Helicopter crash off the coast of Newfoundland - 18 aboard, March 2009
And so the lesson was learned by all the automotive industry - shame the helicopter aviation industry didn't.
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from the 2009 December 21st (effective date) AD :
"
SUPPLEMENTARY INFORMATION: This amendment adopts a new AD for the Sikorsky Model S-92A helicopters. This action requires a one-time visual inspection of the MGB lube system filter assembly for oil filter damage. This action also requires if either the primary or secondary oil filter is damaged, replacing both filters, all packings, and the studs before further flight. This action also requires replacing the oil filter bowl within 30 days after replacing a damaged filter and a daily inspection for an oil leak (no oil leaks allowed) during that 30- day interim period. This amendment is prompted by three reports of damaged oil filters or packings resulting from operating with an oversized packing possibly because of incorrect part numbers in the maintenance manual. Sikorsky has issued a temporary revision, T-Rev 63- 19, to the maintenance manual to correct any errors. Installing the filter assembly with an oversized packing (also known as an O-ring) in the oil filter double bypass valve can produce excessive assembly and fatigue loads in the oil filter bowl or the mounting studs that secure the oil filter bowl to the MGB. Based on rig testing, these conditions can result in reduced fatigue life in the studs and the oil filter bowl. Based on information from a previous accident investigation, failure of the oil filter bowl or mounting studs can result in sudden and complete loss of oil from the MGB. This condition, if not corrected, could result in complete loss of oil from the MGB, failure of the MGB, and subsequent loss of control of the helicopter. "
SUPPLEMENTARY INFORMATION: This amendment adopts a new AD for the Sikorsky Model S-92A helicopters. This action requires a one-time visual inspection of the MGB lube system filter assembly for oil filter damage. This action also requires if either the primary or secondary oil filter is damaged, replacing both filters, all packings, and the studs before further flight. This action also requires replacing the oil filter bowl within 30 days after replacing a damaged filter and a daily inspection for an oil leak (no oil leaks allowed) during that 30- day interim period. This amendment is prompted by three reports of damaged oil filters or packings resulting from operating with an oversized packing possibly because of incorrect part numbers in the maintenance manual. Sikorsky has issued a temporary revision, T-Rev 63- 19, to the maintenance manual to correct any errors. Installing the filter assembly with an oversized packing (also known as an O-ring) in the oil filter double bypass valve can produce excessive assembly and fatigue loads in the oil filter bowl or the mounting studs that secure the oil filter bowl to the MGB. Based on rig testing, these conditions can result in reduced fatigue life in the studs and the oil filter bowl. Based on information from a previous accident investigation, failure of the oil filter bowl or mounting studs can result in sudden and complete loss of oil from the MGB. This condition, if not corrected, could result in complete loss of oil from the MGB, failure of the MGB, and subsequent loss of control of the helicopter. "
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Oil filter studs.
madrock,
One thing I noticed looking at pictures of the recovered hardware from the S-92 that crashed due to the MRGB oil filter housing failure, was that it had what appeared to be silver-plated locknuts on the housing's titanium studs. The combination of silver and titanium is usually not acceptable due to galvanic corrosion issues. This galvanic corrosion issue would also be exacerbated in a marine environment.
The FAA AD did not specifically mention this issue. But it is something they should have been aware of when qualifying the S-92's MRGB design.
Regards,
riff_raff
One thing I noticed looking at pictures of the recovered hardware from the S-92 that crashed due to the MRGB oil filter housing failure, was that it had what appeared to be silver-plated locknuts on the housing's titanium studs. The combination of silver and titanium is usually not acceptable due to galvanic corrosion issues. This galvanic corrosion issue would also be exacerbated in a marine environment.
The FAA AD did not specifically mention this issue. But it is something they should have been aware of when qualifying the S-92's MRGB design.
Regards,
riff_raff
If that is true I wonder why Eurocopter use a silver plated shim between the titanium rotor head and the steel mast on the BO 105. They also use silver plated bushes between the titanium head studs and the steel mast.
Seems to me that they believe silver is an effective anti corrosion measure at a steel titanium interface.
