EC225 crash near Bergen, Norway April 2016
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Actually this is the crux of the matter;
So there is one type that has done this. And it's manufacturers response has been to squirm and dissemble.
How does it compare? Well I have a technical interest because this newer 'safer' generation of helicopters seems to be anything but that.
One seems to have issues, some possible caused by marketing hype and the rest by measures which need to be sorted out (4.5 hrs warning and no actions????) and one has what appears to be a fundamental problem which it's manufacturers just want to 'go away'.
Comparisons of the various types of helicopter, while interesting, aren't really helpful...
The problem is that MRG has failed causing two hull losses and the loss of the lives of all on board. After two incidents and major technical investigations we do not yet have a fully developed understanding of the failure mode, a package of modifications to prevent its recurrence, or a workable system to detect the failure once initiated.
The problem is that MRG has failed causing two hull losses and the loss of the lives of all on board. After two incidents and major technical investigations we do not yet have a fully developed understanding of the failure mode, a package of modifications to prevent its recurrence, or a workable system to detect the failure once initiated.
How does it compare? Well I have a technical interest because this newer 'safer' generation of helicopters seems to be anything but that.
One seems to have issues, some possible caused by marketing hype and the rest by measures which need to be sorted out (4.5 hrs warning and no actions????) and one has what appears to be a fundamental problem which it's manufacturers just want to 'go away'.
After the second incident the manufacturer initially and publically concluded that MRG failure was not likely and suggested the investigation of the suspension bar assembly and a thorough review of maintenance records. Then debris was recovered which enabled the AIBN to conclude that the two incidents did indeed result from similar events in the epicyclic of the MRG. The investigators publically disagreed with the manufacturer and some of the regulators over allowing the type to return to service with increased inspections.
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was found in the sea between the area of the main rotor separation and the crash site.
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Progress!
I have with great interest followed this accident thread.
Can any of you with experience please comment on how this important finding might help solve or prove the likely cause of the failiure .
I have to say I am very happy to see the Norwegian Navy finding this important part.
Respectfully
Cpt B
Can any of you with experience please comment on how this important finding might help solve or prove the likely cause of the failiure .
I have to say I am very happy to see the Norwegian Navy finding this important part.
Respectfully
Cpt B
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Pretty straightforward really, FED, one or more chunks from the failed gear get carried forwards by the faster rotating sun gear and get entrained between the sun and those next 2 planet gears. With nowhere else to go it pushes the 'spigots' (or carrier pins) outwards causing the carrier to bend and the ring gear to burst.
It appears to have happened quicker and with a lot more energy than REDL where 7 planets and the inner race from the 8th stayed with the carrier.
It is not clear from the other photo (Close-up of the inner race from the failed planet gear) posted by AIBN whether it is showing the loaded arc or the reverse side of the inner race. Once cleaned up, if there is no evidence of pitting it would suggest little or no spalling of the outer race prior to fracture.
It appears to have happened quicker and with a lot more energy than REDL where 7 planets and the inner race from the 8th stayed with the carrier.
It is not clear from the other photo (Close-up of the inner race from the failed planet gear) posted by AIBN whether it is showing the loaded arc or the reverse side of the inner race. Once cleaned up, if there is no evidence of pitting it would suggest little or no spalling of the outer race prior to fracture.
Last edited by Concentric; 12th Mar 2017 at 08:45. Reason: attached AIBN photo & link to source
I'm surprised it took 10 days to release the information that it was found. Love to see the details of how they found it. I had thought the search was long over or at least over. Was Airbus supporting the continued effort to find the parts or was it all AIBN? Makes you wonder if they can find this how hard could it be to find MH370. I guess a lot harder.
Well once proven for a 225, but never mind! Anyway I am not suggesting that everyone jumps back into a 225 right now. Even though the probability of a rotor head coming off again is probably much less than the probability of another sort of accident, it is of course sensible to wait until we know exactly what the cause of the problem was and there is a satisfactory remedy. But my point is that if those two criteria are met, the only reason not to fly it again seems to be its trial and guilty verdict by social media, hysteria and general ignorance.
I think we are having parallel arguments, rather than totally disagreeing with each other.
We both agree, that we wouldn't like to fly (in) a machine that has a known fault. A fault that can't be mitigated or compensated for.
Personally, after what has been claimed by AH up to now, I'm disinclined to believe anything they say, especially in regards a "fix". Apparently within 24hrs of the Norwegian tragedy, there was "no problem" that wasn't "caused by maintenance issues". Disgraceful.
