EC225 crash near Bergen, Norway April 2016

[TylerMonkey]

AIBN has released photos of all 3 upper ends of the struts showing main pins and nappy pins. They now say that they have all three mounting brackets for the lower ends and we have seen photos of only two, both with main pins and nappy pins.
The front strut is missing a center section, we don't know how long it is.
The answer they gave to the journalist about whether they recovered all pins and bolts is still not 100% clear., at least to me. We know the 12 mount bolts may have been ripped out during the event.
AH suggests that this event it is a strut problem . . .
If AH has seen all 3 brackets and both ends of the strut that broke in 3 pieces then they must have concluded something (with their lawyers of course) that makes them feel the 225 is safe to fly.
A photo of the lower bracket and the remaining lower front strut with any recovered fittings would be a big event but I have limited expectation that they will release that to the public.
It could be a deal breaker IMHO.

[aeropierre]

Holy crap.
Why are you so desperately panicked to insist on one cause despite not even the Investigators being sure about the cause at this point in time. Did you think about talking to your psychiatrist about this?

A little bit of speculation is fine but what is all this crap with you Amateur accident investigators all about? And any one who doesn't follow your amateurish reasoning blindly will be madly attacked by you.

Is it asking too much to wait with the final verdict until someone KNOWLEDGEABLE has come up with some real evidence (not Armchair evidence)?

(Taking this one of your posts randomly I could have chosen any other one.
Here's hoping your not a Professional Pilot (Or professional anything else for that matter)). Rant over!
Thank you henra : so much crap being published on pprune made me loose interest in opening this website , especially in the rotorhead section where too many non-professional dare to express their fantasy .Good to know that you exist and dare to put people where they belong.

[Satcomm]

AH came out 48 hours after the accident and effectively said this was not an epicyclic incident.

Birimingham, I believe you are wrong with the above statement. They said that it was not a repeat of the issue that caused the 2012 ditchings. Which has nothing to do with the previous epicyclic failures.

[birmingham]

Indeed thank you for the correction. It wasn't until 27 May they openly stated that epicyclic failure was improbable. They have, however, been alluding to the suspension bar failure mode from the outset and still are. I can't believe they would do this unless they could stand it up. But we will see.

[Nadar]

Birimingham, I believe you are wrong with the above statement. They said that it was not a repeat of the issue that caused the 2012 ditchings. Which has nothing to do with the previous epicyclic failures.

Looking at AH's statements (http://www.airbushelicopters.com/website/en/ref/Norway-Statement_347.html) I disagree, although the statement came after 4 days. After 2 days/48 hours they only lifted the grounding of the EC225LP. Their statement at May 3 includes:

At this stage and based on the latest information, preliminary inspection of the main gearbox vertical shaft shows no link with the 2012 ditching events.

In addition to the SIN 3031-S-00 and based on the on-going root cause analysis process, precautionary measures are requested:
An airworthiness directive has been issued requesting measures newly defined in the EASB 53A058 and additional one-off maintenance checks.

The EASB 53A058 requests the verification of the correct installation of all MGB suspension bar attachments for the EC225LP. Similar measures will be published shortly for the EC725AP in a specific ASB.



EASB 53A058 (http://dlapilota.pl/files/EASBEC22553A058ENR0%20%282%29.pdf) also issued May 3 only calls for inspection of the suspension bars while EASA AD 2016-0089-E (http://ad.easa.europa.eu/blob/EASA_AD_2016_0089_E.pdf/AD_2016-0089-E_1) calls for inspection of both suspension bars and gearbox (although only for metallic particles and HUMS data). Both are issued May 3, and this further implies that AH consider the suspension bars the only possible cause.

Then on May 27 they finally dare to say what they have implied (that they consider a suspension bar failure the only probable cause) all along with:
According to Airbus Helicopters’ analysis, seven potential initial events have been retained to explain the main rotor detachment of LN-OJF. Out of these seven scenarios, only one – the failure of the attachment of a suspension bar – can be assessed as probable by Airbus Helicopters, based on the information available to date.

At this stage, the exact cause of this possible event is still unknown. Analysis of the helicopter’s maintenance history has just started and should provide a better understanding of the most likely causes.In the second paragraph quoted they also use this statement to imply that the cause can be found in the maintenance history and thus isn't a design or manufacture issue.

I know that you didn't comment on what AH said May 27, but I think it makes it easier to "read between the lines" in their earlier actions.

[Jdbelo]

I am completely confident in these aircraft, H 225, because I am pilot of Super Puma since 1990, and I HAD NEVER HAD a RED emergency. I have around 5000 hours flying L1 and 225. For me it is clear that the problem in LN-OJF, it is not inside the MGB. Both scenarios of epicyclic or conical housing would be accused in HUMS or in the FCP. No of them wouldd immediately break without any warning. Because of these I agree with AH and their last statement :

Originally Posted by Airbus Helicopers
According to Airbus Helicopters’ analysis, seven potential initial events have been retained to explain the main rotor detachment of LN-OJF. Out of these seven scenarios, only one – the failure of the attachment of a suspension bar – can be assessed as probable by Airbus Helicopters, based on the information available to date.

At this stage, the exact cause of this possible event is still unknown. Analysis of the helicopter’s maintenance history has just started and should provide a better understanding of the most likely causes.

