North Sea heli ditching: Oct 2012
The longer this goes on the more likely it is that some contracted EC225s will be replaced by S-92s, even though that may not be a perfect solution to some (HC) It is better than flying in 30 year old 332Ls which is happening in some places where they are providing a limited service.
This situation is not good for the helicopter operators. Mixed fleets will be the way of the future and one company one type and another company a different type with mutual cross backup and increased sharing being discussed as the new way forward from now on.
This situation is not good for the helicopter operators. Mixed fleets will be the way of the future and one company one type and another company a different type with mutual cross backup and increased sharing being discussed as the new way forward from now on.
When HC winds up flying 92's.....I will accept there is a God in Heaven!
I know I am safe because HC is too old for a Conversion course unless the rules have changed.
I know I am safe because HC is too old for a Conversion course unless the rules have changed.
Last edited by SASless; 9th Nov 2012 at 12:31.
II - yes, many years ago we used to have a mixed fleet of S61, SA330, AS332L, B214ST, S76 in Aberdeen. Then it was realised that a single fleet would allow cost reductions because only 1 set of pilots, engineers, 1 pool of spares etc. An accountant's dream.
But now the old lessons have been re-learnt and the single fleet concept is seen as high risk in the event of a grounding such as we have. The future will involve more mixed fleets - that is until the current guard, soon to be old guard, fall off their perches and then the shiny new accountants and business school graduates will make the same mistakes all over again!
SAS - alas no more age discrimination for conversions and I potentially have 9 years left in me so it cannot be ruled out! However it seems we will have some alternatives such as 139, 189, 175 so I may yet be able to stave off the dreaded Shorts 360 bus with bolt on rotors and a dining table on the tailboom!
But hopefully I will be the last of the dying breed of 225 pilots, left to fly single pilot and then turn out the lights at the end...
But now the old lessons have been re-learnt and the single fleet concept is seen as high risk in the event of a grounding such as we have. The future will involve more mixed fleets - that is until the current guard, soon to be old guard, fall off their perches and then the shiny new accountants and business school graduates will make the same mistakes all over again!
SAS - alas no more age discrimination for conversions and I potentially have 9 years left in me so it cannot be ruled out! However it seems we will have some alternatives such as 139, 189, 175 so I may yet be able to stave off the dreaded Shorts 360 bus with bolt on rotors and a dining table on the tailboom!
But hopefully I will be the last of the dying breed of 225 pilots, left to fly single pilot and then turn out the lights at the end...
Last edited by HeliComparator; 9th Nov 2012 at 12:45.
HC - Yes and actually even in the most recent case the change in trend which leads to alarms are very close to the point of failure (timewise).
What surprises me is that visual inspection of parts physically that yields nothing of interest and then a few hours later its failed.
What surprises me is that visual inspection of parts physically that yields nothing of interest and then a few hours later its failed.
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Originally Posted by HeliHenri
At the present time, even the non salty 225 are'nt flying ...
Perhaps you have more up-to-date information, but my understanding from yesterday's customer update was that other EC225s (/EC725s) are still flying, including at least one 'salty' operator in Asia?
I/C
Hello I C,
You're right, I was speaking about flying over water (the main reason of 225's use) but now the Civil Aviation Authority revoked its ban on overwater use, I was late, sorry about that.
.
You're right, I was speaking about flying over water (the main reason of 225's use) but now the Civil Aviation Authority revoked its ban on overwater use, I was late, sorry about that.
.
Heli,
If you have to fly the S-92 look on the positive side! You will not be able to hear the laughter after a couple of months.
Literally!
The Sultan
If you have to fly the S-92 look on the positive side! You will not be able to hear the laughter after a couple of months.
Literally!
The Sultan
Last edited by The Sultan; 9th Nov 2012 at 22:23.
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HC-
Your point is well made. Most folks fail to appreciate that there are numerous flight critical components in a typical rotorcraft drivetrain that have no functional redundancy. The main rotor mast & hub are perfect examples. But as I noted, these flight critical structures are usually subject to a rigorous fracture control plan during design, manufacture and service.
The only other option would be to use functionally independent dual rotors, gearboxes, etc. And obviously that would not be practical.
riff_raff
Your point is well made. Most folks fail to appreciate that there are numerous flight critical components in a typical rotorcraft drivetrain that have no functional redundancy. The main rotor mast & hub are perfect examples. But as I noted, these flight critical structures are usually subject to a rigorous fracture control plan during design, manufacture and service.
The only other option would be to use functionally independent dual rotors, gearboxes, etc. And obviously that would not be practical.
riff_raff
the S92 oil pump drive ultimately has a single path / point if failure, just like the 225 one does.
However the S92 design is such that it is not susceptible to the kind of failure that led to loss of oil pressure and the subsequent ditching of REDW and CHCN i.e. a welded on addition to the main bevel gear that drives the oil pumps.
But you already knew that
Last edited by Variable Load; 10th Nov 2012 at 01:28.
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Correct me if I am wrong...
... but didn't the S92 have a design flaw in the way the two oil pumps were driven? Something about the debonding of a plastic component that had been glued to a metal shaft.
