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EC225 crash near Bergen, Norway April 2016

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EC225 crash near Bergen, Norway April 2016

Old 31st May 2016, 17:59
  #1021 (permalink)  
 
Join Date: May 2016
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@Satcomm I'm not a reporter or in any way a party in this. Neither have I landed on any specific theory that I believe strongly in.

I simply react to AH seemingly trying to "guide" the opinion in a certain direction. If they turn out to be correct I guess their actions can be justified. I simply have a hard time to believe that they have strong enough evidence to take this stance without being able to convince AIBN of the same.

The only thing I am fairly convinced is that the earlier much discussed missing suspension bar bolt or nappy pin is too simple a solution. Except for that, I'm still very much open minded and frankly don't have the expertise or depth of knowledge about this to draw any further conclusion.

Last edited by Nadar; 31st May 2016 at 18:46. Reason: Grammar
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Old 31st May 2016, 18:13
  #1022 (permalink)  
 
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Originally Posted by birmingham View Post
...everyone will start the slow or not so slow conversion to other types.

Seems to have already started. Getting busy around Stavanger and Farnborough.
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Old 31st May 2016, 19:05
  #1023 (permalink)  
 
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After numberless upload-attempts all three links in http://www.pprune.org/rotorheads/578...ml#post9394038 are working now
Two of them are AIRBUS-Documents!

Last edited by AW009; 31st May 2016 at 19:34.
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Old 31st May 2016, 22:10
  #1024 (permalink)  
 
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Originally Posted by birmingham View Post
Unfortunately it is now looking very unlikely this machine will survive, at least offshore.

If it is another epicyclic then the game is effectively over and everyone will start the slow or not so slow conversion to other types.

If it is (as they clearly expect) the suspension bar, maintenance related or not. then they will have to explain to an already spooked workforce why the failure of a single item; bar, bolt, or worse missing nappy pin would result in the destruction of the entire structural integrity of the machine.

Now sure, there are many single points of failure on a helicopter- we know that. Many are completely unavoidable.

But could the design of the sus bar assembly have redundancy built in? Other types have at least some. If so why didn't it?

The public will see it this way whatever we think.

The puma in all its types has been around a long while

Recently 5 accidents 7 years 3 fatal 33 dead. All in the NS. 1970s levels of fatal accidents. Regularly grounded, rapid redesigns.

A series of "extremely improbable
" events will "extremely probably" mean the end of the road this time.

Maybe I am wrong, but even If I am I would certainly wager we will never see another AH helicopter with a zero redundancy three bar mrh suspension arrangement.
Birmingham, keep in mind that it could be possible that integrity of the h/c is satisfied with a single point failure in certain flight condition(e.g. Forward flight at 140kts) but not in another (e.g. Descent at certain fpm). From a certification point of view, depending on the hazard assessment, it has to be proven that in certain conditions (which ones I can't figure out) the safety is guaranteed.
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Old 31st May 2016, 23:51
  #1025 (permalink)  
 
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Alby3z ... agreed - just going to be a tough sell after the unfortunate recent history. Also if it were to happen in the sus bar assembly it would be hard to see how the crew would be in any way able to manage such an event.

Last edited by birmingham; 1st Jun 2016 at 11:05.
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Old 1st Jun 2016, 00:32
  #1026 (permalink)  
 
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MITCHAA

I think there have been about another seven or eight serious oil and gas related S76 incidents with two of them including fatalities within the 2009/2016 time frame.
Another incident within this time frame included the unexplained loss of an ERA helicopters tail rotor blade. This also resulted in fatalities.

There appears to be about 42 fatal crashes/incidents in the S76 history for all areas of operation.

https://aviation-safety.net/wikibase...php?AcType=S76
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Old 1st Jun 2016, 00:36
  #1027 (permalink)  
 
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Mitchaa, you can also add the AS332L1 ditching (CFIT?) by Bristow Nigeria in Dec 2009.
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Old 1st Jun 2016, 03:45
  #1028 (permalink)  
 
Join Date: May 2016
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New speculation in the press

Some new speculation has hit the Norwegian press. Some of the information can be relevant if true. What seems to be the original article, by Bergens Tidende, is unavailable to me because it's behind a paywall, but the link is here for those with access: Warned about loose bolts in 2006.