[500e]

The report also provided an update on the retrieval of data from the aircraft’s health and usage monitoring system (HUMS). It stated that due to HUMS data being saved on a memory card only after a helicopter has landed, data from the accident flight was not available.
Latest News
http://www.verticalmag.com/news/article/Norway-crash-Investigators-release-update-on-likely-cause-scenarios

[Jdbelo]

Potential initial event 7): Suspension bar attachment failure
This potential initial event may have two main different origins:
1. Detachment of suspension bar fitting from the airframe: such a detachment could be due to failure of
attachment fitting bolts.
Airbus Helicopters is finalizing additional calculations and fatigue tests. Conclusions are expected in
the beginning of June 2016.
2. Displacement and disengagement of one suspension bar pin due to the absence of safety pins
Dedicated tests are being done to further assess this scenario. Results are expected by end of June
2016.
The AIBN investigation team is still searching for the missing parts from the front suspension bar at the
accident site.
At this stage of the investigation, Airbus Helicopters considers that this potential initial event is not
contradicted by any available technical evidence.
For all potential initial events, analysis of the helicopter’s maintenance history should support a better
understanding of the most likely causes.
Airbus Helicopters will provide updated information as the investigation progresses.

[OnePerRev]

HUMS analysis is only as good as the signal picked up by on-board accelerometers.
A shame the data is not recorded - surprising also.
Planetary systems are notoriously difficult to record early symptoms. This is due to the signal loss through the carrier to another bearing before it can get to a nonrotating hard mount. On direct locations adjacent to bearings, they are very good at picking up small benign issues. On planetary systems a defect noise is faint, and washed out by all the other planet clash that passes around the ring.
Absence of HUMS signal does not mean absence of problem in the epicyclic. In fact if there was any sign previously, then it was probably already more developed, enough to actually affect the planet clash by large deflections.

[HeliComparator]

AH published a new SIN yesterday. They are still pushing the suspension bar issue. There will be a new ESB about it shortly. One point they made which I don't think has been covered on here, is that (they say) there is evidence that the engines and tail rotor were still running / being driven up to the point of impact which, they say, shows the epicyclic didn't seize up.

[212man]

Interesting additional comment from them today!:


May 31, 2016

Following the statement published on May 27th, Airbus Helicopters feels the need to clarify its position to avoid any possible misunderstanding.

Airbus Helicopters is not ruling out any of the scenarios described by the AIBN in its updated preliminary report into the tragic LN-OJF accident. Although significant progress has been made in analyzing information regarding the suspension bar attachments, more work needs to be done on scenarios involving the epicyclic module and the MGB conical housing.

We would like to stress that our chief priority is to further support the ongoing AIBN investigation and to identify the accident’s root cause

[AW009]

Originally Posted by HeliComparator http://www.pprune.org/images/buttons/viewpost.gif (http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-51.html#post9393646): One point they made which I don't think has been covered on here, is that (they say) there is evidence that the engines and tail rotor were still running / being driven up to the point of impact which, they say, shows the epicyclic did not seize up.Running engines and running tail rotor must in principle not be a proof that the Epicyclic modules suffered no self-destruction. This seems to me as a very weak argumentation because the two engine drive shafts and the tail rotor drive shaft are below the bevel gear and the epicyclic gears, see https://www.youtube.com/watch?v=UnpvtFQowKc

@Jdbelo: Although or just because you are (military? Brazil?) pilot of Super Puma since 1990, may be that you assess the situation a little bit unrealistic? The EC225 crash near Bergen has to be seen in a larger context, under technical and economical aspects and under the tooth of time, especially if the epicyclic gear box will prove as cause.

More than ever, the old adage is relevant 'A liar will not be believed even when he speaks the truth'. This spirit runs like a red thread through the history of (Super) PUMA, NH-90, AH-TIGER, A400M, EUROFIGHTER, EUROHAWK and the UAV-Scenario. The ‘Bergen Crash’ might be the 'Causa finalis' for a mutual gloom and doom. AIBN, Norway CAA and UK CAA know these interdependencies and their serious implications very thoroughly. Therefore they will take their time for the final report, which probably might be the ’coup de grâce’.

AIRBUS Helicopters, AIRBUS Defense & Space and ’Major Tom’ have forgotten in the past, 'the higher the energy of the particle collision, the deeper physicists are able to gaze into the proton, and the more details are revealed'.

Up to now AIRBUS Group is loosing itself within each distinguished project in more or less stupid tactics of cock-and-bull stories about any shortcomings in catch-up development, about gap-fill of quality failures and about lack of delivery reliabilities and this is the cause for having overslept solid corporate strategies. The military must repent and pay for what they have ordered. In the industry however, the rules of supply and demand and of free competition are valid.

This behavior seems typical of an artificial or state-created (Germany, France, Spain, UK) Major Corporation, which is indeed in the meantime pseudo-privatized, but as an European monopolist also lives on hidden subsidies in future. Just have a closer look at the Annual Report 2015 of AIRBUS GROUP. 50% of external revenues are attributable to defense and 19.5 billons Revenues of divisions AH and AD & S are representing 46% of total revenues.

Airbus Helicopters took after deduction of 50 cancellations for government helicopter a total of 181 net orders. The new orders included orders for 38 x H175(!) and 67 x H145. The product sales of Airbus Helicopters presents a total of 53% of external revenues, the remaining 47% were are achieved by services.

