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225 cleared to fly in UK & Norway

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225 cleared to fly in UK & Norway

Old 8th Oct 2017, 19:51
  #141 (permalink)  
 
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Originally Posted by S92PAX View Post
I think this could be challenged. ERA stated in their briefing about they court claim against Airbus that they inspected the gearbox on their aircraft and found similar spalling on both types of bearing/gear. I think their is a lot more information to come out before a factual opinion can be formed.



That is actually quite troublesome.
It suggests both these bearing versions are overstressed and that it was merely chance that caused two MGBs with the same kind of bearing to possibly be subjected to unusual stresses, via lightning strikes or road accidents.
If comparable spalling is indeed found in both bearing types, reliable failure warning becomes essential. Not sure how this could be achieved, possibly radioactive tracer material in the bearings might add sensitivity, perhaps enough to allow timely intervention.
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Old 20th Oct 2017, 17:37
  #142 (permalink)  
 
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Video from AH

video - Airbus Helicopters
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Old 20th Oct 2017, 19:08
  #143 (permalink)  
 
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Originally Posted by diginagain View Post
See post #118
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Old 21st Oct 2017, 09:38
  #144 (permalink)  
 
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‘Faith’

Nice video, good narration and graphics. Big company big budget.

The problem is, Airbus Helicopters, you exposed us to your ‘company values’ after the crash when, in your desperation to keep the machine selling, you tried to blame innocent parties. Maybe it was sinister and deliberate, maybe it was just wishful thinking. It worked, for a very short time and even now your lies have not completely disappeared as those who lent on them are too stupid to let them go. The victims of your deception were offered no apology or compensation. The lies were concocted and propagated by your highest level managers and ‘best’ experts. Even the president of France got involved.

You need a new helicopter with a gearbox of more robust design. You also need a new management team and a new set of values, which you cannot buy from a marketing sub contractor. You need to go back to how you used to be.
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Old 21st Oct 2017, 09:54
  #145 (permalink)  
 
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More trouble

Airbus has mandated the replacement of the gears of the same supplier in the dauphin gearboxes. Good move but now there are problems supplying sufficiënt replacement parts. Potential grounding into 2019!

https://www.flightglobal.com/news/ar...s-grou-442356/

SLB
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Old 21st Oct 2017, 11:19
  #146 (permalink)  
 
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Originally Posted by Hompy View Post
Nice video, good narration and graphics. Big company big budget.

The problem is, Airbus Helicopters, you exposed us to your ‘company values’ after the crash when, in your desperation to keep the machine selling, you tried to blame innocent parties. Maybe it was sinister and deliberate, maybe it was just wishful thinking. It worked, for a very short time and even now your lies have not completely disappeared as those who lent on them are too stupid to let them go. The victims of your deception were offered no apology or compensation. The lies were concocted and propagated by your highest level managers and ‘best’ experts. Even the president of France got involved.

You need a new helicopter with a gearbox of more robust design. You also need a new management team and a new set of values, which you cannot buy from a marketing sub contractor. You need to go back to how you used to be.
Great summation
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Old 21st Oct 2017, 20:43
  #147 (permalink)  
 
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The multi engined helicopter is inherently more likely to have catestrophic failures of this kind.
This must be taken into account when weighing the upsides of engine redundancy.

(Anyone know why the BK117 fell out of the sky ? Gearbox also?)

Complexity is inherently more prone to several classes of failure (including pilot error)
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Old 21st Oct 2017, 21:45
  #148 (permalink)  
 
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AnFI - I suggest you read the detail behind this failure before trotting out your nonsense.

G.
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Old 22nd Oct 2017, 09:48
  #149 (permalink)  
 
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Originally Posted by AnFI View Post
The multi engined helicopter is inherently more likely to have catestrophic failures of this kind.
This must be taken into account when weighing the upsides of engine redundancy.
Oh, How have I missed these stupid comments, free of any (meaningful) connection to the topic on hand....

Gearbox Failure of second stage Planetary gear has absolutely zero to do with the number of Donks all the way down the transmission chain.
Null, Nada, Zilch.
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Old 22nd Oct 2017, 19:26
  #150 (permalink)  
 
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Henra do you say that because the failure in this exceptionally complex gearbox was downstream of the gearing concerning combination of engines?
If so
I'm not sure in Nada is the right analysis. For example, if one gearbox has 400 tapered roller bearings and another has 10 then which one is more likely to experience a failure of a tapered roller bearing?
So regardless of the contention that this planet gear was working in an area that would be present if it were a single, it doesn't mean it's nada.
Not to mention that lower margins of critical components to carry spare engines is not neccessarily better.