Seems to me that they believe silver is an effective anti corrosion measure at a steel titanium interface.
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Can anyone supply the dimensions of the incorrect and correct o-rings and the o-ring groove?
I'm interested in calculating just how much difference the two o-rings would make to the bolt loading.
I'm interested in calculating just how much difference the two o-rings would make to the bolt loading.
riff_raff
That's the second time you have thrown your conjecture into this thread. The last time produced no response. However seeing as you are being persistent I will take you up on your assertion. Can you provide some scientific backup to your statement.
I've had a quick look at the anodic indices of silver and titanium, and they are actually acceptably close. Much better than titanium and steel, for example.
That's the second time you have thrown your conjecture into this thread. The last time produced no response. However seeing as you are being persistent I will take you up on your assertion. Can you provide some scientific backup to your statement.
I've had a quick look at the anodic indices of silver and titanium, and they are actually acceptably close. Much better than titanium and steel, for example.
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from The Canadian Press today (Telegram online)
"The families of passengers who died in the crash of a Sikorsky helicopter off the coast of Newfoundland last year, as well as the sole survivor of the tragedy, have reached a settlement in their lawsuit against the U.S. company.
The families of 15 passengers and the survivor launched a lawsuit last year in the Philadelphia court of common pleas, alleging that Sikorsky, Keystone Helicopters and their parent company, United Technologies Corp., made false claims about the aircraft’s safety.
Paul Jackson, a spokesman for Sikorsky, said in an email Tuesday that the lawsuit has been settled but details are confidential.
The plaintiffs said in documents filed with the court last July that they had “voluntarily discontinued” their lawsuit to begin negotiations on a possible settlement.
Jackson said a settlement with the families of the helicopter’s two pilots has also been reached.
“All of the claims in regard to the Cougar Flight 491 crew and passengers have been resolved,” Jackson said in the email. “The settlement agreements are private and confidential, so I must decline to provide any details.”
The Cougar Helicopters flight was carrying 16 passengers and two crew members when it crashed in the North Atlantic on March 12 as it was ferrying workers to two offshore oil platforms.
In the lawsuit, the plaintiffs alleged the U.S. firms hadn’t correctly indicated how long a helicopter could safely fly if oil leaked out of its gearbox.
In mid-June, the federal Transportation Safety Board released an update into its probe of the crash and found that while the main rotor blades continued to rotate when the chopper crashed, the tail rotor drive gears were severely damaged.
Investigators said the pilots of the Sikorsky S-92A lost control in the flight’s final moments because of the tail rotor failure.
The issue of the aircraft’s ability to operate without lubricating oil for the gearbox was a key allegation in the 113-page statement of complaint filed in the court in Philadelphia.
The plaintiffs argued the pilots believed the aircraft met U.S. Federal Aviation Administration regulations that certified the aircraft could operate for 30 minutes after losing oil.
They alleged the pilots kept flying the aircraft towards land on that basis, rather than rapidly landing it on the water."
The families of 15 passengers and the survivor launched a lawsuit last year in the Philadelphia court of common pleas, alleging that Sikorsky, Keystone Helicopters and their parent company, United Technologies Corp., made false claims about the aircraft’s safety.
Paul Jackson, a spokesman for Sikorsky, said in an email Tuesday that the lawsuit has been settled but details are confidential.
The plaintiffs said in documents filed with the court last July that they had “voluntarily discontinued” their lawsuit to begin negotiations on a possible settlement.
Jackson said a settlement with the families of the helicopter’s two pilots has also been reached.
“All of the claims in regard to the Cougar Flight 491 crew and passengers have been resolved,” Jackson said in the email. “The settlement agreements are private and confidential, so I must decline to provide any details.”
The Cougar Helicopters flight was carrying 16 passengers and two crew members when it crashed in the North Atlantic on March 12 as it was ferrying workers to two offshore oil platforms.
In the lawsuit, the plaintiffs alleged the U.S. firms hadn’t correctly indicated how long a helicopter could safely fly if oil leaked out of its gearbox.
In mid-June, the federal Transportation Safety Board released an update into its probe of the crash and found that while the main rotor blades continued to rotate when the chopper crashed, the tail rotor drive gears were severely damaged.