If so then in my book this would count as exposure to extreme risk via single failure in both systems.
Or was this classified as another 'extremely remote' possibility.
Where else could we look for a single design flaw that has serious consequences in the multiple systems of our helicopter fleet.
When you take a well established type of helicopter and make the slightest change to the profile of it's design, manufacture or overhaul you are exposed to the possibility of disaster. Are the certification authorities alive to these possibilities? Are they in the loop?
Examples of what I mean :-
Chinook gearbox - gear wheel design
S61 gearbox - following the outsourcing of overhaul tasks there was a spate of freewheel failures put down to incorrect overhaul procedures.
Perhaps one of our technical guys who subscribe to Prune can add to that list. I'm sure it would be longer than you imagine. Stories abound about the inspector who retired and then his replacement had to pick up the job without the benefit of his years of experience.
One amusing version of the same story was what happened to us at KLM Helis back in the late 90s. Redundancies where being dished out willy nilly as the focus on costs came down to the need for multitasking. We had two storemen who had been there since the year dot but one of them had to go. KLM being what it is - a state run airline - just sent one from Den Helder back to mainline in Amsterdam. Chaos ensued when after a month or so there was a lack of spare hydraulic components. It was then they found out that one guy in stores was in charge of 'parts returned from overhaul' and the second for 'parts to be sent for overhaul'. They made the second guy redundant but turned out he was the only one who knew where each component was supposed to be sent. All outgoing parts ended up in the wrong place and screwed up the turn around times. Sometimes you don't know what you don't know until it bites you in the arse.
G. 
If so then in my book this would count as exposure to extreme risk via single failure in both systems.
Or was this classified as another 'extremely remote' possibility.
Where else could we look for a single design flaw that has serious consequences in the multiple systems of our helicopter fleet.
When you take a well established type of helicopter and make the slightest change to the profile of it's design, manufacture or overhaul you are exposed to the possibility of disaster. Are the certification authorities alive to these possibilities? Are they in the loop?
Examples of what I mean :-
Chinook gearbox - gear wheel design
S61 gearbox - following the outsourcing of overhaul tasks there was a spate of freewheel failures put down to incorrect overhaul procedures.
Perhaps one of our technical guys who subscribe to Prune can add to that list. I'm sure it would be longer than you imagine. Stories abound about the inspector who retired and then his replacement had to pick up the job without the benefit of his years of experience.
One amusing version of the same story was what happened to us at KLM Helis back in the late 90s. Redundancies where being dished out willy nilly as the focus on costs came down to the need for multitasking. We had two storemen who had been there since the year dot but one of them had to go. KLM being what it is - a state run airline - just sent one from Den Helder back to mainline in Amsterdam. Chaos ensued when after a month or so there was a lack of spare hydraulic components. It was then they found out that one guy in stores was in charge of 'parts returned from overhaul' and the second for 'parts to be sent for overhaul'. They made the second guy redundant but turned out he was the only one who knew where each component was supposed to be sent. All outgoing parts ended up in the wrong place and screwed up the turn around times. Sometimes you don't know what you don't know until it bites you in the arse.
G.
Geoff, almost right. Each pump is connected to it's individual gearbox drive by a plastic vespel spline (so there are two vespel splines, one for each pump).
There was an issue with the design (now corrected) that led to the vespel spline wearing and then slipping, therefore one of the two pumps lost drive and therefore pressure. There was never a case of both pumps failing as the drive systems are separate (redundant).
There was an issue with the design (now corrected) that led to the vespel spline wearing and then slipping, therefore one of the two pumps lost drive and therefore pressure. There was never a case of both pumps failing as the drive systems are separate (redundant).
Last edited by Variable Load; 10th Nov 2012 at 05:52.
... and when 1 pump drive was lost, the pressure dropped such that the flight manual originally said to Land Immediately. That was good design!
But your point about the pumps being driven direct from the main bevel gear raises an interesting design issue. By doing so on the 92, you add some non-flight critical components (oil pump drive) to a flight critical zone (bevel gear). It is not impossible to imagine some failure of the oil pump drive (gear seizing / breaking up and stripping /damaging the bevel gear etc) that could cause a catastrophic failure of the bevel gear. So the design concept trades off reduced probability of non-catastrophic failure (oil pumps) with increased possibility of a catastrophic failure (bevel drive). Of course such a failure is pretty unlikely, but then so is having the lower part of the same equivalent shaft detach in a design that has hitherto successfully flown millions of flight hours.
But your point about the pumps being driven direct from the main bevel gear raises an interesting design issue. By doing so on the 92, you add some non-flight critical components (oil pump drive) to a flight critical zone (bevel gear). It is not impossible to imagine some failure of the oil pump drive (gear seizing / breaking up and stripping /damaging the bevel gear etc) that could cause a catastrophic failure of the bevel gear. So the design concept trades off reduced probability of non-catastrophic failure (oil pumps) with increased possibility of a catastrophic failure (bevel drive). Of course such a failure is pretty unlikely, but then so is having the lower part of the same equivalent shaft detach in a design that has hitherto successfully flown millions of flight hours.