In 2015, the order situation was much better: The 383 net orders are divided:
H120 / H125 / H130 series: 163; H135: 49; H145: 107; H155-series, 13;Tiger: 7; NH90: 6; H175: 36 (!); H225-series: 2 (1 = Japan Coast Guard (JCG), scheduled for delivery by the end of 2018). (compare http://www.airbusgroup.com/dam/assets/airbusgroup/int/en/investor-relations/documents/2016/Annual-Reports/Annual-Report-2015-Airbus-Group-SE-/Annual%20Report%202015%20Airbus%20Group.pdf and http://www.airbushelicopters.com/website/de/press/Airbus%20Helicopters%20sichert%202015%20seine%20F%C3%BChrung sposition%20auf%20dem%20Zivilmarkt%20und%20verbucht%20Verkau fserfolge%20bei%20Neuprodukten_1903.html)

Whilst expectations of crude oil and natural gas industry for the coming three years are lower than previously anticipated (by between -4% and -7% year-on-year) the overall picture remains a long-term growth story with the offshore helicopter industry expected to be relatively resilient as the majority of demand will arise from ongoing production phase support. To take a Pollyanna view of Helicopter Offshore OPs, the coming years will be an important time for the industry as a new generation of medium-class helicopters, such as the S92, H175, AW189 and and soon Bell 525, will continue increasingly their introduction. These models are characterized by technical growth potentials, highly efficient with new advanced safety systems and are, therefore, expected to perform well in the offshore arena. But H225 is trending towards the tribal wisdom of the Dakota Indian ’When you discover that you are riding a dead horse, the best strategy is to dismount.’

Therefore the “Bergen Crash“ will prove as the key issue for the future of AIRBUS Helicopters as well as for AIRBUS Defense & Space and the aforementioned projects. TIGER (in Australia), NH90 (in Australia and Sweden) and H225-series (worldwide?) are already spinning in a death spiral.

(just my 2 cent or my purely personal assessment of the market situation).

[birmingham]

AH published a new SIN yesterday. They are still pushing the suspension bar issue. There will be a new ESB about it shortly. One point they made which I don't think has been covered on here, is that (they say) there is evidence that the engines and tail rotor were still running / being driven up to the point of impact which, they say, shows the epicyclic didn't seize up.

tbf any reponsible manufacturer would do this. They obvious believe that this is the most likely of the seven scenarios and one of the seven where a SIN and associated checks could have most benefit. It is difficult to see what nore they coud suggest to monitor the epicyclic without a redesign. The encouraging news is they are working on tests to stand up this theory and they don't yet completely disount the other 6

[HeliComparator]

Running engines and running tail rotor must in principle not be a proof that the Epicyclic modules suffered no self-destruction. This seems to me as a very weak argumentation because the two engine drive shafts and the tail rotor drive shaft are below the bevel gear and the epicyclic gears, see https://www.youtube.com/watch?v=UnpvtFQowKc


There will presumably be a weak point that would likely shear or at least be severely damaged in the event of a sudden stoppage of the epicyclic. Personally I have no idea where that might be but it seems AH do, and they think it is between the engines and the bevel gear.

[SASless]

"The harder you have to work to deny you have a problem....the greater the problem you have."

Paraphrasing the comment a well known Helicopter Design Engineer and Test Pilot once said.

[Satcomm]

Nadar, once again I do not believe Airbus has ever said that it was not an epicyclic failure. Just that it definitely was not the same issue that caused the 2012 ditchings.

And again with the latest statement, if you "read between the lines" obviously yes, they want it to be a suspension bar failure or some sort of maintenance issue. However, every statement they made to date has a "but we could be wrong ending". The 7 possilble cause statement ends with a statement about "information available to date". The maintenance history statement ends with the word "causes." This could be viewed as "causes" to the suspension bar failure or which of the 7 possible "causes" may be the cause.

The news over the pass few days have been reading between the lines as well and reporting what they feel as Airbus definitively saying it's not a gearbox issue and that they pinpointed maintenance. (Are you a reporter?) Airbus are obviously reacting to this propaganda and clarifying the issue, with more smoke and mirrors!!

[AW009]

@HeliComparator, @SASless: Just have a look on https://www.youtube.com/watch?v=oD4jKBOIBwc ,
https://www.youtube.com/watch?v=iJKZPbf_kPI (https://www.youtube.com/watch?v=iJKZPbf_kPI)
https://www.youtube.com/watch?v=2SdJvHUuBgg

.

[birmingham]

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.

[AAKEE]

Running engines and running tail rotor must in principle not be a proof that the Epicyclic modules suffered no self-destruction

Is it is possible that if the MGB epicyclic module seizes the connection to the engines is lost and the resulting inertia is to small to stop the engine from shutting down due to overspeed ? And, wise versa, if MGB still intact the inertia is big enough to allow the ECUs to limit power before overspeed rpm is reached ? Just a thought, to try to understand AH...

[Nadar]

@Satcomm (http://www.pprune.org/members/456723-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.

[PlasticCabDriver]

...everyone will start the slow or not so slow conversion to other types.


Seems to have already started. Getting busy around Stavanger and Farnborough.

[AW009]

After numberless upload-attempts all three links in http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-52.html#post9394038 are working now
Two of them are AIRBUS-Documents!

[alby3z]

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.

[birmingham]

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.

[ericferret]

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/dblist.php?AcType=S76

[Variable Load]

Mitchaa, you can also add the AS332L1 ditching (CFIT?) by Bristow Nigeria in Dec 2009.

[Nadar]

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 (http://www.bt.no/nyheter/lokalt/Advarte-mot-lose-bolter-i-2006-3605224.html).