Investigators said the pilots of the Sikorsky S-92A lost control in the flight’s final moments because of the tail rotor failure.
The issue of the aircraft’s ability to operate without lubricating oil for the gearbox was a key allegation in the 113-page statement of complaint filed in the court in Philadelphia.
The plaintiffs argued the pilots believed the aircraft met U.S. Federal Aviation Administration regulations that certified the aircraft could operate for 30 minutes after losing oil.
They alleged the pilots kept flying the aircraft towards land on that basis, rather than rapidly landing it on the water."
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Ag on Ti galvanic potential
Variable Load,
Sorry for the tardy reply. Silver against Ti is usually prohibited due to galvanic corrosion issues. This situation would likely be exacerbated by a marine atmosphere.
Here's NASA's position on the issue (page 3, last sentence):
"Due to corrosion potential, silver plated parts must not contact titanium."
http://engineer.jpl.nasa.gov/practices/2201.pdf
The galvanic potential between silver and titanium is normally less than 0.20V, which would be considered borderline acceptable for other metal combinations. But apparently Ag on Ti is a problem, and I can't give you a technical explanation why.
Hope that satisfies your need for a "scientific" validation of my comments.
Regards,
riff_raff
Sorry for the tardy reply. Silver against Ti is usually prohibited due to galvanic corrosion issues. This situation would likely be exacerbated by a marine atmosphere.
Here's NASA's position on the issue (page 3, last sentence):
"Due to corrosion potential, silver plated parts must not contact titanium."
http://engineer.jpl.nasa.gov/practices/2201.pdf
The galvanic potential between silver and titanium is normally less than 0.20V, which would be considered borderline acceptable for other metal combinations. But apparently Ag on Ti is a problem, and I can't give you a technical explanation why.
Hope that satisfies your need for a "scientific" validation of my comments.
Regards,
riff_raff
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more titanium and silver
Variable Load,
I did a little research on the subject and I'd like to update my response to you. From what I have read, the issue between silver and titanium alloys is more correctly a stress corrosion phenomena, and not a galvanic corrosion problem. Apparently, under certain conditions, titanium alloys will suffer stress corrosion when in contact with a more noble metal such as silver.
This only occurs with a titanium surface that is not passivated. While titanium fasteners usually have a passivated surface on the threads when new, after a few installation and removal cycles of an all metal locknut, the passivated surface of the titanium threads would be scuffed off. So one can imagine that the unpassivated titanium thread surface in intimate contact with the silver plating on the locknut would present the conditions for stress corrosion cracking to occur. The fact that the titanium studs were highly loaded (or possibly overloaded), combined with the natural stress concentrations the thread roots create, and the extreme notch sensitivity that titanium exhibits, all would contribute to a structural failure initiated by a stress corrosion crack.
Looking forward to your comments on the issue.
Regards,
riff_raff
ps. In response to ericferret's comments on silver plated shims and bushings, the (soft) silver plating is used as an anti-fretting coating, and not for corrosion prevention.
I did a little research on the subject and I'd like to update my response to you. From what I have read, the issue between silver and titanium alloys is more correctly a stress corrosion phenomena, and not a galvanic corrosion problem. Apparently, under certain conditions, titanium alloys will suffer stress corrosion when in contact with a more noble metal such as silver.
This only occurs with a titanium surface that is not passivated. While titanium fasteners usually have a passivated surface on the threads when new, after a few installation and removal cycles of an all metal locknut, the passivated surface of the titanium threads would be scuffed off. So one can imagine that the unpassivated titanium thread surface in intimate contact with the silver plating on the locknut would present the conditions for stress corrosion cracking to occur. The fact that the titanium studs were highly loaded (or possibly overloaded), combined with the natural stress concentrations the thread roots create, and the extreme notch sensitivity that titanium exhibits, all would contribute to a structural failure initiated by a stress corrosion crack.
Looking forward to your comments on the issue.
Regards,
riff_raff
ps. In response to ericferret's comments on silver plated shims and bushings, the (soft) silver plating is used as an anti-fretting coating, and not for corrosion prevention.
