North Sea heli ditching: Oct 2012
Flyer, perhaps the operator could be found culpable in a civil case, but not the OEM since how the aircraft are operated and the approved maintenance programmes are not within their control. I am sure the OEM would be seen to be squeaky clean if they provided the technology but the operator discounted it on the basis of a reasonable cost.
Geoffers - you are right. It is those un-thought-of problems that catch everyone out. The thought-of ones are usually no problem!
Geoffers - you are right. It is those un-thought-of problems that catch everyone out. The thought-of ones are usually no problem!
HC....be careful.....you might break your arm patting yourself on the back like that!
HC....be careful.....you might break your arm patting yourself on the back like that!
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Using HUMS data sounds like a step in the right direction. Afterall, how were component retirement hours figured before? Several thousand hours of test flying, examining the parts and them sitting down in a commitee and more or less compromising on a figure. Then once those components went to their retirement hours, the parts were returned, examined and, after enough were looked at, another committee descision to ask for an extension?
Hopefully HUMS will be another useful tool, as long as it doesn't become the be all and end all in determining a components life.
Hopefully HUMS will be another useful tool, as long as it doesn't become the be all and end all in determining a components life.
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Perfection on production is key.....
..... but is it achievable? Probably not. Sad to say that ours is one of the industries that demands the highest standards of manufacturing but it is far from perfect.
One possible step in the right direction is deal with the problems created by the way each OEM works within a silo that generates a terrible mindset that precludes things they have not seen before but have been seen in other types made by other people.
To what extent, I wonder do OEM's study and test the equipment made by their rivals? Are there any formal liaisons between OEMs on safety critical issues? Should there be? What can EASA do about it?
G.
.
One possible step in the right direction is deal with the problems created by the way each OEM works within a silo that generates a terrible mindset that precludes things they have not seen before but have been seen in other types made by other people.
To what extent, I wonder do OEM's study and test the equipment made by their rivals? Are there any formal liaisons between OEMs on safety critical issues? Should there be? What can EASA do about it?
G.
.
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It is very worthwhile to work hard at improving drivetrain HUMS technology used by the rotorcraft industry, and there are lots of engineers currently doing just that. But even the best HUMS in use today really only monitor for problems that are already occurring, and they have very little predictive capability.
We should also consider the nature of what occurred in this particular failure. Based on the published statements from Eurocopter, it sounds like there was a manufacturing/QA problem with the weld joint on the shaft:
"....As already indicated in the AAIB Special Bulletin S6/2012, the initial visual examination has identified a 360° circumferential crack on the bevel gear vertical shaft (which drives the two Main Gear Box (MGB) lubrication pumps), in the vicinity of the weld that joins two sections of the shaft....".
Eurocopter's use of welding for highly stressed components is actually very common in the aircraft industry. The process used is friction welding. It is a "solid state" joining process and produces joints of extremely high quality. Friction welding is used to save weight and material cost, primarily in situations where the cross section of the component has large changes, such as the given example of a short large diameter gear disc on the end of a long slender shaft.
However, getting good results from friction welding does require careful control of the process. The other factor that would seem to indicate there was a manufacturing issue is the shaft appears to have failed in a location that would not likely be highly stressed (and that's what makes it a good location for the weld joint).
Just all speculation on my part. But it's certainly an interesting topic of discussion!
We should also consider the nature of what occurred in this particular failure. Based on the published statements from Eurocopter, it sounds like there was a manufacturing/QA problem with the weld joint on the shaft:
"....As already indicated in the AAIB Special Bulletin S6/2012, the initial visual examination has identified a 360° circumferential crack on the bevel gear vertical shaft (which drives the two Main Gear Box (MGB) lubrication pumps), in the vicinity of the weld that joins two sections of the shaft....".
Eurocopter's use of welding for highly stressed components is actually very common in the aircraft industry. The process used is friction welding. It is a "solid state" joining process and produces joints of extremely high quality. Friction welding is used to save weight and material cost, primarily in situations where the cross section of the component has large changes, such as the given example of a short large diameter gear disc on the end of a long slender shaft.
However, getting good results from friction welding does require careful control of the process. The other factor that would seem to indicate there was a manufacturing issue is the shaft appears to have failed in a location that would not likely be highly stressed (and that's what makes it a good location for the weld joint).
