Pack him in with 18 other blokes, dressed in a gimp suit and EBS/ lifejacket combo, and take the scenic route to work.

Only my opinion but the reason for so many people being willing to fly in the 225 now could possibly be to do with the current state of the oil industry.

With so many oil workers and contractors losing their jobs and with little possibility of finding similar employment at the moment, maybe many of the people willing to fly in the 225 are simply agreeing to do so out of fear of losing their livelihood if they refused.
If people could walk out of a job and find another one shortly afterwards, the survey results may well be a lot different.

I have watched the video, indeed interesting. Outside the video they say that they know what happened but in the video they bet on 4 horses: different types bearings; better detection of smaller spalling particles; preventing or signalling shock loads when in transport and preventing dirt ingress while not mounted in aircraft.

All four good measures but they also cut TBO to a quarter and maintenance is limited to Airbus approved maintenance centers.
(Was this not always the case?)

This is only right if they would know and could prove that all these 3 or 4 cheese holes have lined up in this crash. (I.e. Dirt ingress has caused spalling on a previously shock loaded surface of a higher stressed bearing type)

But removal of the more vunerable bearing type is not the complete solution?

I am willing to give credits for the measures they have taken.
But I think they still not know precise.

The maintenance and inspections they have implemented will probably eliminate a sound business case for commercial use?
Perhaps somebody can give insight in what this means on Cost per seat Mile (not down to the penny but more or less relative to S92)

SLB

I’m only a simple ex EC225 driver, but how many of the “4 factors” were present in both fatal failures? The manufacturer of the bearing?

Is that a mirror, almost hidden by all this smoke?

You might want to take another look at the voting figures...
It doesn't take a maths guru to see that the voting trend is now more and more towards "No", currently 49% overall and that very few have been added to the "Yes" vote, currently 43% overall. In the last 24 hours the additional voting has been 71% "No" and 19% "Yes". Interestingly the Sikorsky popularity is climbing slowly so maybe the Airbus lobby had their say yesterday:=

It depends how you interpret the video...
THE cause of the crash was the minor spalling on the inside of the ring gear, this seems 100% certain. Now the question is: how did this spalling happen??? For this they made this huge fault tree analysis and came up with the following possible causes:
A: by intrusion of small particles
B: by shockload
C: by pressure of the roller bearings
D: by fatigue
E: a possible combination of the above.
To counter this they;
A: Reduced the risk of particles entering the gearbox by the additional covers and to perform the work only in certified maintenance centers.
B: To counter effect of shock loads they installed monitor sensors on transport cases, remove gearboxes with "incidents" from the fleet and have maintenance done in certified maintenance centers.
C: To counter the effect of the pressure of the rolling bearings they have removed the version with the generally higher pressure from the fleet, reduced lifetime of MGB.
D: To counter the effect of fatigue they have reduced lifetime on MGB, reduced stress with only allowing the better bearings.
E: To counter the risk of undetected spalling they raised inspection intervals and installed better chip detectors.

Now with all those measures in place I think they covered all most likely causes of the accident. Is it a 100% guarantee??? No, but we will never have a 100% certainty with mechanical things flying through the air... If you additionally add up the fact that these gearboxes also have 100 of thousands if not millions of hours of flighttime I think it is currently even safer than when putting in a brand new gearbox design as some have suggested. I would get on one without hesitation.

As Twist and Shout points out, we have two very similar accidents and the bearings are the only obvious common element.
The discussion in this thread suggests that the internal component failure process may not produce significant particles before complete disintegration.
Passengers would be more confident in the fixes if the huge effort AH has put into analyzing these accidents had allowed them to reproduce the MGB failures that occurred. Without that, concern remains that the fixes are not addressing the problem.

I don't know if the other crashed aircraft had the same bearings, but in case it had, then this is taken care of by removing these bearings from service, as the other ones never had an issue. Additional safety on the MGBs that never had an issue in the first place, is then subsequently provided by increasing inspections, reducing lifetime and better chip detectors. This should take care of the problem... again, 100% guarantee? No. But if you want 100% one should just stay where humans belong: with 2 feet on the ground...

In a way, yes. On the other hand the fact that they couldn't reproduce it straight forward shows that it must be a very unlikely combination of factors. Now they eliminated or reduced multiple additional factors besides the obvious one (the Bearing manufacturer - seeing the different rollers in the video gave me shivers - how can so differently radiused rollers be equally suited to the same application?). Personally I would say with all these measures in place the next helicopter to lose an entire MGB will be a different Make/Model. Will it be economically viable? Well that is a good question.

When combined with the low flying hrs the EC225 fleet is likely to accumulate in the foreseeable future, My personal opinion is the same as yours, well as far as another model goes anyway.

What do you mean? From what I have onderstood they have removed the "bad" bearing variant from the fleet? Totally agree with the last part, it was quite a big difference in radius!

One point to note is that as well as removing any gearbox which has suffered impact from service, they also removed any having had a lightning strike.

The gearbox fitted in the L2 accident had sustained a lightning strike while fitted to a different airframe. Maybe they cannot categorically say it is the gear types because both gearboxes had encountered external factors which could contribute to the cause.

Bottom line....one more fatal occurrence and the Fat Lady will have sung.

If it is not caused by pilot error or external factors but due to further technical reasons, even if not related to a gearbox but again something else: Yes absolutely.

Human nature (for most of us) means we tend to believe things we are told.
Otherwise everything breaks down.

The problem with people/companies that lie, is you can no longer believe anything they say.
Maybe AH had several transmissions fail during their attempts to replicate the catostrophic failure, and are simply lying about that too.

I have no knowledge to suggest this, just pointing out that once someone looks you in the eye and lies to you, it is foolish to ever believe anything they say again.

I won’t.

It probably takes an external damage event (e.g. like lightning strike or transport damage) to trigger premature spalling and propagation of cracks. The design itself seems to be OK as long as no such premature initiation occurs (otherwise more H225/AS332 helicopters would have lost their gearboxes - they accumulated massive fleet hours without such occurrences). It appears that it is simply not very tolerant against such external influences. And the combination of that particular bearing type producing higher peak stresses in the outer race plus an external factor was apparently sufficient in two instances to trigger this premature cracking. The really unfortunate part is that this damage mechanism isn't really properly captured by HUMS&Co. That is what makes it so dangerous.

One more fatal accident caused by mechanical problems (not only Gearbox related) would indeed be the final nail in the coffin at least for civil ops.
That said with the current level of precautionary measures and low flying hours you will probably have to wait rather long for this.

One would hope.....but if you understand Probability Theory the it could happen on the very first flight. It could be a fault not related to the current problem but cause the absolute end to the aircraft in civil service.

A question that does arise.....why no such failures in military aircraft.....or have there been some?

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.

At least I'm not aware of any such occurrence in military use.
Would surely have come up by now.
So why not in the military?
- Luck?
- less intense utilisation?
- More frequent/intense inspections?
- No unfortunate combination of external event (Lightning strike, transport damage) with that same type of bearing?
- any combination thereof?
- other?


Good question.

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.

Video from AH
 

See post #118

‘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.

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

Great summation :ok::ok::ok:

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)

AnFI - I suggest you read the detail behind this failure before trotting out your nonsense.

G.

Oh, How have I missed these stupid comments, free of any (meaningful) connection to the topic on hand.... :ugh:

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.

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.

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?

Simples - the one with the 10 bearings.

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

Scalability laws? Velocity ratio? :D

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

Geoffers scores a Hole in One!:ok:

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 -

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!

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.

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

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.