An open article referencing this has been published by a Norwegian tabloid named Verdens Gang: Issues with helicopter bolts known for ten years (http://www.vg.no/nyheter/innenriks/helikopterstyrten-i-hordaland/helikopterulykken-ved-turoey-problemer-med-helikopterbolter-kjent-i-ti-aar/a/23699505/). English Google translate version here (https://translate.google.no/translate?sl=no&tl=en&js=y&prev=_t&hl=no&ie=UTF-8&u=http%3A%2F%2Fwww.vg.no%2Fnyheter%2Finnenriks%2Fhelikopters tyrten-i-hordaland%2Fhelikopterulykken-ved-turoey-problemer-med-helikopterbolter-kjent-i-ti-aar%2Fa%2F23699505%2F&edit-text=&act=url).

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 (http://ad.easa.europa.eu/blob/easa_ad_2006_0163_R1.pdf/AD_2006-0163R1_2) 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.

[AW009]

@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)? (http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-31.html#post9372108)?)


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.

[birmingham]

@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)? (http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-31.html#post9372108)?)


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.

[HeliComparator]

... 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.

[ericferret]

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.

[birmingham]

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

[Satcomm]

@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.

[Nadar]

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.

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.

[birmingham]

@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?

[TylerMonkey]

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.

[AW009]

@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.

[GenuineHoverBug]

AIBN has published a new preliminary report (http://www.aibn.no/Aviation/Investigations/16-286). It contains an urgent safety recommendation adressed to EASA. It does not appear to support the suspension bar hypothesis.

[SansAnhedral]

Oh boy, the epicyclic is implicated again...

[helicrazi]

Nail in coffin...

[SansAnhedral]

G-REDL (https://www.gov.uk/aaib-reports/2-2011-aerospatiale-eurocopter-as332-l2-super-puma-g-redl-1-april-2009)

An extensive and complex investigation revealed that the failure of the MGB initiated in one of the eight second stage planet gears in the epicyclic module. The planet gear had fractured as a result of a fatigue crack, the precise origin of which could not be determined. However, analysis indicated that this is likely to have occurred in the loaded area of the planet gear bearing outer race.



LN-OJF (http://www.aibn.no/Aviation/Investigations/16-286?iid=19936&pid=SHT-Report-Attachments.Native-InnerFile-File&attach=1)

Among the recovered parts were two pieces which together form approximately half a second stage planet gear (ref. Figure 2). Examinations of these parts have revealed features strongly consistent with fatigue. The fatigue appears to have its origin in the outer race of the bearing (inside of the gear), propagating towards the web of the gear teeth. There is sign of spalling in front of the fracture surface.

[helicrazi]

Airbus respond with an EASB that is H225 specific, what about other variants?

Obviously still trying to promote the suspension bar theory...

[Hompy]

Everybody still happy with their choice of toothpaste?

[Pltnorway]

Airbus respond with an EASB that is H225 specific, what about other variants?

Obviously still trying to promote the suspension bar theory...

That was not a response to the findings announced by the AIBN this afternoon. The EASB was announced yesterday and issued today.

[helicrazi]

I used the word 'respond' as tongue in cheek, however it was spectacularly timed!

[SpotOn_No]

Updated report from AAIB/N issued today: "Recent metallurgical findings have revealed features strongly consistent with fatigue in the outer race
of a second stage planet gear in the epicyclic module of the MGB. "

http://www.aibn.no/Luftfart/Undersokelser/16-286?iid=19942&pid=SHT-Report-Attachments.Native-InnerFile-File&attach=1

EDIT: Sorry... did not see that there was already a post that referenced this updated report. Rookie mistake.

[OnePerRev]

Okay, not good news here at all, but not surprising based on earlier photos we saw.


Next hard part is to determine "Why". Parts break when strength is exceeded by load. designers keep that from happening in theory, supported by testing. But if something breaks, you look at both ends of that basic equation. Was the part weaker than designed or are the loads higher than expected. If the former, due to quality issue, that can usually be contained. If the latter, then heads scratch on entire substantiation, heavy inspections, life limits, etc.
Also note (as stated earlier) the symmetry in fractures - and the number of parts affected. Less likely a quality issue, when affects multiple parts, unless same batch. There may well be a vibratory deflection content that was not anticipated, thus not deigned for. The issue that doomed Norne event was a resonance that AH discounted. They probably are paying attention now...

[FNTC]

Article from a Norwegian website an hour ago, where the Technical Director of the Norwegian Aviation Authority says that they are "strongly considering" to ground even the SAR 225s (which have been flying after the accident). He also says they are waiting for a reply from EASA, and the article says that this could end in a global grounding of the Super Puma fleet.

Brudd på giret avdekket i ulykkeshelikopteret - samme feil oppdaget også i 2009 - Tu.no (http://www.tu.no/artikler/brudd-pa-giret-kan-vaere-arsaken-til-helikopterstyrten/347781)

[TylerMonkey]

I am curious if this (looks like a) similar crack radiating out from the inner race has ever been discussed since the event.

Don't remember any comments . . . .

http://i86.servimg.com/u/f86/11/94/64/62/gears210.jpg

[turboshafts]

I am writing here now, as it becomes evident that the
MGB and Rotor assembly change as claimed by CHC and referred in the media have probably not taken place.


MGB change 17 January 2016
MRA change 27 March 2016


With relation to todays released pictures by AIBN
I find it strange that there is already fatigue cracks in
crucial parts of the Main Rotor assembly. A mere month and few flying hours after the claimed change.


In the Public Electronic Postjournal in Norway all the official correspondance between CAAN and CHC are stored in the
Aviation Technical Folder of LN-OJF.
https://oep.no/search/result.html?1=1&searchType=advanced&caseNumber=2010/1580&list2=110&caseSearch=true&sortField=documentNumber&start=0




These are available to the public, and is now matter of attention to AIBN.


