North Sea heli ditching: Oct 2012
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......The end result is no one looking at that design prior to these two incidents would imagine the shaft(s) shearing and causing this problem.......
To make a long story short, from the limited information I have seen, I do not see anything in the design of the EC 225 MRGB that would not be considered currently acceptable design practice. Could the design have been made more reliable? In hindsight, maybe so. But we can also assume that it met all regulatory safety requirements at the time the design was qualified/certified.
Here's a good description of the EC225 lube system function from an AAIB bulletin:
http://www.stepchangeinsafety.net/te...setFileID=1542
It is quite stunning for this non-technically qualified pilot to hear that the design of both the S92 and the 225 used single pathways for the activation of both main and back-up oil pumps that serve the single most important component in the drive train - the Main Transmission Gearbox. Tell me I have it wrong somebody - please.
Apologies for having used "crash" rather than "controlled ditch and loss of aircraft" in my brief post up there. Not fair to the crew to call a "crash" what was instead an exercise in sound airmanship when faced with a mechanical failure. 
HeliHenri was quite right to tweak my nose for that.
HeliHenri was quite right to tweak my nose for that.
Last edited by Lonewolf_50; 8th Nov 2012 at 13:09.
Apologies for having used "crash" rather than "controlled ditch and loss of aircraft" in my brief post up there
Please, don't think I'm a bad man but if you withdraw "loss of aircraft" (it's safe too), it'll be perfect !
BRGDS Henri
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swaping sides
Last edited by Soave_Pilot; 8th Nov 2012 at 18:03.
Will it fly again? That would be nice!
Or did the insurance company just "buy" it? I may have misunderstood some of the above discussion.
Or did the insurance company just "buy" it? I may have misunderstood some of the above discussion.
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Will it fly again
She was perfect when she went in the water but she got bent during the night when the tug put a line on her tail to stabilise her, they also broke a couple of windows during the lifting process.
Rifraf - oil pumps are driven from a single gear but not using the same part of the teeth, so eg if one pump seizes and strips the teeth, the other pump isn't affected.
I am amused by VL's foot shooting where he explains that the S92's pumps are independently driven from the same bevel gear..... Dur ... doesn't that mean that they also have a single failure point - the bevel gear?
It would be nice to have no single point failures in a heli gearbox but That is not really feasible. They all most definitely have a big single point failure item and that is the main rotor mast!
I think one has to distinguish between a single point failure that is catastrophic - eg the main rotor mast, vs something like oil pump drives the failure of which, as has been recently demonstrated twice, is not catastrophic.
I am amused by VL's foot shooting where he explains that the S92's pumps are independently driven from the same bevel gear..... Dur ... doesn't that mean that they also have a single failure point - the bevel gear?
It would be nice to have no single point failures in a heli gearbox but That is not really feasible. They all most definitely have a big single point failure item and that is the main rotor mast!
I think one has to distinguish between a single point failure that is catastrophic - eg the main rotor mast, vs something like oil pump drives the failure of which, as has been recently demonstrated twice, is not catastrophic.
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What effect is this having on you the pilots, obviously 'we' the bears are very apprehensive and yes most put a face on it but are the the pilots feeling under extra pressure what with offshore aviation being at the highest profile that its been at in 20 years that ive been working offshore id say.
I, like most others have the utmost respect for you guys and am well aware of some of the crap you have to fly in weather wise, but it must be in the back of pilots minds that god forbid another incident related or not to the recent MGB incidents would almost finish helicoper use for rig use.
We are not interested in boats or sea transfers (STV is it seems), we want the quick escape and 45 minutes noddy dog sleep that the choppers offer but there are way to many 'non offshore' flyers who have a lot of clout and swing some heavyweight punches about what we the actual offshore guy does and doesnt want. Peer pressure right now is the last thing that anybody wants ?
I, like most others have the utmost respect for you guys and am well aware of some of the crap you have to fly in weather wise, but it must be in the back of pilots minds that god forbid another incident related or not to the recent MGB incidents would almost finish helicoper use for rig use.
We are not interested in boats or sea transfers (STV is it seems), we want the quick escape and 45 minutes noddy dog sleep that the choppers offer but there are way to many 'non offshore' flyers who have a lot of clout and swing some heavyweight punches about what we the actual offshore guy does and doesnt want. Peer pressure right now is the last thing that anybody wants ?
I am amused by VL's foot shooting where he explains that the S92's pumps are independently driven from the same bevel gear..... Dur ... doesn't that mean that they also have a single failure point - the bevel gear?
