequent condition of the input module resulted in some leakage, but not to any significant degree
Whilst I'm in clarification mode, the main S-92a thread has mentioned that the latest S-92a incident over in Norway is believed to be a hydraulic fluid leak. This brought back to memory my own personal recollection of a similar incident. I had the unfortunate pleasure of experiencing a similar hydraulic leak issue back in Nov 15, 2006. Luckily we had just landed on the Henry Goodrich and I spied the drip-drip as we got off for refuelling. We then were told that it was a minor leak and not to worry, took off and promptly landed again. The helo had to be fixed by Cougar in situ which meant a wee boat trip and crane transfer for the techs and us PAX who were going to Terra Nova. No mention in CADORS on that one...Kudos to the Cougar pilots for immediately grounding that helo, probably saved us getting our feet wet or even worse.
The point I'm trying to make is that this didn't stop me from flying in the 92 after the event, we were well de-briefed on the problem and again trusted the whole team to keep us flying safely. This will hopefully be the case in the future.
The only positive thing that can come out of 491 is that we're hopefully going to have safer operations and a greater understanding of the inherent risks in helo flying. The big question now is will the S-92a type 'A' certification be pulled in light of the now well-known facts?
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Survivor of N.L. chopper crash tells tale of escape
By THE CANADIAN PRESS
ST. JOHN'S, N.L. - Robert Decker escaped through the window of a helicopter that crashed in the North Atlantic, killing 17 people, and remained calm throughout the ordeal until he was rescued, he said Thursday.
In a statement provided by a family friend, Decker offered his first public account of how he survived last month's tragedy at sea.
"I escaped through a window after I released my seatbelt shortly after impact," said Decker, the sole survivor of the crash. "I reached the surface and managed to remain calm until I was rescued."
Decker said he didn't know how Allison Maher, the only other person who managed to get out of the helicopter, escaped. She died and her body was recovered on the surface.
"Things happened extremely fast," he said. "There was no time for panic. There were no words spoken. There was no time for suffering."
Decker said he spoke with the RCMP in an effort to help out with the Transportation Safety Board's investigation into the crash. He said he won't speak further publicly until the federal agency's final report is released, or until he's certain his comments won't hinder its probe.
Decker was released from a hospital in St. John's last week after suffering lung injuries and multiple fractures. He continues his recovery at home.
"I will continue to work really hard at resuming a normal life," he said. "I continue to appreciate your support and patience with this, and the untold kindness of the public."
Cougar Flight 491 crashed March 12, about 65 kilometres southeast of St. John's, as it was ferrying workers to two of the province's offshore oil platforms.
The Transportation Safety Board has said that titanium mounting studs that attach an oil filter bowl assembly to the main gearbox broke during the flight. The board says the pilots indicated there was a problem with the main gearbox oil pressure before the crash.
The board said it remains unclear precisely what caused the crash, but less than 10 minutes after the oil pressure loss, the transport chopper slammed at high speed into the Atlantic.
By THE CANADIAN PRESS
ST. JOHN'S, N.L. - Robert Decker escaped through the window of a helicopter that crashed in the North Atlantic, killing 17 people, and remained calm throughout the ordeal until he was rescued, he said Thursday.
In a statement provided by a family friend, Decker offered his first public account of how he survived last month's tragedy at sea.
"I escaped through a window after I released my seatbelt shortly after impact," said Decker, the sole survivor of the crash. "I reached the surface and managed to remain calm until I was rescued."
Decker said he didn't know how Allison Maher, the only other person who managed to get out of the helicopter, escaped. She died and her body was recovered on the surface.
"Things happened extremely fast," he said. "There was no time for panic. There were no words spoken. There was no time for suffering."
Decker said he spoke with the RCMP in an effort to help out with the Transportation Safety Board's investigation into the crash. He said he won't speak further publicly until the federal agency's final report is released, or until he's certain his comments won't hinder its probe.
Decker was released from a hospital in St. John's last week after suffering lung injuries and multiple fractures. He continues his recovery at home.
"I will continue to work really hard at resuming a normal life," he said. "I continue to appreciate your support and patience with this, and the untold kindness of the public."
Cougar Flight 491 crashed March 12, about 65 kilometres southeast of St. John's, as it was ferrying workers to two of the province's offshore oil platforms.
The Transportation Safety Board has said that titanium mounting studs that attach an oil filter bowl assembly to the main gearbox broke during the flight. The board says the pilots indicated there was a problem with the main gearbox oil pressure before the crash.
The board said it remains unclear precisely what caused the crash, but less than 10 minutes after the oil pressure loss, the transport chopper slammed at high speed into the Atlantic.
Last edited by Senior Pilot; 9th Apr 2009 at 23:59. Reason: Add text as quote
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I'm totally amazed that Robert survived the impact, to me this is nothing short of a miracle. I know the S-92a seats are designed to reduce impact, but if the helo did indeed hit the water with a 20g force this is unbelievable.
I'm really glad that some of the real facts are coming out now, there's been so many rumours e.g. that Robert jumped out before impact.
Does anyone know what the maximum survivable impact force is supposed to be for this helo? How do we safeguard to ensure that the landing is soft enough to survive and the helo stays upright long enough to get into the life-rafts? Shear-pin type main rotor bearing to allow auto-rotate with complete MGB failure? Improved flotation devices to cope with Grand Banks sea states? Will HUBA's become mandatory now to cope with cold-water shock?
Robert, here's to your continuing recovery and hopefully more recollections to help the TSB work this one out.
I'm really glad that some of the real facts are coming out now, there's been so many rumours e.g. that Robert jumped out before impact.