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Some more details
Sikorsky settles with survivor, families of Cougar S-92A crash victims-07/01/2010-Washington DC-Flightglobal.com
Sikorsky settles with survivor, families of Cougar S-92A crash victims
By John Croft
Sikorsky has reached out-of-court settlements with the lone survivor and families of the 17 passengers and crew killed in the crash of an oil industry S-92A off the coast of Newfoundland in March 2009. The company is not revealing details of the settlements, other than to say that “all of the claims in regard to the Cougar Flight 491 crew and passengers have been resolved.”
Named in a lawsuit (shown below) filed in Philadelphia by the lone survivor and 15 other passengers were Sikorsky, its parent company, United Technologies, and its S-92A final assembly centre in Pennsylvania, formerly Keystone Helicopter.
That lawsuit, which had asked for jury trial, claimed that Sikorsky “engaged in a pattern of reckless and conscious disregard for the safety passengers of their S-92A helicopters”, in part by falsely advertising that the S-92A had a 30-min run-dry capability for its main gear box, a factor they say prompted the crew to try to fly back to land rather than plan for an orderly ditching. Canadian press reports that Sikorsky settled separately with the families of the two pilots.
Canadian investigators have determined that the helicopter’s main rotor was turning when the aircraft hit the water belly-first about 10 minutes after pilots received an indication that the main gearbox (MGB) transmission fluid had leaked out, but that the gearing to its tail rotor was badly damaged and an autorotation had been attempted.
Flight International previously reported that pre-certification testing of the helicopter revealed a similar duration of the MGB after oil loss, though Sikorsky had determined that an emergency transmission oil bypass system would prevent such an occurence. The company certified the helicopter under the assertion that other MGB failures were "extremely remote", which in US Federal Aviation Administration certification language means one failure per 10 million flight hours for the entire fleet of aircraft type.
Several MGB oil problems in the field before the Cougar accident however indicate that the failure rate was approximately once per 50,000 flight hours.
By John Croft
Sikorsky has reached out-of-court settlements with the lone survivor and families of the 17 passengers and crew killed in the crash of an oil industry S-92A off the coast of Newfoundland in March 2009. The company is not revealing details of the settlements, other than to say that “all of the claims in regard to the Cougar Flight 491 crew and passengers have been resolved.”
Named in a lawsuit (shown below) filed in Philadelphia by the lone survivor and 15 other passengers were Sikorsky, its parent company, United Technologies, and its S-92A final assembly centre in Pennsylvania, formerly Keystone Helicopter.
That lawsuit, which had asked for jury trial, claimed that Sikorsky “engaged in a pattern of reckless and conscious disregard for the safety passengers of their S-92A helicopters”, in part by falsely advertising that the S-92A had a 30-min run-dry capability for its main gear box, a factor they say prompted the crew to try to fly back to land rather than plan for an orderly ditching. Canadian press reports that Sikorsky settled separately with the families of the two pilots.
Canadian investigators have determined that the helicopter’s main rotor was turning when the aircraft hit the water belly-first about 10 minutes after pilots received an indication that the main gearbox (MGB) transmission fluid had leaked out, but that the gearing to its tail rotor was badly damaged and an autorotation had been attempted.
Flight International previously reported that pre-certification testing of the helicopter revealed a similar duration of the MGB after oil loss, though Sikorsky had determined that an emergency transmission oil bypass system would prevent such an occurence. The company certified the helicopter under the assertion that other MGB failures were "extremely remote", which in US Federal Aviation Administration certification language means one failure per 10 million flight hours for the entire fleet of aircraft type.
Several MGB oil problems in the field before the Cougar accident however indicate that the failure rate was approximately once per 50,000 flight hours.
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Another N.L. chopper crash inevitable: union
A union leader representing oil workers says another offshore chopper crash will happen in Newfoundland and Labrador — and he's calling for changes to improve workers' chances of survival when it does.
Another N.L. chopper crash inevitable: union
Last Updated: Tuesday, February 9, 2010 | 5:11 PM NT
CBC News
Brian Murphy of the Communications, Energy and Paperworkers union appeared at the offshore helicopter safety inquiry Tuesday. (CBC)
A union leader representing oil workers says another offshore chopper crash will happen in Newfoundland and Labrador — and he's calling for changes to improve workers' chances of survival when it does.