Last edited by Variable Load; 9th Nov 2012 at 02:26.
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If the main bevel gear were to fail then the lack of oil pressure would be the least of your problems - drive from both engines and tail rotor drive would also be lost
That's what I've been thinking all along. Am I missing something ... ?
That's what I've been thinking all along. Am I missing something ... ?
Vertical
BRISTOW SIGNS DEAL FOR 10 S-92S TO RELIEVE GROUNDING OF SUPER PUMA FLEET
Thursday November 8th 2012 - by Vertical Staff
Offshore transportation company Bristow has signed a deal for 10 Sikorsky S-92s as part of the company’s effort to cope with the potential long-term fall-out of two recent ditchings of Eurocopter Super Pumas in the North Sea.
Bristow currently has a fleet of 16 Super Pumas (15 EC225s and one AS332L2) that are grounded following the most recent ditching of a CHC-operated EC225 on Oct. 22. All 17 passengers and two crew escaped the incident without injury, but the follow-up investigation found that a failure of the vertical shaft in the main gearbox was to blame – the same cause for a similar incident back in May.
“We’ve been working very hard with Eurocopter and other industry participants to determine the root cause of the accident and the impact on the long term availability of the Super Puma and the EC225s,” said Bill Chiles, Bristow’s president, CEO & director. “This is a moving situation that’s changing every day."
The purchase of the S-92s was revealed in the company’s recently-released financial results, which said the it was part of the company’s effort to “minimize or eliminate the impact on our clients” of the current grounding.
“We’re supporting very critical operations out there, so we can’t afford to stop the flow of people and material, and that has to continue,” said Chiles. “We’re going to work with each of our clients individually to solve their challenges, because they are different.”
In a conference call following the release of the results, Jonathan Baliff, senior vice president, chief financial officer, said the S-92s would also work to enable fleet replacement. “When we make big purchases, we partner with our OEM suppliers to, in essence, recycle the older technology [in the fleet]. The purchase of these 10 new Sikorsky S-92s has directly led to us being able to exit the old S-76a model completely. That will happen over time.”
Chiles said the company’s focus was currently on safety, as it seeks to relieve the pressure built by the grounding of the Super Puma fleet. “We’re going around and freeing up all available resources around the world, turning over every stone to make sure we’re covered both short term and long term,” he said. “We’re moving new aircraft in, we’re moving AW139s, and S-76s in there and S-92s in there. And that creates a lot of challenges with resources, not only with aircraft, but pilots and engineers. So we’ve got to be very focused in safety.”
Chiles said any specifics on a return to service of the company’s Super Puma fleet was yet to be released. “We’re dealing with the short-term issues and we’re also looking at what we do on the long-term basis if this situation continues,” he said. “It will evolve very quickly. Over the next few weeks, we should be in a better position to talk.”
P1
BRISTOW SIGNS DEAL FOR 10 S-92S TO RELIEVE GROUNDING OF SUPER PUMA FLEET
Thursday November 8th 2012 - by Vertical Staff
Offshore transportation company Bristow has signed a deal for 10 Sikorsky S-92s as part of the company’s effort to cope with the potential long-term fall-out of two recent ditchings of Eurocopter Super Pumas in the North Sea.
Bristow currently has a fleet of 16 Super Pumas (15 EC225s and one AS332L2) that are grounded following the most recent ditching of a CHC-operated EC225 on Oct. 22. All 17 passengers and two crew escaped the incident without injury, but the follow-up investigation found that a failure of the vertical shaft in the main gearbox was to blame – the same cause for a similar incident back in May.
“We’ve been working very hard with Eurocopter and other industry participants to determine the root cause of the accident and the impact on the long term availability of the Super Puma and the EC225s,” said Bill Chiles, Bristow’s president, CEO & director. “This is a moving situation that’s changing every day."
The purchase of the S-92s was revealed in the company’s recently-released financial results, which said the it was part of the company’s effort to “minimize or eliminate the impact on our clients” of the current grounding.
“We’re supporting very critical operations out there, so we can’t afford to stop the flow of people and material, and that has to continue,” said Chiles. “We’re going to work with each of our clients individually to solve their challenges, because they are different.”
In a conference call following the release of the results, Jonathan Baliff, senior vice president, chief financial officer, said the S-92s would also work to enable fleet replacement. “When we make big purchases, we partner with our OEM suppliers to, in essence, recycle the older technology [in the fleet]. The purchase of these 10 new Sikorsky S-92s has directly led to us being able to exit the old S-76a model completely. That will happen over time.”