Does anyone know what the maximum survivable impact force is supposed to be for this helo? How do we safeguard to ensure that the landing is soft enough to survive and the helo stays upright long enough to get into the life-rafts? Shear-pin type main rotor bearing to allow auto-rotate with complete MGB failure? Improved flotation devices to cope with Grand Banks sea states? Will HUBA's become mandatory now to cope with cold-water shock?
Robert, here's to your continuing recovery and hopefully more recollections to help the TSB work this one out.
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Re 20g an article in Aviation Weeks "Business and Commercial Aviation", February 2002, on the 92 has,
Article also says,
Sikorsky can't have been ignorant of the claims being printed in the press and certainly did nothing to refute what had been published.
The airframe itself is designed to withstand a 21 foot/second vertical crash (20g downward momentum).
“ “No such “run dry” requirement, as described in media reports, exists for civil certified rotorcraft”, said Sikorsky in a statement released late Monday evening.
The main gearbox is designed to go 6,000 hours between overhauls and can run completely dry for up to 30 minutes. The case is made out of WE-43A magnesium alloy, which is resistant to saltwater corrosion.
If memory serves, the maximum g the human body can absorb (and certainly not without serious damage) is 25g - Robert Decker was very lucky indeed that his injuries allowed him sufficient mobility to escape from the fuselage and I hope he makes a full recovery.
Crab
Yes, but the stroking seats would reduce the peak g. If the airframe suffered a peak of 20g, the occupants of the seats would suffer somewhat less. Still very lucky though!
I wonder if this is the first time a crashworthy helicopter seat has saved a passenger's life?
HC
Yes, but the stroking seats would reduce the peak g. If the airframe suffered a peak of 20g, the occupants of the seats would suffer somewhat less. Still very lucky though!
I wonder if this is the first time a crashworthy helicopter seat has saved a passenger's life?
HC
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Broadly speaking the human tolerance with harness and lap belt are given as,
Longitudinal
45 G (0.1 second)
25 G (0.2 seconds)
Vertical
25 G (0.1 second)
Lateral
20 G (0.1 second)
Of interest the lap belt only figures are,
Longitudinal
15 G (0.002 second)
Vertical
4 G (injured)
Lateral
11 G (0.1 second)
The latest seat standards if I recall correctly, is 16 G Forward, 8 G Lateral, 20 G Downwards and 4 G Upwards.
For bedtime reading see www.everyspec.com/MIL-STD/MIL-STD+(1100+-+1299)/download.php?spec=MIL_STD_1290A.860.pdf and http://ntrs.nasa.gov/archive/nasa/ca...1998394351.pdf
Longitudinal
45 G (0.1 second)
25 G (0.2 seconds)
Vertical
25 G (0.1 second)
Lateral
20 G (0.1 second)
Of interest the lap belt only figures are,
Longitudinal
15 G (0.002 second)
Vertical
4 G (injured)
Lateral
11 G (0.1 second)
The latest seat standards if I recall correctly, is 16 G Forward, 8 G Lateral, 20 G Downwards and 4 G Upwards.
For bedtime reading see www.everyspec.com/MIL-STD/MIL-STD+(1100+-+1299)/download.php?spec=MIL_STD_1290A.860.pdf and http://ntrs.nasa.gov/archive/nasa/ca...1998394351.pdf
Last edited by Brian Abraham; 10th Apr 2009 at 10:17.
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Seeing as we're now talking about the helo's safety capabilities, what's the maximum allowable force that the fuel tanks can cope with? It was mentioned earlier in the media that Robert Decker had fuel in his lungs as well as salt water. I thought that these tanks were designed to withstand a crash scenario.
In our HUET training we wear goggles to prevent eye damage from fuel etc. in the water during a ditching. The HUBA would potentially have saved Robert's lungs from chemical damage, plus given perhaps some other poor souls the chance to escape.
One thing with HUBA or rebreathers, they shouldn't be used until post-impact as the mouthpieces can do more damage than good on impact.
I am assuming that the RCMP know now exactly where Robert was sitting, that may or may not have had a contributory factor to his survival.
In our HUET training we wear goggles to prevent eye damage from fuel etc. in the water during a ditching. The HUBA would potentially have saved Robert's lungs from chemical damage, plus given perhaps some other poor souls the chance to escape.
One thing with HUBA or rebreathers, they shouldn't be used until post-impact as the mouthpieces can do more damage than good on impact.
I am assuming that the RCMP know now exactly where Robert was sitting, that may or may not have had a contributory factor to his survival.
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The Black Hawk refers to run dry for 30 minutes at cruise power (in the RFM), the S-92 transmission is bigger and better, and will be fitted as-is onto the Hawks as future upgrades but has no run dry, the S-92’s FBY military variant CH-148 for Canada under a 2004 contract that called for run dry (according to the Globe & Mail) had first flight last year, but SAC are now saying the MGB for the CH-148 is still in the design stage?
Will someone with big boots now tell SAC to put ELS systems in place and not allow them to invoke any clause that excludes them from testing to confirm MGB run dry redundancy ?
If the S-92/Blackhawk MGB is a bolt-on transplant it would happen sooner rather than later ?
Would be real nice to see the 20 year old “30 minute” figure improved on as well ?
Will someone with big boots now tell SAC to put ELS systems in place and not allow them to invoke any clause that excludes them from testing to confirm MGB run dry redundancy ?
If the S-92/Blackhawk MGB is a bolt-on transplant it would happen sooner rather than later ?
Would be real nice to see the 20 year old “30 minute” figure improved on as well ?
Any update on Robert Decker the sole suvivor ?