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North Sea heli ditching: Oct 2012

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Old 13th Nov 2012, 19:59
  #361 (permalink)  
 
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Lone Wolf

You wil I'm sure be aware that component lives are given a notional life extension of 10% to allow for the scheduling of maintenance in line with operational requirements. It was envisaged that one would plan to have the component changed as close to the published life as possible and in the UK I believe we were required to base our planning on that strategy.

In other parts of the globe it is common practice to base the DOCs of the component lives plus the 10%. These operators PLANNED to use the life extension as a matter of course.

Now compare that with a military philosophy of keeping the hardware in tip top condition. Why do the military behave this way? Because they know darn well that when the bullets start to fly the maintenance schedule goes out the window and you do what you can when you can and it pays to be ahead of he game when the war starts.

The commercial world is another kind of war but the enemy is Chapter 11. If you can't pay the bills you go down. Those that play the game are those the have been around the longest and have learned the hard way not to cut corners or waste money. They are also aware of the false econmoy associated with cutting corners on maintenance but I doubt that even these guys would be changing a component early because it was looking a bit worn. They might run a surveillance programme on it but if it is going to last the course then they will make it last the course. To be sure to do that you need engineers that know what they are doing - that's another story. Maybe HUMS can be a useful tool in that quality engineer's toolbox but as you say, it's not the be all and end all.

A few years ago I was auditing in the Americas and found a pair of engineers dismembering a C20 (splitting the modules) on a grubby hangar floor. No approvals and no special tools. A Chief engineer had just been disciplined for splitting a pair of u/s 332L1 MGBs and swapping gearwheels in order to make one serviceable unit. Once again no approvals and no special tools. This is what we are up against. Why? Well in my opinion out of sight out of mind. If the person authorising the use of a machine to carry his employees to and fro actually had to fly his wife and kids in them once a week to prove his faith in the choice he has made then maybe things would be different and he would pay the going rate for a PROPER service.

Grrrrrrr.

G.
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Old 14th Nov 2012, 00:11
  #362 (permalink)  
 
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.......Of course, however in this case it (CBM) is being used to increase component lives in order to decrease costs, not to improve safety. In fact reducing safety margins.....
HeliComparator- You are correct about why CBM was adopted. It allowed components like bearings & gears to remain in service until they gave an indication of the onset of failure, which saves O&M costs. Gears and bearings are designed with very conservative fatigue margins, and in fact current industry practice is to design gears for unlimited fatigue life in tooth bending at 100% torque.

Quite often, due to the statistical nature of fatigue life calculations, gears and bearings may also last 2 or 3 times their predicted fatigue life for surface durability. Gear and bearing surface fatigue failures tend to be fairly benign in nature and are easy to detect with magnetic chip detectors long before they become a serious problem. With regards to false indications, the early types of magnetic chip detectors tended to produce false indications quite often due to nuisance debris in the lubricant. But the new generation of chip detectors have fuzz suppression circuitry and are much more reliable.
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Old 14th Nov 2012, 06:34
  #363 (permalink)  
 
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Facts straight

AbzOilWorker,

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.
Just to be clear as you're right - information is key:

1) All three operators (at ABZ) have excellent maintenance procedures in accordance with the manufacturers specifications and approved by the CAA.

2) All three operators employ HUMS, analyse the data and refer back to the manufacturer on discovery of any issues.

3) All three operators share an equal risk of having "an incident" - lady luck seems to cast her wand at will. Just because an operator has not had a "recent" incident does not mean they're not going to have one.

4) The ditching of G-REDW in May was caused by a failure in the the MGB module (and subsequent failure of EMLUB) - this is a sealed unit that comes from the manufacturer - NOTHING to do with maintenance procedures. Lady luck deemed that it should be in a red helicopter. HUMS had detected a rising trend - the MANUFACTURER dictated a "close monitor".

4) After the ditching of G-REDW, BOND began a program of communication to customers and workforce - this was well accepted widely.

5) The ditching of G-CHCN in May was caused by a failure in the the MGB module (and subsequent failure of EMLUB) - Lady luck deemed that this time it should be in a red/white/blue helicopter

5) After the ditching of G-CHCN, CHC put out information regarding the incident and what is being done to mitigate risk - I suggest you ask your company reps / OIMs etc to request similar of Bristow if you feel that you're not being given sufficient information.

6) Eurocopter have provided an area of their website for you to track the incidents and what they're doing about it: EC225

7) None of the three operators would willfully shortcut maintenance procedures - this would be commercial suicide.

8) All three operators cite "satefy is our primary concern" - of course it is - see #7

9) No pilot will take an aircraft if they have concerns over it's integrity - our desire to get home is far greater than your desire to get to work - trust me.