An open article referencing this has been published by a Norwegian tabloid named Verdens Gang: Issues with helicopter bolts known for ten years. English Google translate version here.

I'm not going to translate the whole article, but I'll try to sum it up:
  • EASA warned about problems with the attachement bolts back in 2006.
  • They reference EASA AD 2006-0163R1 : Fuselage - Main Gearbox (MGB) Suspension Bar Attachment Fittings - Checks which applies to 225 and L2. The AD require regular checks for the suspension bar attaching fitting bolts torque. If over-torque is found, both the bolts and the fitting is also to be inspected for cracks.
  • Kåre Halvorsen from AIBN are said to have confirmed to Bergens Tidene that parts of some of the bolts were found in the airframe while others were absent (although no description of the state of the threads in the airframe is given).
  • CHC claim to have performed the required regular checks.
If I interpret this correctly and the threads in the airframe are intact it's hard to se how these can have unscrewed during the accident. I would think that the bolts would either snap leaving the threaded part behind or rip the threads out of the airframe. In the case of snapping I would think that enough damage would be done to the threads that they would be stuck there on the way down instead of being able to be unscrewed by vibrations.

If this is correct and has been known this whole time I can certainly see how AH can be this convinced of what the cause is. What I have trouble understanding is how such an apparant design flaw can be left there for 10 years without any changes to the fittings or the bolts being designed, and simply relying on that the AD with the extra checks will make up for the design flaw.
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Old 1st Jun 2016, 04:28
  #1029 (permalink)  
 
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@Nadar: From my point of view the game is already over. This is just not officially and publicly acknowledged, because the final report of AIBN still is pending.

Breakdown of suspension bar or of epicyclic gear box, what occurred first’, is rather an insignificant ‘hen or egg question’ due to a supserannuated design of (SUPER) PUMA. The results and similitudes are constant since years and since a series of crashs.

How do you reach a consensus without endless circular discussions (see http://www.pprune.org/9372108-post612.html)?
  • Retrospective: The pitcher goes often to the well and gets broken at last.
  • Prospective: Let us wish in a new technical savety-, performance- and market-scenario to H175 and to AH a prosper and sucessfull future and the very same to their competitors.

Last edited by AW009; 1st Jun 2016 at 05:03. Reason: Link to circular diskussions
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Old 1st Jun 2016, 10:03
  #1030 (permalink)  
 
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Originally Posted by AW009 View Post
@Nadar: From my point of view the game is already over. This is just not officially and publicly acknowledged, because the final report of AIBN still is pending.

Breakdown of suspension bar or of epicyclic gear box, what occurred first’, is rather an insignificant ‘hen or egg question’ due to a supserannuated design of (SUPER) PUMA. The results and similitudes are constant since years and since a series of crashs.

How do you reach a consensus without endless circular discussions (see http://www.pprune.org/9372108-post612.html)?
  • Retrospective: The pitcher goes often to the well and gets broken at last.
  • Prospective: Let us wish in a new technical savety-, performance- and market-scenario to H175 and to AH a prosper and sucessfull future and the very same to their competitors.
If it is a fatigue failure from torque loosening/overtorque, known for 10 years, mitigated only by an 825 hour inspection cycle that CHC insist they have diligently adhered to, then it will be game,set,match and tournament.

A horrible irony is this tragedy even took the life of the CHC union representative who tirelessly promoted safety.

Last edited by birmingham; 1st Jun 2016 at 10:51.
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Old 1st Jun 2016, 12:47
  #1031 (permalink)  
 
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Originally Posted by birmingham View Post
... then it will be game,set,match and tournament.
You really are desperate for the 225 to be killed off, aren't you. I wonder why? This is the first fatal accident on a 225. There will be fatal accidents on 189s, on the 175, more on the S92. It's funny how you weren't clamouring for the S92 to be killed off after its fatal crash. Biased, by any chance?