Once the problem has been fixed, and scrutinized by an independent authority, Ill happily fly the Super Doopa Puma again.
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HC
I think we are having parallel arguments, rather than totally disagreeing with each other.
We both agree, that we wouldn't like to fly (in) a machine that has a known fault. A fault that can't be mitigated or compensated for.
Personally, after what has been claimed by AH up to now, I'm disinclined to believe anything they say, especially in regards a "fix". Apparently within 24hrs of the Norwegian tragedy, there was "no problem" that wasn't "caused by maintenance issues". Disgraceful.
Once the problem has been fixed, and scrutinized by an independent authority, Ill happily fly the Super Doopa Puma again.
I think we are having parallel arguments, rather than totally disagreeing with each other.
We both agree, that we wouldn't like to fly (in) a machine that has a known fault. A fault that can't be mitigated or compensated for.
Personally, after what has been claimed by AH up to now, I'm disinclined to believe anything they say, especially in regards a "fix". Apparently within 24hrs of the Norwegian tragedy, there was "no problem" that wasn't "caused by maintenance issues". Disgraceful.
Once the problem has been fixed, and scrutinized by an independent authority, Ill happily fly the Super Doopa Puma again.
Last edited by birmingham; 9th Mar 2017 at 11:58.
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Actually, that is the planet carrier. There are no planet gears present, but there is a single planet gear inner bearing race still attached at the 3 o'clock position. You can also see what remains of one of the tabs used to retain the planet gear inner bearing races at the 2 o'clock position. Took a significant amount of axial force to tear all those planet gears off the carrier pins.
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One might assume it took a similar magnitude of axial force to break 4 tabs on REDL as you can see in the photo below (Source AAIB Report 2-2011) but it is interesting that its gears stayed on and there seems to have been a limit to the axial displacement of the inner races – possibly contact with the 1st stage carrier?
Of course, the axial force component on LN-OJF may well have been much, much larger than that needed to just break these tabs.
I think the major difference was in whether the larger gear fragments went outwards between planet cluster and ring gear (G-REDL) or inwards between the cluster and the sun gear (LN-OJF). All consequential to the root cause – fatigue failure of a planet gear.
Last edited by Concentric; 10th Mar 2017 at 16:01. Reason: typo
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HC, as you predicted the next fatal incident was indeed an s92 sadly killing an Irish Coastguard crew who were only there to rescue others. At this very early stage no information is available as to what was the cause. I am sure that unless evidence of technical failure is found the S92s will keep flying. If it transpires there was a technical reason and a grounding of S92s as well as 225s is necessary it will be seriously testing for the oil and gas people. For everyone's sake let's hope they can establish the facts quickly. Another sad reminder, if it were needed, of how dangerous helicopter ops can still be.
Last edited by birmingham; 14th Mar 2017 at 17:27.
HC, as you predicted the next fatal incident was indeed an s92 sadly killing an Irish Coastguard crew who were only there to rescue others. At this very early stage no information is available as to what was the cause. I am sure that unless evidence of technical failure is found the S92s will keep flying. If it transpires there was a technical reason and a grounding of S92s as well as 225s is necessary it will be seriously testing for the oil and gas people. For everyone's sake let's hope they can establish the facts quickly. Another sad reminder, if it were needed, of how dangerous helicopter ops can still be.
Obviously we have no idea yet but if it turns out to be CFIT during an instrument approach in bad weather, it does raise the question of whether one sort of fatal accident is worse than another. I'm thinking that, e.g. the Sumburgh L2 accident could have happened to both an L2 and an S92, but not to a 225. What if this accident could not feasibly have happened to a 225?
From the pilots' point of view, we hate the idea of a sudden rotor detachment as it's out of our control. Even though the probability of a CFIT is perhaps greater, we dismiss that as being something that couldn't happen to us because we are competent. And yet it still does.
From the passengers' point of view, I doubt that such a distinction is made since either scenario is out of their control.
Ok, what am I missing here?
(March 17th 2017)
When I look at the document: https://assets.publishing.service.go..._Header_V1.pdf
The latest comments I see are still from 2015.
The Safety Recommendation document relating to the accident concerning AS332L2 Super Puma, G-REDL has been updated.
When I look at the document: https://assets.publishing.service.go..._Header_V1.pdf
The latest comments I see are still from 2015.