Having worked for 2 out of the 3, I speak from experience and have intentionally avoided praising one / slating another. Please, let us stick to the facts and avoid finger pointing. I would be very careful about "thinking" that one operator is better / worse than another.

The manufacturer is currently working to identify the problem, rectify it and ultimately rebuild confidence in it's product.

Once this is achieved I shall have no qualms about flying the 225 again, although I must confess to wanting some convincing arguments that the problem truly is rectificed rather than a guess at some affected serial / part numbers with a cursory limit on flying hours based upon how long it has taken previous modules to fail.

The problems to be resolved are simply: prevent another MGB shaft failure; and, providing an EMLUB system that is fit for purpose.

Just remember, if the guy up front is happy to take the aircraft, then you should be happy to get on board.

The commercial fixed wing world suffers maintenance / failure issues similarly yet we all take flights to go on holiday, don't have the chance to, or the inclination to question the pilots, maintenance procedures and credibility of the operator.

The North Sea is a unique environment in that respect, and that should give you some comfort.

OMB

Last edited by OneManBand; 14th Nov 2012 at 06:35.
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Old 14th Nov 2012, 07:22
  #364 (permalink)  
 
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The manufacturer is currently working to identify the problem, rectify it and ultimately rebuild confidence in it's product.

Once this is achieved I shall have no qualms about flying the 225 again, although I must confess to wanting some convincing arguments that the problem truly is rectificed rather than a guess at some affected serial / part numbers with a cursory limit on flying hours based upon how long it has taken previous modules to fail.
OMB - and what metric will you use to assess EC's indentification of the problem and its rectification?

There is no way the gearbox in its current state (meaning current design, material spec and production venue) can have been tested properly because in the words of Eurocopter themselves:-

"Eurocopter is able to confirm that the latest analyses have validated various similarities between the two controlled ditchings in the North Sea, which took place in May and October of this year."

i.e. it is beyond coincidence or to use your words "lady luck".

These seems to be a creeping view that HUMS can be used as a safety net for flakey engineering.
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Old 14th Nov 2012, 09:25
  #365 (permalink)  
 
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Quote of the Week

... - our desire to get home is far greater than your desire to get to work - trust me.
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Old 14th Nov 2012, 09:33
  #366 (permalink)  
 
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What metric will I use ? Gut feeling - what else can I use ? I am merely a pilot - people with far bigger brains will put the case forward, I will then assess whether I have confidence in the product.

Whether it has been tested properly is not for me to assess. I have to have confidence in the aircraft I fly, and the training I'm given, otherwise I should change career.

I didn't state that the failures were beyond coincidence ... I was merely making the point that it was bad luck for Bond and CHC to have faulty MGBs - it could EASILY have been in a Bristow machine and I wanted AbzOilWorker to understand that it was NOTHING to do with maintenance procedures, and to think that AbzOilWorker is immune from an incident because of the operator that takes them to work would be an incorrect assumption.

I trust your comment regarding "flakey engineering" is directed towards the manufacturer, albeit an unfair comment. I look forward to the day when a product is designed that never has a fault - hindsight is a wonderful tool. Your comment implies that the design process contained an element of "it shouldn't fail, but who cares, we'll try it anyway and not test too thoroughly in case it doesn't pass". What is important is that lessons are learned from these events and the product improved. What more can we expect ?

The offshore workers have a habit of stirring themselves into a flap due to a lack of understanding / information / fear of the unknown. This is certainly not their fault, however, comments that suggest an operators maintenance procedures may be "sub standard" have a detrimental effect on their confidence and (wrongly) sews the seed that an operator may be less than professional.

I, like my peers in the offshore world, eagerly await a satisfactory resolution to the current issues, however a witch hunt helps no one. Lets stay professional and comment from a position of knowledge.

OMB
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Old 14th Nov 2012, 11:06
  #367 (permalink)  
 
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OMB don’tget me wrong I’m not having a pop at you, the term “lady luck” was merely paraphrase.

I hear you re: gut feel but standalone that risks you becoming an EC test pilot and the pax ballast.

Totallyagree could have happened to anyone (operator wise) and the criticism is squarely aimed at EC. Since May (whichis six months ago btw) tell me how you see the actions that have been taken?

As I callit there has been a punt on part/serial numbers and a (in my view) overreliance on monitoring alarms, which is not and has not been a reliable indicator in predicting failure in Eurocopter products.

In fact itgets worse because now we’ve had a failure in the emergency system such that EASA requires a review of its design.

The comments are not unprofessional nor a witch hunt, but frankly its amateur hour at EC.


Edit: font all gone wrong!!

Last edited by Pittsextra; 14th Nov 2012 at 11:07.
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Old 14th Nov 2012, 11:23
  #368 (permalink)  
 
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OMB - as you say, trying to pick on an individual operator as having better or worse maintenance procedures than another is dangerous ground, however overall competancy aside, in the 3 accident reports (interim in the case of the CHC one) there were specific areas where the operator had fallen short of the best practice used by other operators. There is no point in denying that as it makes your credibility seem wanting to observers such as our passengers.