Just all speculation on my part. But it's certainly an interesting topic of discussion!
We certainly have a networked laptop for each airframe in Scatsta, whether we realise we don't need that, I am not sure. Has it always been the case that a single PC can be used, or was this a development?
As an aside, the toughbook was also touted as a reference library containing electronic and up to date versions of the MM, IPC, etc that could be used "beside" the aircraft. I'm not sure if they are ever used this way?
AAD
Flyer,
Thanks, for the info. I assume the 6k is per aircraft per year.
The flip side of the AAD argument is that you are paying for it and something happens then the AAD provider should be held liable. In the recent incidences including the loss of rotor on the Puma the AAIB report indicated that AAD techniques provided no improvement in warning time. Actually if all chip detections had been reported to the crew there would have not been a crash.
The Sultan
Thanks, for the info. I assume the 6k is per aircraft per year.
The flip side of the AAD argument is that you are paying for it and something happens then the AAD provider should be held liable. In the recent incidences including the loss of rotor on the Puma the AAIB report indicated that AAD techniques provided no improvement in warning time. Actually if all chip detections had been reported to the crew there would have not been a crash.
The Sultan
This is what EC concluded:-
Manufacturer’s analysis of G-REDL HUMS
The helicopter manufacturer was provided with a copy of the G-REDL HUMS database and the downloaded HUMS data card from 1 April 2009 operations. Their analysis was performed by two teams; the first being by their customer
technical support team which reviewed all CIs. They concluded that there was ‘nothing abnormal to report’.
Manufacturer’s analysis of G-REDL HUMS
The helicopter manufacturer was provided with a copy of the G-REDL HUMS database and the downloaded HUMS data card from 1 April 2009 operations. Their analysis was performed by two teams; the first being by their customer
technical support team which reviewed all CIs. They concluded that there was ‘nothing abnormal to report’.
Pitts - We have already discussed at great length the problem of using current HUMS technology to establish the health of planet gears in an epicyclic, I suggest you look back for that discussion which was only a month or so ago, rather than trying to re-start it.
HC - no the point I was making is that its irrelevant what data sharing exists or doesn't exist if the data isn't going to make a difference.
In the EC225 cases it alarmed and allowed a controlled ditch but HMES isn't in my view anything more than a "best efforts" and depends hugely on which component fails.
Of greater interest is the mechanical issues which I can't see being resolved anytime soon. Does anyone know what % EC225 sales are as a total of Eurocopter revenues??
In the EC225 cases it alarmed and allowed a controlled ditch but HMES isn't in my view anything more than a "best efforts" and depends hugely on which component fails.
Of greater interest is the mechanical issues which I can't see being resolved anytime soon. Does anyone know what % EC225 sales are as a total of Eurocopter revenues??
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I do not know what to make of this as yes 2 shafts failed and it got the treatment it deserved with all subject to 3hr download of HUMS and yes most grounded in the interest of aviation safety etc. I do find it sad as somebody nowhere involved in this market that the 225 is treated so harshly(correctly again?) and being replaced by models with problems too yet not as defined as a specific shaft failure as on the 225 so flying threw their issues? Are the unions as informed about the MGB cracking and now airframe cracking issues on the 92 or the tailboom issues on the 139 as they are of the obvious and clear issue of the post 2009 shaft with 2 failures on the 225 which has a clear solution? What if the next one is not a 225-and I hope there is no next one?
There is a huge argument between HC and the rest as to HUMS data and the usage there of with speculation on all sides towards what EC does. The facts have been stated about Sikorsy and Bell but has anyone actually established how euroarms work and what EC does or doesnt do with the data? It is a argument with facts from Sikorsky and Bell it seems and a assumption that EC does nothing despite having euroarms I think is the EC specific HUMS version? As said I do not know this market or am involved, just find it astonishing the arguments and sentiment!
Not a good time for EC I presume at all but so the industry goes and it seems that they at least have a clear target to fix and as per the B3e restrictions and issues with the TR bearings after no previous issues on the B3's it seems that maybe our thurst for power has caught up with our technology? People referred in this threat to older more reliable platforms than the 225, 332L2,S-92, AW 139 but then those were the times when we all demanded more power from the engines!?