"Undersøkelser av helikopterets vedlikeholdshistorikk har nettopp begynt og vil trolig gi en bedre forståelse av de mest sannsynlige årsakene"


"Investigations of the helicopters maintainance history have just started and will probably give a better understanding of the most plausible causes."




Here are some main points of the maintainence history:


Last Airworthiness Review Certificate is released
11.01.2016


This is the last record in the Aviation Technical Folder of LN-OJF


It is strange that this is released one week before the change of MGB
but no documents thereafter?


The rest of the maintainance history of the MGB is as follows:
14.11.2014:
CHC send Airbus Technical Agreement on extended TBO on MGB
to CAAN. [Can anyone refer to the main points in extended TBO on MGB technical agreement? ]


20.11.2014:
Application for extended TBO on MGB sent from CHC to CAAN


09.12.2014:
Approval of extended TBO by CAAN


16.12.2014:
Airworthiness Review Certificate sent by CHC to CAAN


09.11.2015:
Application for extended TBO on MGB sent by CHC to CAAN


03.12.2015:
Approval of extended TBO on MGB by CAAN


11.12.2015:
Application for second extended TBO on MGB sent by CHC to CAAN


18.12.2015:
Approval of extended TBO on MGB


11.01.2016:
Last Airworthiness Review Certificate sent from CHC to CAAN.




So these electronic journals of the communication between CHC and CAAN are pointing in the direction that someone has information shared with the Media that is not correct.


Where are the documentation, approval and correspondance between CHC and CAAN
after 17 of January until 27 of March, where the claimed MGB and MRA change have taken place?


After that and until the breakdown incident there are no records.


4 times extended TBO on MGB
and there are found fatigue cracks in critical components.




//T

[n305fa]

I am curious if this (looks like a) similar crack radiating out from the inner race has ever been discussed since the event.

Don't remember any comments . . . .

http://i86.servimg.com/u/f86/11/94/64/62/gears210.jpg

I think if you compare the shape of the inner edge,(raceway) you will see that cracked gear you point to is "ovalised" compared to the other example. The location of the crack is where the tensile loads caused by the ovalisation would be very high. I expect the crack to turn out to be as a result of overload. If it was a fatigue crack it would remain 'tight' ( both fracture faces close together) until the remaining material failed in overload. The fact that this crack is "open" also supports the possibility of an overload scenario.

[whoknows idont]

I am curious if this (looks like a) similar crack radiating out from the inner race has ever been discussed since the event.


Seems like that gear was heavily deformed during (self-?) destruction of the gear box and/or on ground impact.
Does not look properly circular in my eyes.

[n305fa]

I am writing here now, as it becomes evident that the
MGB and Rotor assembly change as claimed by CHC and referred in the media have probably not taken place.


MGB change 17 January 2016
MRA change 27 March 2016


With relation to todays released pictures by AIBN
I find it strange that there is already fatigue cracks in
crucial parts of the Main Rotor assembly. A mere month and few flying hours after the claimed change.


In the Public Electronic Postjournal in Norway all the official correspondance between CAAN and CHC are stored in the
Aviation Technical Folder of LN-OJF.
https://oep.no/search/result.html?1=1&searchType=advanced&caseNumber=2010/1580&list2=110&caseSearch=true&sortField=documentNumber&start=0




These are available to the public, and is now matter of attention to AIBN.


"Undersøkelser av helikopterets vedlikeholdshistorikk har nettopp begynt og vil trolig gi en bedre forståelse av de mest sannsynlige årsakene"


"Investigations of the helicopters maintainance history have just started and will probably give a better understanding of the most plausible causes."




Here are some main points of the maintainence history:


Last Airworthiness Review Certificate is released
11.01.2016


This is the last record in the Aviation Technical Folder of LN-OJF


It is strange that this is released one week before the change of MGB
but no documents thereafter?


The rest of the maintainance history of the MGB is as follows:
14.11.2014:
CHC send Airbus Technical Agreement on extended TBO on MGB
to CAAN. [Can anyone refer to the main points in extended TBO on MGB technical agreement? ]


20.11.2014:
Application for extended TBO on MGB sent from CHC to CAAN


09.12.2014:
Approval of extended TBO by CAAN


16.12.2014:
Airworthiness Review Certificate sent by CHC to CAAN


09.11.2015:
Application for extended TBO on MGB sent by CHC to CAAN


03.12.2015:
Approval of extended TBO on MGB by CAAN


11.12.2015:
Application for second extended TBO on MGB sent by CHC to CAAN


18.12.2015:
Approval of extended TBO on MGB


11.01.2016:
Last Airworthiness Review Certificate sent from CHC to CAAN.




So these electronic journals of the communication between CHC and CAAN are pointing in the direction that someone has information shared with the Media that is not correct.


Where are the documentation, approval and correspondance between CHC and CAAN
after 17 of January until 27 of March, where the claimed MGB and MRA change have taken place?


After that and until the breakdown incident there are no records.


4 times extended TBO on MGB
and there are found fatigue cracks in critical components.




//T

The maintenance review Cert is an annual check / review of the airframe, at the time of the review.

Given the findings of the investigation I would suggest that it is more appropriate to follow the history of the MGB rather than the airframe.

[SASless]

AW009....I enjoyed the Video's you linked.

With the latest news being discussed extant....you wish to expend some additional effort in discounting the possible involvement of the Epicyclic Module as in the previous tragedy?