In the case of the L2, the epicyclic was not checked as it should have been following the chip. In the case of the CHC 225, whilst everyone else was reviewing HUMS data prior to despatch (not because it was mandatory, but because it was best practice) CHC didn't and the ditching resulted.

Even in the case of the May ditching, I am told (although this is of course hearsay) that we would have had a look at the oil pump area by dropping the sump prior to despatch.

Therefore whilst overall maintanance standards are generally the same, it only takes one error or sub-optimal practice to allow a preventable accident to occur.

Contributory to these accidents was not "bad luck" but some specific maintenance standard issues, even though in general the companies concerned have good standards.

Edited to say that I would of course agree that the main problem lies with EC's shaft, not the operators. However it is the operators' job to catch EC's mistakes before they become an accident.

Last edited by HeliComparator; 14th Nov 2012 at 11:37.
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Old 14th Nov 2012, 12:04
  #369 (permalink)  
 
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Pitts - thanks, none taken.

HC - Curious to know how "dropping the sump" would have identified an impending fratcure in a sealed MGB module that had a HUMS trend but was not producing metal ? Do Bristow not "close monitor" but simply change any MGB that has a HUMS issue ? Or maybe the engineers sign out a "hindsight tool" from stores to help identify problems ?

Last edited by OneManBand; 14th Nov 2012 at 12:05.
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Old 14th Nov 2012, 12:46
  #370 (permalink)  
 
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Dropping the sump would give internal access to the 'sealed unit' and allow a visual inspection to be carried out on the shaft concerned. I believe Bristow have been doing this, but I'm not sure about other operators. I am sure it would have been done if it had been a requirement, which it wasn't. So HC is correct about that. Maybe Bristow should re-launch their 225 fleet if they and their passengers are so confident in their own ability to detect these defects?

Whether checking Hums before despatch would have prevented the CHC ditching is debatable, it's far more likely the accelerometer would have been checked and the component would have been put on a close monitor, and that certainly wouldn't have prevented the ditching. I am, of course, speculating about that.

The root problem however remains the shaft in question, and why it is suddenly failing on a regular basis after years of trouble free motoring. I have a feeling there is still much more to come out about that.
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Old 14th Nov 2012, 12:55
  #371 (permalink)  
 
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ABZ OIL WORKER - PM me and I may be able to restore at least some confidence that the EC225 is a superb flying machine (albiet with a small problem that will get fixed).

DB
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Old 14th Nov 2012, 13:02
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OMB - Congratulations on your excellant post to ABZ OIL WORKER. I hope he benefits from the wise words you have written.

DB

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Old 14th Nov 2012, 15:53
  #373 (permalink)  
 
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Geoffers, life limited components in my experience were typically afforded the 10%, depending ... Some parts yes, some no, some with an engineering authorization. (As in actual engineers doing engineering analysis, not "engineers" as "people who repair aircraft" in Brit aviation parlance).

Getting extensions was a bit of an art, depending upon one's aircraft. With the T-700, for example, the Navy started going away from "life" removals and basically "flew to failure" of certain sub components. Brain hazy on details, but I recall the four module/section design being a nice way to make that a practical strategy.

Cheers.

HC:

Of course, however in this case it is being used to increase component lives in order to decrease costs, not to improve safety. In fact reducing safety margins. Do you understand?
I don't think you understand, yet. You are making some assertions and assumptions that I don't think you can support.

As I am not familiar enough with blueprints and particulars of each part on the EC helicopters in question, I'll not defend a particular decision. The criticisms of the maintenance on this particular aircraft loss are of interest to me. My previous point to you was not limited to this mishap. Try not to bait and switch like that, will you?
I tend to agree more with Campen, however.
The root problem however remains the shaft in question, and why it is suddenly failing on a regular basis after years of trouble free motoring. I have a feeling there is still much more to come out about that.
Remember: you can reduce cost without reducing any safety margins if your data tell you that the part remains sound. (Mind you, in service data sometimes give you the opposite result, and life/change cycles shorten, rather than lengthen).

It makes no sense to change a part that is working unless you have a good reason to believe that it will soon not work/perform as needed. The criticism in this case appears to be that there was some reason to believe a given part was in that zone. That doesn't change what HUMS can do, though as I noted above, it is hardly a silver bullet as things stand now.

The belief of the long term benefit of HUMS lives and dies on data, and on detailed anlaysis. Neither data nor analysis come free, nor quickly, nor easily.

Remainder edited, as it was pointless sniping.