"When the next one goes down, it is going to be full of us," Brian Murphy of the Communications, Energy and Paperworkers (CEP) told the inquiry into offshore helicopter safety on Tuesday in St. John's.
"When this happens, it is going to be, 'Put it down wherever you can.' Given that, we want every possible impediment to survival removed."
He was speaking before the inquiry established after a Cougar Helicopters Ltd. chopper crashed into the ocean 55 kilometres east of St. John's on March 12, 2009. Seventeen people died.
Murphy, who is CEP vice-president for the Terra Nova offshore oil production platform, said an auxiliary fuel tank that is now placed in the cabin of the helicopters used by Cougar to transport offshore workers must be removed.
"Why are we flying with these auxiliary tanks inside?" said Murphy, an electrical technician on the Terra Nova oil production platform east of St. John's.
"We are not comfortable with it. If I'm upside-down in a chopper in the water and I'm struggling for my life, I don't want anything in my way."
Cougar Helicopter Ltd. uses Sikorsky S92-A choppers to transport oil industry workers offshore. (Cougar)
Last week a Cougar representative said the tanks are necessary for the company's Sikorsky helicopter to fly hundreds of kilometres offshore to oil industry platforms.
"When it comes to transportation, we are at the mercy of the oil operators, Cougar, Sikorsky and regulators such as the Transportation Safety Board," Murphy said.
He also said survival training for workers must be improved.
He called on the inquiry led by retired Supreme Court Judge Robert Wells to recommend that a fully dedicated, full-time search-and-rescue service be established in St. John's.
"We believe a Department of National Defence search-and-rescue crew like the ones based in Gander — [is] the best suited to do the job," said Murphy.
Right now Cougar is contracted to provide a search-and-rescue service but it must transform one of its transportation choppers into a search-and-rescue chopper before it can answer a call.
2nd union leader also opposes auxiliary tank
A second union leader also spoke at the inquiry.
Sheldon Peddle, president of CEP Local 2121, refused to fly on offshore helicopters because of his concern that the auxiliary tank would prevent passengers from escaping after a crash.
"In our survival training, the simulators that we learned to escape from didn't include an auxiliary tank," he said.
His concerns were investigated and it was decided by the Canada-Newfoundland Offshore Petroleum Board — the body that regulates Newfoundland and Labrador's offshore industry — that his concerns were not valid and the auxiliary tanks don't make the helicopters more dangerous.
He was advised to go back to work. He has but he said he disagrees with the CNLOPB's decision.
"It's not just my issue; there was a petition signed by more than 100 workers on this issue," said Peddle.
Family members of some of the people who died in the crash were also expected to speak at the inquiry Wednesday.
Last Updated: Tuesday, February 9, 2010 | 5:11 PM NT
CBC News
Brian Murphy of the Communications, Energy and Paperworkers union appeared at the offshore helicopter safety inquiry Tuesday. (CBC)
A union leader representing oil workers says another offshore chopper crash will happen in Newfoundland and Labrador — and he's calling for changes to improve workers' chances of survival when it does.
"When the next one goes down, it is going to be full of us," Brian Murphy of the Communications, Energy and Paperworkers (CEP) told the inquiry into offshore helicopter safety on Tuesday in St. John's.
"When this happens, it is going to be, 'Put it down wherever you can.' Given that, we want every possible impediment to survival removed."
He was speaking before the inquiry established after a Cougar Helicopters Ltd. chopper crashed into the ocean 55 kilometres east of St. John's on March 12, 2009. Seventeen people died.
Murphy, who is CEP vice-president for the Terra Nova offshore oil production platform, said an auxiliary fuel tank that is now placed in the cabin of the helicopters used by Cougar to transport offshore workers must be removed.
"Why are we flying with these auxiliary tanks inside?" said Murphy, an electrical technician on the Terra Nova oil production platform east of St. John's.
"We are not comfortable with it. If I'm upside-down in a chopper in the water and I'm struggling for my life, I don't want anything in my way."