It is still early in the investigation and lots of questions remain and more work needs to be done but even as an idle spectator to discussion One simply must think Gearboxes just do not fail that often anymore and for two to have gross similarities resulting in a loss of the Main Rotors as a group.....One must wonder why!

I am quietly waiting to hear how all this turns out but evidence keeps turning up that brings us back to a possible cause a lot of folks just do not want to confront for any number of reasons.

[Pi1ot]

From the sideline it is disturbing to observe the similarities to the G-REDL accident.
It is even more disturbing to read the safety recommendations after G-REDL, and probably also the 2012 accidents which Airbus never satisfactory closed.

Adding to this the latest EASB mandates replacements of all bolts related to suspension bars. Airbus states that one of the reasons are findings of wrong washer installation on the suspension bar fitting bolts. The reality is that the washers found to have missing chamfered face toward the bolt head, was an Airbus production flaw, and NOT a wrong installation.

What is wrong with the Airbus organization, and where is EASA???

[ericferret]

n305fa

Normally an extension to maintenance of any type once agreed with the aviation authority would only require further paperwork to be submitted if for example an ammendment was required. Providing the operator has replaced the component within the agreed timescale no further information would be supplied to the airworthiness authority. So I would assume that the gearbox in this case had been replaced or was still within the agreed extension. I cant see why there would need to be further correspondence with the Norwegian authority. As it appears to have been stated that the box was replaced I see nothing in the documents to suggest that this was not the case.

Pi1ot

The use of chamfered washers is common on all helicopters. The maintenance procedures are clear requiring the chamfer to be fitted against the bolt head. If a washer is installed with the chamfer facing the wrong way or without a chamfer then that is clearly a "wrong" (incorrect) installation that should have been picked up on assembly.

[G0ULI]

Helicopters are relatively inefficient flying machines when compared to fixed wing aircraft. In a hovering and low speed manouvering the engine is required to supply sufficient power to support the entire weight of the aircraft rather than being assisted by aerodynamic lift from winged surfaces. This means that weight is of critical importance in helicopter design. Every gram saved increases performance.

I highly suspect that the designers of the gearbox calculated the minimum size and strength requirements for the gear parts and added the necessary safety factors considering only the total cross sectional dimensions of the gears. This is perfectly satisfactory if the parts are of uniform material construction.

Problems arise when parts are surface hardened or carburised (carburized). The dimension of the parts are unaffected but an hardened and brittle outer layer is produced on the component which gives exceptional wear resistance. If for some reason the brittle hardened outer layer fractures, there may be no obvious signs of failure. The softer inner metal layer remains bonded to the hard outer surface and there may be no metal debris, chips or vibrational changes at all.

However, the load on that part is now being carried completely by the softer inner metal of that part. In effect the cross sectional area has been reduced somewhat and its load carrying characteristics are below what the original designer intended. The part does not fail immediately because of the safety factors designed in, but it is subjected to loads in excess of the design limits. The extra stress slowly causes the softer material to start to break up. The part may start to deform slightly and metallic debris and chips are most likely to be found at this stage.

Eventually the part will fail in overload. The problem is that the time span between a crack or fracture in the hardened surface and deformation and failure of the softer carrier metal cannot be calculated. It is unique for every event and dependent on too many variables to be calculated with any accuracy.

Such a damaged part may continue to function for years or fail suddenly due to a momentary extreme load such as an inadvertant abrupt control input causing a sudden demand for power, or sudden air turbulence imposing greater loads on the drivetrain.

So it may prove in this case that the design has shaved just a little too much off of certain critical parts in order to gain that extra bit of performance.

Aviation is by no means unique in having this type of failure mode. Motor racing has exactly the same problems. Designers keep stiffening components and reducing their weight and size until something breaks. Then it is redesigned and beefed up a bit to perform as it needs to. That is the way design progresses.

[Nadar]

@G0ULI (http://www.pprune.org/members/423021-g0uli) Every gram counts both for fixed wing and rotary (or cars for that matter). It all boils down to economics and market forces. Weight costs fuel consumption. The less the aircraft weighs the more freight it can carry (self loading or not) given a specific engine. In effect the fuel cost per unit of freight is reduces. Almost the same goes for the crew: The more freight any aircraft can take, the cheaper the wages for the crew get per unit of freight.

All the bean counters care about is the cost per unit of freight. They constitute "the market", meaning that market forces will drive the manufacturers to produce lighter and lighter aircraft. If you want to get ahead in the market, the trick is to make it as light as possible both by creative use of materials and design, and by minimizing safety margins/shed excess weight. Those that are the boldest pushing this while managing to make people believe it's still safe, will be the market winner. It's going on everywhere you look in society today.

I know way to little about this particular situation and to which degree this philosophy are used with the different aircraft manufacturers, but ever since I read in this thread that the 225 can carry more passengers while being lighter than it's competitors this immediately popped up on my radar. It might be that they have simply pushed it too far.

[john6016]

Part of a smoke screen or not?

[buzz66]

Okay, not good news here at all, but not surprising based on earlier photos we saw.


Next hard part is to determine "Why". Parts break when strength is exceeded by load. designers keep that from happening in theory, supported by testing. But if something breaks, you look at both ends of that basic equation. Was the part weaker than designed or are the loads higher than expected. If the former, due to quality issue, that can usually be contained. If the latter, then heads scratch on entire substantiation, heavy inspections, life limits, etc.
Also note (as stated earlier) the symmetry in fractures - and the number of parts affected. Less likely a quality issue, when affects multiple parts, unless same batch. There may well be a vibratory deflection content that was not anticipated, thus not deigned for. The issue that doomed Norne event was a resonance that AH discounted. They probably are paying attention now...
There is basically Zero chance of a Planetary Gearbox failure that won't result in total destruction, nature of the beast

[Geoffersincornwall]

Can the engineers tell us if the gearwheel design that integrates a bearing race with the gear teeth is a normal solution to the space limitations within an MRG? Would it not be better to install a standard bearing within the wheel? By standard bearing I mean one that includes both races and the rollers.