There is a huge argument between HC and the rest as to HUMS data and the usage there of with speculation on all sides towards what EC does. The facts have been stated about Sikorsy and Bell but has anyone actually established how euroarms work and what EC does or doesnt do with the data? It is a argument with facts from Sikorsky and Bell it seems and a assumption that EC does nothing despite having euroarms I think is the EC specific HUMS version? As said I do not know this market or am involved, just find it astonishing the arguments and sentiment!
Not a good time for EC I presume at all but so the industry goes and it seems that they at least have a clear target to fix and as per the B3e restrictions and issues with the TR bearings after no previous issues on the B3's it seems that maybe our thurst for power has caught up with our technology? People referred in this threat to older more reliable platforms than the 225, 332L2,S-92, AW 139 but then those were the times when we all demanded more power from the engines!?
Victor, I think one thing to bear in mind is that the algorithms, signal processing etc in the HUMS systems of all the OEMs is pretty much the same. The AAD process is a newer devlopment but as far as I am aware, it is not built in to any of the OEM's systems, rather it is a bolt-on provided by GE.
The system on the 225, by the way, is called M'ARMS.
You are of course absolutely right in that the 225 is the demon of the moment, but other types such as 139 and S92 have all had substantial technical problems in the past that grounded or nearly grounded them. I hope and expect that once this shaft issue is resolved, the EC225 will come back into favour, though a lesson has been learnt about not having all your eggs in 1 basket.
The system on the 225, by the way, is called M'ARMS.
You are of course absolutely right in that the 225 is the demon of the moment, but other types such as 139 and S92 have all had substantial technical problems in the past that grounded or nearly grounded them. I hope and expect that once this shaft issue is resolved, the EC225 will come back into favour, though a lesson has been learnt about not having all your eggs in 1 basket.
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Thanks for the correction HC, I last dealt with a offshore EC many years ago and then the state of the art was the euroarms. It was a L2 and a very old L2. I just wonder if the 2 225 failues had more than 1 possible cause whether it would have been this easy to ground a fleet. It almost is so simple the cause that is so clear and the cure that it is easy to say ground until fixed whiilst most modern helos are flying threw issues but they are not as clearly defined so no clear demand to fix before we fly again etc! I am probably way of base but it seems that the obvious and simple is the problem here?
Given the process - or rather lack of - EC can not be surprised.
In the end, without wishing to sound smart after the event but where in the process have EC taken care of their brand and reputation in this pre-accident?
It all seems very "matey" and customer friendly without a thought that actually if something ends in a million pieces who did we put the trust in the hands of? After all the operator is a commercial entity and personally I don't think it is a great idea having alarms (in this case yellow, red) and then a woolley grey area beyond that.
You look at recent AAIB findings on EC machinary that has HUMS and there is a lack of consistancy with its usage and indeed understanding as to what and how it should be used.
In the end, without wishing to sound smart after the event but where in the process have EC taken care of their brand and reputation in this pre-accident?
It all seems very "matey" and customer friendly without a thought that actually if something ends in a million pieces who did we put the trust in the hands of? After all the operator is a commercial entity and personally I don't think it is a great idea having alarms (in this case yellow, red) and then a woolley grey area beyond that.
You look at recent AAIB findings on EC machinary that has HUMS and there is a lack of consistancy with its usage and indeed understanding as to what and how it should be used.
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I must say I have found this thread enlightening. I am an amateur pilot who works offshore. We normally fly out on 225's. I must say that a huge majority of the offshore work force has lost all confidence in this aircraft due to the events of late. I am glad to see it is held in such high regard by those who fly it and work on it. Our operator had not had any incidents as I believe they have excellent maintenance procedures.
We have received very little in the way of information as to what the problems actually are with the gearbox issues which only serves to enhance the fear of flying as a passenger in one.
We have received very little in the way of information as to what the problems actually are with the gearbox issues which only serves to enhance the fear of flying as a passenger in one.
If you are a pilot and not serious about maintenance ...
HC, I am amazed at your attitude regarding aircraft maintenance. Perhaps what you are saying is not how you actully go about your day to day business.
Maybe it was my military training, but I suggest to you that if you don't become personally familiar with what is behind keeping your bird in the air, you are setting yourself up to make some incorrect decisions on taking a bird up, or keeping one flying, or not keeping one flying. (This goes particularly for helicopters, who have more moving parts than fixed wing).