Cougar Helicopter Ltd. uses Sikorsky S92-A choppers to transport oil industry workers offshore. (Cougar)
Last week a Cougar representative said the tanks are necessary for the company's Sikorsky helicopter to fly hundreds of kilometres offshore to oil industry platforms.
"When it comes to transportation, we are at the mercy of the oil operators, Cougar, Sikorsky and regulators such as the Transportation Safety Board," Murphy said.
He also said survival training for workers must be improved.
He called on the inquiry led by retired Supreme Court Judge Robert Wells to recommend that a fully dedicated, full-time search-and-rescue service be established in St. John's.
"We believe a Department of National Defence search-and-rescue crew like the ones based in Gander — [is] the best suited to do the job," said Murphy.
Right now Cougar is contracted to provide a search-and-rescue service but it must transform one of its transportation choppers into a search-and-rescue chopper before it can answer a call.
2nd union leader also opposes auxiliary tank
A second union leader also spoke at the inquiry.
Sheldon Peddle, president of CEP Local 2121, refused to fly on offshore helicopters because of his concern that the auxiliary tank would prevent passengers from escaping after a crash.
"In our survival training, the simulators that we learned to escape from didn't include an auxiliary tank," he said.
His concerns were investigated and it was decided by the Canada-Newfoundland Offshore Petroleum Board — the body that regulates Newfoundland and Labrador's offshore industry — that his concerns were not valid and the auxiliary tanks don't make the helicopters more dangerous.
He was advised to go back to work. He has but he said he disagrees with the CNLOPB's decision.
"It's not just my issue; there was a petition signed by more than 100 workers on this issue," said Peddle.
Family members of some of the people who died in the crash were also expected to speak at the inquiry Wednesday.
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N.L. chopper's flaw known in 2008
Sikorsky crash killed 17 in March 2009
Last Updated: Friday, March 12, 2010 | 5:37 AM
CBC's The Fifth Estate has found that the maker of a helicopter that crashed near Newfoundland a year ago, killing 17 people, knew more than six months earlier about the gearbox problem that downed the chopper.
The CBC investigation also revealed that U.S. and Canadian aviation safety organizations knew about the Sikorsky helicopter's flaw in August 2008.
On March 12, 2009, Cougar Helicopters Flight 491 slammed into the Atlantic Ocean 55 kilometres southeast of St. John's. Both pilots and 15 passengers died, leaving one survivor: Robert Decker, 28.
The S-92 chopper, made by U.S.-based Sikorsky Aircraft Corp., was ferrying workers to offshore oil-production platforms hundreds of kilometres east of St. John's.
It crashed minutes after the pilots reported the helicopter was losing oil pressure.
It was later determined the crash happened after oil leaked from the chopper's main gearbox, an integral part of the system that turns the helicopter's main rotors.
"Sikorsky should have been paying attention to this," said Shawn Coyle, who used to work for Transport Canada as a helicopter test pilot and now works as a consultant to the industry. "Someone in Sikorsky's organization should have been watching for this sort of thing."
On March 20, just over a week after the crash, Transportation Safety Board of Canada investigators said broken bolts, or studs, securing the oil filter mount to the main gearbox on the helicopter were suspect.
"We went public after we were told by the U.S. Federal Aviation Administration and by Sikorsky that they were planning on taking action," said the TSB's Mike Cunningham. "We wanted to make sure that all the operators, worldwide, of S-92s got that information in the quickest manner possible."
Less than two weeks after the crash, the U.S. Federal Aviation Administration — the organization that had certified the Sikorsky S-92 as safe to fly — grounded all of the choppers and ordered their owners to change titanium studs to steel studs.
It may appear they reacted quickly, but The Fifth Estate's investigation questions that conclusion. The CBC investigation shows that during the summer of 2008, Sikorsky, TSB and the FAA were aware of the possibility of the titanium studs breaking.
On July 2, 2008, a Sikorsky S-92 chopper carrying Australian offshore oil industry workers narrowly avoided tragedy after two studs securing the oil-filter assembly to the main gearbox broke and the helicopter lost oil pressure. The pilots were close enough to land to bring the chopper down safely.