Chiles said the company’s focus was currently on safety, as it seeks to relieve the pressure built by the grounding of the Super Puma fleet. “We’re going around and freeing up all available resources around the world, turning over every stone to make sure we’re covered both short term and long term,” he said. “We’re moving new aircraft in, we’re moving AW139s, and S-76s in there and S-92s in there. And that creates a lot of challenges with resources, not only with aircraft, but pilots and engineers. So we’ve got to be very focused in safety.”
Chiles said any specifics on a return to service of the company’s Super Puma fleet was yet to be released. “We’re dealing with the short-term issues and we’re also looking at what we do on the long-term basis if this situation continues,” he said. “It will evolve very quickly. Over the next few weeks, we should be in a better position to talk.”
P1
VL -so you agree that the S92 oil pump drive ultimately has a single path / point if failure, just like the 225 one does.
DWT I can only speak for myself. The industry having had 4 events in the past few years (fortunately none affecting our company) that is pretty unusual compared to the last 10 or so years of calm.
One very nasty event (the L2) stands out as being unsurvivable, with some remaining uncertainty about the cause of the failure. However I am slightly reassured that the event could probably have been prevented had correct maintenance procedures been followed.
The ETAP ditching was a result of inappropriate procedures and a degree of pilot foolishness. Since it would be me at the sharp end, it would be up to me to not repeat that type of accident, but anyway our company's procedures are pretty robust in this area.
The two oil pump drive failures, both detectable by HUMS had it been used rigorously, is what seems to have really upset the apple cart, merely because the cause was believed to be known but then there was a repeat, indicating the cause was not in fact known.
Not that I have any desire to be one of those passengers or pilots finding themselves in the water, but the outcomes were: no injuries except perhaps mental ones. This I think we can put down to wrapping things up in a thick layer of training for both pilots and pax, safety equipment and the availability of SAR. It is this layer of "extras" that turns a potentially disastrous accident into no more than an unpleasant event.
So 1 fatal accident in the last 10 yrs or so, whilst being 1 too many, is not a bad record I think when we in Bristow have completed perhaps 100,000 hrs just out of Abz, with other operators probably matching that.
Put it another way, when you or I die, it will almost certainly not be as a result of a helicopter accident (mind you, I do drive a motorbike!). Drinking and smoking will kill far more of your colleagues than a heli will.
Life is tenuous and precious, but if we become too bogged down with thinking about the remotest possible ways we might die, we would never get anything done and lead a long but valueless life.
Personally I am really looking forward to getting back into the air in an EC225 because it is a fantastic and safe machine, albeit with one component out of thousands suffering from a serious design problem that has to be fixed.
Of course, if my company decides I have to do an S92 conversion in the mean time, that would be a catastrophe!
DWT I can only speak for myself. The industry having had 4 events in the past few years (fortunately none affecting our company) that is pretty unusual compared to the last 10 or so years of calm.
One very nasty event (the L2) stands out as being unsurvivable, with some remaining uncertainty about the cause of the failure. However I am slightly reassured that the event could probably have been prevented had correct maintenance procedures been followed.
The ETAP ditching was a result of inappropriate procedures and a degree of pilot foolishness. Since it would be me at the sharp end, it would be up to me to not repeat that type of accident, but anyway our company's procedures are pretty robust in this area.
The two oil pump drive failures, both detectable by HUMS had it been used rigorously, is what seems to have really upset the apple cart, merely because the cause was believed to be known but then there was a repeat, indicating the cause was not in fact known.
Not that I have any desire to be one of those passengers or pilots finding themselves in the water, but the outcomes were: no injuries except perhaps mental ones. This I think we can put down to wrapping things up in a thick layer of training for both pilots and pax, safety equipment and the availability of SAR. It is this layer of "extras" that turns a potentially disastrous accident into no more than an unpleasant event.
So 1 fatal accident in the last 10 yrs or so, whilst being 1 too many, is not a bad record I think when we in Bristow have completed perhaps 100,000 hrs just out of Abz, with other operators probably matching that.
Put it another way, when you or I die, it will almost certainly not be as a result of a helicopter accident (mind you, I do drive a motorbike!). Drinking and smoking will kill far more of your colleagues than a heli will.
Life is tenuous and precious, but if we become too bogged down with thinking about the remotest possible ways we might die, we would never get anything done and lead a long but valueless life.