G

[ORAC]

Safety alert issued after metal fatigue found in Norway crash helicopter | World news | The Guardian (http://www.theguardian.com/world/2016/jun/02/safety-alert-issued-after-metal-fatigue-found-in-norway-crash-helicopter)

Aviation experts investigating the Norway helicopter crash that killed 13 people have found signs of metal fatigue in the gearbox of the downed aircraft. The Accident Investigation Board of Norway (AIBN) is calling on the European Aviation Safety Agency (EASA) to take “immediate action” to ensure other Super Puma H225 helicopters are safe. The board warns that “the current means to detect a failure in advance are not effective”.

Eleven passengers, including oil worker Iain Stuart from Laurencekirk, Aberdeenshire, and two crew members were killed after the aircraft crashed near the city of Bergen on 29 April. Earlier investigations revealed that the helicopter was travelling at 2,000ft when the main rotor head suddenly detached from the body of the helicopter, which then smashed into a tiny island and burst into flames. Investigators said the “sudden catastrophic failure” developed in one to two seconds.

The latest report, published on Wednesday, said metallurgical examinations of parts of the gear workings found “features strongly consistent with fatigue”. The AIBN prelimary report said the findings were of “such significance” that a safety recommendation was required to ensure the continued airworthiness of the main gearbox (MGB) of all helicopters of the same type.

The recommendation states: “It cannot be ruled out that this signifies a possible safety issue that can affect other MGBs of the same type. The nature of the catastrophic failure of the LN-OJF main rotor system indicates that the current means to detect a failure in advance are not effective. The AIBN therefore recommends that EASA take immediate action to ensure the safety of the Airbus Helicopter’s H225 MGB.”........

[Nige321]

This new interim report shows a picture of a second-stage planetry gear. Although it's not mentioned in the text, the caption notes that 3x of the rollers are missing...

How? How do they escape? Or were they never fitted...??

[birmingham]

I think the key statement is this ...

"The nature of the catastrophic failure of the LN-OJF main rotor system indicates that the current means to detect a failure in advance are not effective."

It's important that AH respond to this as quickly as possible so as we can agree on the initial cause. Is this a simple repeat of REDL or did the Airbus scenario occur and the resulting load trigger the secondary fatigue failure of the weakened planetary stage .

What is now undeniable (surely) is that the industry has a real problem with MGBs in mid range shuttles. 3 total loss fatal accidents since 2009 in three types (S92, L2 and 225). This is not just an issue with Pumas there will need to be a major reappraisal of the design of these units to try and get these accident rates down.

[n305fa]

I think the key statement is this ...

"The nature of the catastrophic failure of the LN-OJF main rotor system indicates that the current means to detect a failure in advance are not effective."

It's important that AH respond to this as quickly as possible so as we can agree on the initial cause. Is this a simple repeat of REDL or did the Airbus scenario occur and the resulting load trigger the secondary fatigue failure of the weakened planetary stage .

What is now undeniable (surely) is that the industry has a real problem with MGBs in mid range shuttles. 3 total loss fatal accidents since 2009 in three types (S92, L2 and 225). This is not just an issue with Pumas there will need to be a major reappraisal of the design of these units to try and get these accident rates down.

It's also worth noting that, if the ultimate cause of the accident is in the H225 epicyclic, the AS332L2 uses the same module as the H225 , so they would be similarly affected.

[turboshafts]

Yes but the extended TBO several times induces a
higher risk of failure, and leads to a probable connection to the failure incident

Fatigue cracks in a new MRA and MGB is less probable due to the breakdown
statistics of the helicopter type. The breakdown incidents in the past support this.

Also the part of the MRA where the suspension bar fitting is broken,
it coincides with the part of the Outer planetary gear on the epicyclic module
that has a crack that cannot be explained by an other probably cause than a gear failure. If the suspension bar came loose and that ultimately leads to a gearbox failure,
it could be anywhere on the outer planetary gear of the epicyclic module, but it is not.

[halsandberg]

Airbus preliminary reaction to the AIBN report:

"We have seen the AIBN report and are reviewing it. In light of this important new finding, we continue to fully support ‎AIBN, EASA, our customers and the ongoing investigation by providing information in full transparency. Safety of the passengers travelling in our helicopters remain our chief priority. We do not wish to comment further as the investigation continues."