Claimed to be safest
The mechanical failure left some people in the helicopter transportation industry with questions about the S-92 — a helicopter Sikorsky advertised as the safest in the world.
The Australian helicopter was owned by CHC Helicopter Corp. of Vancouver. CHC asked Transportation Safety Board of Canada's West Coast manager, Bill Yearwood, to oversee an independent analysis of what happened to that chopper.
That crucial third-party analysis took place in Richmond, B.C., in the presence of the helicopter's owners and Sikorsky officials.
An Aug. 29, 2008, summary of that examination written by the TSB noted some troubling findings.
"There appears to be several unresolved issues with the oil system, aside from the fractured studs, on this particular aircraft. It seems likely that these issues are related to stud failures," the TSB found.
The TSB also noted that: "It is reported the military S-92s use steel studs to attach the filter bowl to the transmission."
FAA told in 2008
In late August of 2008, the TSB advised the FAA of its findings.
But it wasn't until five months later — on Jan. 28, 2009 — that Sikorsky issued an alert saying the titanium mounting studs should be replaced by steel studs on every helicopter within a year, or within 1,250 flight hours.
Two months after that, on March 23, 2009 — more than seven months after the Australian chopper failure — that the FAA grounded the S-92s and ordered the studs changed.
The Fifth Estate 's Linden MacIntyre asked Coyle about the time it took authorities and Sikorsky to respond to what they learned in August 2008.
"You tell me, is that a reasonable lapse of time?" he asked.
"Well, in hindsight, no," said Coyle.
Neither the FAA nor Transport Canada agreed to on-camera interviews requested by The Fifth Estate. Sikorsky also declined repeated requests for an on-camera interview.
Sikorsky crash killed 17 in March 2009
Last Updated: Friday, March 12, 2010 | 5:37 AM
CBC's The Fifth Estate has found that the maker of a helicopter that crashed near Newfoundland a year ago, killing 17 people, knew more than six months earlier about the gearbox problem that downed the chopper.
The CBC investigation also revealed that U.S. and Canadian aviation safety organizations knew about the Sikorsky helicopter's flaw in August 2008.
On March 12, 2009, Cougar Helicopters Flight 491 slammed into the Atlantic Ocean 55 kilometres southeast of St. John's. Both pilots and 15 passengers died, leaving one survivor: Robert Decker, 28.
The S-92 chopper, made by U.S.-based Sikorsky Aircraft Corp., was ferrying workers to offshore oil-production platforms hundreds of kilometres east of St. John's.
It crashed minutes after the pilots reported the helicopter was losing oil pressure.
It was later determined the crash happened after oil leaked from the chopper's main gearbox, an integral part of the system that turns the helicopter's main rotors.
"Sikorsky should have been paying attention to this," said Shawn Coyle, who used to work for Transport Canada as a helicopter test pilot and now works as a consultant to the industry. "Someone in Sikorsky's organization should have been watching for this sort of thing."
On March 20, just over a week after the crash, Transportation Safety Board of Canada investigators said broken bolts, or studs, securing the oil filter mount to the main gearbox on the helicopter were suspect.
"We went public after we were told by the U.S. Federal Aviation Administration and by Sikorsky that they were planning on taking action," said the TSB's Mike Cunningham. "We wanted to make sure that all the operators, worldwide, of S-92s got that information in the quickest manner possible."
Less than two weeks after the crash, the U.S. Federal Aviation Administration — the organization that had certified the Sikorsky S-92 as safe to fly — grounded all of the choppers and ordered their owners to change titanium studs to steel studs.
It may appear they reacted quickly, but The Fifth Estate's investigation questions that conclusion. The CBC investigation shows that during the summer of 2008, Sikorsky, TSB and the FAA were aware of the possibility of the titanium studs breaking.
On July 2, 2008, a Sikorsky S-92 chopper carrying Australian offshore oil industry workers narrowly avoided tragedy after two studs securing the oil-filter assembly to the main gearbox broke and the helicopter lost oil pressure. The pilots were close enough to land to bring the chopper down safely.
Claimed to be safest
The mechanical failure left some people in the helicopter transportation industry with questions about the S-92 — a helicopter Sikorsky advertised as the safest in the world.