Personally I am really looking forward to getting back into the air in an EC225 because it is a fantastic and safe machine, albeit with one component out of thousands suffering from a serious design problem that has to be fixed.
Of course, if my company decides I have to do an S92 conversion in the mean time, that would be a catastrophe!
Last edited by HeliComparator; 9th Nov 2012 at 08:58.
Dry Wretched Thunder. Like Helicomparator I would get back into the EC225 right now and fly it knowing that Bristow will be monitoring everything as closely as they have always done, even before the May ditching. Both of the 2012 ditchings almost certainly (some might say certainly) wouldn't have happened if the vibration data had been downloaded after each flight.
Please believe me that I'm a very cautious pilot and have enjoyed a long flying career by striving to fly only when everything indicates that it is safe to do so. My attitude is no different from every North Sea pilot in all the companies. We all want to reach pensionable age without incident.
There is no doubt that Eurocopter will be pulling out all the stops to come up with a very convincing solution, if for no other reason than not wishing to lose even more future sales to their rivals. They know that they can't afford any repeats.
Please believe me that I'm a very cautious pilot and have enjoyed a long flying career by striving to fly only when everything indicates that it is safe to do so. My attitude is no different from every North Sea pilot in all the companies. We all want to reach pensionable age without incident.
There is no doubt that Eurocopter will be pulling out all the stops to come up with a very convincing solution, if for no other reason than not wishing to lose even more future sales to their rivals. They know that they can't afford any repeats.
Both of the 2012 ditchings almost certainly (some might say certainly) wouldn't have happened if the vibration data had been downloaded after each flight.
Page 9 of this relates:-
Air Accidents Investigation: S3/2012 EC225 LP Super Puma, G-REDW
But it says :-
Health and usage monitoring system (HUMS)
A review of the HUMS data showed no indication of any
significant rising vibration trends until approximately six flying hours prior to the start of the accident flight. Prior to this period, the vibration levels on indicators associated with the bevel gear vertical shaft were below the mean level established from data collected from 23 other EC225 LP helicopters.
During the last six flying hours, which covered the two flights prior to the accident flight, the trend for indicator
MOD 45, which monitors the meshing frequency of the bevel gear, and MOD 70 which monitors the meshing frequency of the oil pump wheels, increased. An amber4 alert was generated for MOD 45 following the last flight on 9 May 2012, and for both indicators following the first flight on 10 May 2012. The operator’s engineers followed the fault diagnosis chart in the Aircraft Maintenance Manual (AMM), Chapter 45.11.08.211. The washer on the accelerometer for these parameters was replaced following the first amber alert on 9 May 2012, and the MGB magnetic chip detectors were checked, and found to be free of debris, following the alerts on the 10 May 2012. Thirty six other indicators were checked
and no significant trends were detected. In accordance with the guidance in the AMM, the aircraft was placed on 10 hourly close monitoring and released for flight.
Following the accident, the helicopter manufacturer analyzed the data for indicators MOD 45 and MOD 70 and reduced the vibration level required to generate an amber alert. Red alert thresholds have also been introduced for both these indicators
5.
Footnote
4
An amber alert requires the operator to determine if a maintenance action is required, whereas a red alert requires a maintenance action
Footnote
5
Eurocopter Service Bulletin No 45-001.
Pitts yes I think you are correct in what you say. For the May ditching, the correct manufacturer's procedures were followed, therefore the operator cannot be blamed for failing to follow the rules.
But at the time I was told by our engineers that they would have dropped the sump to have a quick look, rather than presuming it to be a false warning and dispatching it again having re-washered the sensor, and certainly on the second warning. Whether that is a case of hindsight or that is what would genuinely have happened I can't be sure.
But, trying to apportion blame aside, with the hindsight that we now have that accident was technically avoidable even if the manufacturers procedures did not cater for it. Of course they do now and so future such events should be detected before becoming critical... But of course we are not going to put that to the test it seems!
But at the time I was told by our engineers that they would have dropped the sump to have a quick look, rather than presuming it to be a false warning and dispatching it again having re-washered the sensor, and certainly on the second warning. Whether that is a case of hindsight or that is what would genuinely have happened I can't be sure.
But, trying to apportion blame aside, with the hindsight that we now have that accident was technically avoidable even if the manufacturers procedures did not cater for it. Of course they do now and so future such events should be detected before becoming critical... But of course we are not going to put that to the test it seems!