What is the probability of executing a successful Engine Off Landing compared to the probability of executing a Rotor Head Off Landing ?
Pretty poor i'd say.
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Old 22nd Oct 2017, 19:51
  #151 (permalink)  
 
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AnFI, i get your last statement....but I think in the middle ground you get really cloudy on the comparison. Im not sure if you're over thinking it or what.
More parts equals more possible problems, but when engineered to spread the loading, than more parts equals more reliability.

I'm not going to try and compare anything inside the gearbox to try and convince you, i'm simply going to use rope as an example and perhaps that simple comparison will suffice.

How strong is rope when there is 1 strand, versus rope with multiple strands?
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Old 22nd Oct 2017, 20:30
  #152 (permalink)  
 
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Simples - the one with the 10 bearings.

It would never be a safety issue as it would never actually fly.

Scalability laws? Velocity ratio?
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Old 23rd Oct 2017, 00:09
  #153 (permalink)  
 
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So, after reading all these posts... Has any operator in the world started using the affected 225's again, or getting pilots current again to bring them back to operational standards????
Cheers, KP
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Old 23rd Oct 2017, 02:07
  #154 (permalink)  
 
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AnFI - I suggest you read the detail behind this failure before trotting out your nonsense.
Geoffers scores a Hole in One!
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Old 23rd Oct 2017, 06:35
  #155 (permalink)  
 
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Originally Posted by Kulwin Park View Post
So, after reading all these posts... Has any operator in the world started using the affected 225's again, or getting pilots current again to bring them back to operational standards????
Cheers, KP

Yes I believe COHC in China has for some time.
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Old 23rd Oct 2017, 08:21
  #156 (permalink)  
 
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Originally Posted by P2bleed View Post
Yes I believe COHC in China has for some time.
SFS in Vietnam never stopped. Heli-Union are busy promoting their SAR machine at trade shows right now: AFF AND SAR EUROPE 2017 -
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Old 23rd Oct 2017, 14:09
  #157 (permalink)  
 
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Well there is nothing like blind faith!

The fundamental problem here is that Airbus have not been able to duplicate the failure.

Instead they are relying on trying to use procedural barriers against potential failure causes. But the issue is that these are potential causes, not the definitive cause - which might be something new, but more likely is some threshold value being reached which means that instead of spalling the material cracks.

There was some interesting comment earlier on regarding better lubrication which might be an interesting route of investigation - suppressing surface damage whilst allowing crack initiation. But until Airbus can duplicate the problem, all of this is guesswork. Gearbox has fallen off a truck - don't let gearboxes fall off trucks, gearbox has x hours - don't let gearboxes accumulate x/4 hours and so on.

They might be the answer - alternatively they might just be garlic necklaces - incredibly effective in repelling vampires - and you know I've never been bitten by a vampire since I started wearing it!

Last edited by gasax; 26th Oct 2017 at 10:33.
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Old 25th Oct 2017, 08:22
  #158 (permalink)  
 
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gasax,

Your concern about AH not yet having established the root cause of this problem is valid. Unfortunately, it can be extremely difficult or even impossible to diagnose such problems with 100% certainty since there often can be a combination of factors that contribute to the failure, some of which may not be traceable.

The video describing corrective actions being implemented by AH in response to this problem was actually pretty good. However, one thing I noted was that some of the corrective actions are already standard procedure at other companies I have seen performing similar work. For example, more careful packaging and handling of critical components, better contamination control of the environment used for assembly, etc.

All of the corrective actions being implemented are good steps. But as you noted, it may never be established that they actually address the root cause of this problem.
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Old 25th Oct 2017, 23:06
  #159 (permalink)  
 
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The way I see it the cause of the failure was a fracture resulting from a source that did not produce detectable spalling. If the whole design philosophy of MGB's is dependent on the early detection of spalling to warn of impending failure then the fact that no spalling was detected (if it was ever produced??) then we are not in a very good place and gearbox designers must be quaking in their boots. Mind you as a non-engineer my poor opinion of using a gear wheel as the outer race may not count for much. What might count a little more is the fact that there were two 'qualities of gear wheel out there but no one outside AH appears to have known about that rather interesting and worrying fact.

G
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Old 26th Oct 2017, 23:58
  #160 (permalink)  
 
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Geoffers: "the fact that there were two 'qualities of gear wheel out there"
Do you mean two different (conformal) Curvatures of Tapered roller bearing?

and

GreyHorizons: "How strong is rope when there is 1 strand, versus rope with multiple strands?"
I take your point about the spreading of load, but I'm not so sure it's as good an arguement as it sounds.
A bolt is (a bit) like a one strand cable. A rope made of strands, where every strand is near it limit, is obviously MORE dangerous, since the failure of any one strand will tip the others over their limit. OR imagine a rope where the failure of one strand leads to the failure of the whole crane. That is the parallel with this case.

The scaling point has some truth but the 400 single point failure items in a gearbox of this type should be taken seriously.
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