Professional pilot: not only do you need to know your aircraft inside and out, you need to know how it works, and what makes it work.
Nonsense. Chaging or fixing parts before they fail, and hence before they fail In Flight, has a bit to do with Flight Safety. Do you understand?
I mention this in part to me not being the only person who feels this way.
The US Army (operators of the world's largest helicopter fleet) is currently spending millions on a program to improve their Condition Based Maintenance posture. Their intent is to better ensure that parts that are not wearing out (or otherwise showing signs of impending failure) are left on wing and parts that do show those signs are removed in a timely fashion. It has everything to do with a combined set of factors: readiness, cost, and safety. They are all bound together.
Geoffers.
Amen, Deacon.
As I understand it, yes. But one still has to collect data and know what info aides a decision, and what is noise.
Well put. The fifty pound brains are working on it, but as you point out, it's one of those multi-variable problems that does not lend itself to quick, easy solutions.
Another note on HUMS in real life. (I hope we can all agree that HUMS, in its current form, is NOT a silver bullet by any means).
The US Navy has a number of HUMS-like programs for its helicopter fleet. The operators still run into the problem of identifying and rejecting false positives. It's an ongoing battle no matter who you are, in terms of fleet operation, maintenance, and management.
As Geoffers points out, it's a field with ample opportunity for improvement and development. It is my belief that in due course, HUMS programs and diagnostics will improve and make rotary wing ops both safer and more cost effective.
Tying this post back to the ditching event, the impression being left in some minds, if carelessly presented, might be that HUMS is an ironclad sort of system that allows for no fault or simple go/no go decisions.
That message should be squelched when found.
I doubt you would expect other pilots to be intimate with all their company's engineering processes so I don't understand why you think I should be?
Professional pilot: not only do you need to know your aircraft inside and out, you need to know how it works, and what makes it work.
So I am getting the picture now, the centralised fleet monitoring is all about spares / PBH / increasing component lives. Nothing wrong with that of course -it's a good thing - but also nothing to do with safety.
I mention this in part to me not being the only person who feels this way.
The US Army (operators of the world's largest helicopter fleet) is currently spending millions on a program to improve their Condition Based Maintenance posture. Their intent is to better ensure that parts that are not wearing out (or otherwise showing signs of impending failure) are left on wing and parts that do show those signs are removed in a timely fashion. It has everything to do with a combined set of factors: readiness, cost, and safety. They are all bound together.
Geoffers.
We have to remember that when HUMS was 'invented' the designers said it would take 10 years to gather enough data to understand what the HUMS is telling the end-user. That would appear to be an underestimate on two counts.
Wouldn't it be great if you could implant vibe-sensors into the gear wheels and read the output directly. I wonder if any of the electronics boffins are working on such ideas.
The problems caused by harmonics in a structure with so many rotating components are horrendous and trying to second guess the failure mode is a kind of self defeating process given that identifying a failure mode means that you have put your finger on a weakness. Best answer = remove the weakness.
Another note on HUMS in real life. (I hope we can all agree that HUMS, in its current form, is NOT a silver bullet by any means).
The US Navy has a number of HUMS-like programs for its helicopter fleet. The operators still run into the problem of identifying and rejecting false positives. It's an ongoing battle no matter who you are, in terms of fleet operation, maintenance, and management.
As Geoffers points out, it's a field with ample opportunity for improvement and development. It is my belief that in due course, HUMS programs and diagnostics will improve and make rotary wing ops both safer and more cost effective.
Tying this post back to the ditching event, the impression being left in some minds, if carelessly presented, might be that HUMS is an ironclad sort of system that allows for no fault or simple go/no go decisions.
That message should be squelched when found.
Last edited by Lonewolf_50; 13th Nov 2012 at 14:48.
Nonsense. Chaging or fixing parts before they fail, and hence before they fail In Flight, has a bit to do with Flight Safety. Do you understand?
abzoilworker, I suppose I can't be surprised about your comments regarding the offshore workforce's confidence in the 225, but suffice it to say that all helicopters have their problem areas and, although the 225 is in the spotlight at the moment, the problem will be resolved. I agree that the lack of clear information leads to crewroom / canteen gossip which usually causes a downward spiral of confidence and the catastrophisation of the situation. That is just human nature, regardless of whether there is sound science behind it.