The Australian helicopter was owned by CHC Helicopter Corp. of Vancouver. CHC asked Transportation Safety Board of Canada's West Coast manager, Bill Yearwood, to oversee an independent analysis of what happened to that chopper.
That crucial third-party analysis took place in Richmond, B.C., in the presence of the helicopter's owners and Sikorsky officials.
An Aug. 29, 2008, summary of that examination written by the TSB noted some troubling findings.
"There appears to be several unresolved issues with the oil system, aside from the fractured studs, on this particular aircraft. It seems likely that these issues are related to stud failures," the TSB found.
The TSB also noted that: "It is reported the military S-92s use steel studs to attach the filter bowl to the transmission."
FAA told in 2008
In late August of 2008, the TSB advised the FAA of its findings.
But it wasn't until five months later — on Jan. 28, 2009 — that Sikorsky issued an alert saying the titanium mounting studs should be replaced by steel studs on every helicopter within a year, or within 1,250 flight hours.
Two months after that, on March 23, 2009 — more than seven months after the Australian chopper failure — that the FAA grounded the S-92s and ordered the studs changed.
The Fifth Estate 's Linden MacIntyre asked Coyle about the time it took authorities and Sikorsky to respond to what they learned in August 2008.
"You tell me, is that a reasonable lapse of time?" he asked.
"Well, in hindsight, no," said Coyle.
Neither the FAA nor Transport Canada agreed to on-camera interviews requested by The Fifth Estate. Sikorsky also declined repeated requests for an on-camera interview.
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I haven't seen the program yet, so I'm not sure what was edited out of what was a very long interview.
I was pleased to have the opportunity to put forward some things that had been bothering me about this tragic accident. Hopefully some good will come of it.
I was pleased to have the opportunity to put forward some things that had been bothering me about this tragic accident. Hopefully some good will come of it.
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Shawn Coyle
I watched the Canadian TV documentary " The Fifth Estate" last night and the producers actually did a good job .
You also came across very well Shawn, they used quite a few clips of your interview throughout the hour long show. You came across as knowledgeable and professional yet easy for the non-aviator to understand as well.
I watched the Canadian TV documentary " The Fifth Estate" last night and the producers actually did a good job .
You also came across very well Shawn, they used quite a few clips of your interview throughout the hour long show. You came across as knowledgeable and professional yet easy for the non-aviator to understand as well.
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The show was good, hopefully it will have a positive impact on the industry. IMO they could have put more updated material in the show, but no doubt the relatively short air time they had limited what they could report. Perhaps there will be a follow-up show to address that, most likely aligned with the eventual release of the findings of commissioner Wells's safety enquiry and/or the pending TSB report.
We've already seen improvements in the survival suit hood design, we have a new 6-stud filter housing, and we will have more robust MGBs installed hopefully soon to address the mounting feet cracks to further improve our confidence in this helo.
What's went quiet is whether a true run-dry MGB design is going to be available in the new gearbox, or are the manufacturer going for an "extremely remote" classification again. IMO that classification should not be an option for this helo, so there is still lots of room for improvement.
In memory of the colleagues that we lost just over a year ago it is our duty to ensure that all lessons learned are implemented and this helo and our survival equipment is truly made as safe as reasonably practicable. This was re-enforced on Friday as I attended the memorial services and talked to some of the family members afterwards, who all want to see some good come out of their loss.
Safe flying
Max
We've already seen improvements in the survival suit hood design, we have a new 6-stud filter housing, and we will have more robust MGBs installed hopefully soon to address the mounting feet cracks to further improve our confidence in this helo.
What's went quiet is whether a true run-dry MGB design is going to be available in the new gearbox, or are the manufacturer going for an "extremely remote" classification again. IMO that classification should not be an option for this helo, so there is still lots of room for improvement.
In memory of the colleagues that we lost just over a year ago it is our duty to ensure that all lessons learned are implemented and this helo and our survival equipment is truly made as safe as reasonably practicable. This was re-enforced on Friday as I attended the memorial services and talked to some of the family members afterwards, who all want to see some good come out of their loss.
Safe flying
Max
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