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Grounded for 3 MONTHS
Apparently Lutz Bertling (EC President) has written to CHC saying that the EC225 fleet,will be grounded for another 3 months over hostile terrain while EC does more testing to prove the combined AAIB and EC theory of the failure mode and to continue testing on the Emergency Lube system.
Looking to the future one must consider a continuous HUMS assessment in flight. Should a HUMS computer be able to download information and analyse the results after a flight then surely it must be within the wit of man for it to be able to do it en-route. The processing capacity to launch an Apollo Lunar Mission is now available in something not much bigger than a smartphone so weight and volume should not be a problem.
How much safer would it be if a HUMS panel would warn you of an unusual occurence within your systems or the reassurance of being able to press a check button on it to ensure that everything is normal.
When HUMS first started all those years ago what we wanted was a light that said. "Do not fly this aircraft."
How much safer would it be if a HUMS panel would warn you of an unusual occurence within your systems or the reassurance of being able to press a check button on it to ensure that everything is normal.
When HUMS first started all those years ago what we wanted was a light that said. "Do not fly this aircraft."
Rolls Royce do that with their Trent engines already - real time monitoring.
Its back to the old problem of the false warning rate. If an engine shows a dodgy HUMS, you just shut it down no big deal. But if a main transmission shows a dodgy HUMS you have to ditch, and would look a bit stupid if it was a false alert. You only have to look at the maintenance actions reported in the May ditching to see that even the manufacturer suspects a false warning as the most likely cause - viz the "replace the sensor mounting washer" action. With current technology having cockpit warnings of main transmission problems would dramtically increase the ditching rate.
I am not saying that improvement in self-monitoring of the HUMS system itself and therefore increase in the system integrity is not possible, but it is an area that has received no investment and so no progress has been made since the early 90s when HUMS was invented.
I am not saying that improvement in self-monitoring of the HUMS system itself and therefore increase in the system integrity is not possible, but it is an area that has received no investment and so no progress has been made since the early 90s when HUMS was invented.
At the risk of being flamed by the Comparator a good start would be for Eurocopter to at least have a fleet management operations centre like Sikorsky's FMOC.
Sikorsky takes HUMS from all of its aircraft and compares the readings from the worldwide fleet. Differences in HUMS readouts from the fleet norm are immediately apparent. In fact, some trial aircraft are streamed in real time so it is possible today with helicopters and should be adopted as standard practice.
I would also like to see tail pylon and other cameras fitted to allow the crew to view external parts of the aircraft for oil leaks etc, surely it is also technologically possible to have pictures able to be transmitted back to base.
Sikorsky takes HUMS from all of its aircraft and compares the readings from the worldwide fleet. Differences in HUMS readouts from the fleet norm are immediately apparent. In fact, some trial aircraft are streamed in real time so it is possible today with helicopters and should be adopted as standard practice.
I would also like to see tail pylon and other cameras fitted to allow the crew to view external parts of the aircraft for oil leaks etc, surely it is also technologically possible to have pictures able to be transmitted back to base.
Yes, the Sik HUMS centre is a good idea, although EC do have continuous access (via VPN) to our M'ARMS server in Aberdeen and other such bases. What degree of comparison with other operators' aircraft goes on I wouldn't know.
It is certainly true that American culture in general, and Sik culture in particular, is very good at presenting a fantastic show of fanfares, glossy websites and brochures, but the reality can sometimes be that it is all for show with no meat (not saying that is the case here necessarily).
EC by contrast just get on with it in some dingy monochrome M'ARMS office in Marignane!
Of course that is the point of the AAD system - to detect the sort of abnormality of one aircraft versus the fleet norm, even without the triggering of a threshold, thus making continuous comparison with other operators unnecessary.
One area in which the Sik system is a bit of a pain in the whatsits is that you need a separate computer for each airframe, whereas all more recent EC aircraft (M'ARMS equipped) can use the same single server at a base, which is surely easier for the operator.
On the cameras, yes why not but I am not sure I could point to an event where it would have made a difference? Once you get an oil leak, everything including the camera would be covered in oil so I doubt you would be able to see where it was coming from, or really get an idea of how bad it was.
It is certainly true that American culture in general, and Sik culture in particular, is very good at presenting a fantastic show of fanfares, glossy websites and brochures, but the reality can sometimes be that it is all for show with no meat (not saying that is the case here necessarily).
EC by contrast just get on with it in some dingy monochrome M'ARMS office in Marignane!
Of course that is the point of the AAD system - to detect the sort of abnormality of one aircraft versus the fleet norm, even without the triggering of a threshold, thus making continuous comparison with other operators unnecessary.
One area in which the Sik system is a bit of a pain in the whatsits is that you need a separate computer for each airframe, whereas all more recent EC aircraft (M'ARMS equipped) can use the same single server at a base, which is surely easier for the operator.
On the cameras, yes why not but I am not sure I could point to an event where it would have made a difference? Once you get an oil leak, everything including the camera would be covered in oil so I doubt you would be able to see where it was coming from, or really get an idea of how bad it was.
Last edited by HeliComparator; 10th Nov 2012 at 11:39.