Last edited by Lonewolf_50; 14th Nov 2012 at 16:10.
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Old 14th Nov 2012, 18:09
  #374 (permalink)  
 
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CvB

Bristow is pretty confident that had the CHC aircraft been operated by us, it would not have been despatched. Don't forget that the Maint Manual procs and the general profile of the relevant HUMS parameters had been changed/raised since the May ditching and there is surely no way that any operator who was up to speed with events (which we all are) would simply have put it on close monitoring.

However it is one thing to say that in that particular circumstance the problem would have been identified in time, quite another to say that it would always be. Therefore whilst there remains uncertainty about the exact cause, we will not be operating the aircraft offshore (even if we were allowed to).
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Old 14th Nov 2012, 18:19
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basically "flew to failure" of certain sub components
Fully aware of that practice.

The Sikorsky S76 had its hydraulic pumps lifed as 'on condition'. I had one fail about 60 miles out of Aberdeen. The weather was lousy and I had to go around from an ILS at Aberdeen and proceed IFR to Kinloss on one hydraulic pump knowing that the S76 will not fly without it. It was No 2 so the undercarriage blowdown covered their newly concreted ramp with hydraulic fliud. They were not happy.

The quill shaft had sheared. The other pump I was flying on had 600 hours more than the one that had failed.
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Old 14th Nov 2012, 19:02
  #376 (permalink)  
 
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The quill shaft had sheared. The other pump I was flying on had 600 hours more than the one that had failed.
The qestion this raises to me was "what were the criteria for inspection the pump (and its piece parts)" to determine the "condition" of the pump.
(PS, is the quill shaft that which drives the pump from the transmission, or is it something else? )

(Aren't you glad there were 2? )

Looks like we are in a bit of thread drift, I'll stop there, even though "shaft failure" looks to be a common theme.

Last edited by Lonewolf_50; 14th Nov 2012 at 19:03.
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Old 15th Nov 2012, 08:28
  #377 (permalink)  
 
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Fed.The CAA didn't like both hyd pumps OC, at their request I reviewed all of the Bristow data concerning pump failures and recommended that they had a TBO of 2400 hrs which was taken up. We had a few problems with the ground rigs contaminating the hyd fluid which didn't help.
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Old 15th Nov 2012, 09:42
  #378 (permalink)  
 
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Bristow is pretty confident that had the CHC aircraft been operated by us, it would not have been despatched. Don't forget that the Maint Manual procs and the general profile of the relevant HUMS parameters had been changed/raised since the May ditching and there is surely no way that any operator who was up to speed with events (which we all are) would simply have put it on close monitoring.
HC - its a big claim and without wishing to get bogged down in the could have, would have, should have... it absolutely highlights the lack of clarity and direction from EC with HUMS. Had you got that there would be no question of any operator handling the situation any differently.

Given what had happened in May it isn't good enough to just direct operators to take a close look at certain part numbers and monitor more closely.
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Old 15th Nov 2012, 10:13
  #379 (permalink)  
 
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Whatever the other operators of EC225s may or may not have done prior to and subsequent to the May 2012 ditching, it remains a fact that Bristow always kept to an "iron" discipline of downloading the HUMS after every flight since the first EC225 in Aberdeen, even when rotors running.

Flight operations are not allowed to continue until our engineers have pronounced their satisfaction with the results of the download. Many's the time that I've been told to shut the aircraft down due to amber warnings of various gearbox and engine aspects, until the engineers have completed a more in-depth inspection.

How much of a difference this might have made to preventing the May and October ditchings, I'm not qualified to say. How good the HUMS is in detecting potential oil pump failures, I'm also not qualified to say.

You can now attack me and tell me that Bristow Helicopters is no better than the rest. I'm not going to get drawn into such nonsensical and pointless altercations. I just happen to enjoy the regime of safety which Bristow imposes and if other pilots from other operators are happy too, so much the better.

Last edited by Colibri49; 15th Nov 2012 at 10:14.
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Old 15th Nov 2012, 10:47
  #380 (permalink)  
 
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Whatever the other operators of EC225s may or may not have done prior to and subsequent to the May 2012 ditching, it remains a fact that Bristow always kept to an "iron" discipline of downloading the HUMS after every flight since the first EC225 in Aberdeen, even when rotors running.

Flight operations are not allowed to continue until our engineers have pronounced their satisfaction with the results of the download. Many's the time that I've been told to shut the aircraft down due to amber warnings of various gearbox and engine aspects, until the engineers have completed a more in-depth inspection.
That sounds all very sensible and one would therefore invite comment as to why 1) EC do not advocate such a process for all and 2) why its not adopted as industry standard

You can now attack me and tell me that Bristow Helicopters is no better than the rest. I'm not going to get drawn into such nonsensical and pointless altercations. I just happen to enjoy the regime of safety which Bristow imposes and if other pilots from other operators are happy too, so much the better.
Why would anyone attack you??? We're not 12 year olds at school....!
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