We are focussing on the technical failings of the 225 here buts let's not forget that from an operational point of view the safety is superb, by which I mean no conflict between fuel and payload, and a fantastic autopilot /MMI that protects the pilots from their own incompetence in a way that the S92 most certainly doesn't. There have been a number of pilot induced near-miss crashes on the 92 and in all probability there will be an actual one at some point. What then? Will you be desperate for it too to be pensioned off?

Do tell us what your (not so) hidden agenda is.
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Old 1st Jun 2016, 13:19
  #1032 (permalink)  
 
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NADAR

Re-torques are a common maintenance process and are applied to just about every helicopter I have worked on. I would say that every helicopter operating on the North Sea has re-torques in critical areas.

Interestingly the Chinook had a problem with the bull gear in the aft transmission i.e loss of torque on the attachment bolts. A regular re-torque was introduced. Boeing modified the gear to eliminate the problem. The modified gear failed 45 people died and the Chinooks time on the North Sea drew to a close.

Last edited by ericferret; 1st Jun 2016 at 13:52.
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Old 1st Jun 2016, 14:03
  #1033 (permalink)  
 
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Originally Posted by HeliComparator View Post
You really are desperate for the 225 to be killed off, aren't you. I wonder why? This is the first fatal accident on a 225. There will be fatal accidents on 189s, on the 175, more on the S92. It's funny how you weren't clamouring for the S92 to be killed off after its fatal crash. Biased, by any chance?

We are focussing on the technical failings of the 225 here buts let's not forget that from an operational point of view the safety is superb, by which I mean no conflict between fuel and payload, and a fantastic autopilot /MMI that protects the pilots from their own incompetence in a way that the S92 most certainly doesn't. There have been a number of pilot induced near-miss crashes on the 92 and in all probability there will be an actual one at some point. What then? Will you be desperate for it too to be pensioned off?

Do tell us what your (not so) hidden agenda is.
My hidden agenda?

I genuinely don't have one. As I have previously said I first flew on a Puma at RAF Odiham in the 70s. I have had an association with the type in one way or another ever since. I am currently working in the oil industry but not the NS. I have no commercial or other imperative and have absolutely nothing against them as aircraft - in fact I hold the type in all its historical incarnations in the highest regard and fully accept your point about their design and economics.

I did mention the S92s problems, the fatal accident in Newfoundland and suggested that replacing the Puma was no guarantee of making things safer but could just as easily make things worse.

My view (and it is a view not an agenda) is that a perfect storm of declining NS, low oil price, struggling operators, previous accident history, low workforce confidence, historically high numbers of surplus aircraft, mean that it looks inevitable that the Puma is going to be retired early.

Like you I will be sorry if that happens
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Old 1st Jun 2016, 14:41
  #1034 (permalink)  
 
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@Nadar, AW009 and Birmingham,

By the number of fear mongering post, you guys/gals must be just petrified to sit in the back of any helicopter while being transported offshore (if you even go offshore.

It's just a 825 hour torque check!! If it was thought to be a design flaw where the bolts and securing "nuts" (nadar) underneath could not maintain adequate torque for some unknown reason then something would be done about it. Do you know how many checks take place within a 825 period on any helicopter ? ... A lot of them being torque checks! Would be a very scary world if we did not have torque checks and inspections. Cant remember the interval for the torque check of the S92 MGB bolts but it does have one. It also has a 150 hr frame inspection of the entire area surrounding the MGB mounting. The Jesus nut that is on most helicopters have a torque checks and believe it or not, a lot of time fail initially as the cones are setting.

Last edited by Satcomm; 1st Jun 2016 at 14:57. Reason: Can't say everything I want to
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Old 1st Jun 2016, 15:40
  #1035 (permalink)  
 
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Originally Posted by Satcomm View Post
By the number of fear mongering post, you guys/gals must be just petrified to sit in the back of any helicopter while being transported offshore (if you even go offshore). Based on a rash of your posts I definitely know you are not pilots or engineers ... At least I hope not, then we would truly have something to fear.
I've stated before that I am not a party to this in any way, I don't work in the NS and I don't fly any helicopter on a regular basis. I do have experience with mechanics and metal in general in the world of the deadly (not aviation).

I'm not afraid of flying neither fixed wing nor rotary, and I don't have a "fear agenda" her at all. I'm surprised that you think so, what I've posted here is first and foremost translations of information available in Norwegian. Except for that I'm primarly an observer to the discussion, but I reply when being addressed.

That said, I did sum up AH's statements as a reply to "they haven't really said it is the suspension bars" as I think they consistently let it shine through that they dismiss anything else. What I'm wondering on that is what their motivation for this is, if they know something they can't or won't share or if they just want to "guide" public opinion. If the latest I reported from the Norwegian newspapers is true, it's probably the former.

Originally Posted by Satcomm View Post
It's just a 825 hour torque check!! If it was thought to be a design flaw where the bolts and securing "nuts" (nadar) underneath could not maintain adequate torque for some unknown reason then something would be done about it. Do you know how many checks take place within a 825 period on any helicopter ? ... A lot of them being torque checks! Would be a very scary world if we did not have torque checks and inspections. Cant remember the interval for the torque check of the S92 MGB bolts but it does have one. It also has a 150 hr frame inspection of the entire area surrounding the MGB mounting. The Jesus nut that is on most helicopters have a torque checks and believe it or not, a lot of time fail initially as the cones are setting.
I'm very sorry that I assumed there were threads in the airframe instead of nuts, I didn't realize this was such a deadly sin or I would have thought harder about it. Nuts have always been the better solution as you can easily replace all parts of the threads, but it's all but disappeared on "modern" things I've been in contact with probably because it's more hazzle to get a robot to mount. I realize that's of no importance here, but I've been used to thinking that bolts and nuts are a "thing of the past".

I'm not saying that doing torque checks as a part of normal maintenance is anything wrong. As I see it when EASA has to issue an AD for it being done more often than per AH/Eurocopter's instruction and the parts have to be inspected for cracks as well combined with the fact that a failure here in all likeliness will be catastrophic I think it would be natural to redesign those parts to have more "safety margin" - that is that they can take way more stress before cracks develop. Again I'm sorry if that comes across as fear mongering, to me it's just common sense.
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Old 1st Jun 2016, 16:40
  #1036 (permalink)  
 
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Originally Posted by Satcomm View Post
@Nadar, AW009 and Birmingham,

By the number of fear mongering post, you guys/gals must be just petrified to sit in the back of any helicopter while being transported offshore (if you even go offshore.

It's just a 825 hour torque check!! If it was thought to be a design flaw where the bolts and securing "nuts" (nadar) underneath could not maintain adequate torque for some unknown reason then something would be done about it. Do you know how many checks take place within a 825 period on any helicopter ? ... A lot of them being torque checks! Would be a very scary world if we did not have torque checks and inspections. Cant remember the interval for the torque check of the S92 MGB bolts but it does have one. It also has a 150 hr frame inspection of the entire area surrounding the MGB mounting. The Jesus nut that is on most helicopters have a torque checks and believe it or not, a lot of time fail initially as the cones are setting.
Satcom

Thank you for your kind words.

I'm sure you would agree that a routine torque check/re-torque and an EASA/AD are different things?
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Old 1st Jun 2016, 17:01
  #1037 (permalink)  
 
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Each lower bracket has 4 bolts. I have seen the exploded view of the assembly with barbi plate but it does not show the 12 bolts. Are these bolts attached to individual nuts or screwed into a female thread that is part of the fittings/airframe ? Can the bolts vibrate their way back out if they become loose or are they nylocked / cotter pinned / or other design safetied ? Torque checks implies to me that they can be removed with a single wrench.
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Old 1st Jun 2016, 19:00
  #1038 (permalink)  
 
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@birmingham, @nadar & @tylerMonkey: My thoughts exactly, both from my point of view as pilot and technican.with some experience since 1970, also in offshore ops.
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Old 1st Jun 2016, 19:02
  #1039 (permalink)  
 
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AIBN has published a new preliminary report. It contains an urgent safety recommendation adressed to EASA. It does not appear to support the suspension bar hypothesis.

Last edited by GenuineHoverBug; 1st Jun 2016 at 19:04. Reason: Further info
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Old 1st Jun 2016, 19:06
  #1040 (permalink)  
 
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Oh boy, the epicyclic is implicated again...
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