[n305fa]

Perhaps AH should revisit its response the their reply to the following REDL safety recommendation (in AAIB annual report 2012)
SAFETY RECOMMENDATION – 2011-032
It is recommended that, in addition to the current methods of gearbox condition monitoring on the AS332 L2 and EC225, Eurocopter should introduce further means of identifying in-service gearbox component degradation, such as debris analysis of the main gearbox oil.
Response
Based on FMECA (Failure Mode Effect and Criticity Analysis) and confirmed by the experience, two types of debris can be generated by gearbox deterioration:
3D-particles (volume) or 2D-particles (surface): these types of particles are usually generated by degradation of high-loaded functional surfaces like bearing races or gear tooth (spalling, scale, flaking ...) or by part breakages.
- Wear particles: these types of abrasive particles are usually caused by abnormal high-contact of surfaces (fretting, micro-pitting...) and are generally in suspension in the oil.
A third type of debris can be found in gearboxes is associated with the manufacturing process (swarf...), the assembly process (piece of lockwire, fragment of cotter pin...), or maintenance actions (leading to introduction of foreign objects). All these debris are considered as some 3D or 2D particles.
Because the types of these generated particles are very different, adapted monitoring means must be used in order to monitor each type.
Two monitoring means are presently available to detect such debris:
- Magnetic plugs: these collect the particles and are visually inspected in order to detect 3D or 2D debris, but they can also collect wear particles. An electrical system can be added in order to give an in-service information of particle presence (warning on pilot on instrument panel and/or HUMS system for the maintenance) as soon as the particle(s) collected is (are) able to close the bridge between the two electrical parts of a magnetic plug. All Eurocopter fleet gearboxes are equipped with magnetic plugs (manual or electrical ones) and this is the main monitoring means to detect internal gearbox component degradation (they are also associated to the oil filter cartridge inspection).
- Spectrometric Oil Analysis Program (SOAP): this is used to monitor evolution of the concentration of different metals or else (particle per million) in suspension in the lubricant. It requires following of a dedicated and strict procedure to take periodically a volume of oil in defined conditions (warm and mixed oil taken with specific equipment by qualified personnel with a qualified process) and sending it to qualified laboratory.
SOAP is a monitoring means that is well known to Eurocopter and its principle is described in EC Technical Publications (Standard Practice Manual WC 20.08.02.601 attached). SOAP is considered by Eurocopter as an optional and additional monitoring means. SOAP can be used to monitor the evolution, between two oil replacements, of metallic material concentration or possibly some other material (like mineral) which are in suspension in the oil. SOAP can trigger the requirement of a close monitoring of the main monitoring means (magnetic plugs and filter) if certain dedicated thresholds are exceeded.
This means was introduced in the past during the development of SA 330 (Puma) and at the beginning of AS 332 (Super-Puma) production because the technologies used (bolted assemblies, machining without grinding, etc.) sometimes produced wear particles. This is no longer the case as a result of modern technologies used on the AS332 L2 and EC225 main gear boxes (Electron beam welding instead of bolted assemblies) and manufacturing processes (super finishing, grinding) which generate parts more reliable regarding wear degradation.
Despite the fact that these old technologies could generate some wear particles relevant to SOAP, the experience of Eurocopter demonstrates that this means was not efficient and that, in practice, it had led to many unjustified removals of gear boxes with unnecessarily interference to flight operations and wasted maintenance costs. Against this background, Eurocopter so issued Service Letter 759-00-86 in 1986 25/06/1986.

It also has to be noted that SOAP is not adapted to detect 3D or 2D particles because such particles are not in suspension in the oil. So SOAP is not adapted to detect spalling.
In addition, the magnetic plugs are able to detect incipient spalling at a level where, even if the whole volume of particles generated was in suspension in the oil, the concentration would not be detectable by SOAP taking in account the important oil volume in a main gear box.
Eurocopter considers that magnetic plugs and/or chip detectors are the most efficient means to detect gearbox internal failure modes, and that they are sufficient to ensure the flight safety so that further means of identifying in-service gearbox component degradation, such as debris analysis of the main gearbox oil, are not necessary. Here, it is relevant to note that the particle detection capability of the sump and epicyclic plugs has been enhanced by the removal of the ring of magnets from the lower area of the epicyclic module.”
Status - Rejected

It seems EC/AH got hung up on SOAP and MCDs rather than looking at other methods of monitoring.

[HeliComparator]

What other methods of monitoring would you suggest?

[turboshafts]

Can anyone confirm that Airbus Technical Agreement on extended TBO on MGB

says that only 90% of max cruise speed can be used?

According to flight logs available, it is evident that the aircraft did not
fly at 90% of max cruise speed at the time of the breakdown incident,
nor did it do that at a date before the claimed MGB change.

Is there any flight logs available that claims the downtime of LN-OJF
during the claimed MGB and MRA change?

[birmingham]

Yes but the extended TBO several times induces a
higher risk of failure, and leads to a probable connection to the failure incident

Fatigue cracks in a new MRA and MGB is less probable due to the breakdown
statistics of the helicopter type. The breakdown incidents in the past support this.

Also the part of the MRA where the suspension bar fitting is broken,
it coincides with the part of the Outer planetary gear on the epicyclic module
that has a crack that cannot be explained by an other probably cause than a gear failure. If the suspension bar came loose and that ultimately leads to a gearbox failure,
it could be anywhere on the outer planetary gear of the epicyclic module, but it is not.

...Abolutely, as an engineer it is impossible to argue against what you say. If it were 2009 I think this would be an entirely sensible approach.

The problem is that it is 2016 the only way we could continue as normal is to persuade the passengers that reducing the TBO would be enough to ensure their safety.

5 gear related accidents, 3 total loss fatalities worldwide in E&P since 2009, 4 of them on the same range of A/C.

Plus we have this from the AIBN...

"The nature of the catastrophic failure of the LN-OJF main rotor system indicates that the current means to detect a failure in advance are not effective."

a. Clearly we couldn't give them an absolute guarantee of no failures nor should we.
b. They won't be listening this time.

What will come out of this will be some form of industry wide initiative so that future aircraft have more reliable gearboxes.

[turboshafts]

...Abolutely, as an engineer it is impossible to argue against what you say. If it were 2009 I think this would be an entirely sensible approach.

The problem is that it is 2016 the only way we could continue as normal is to persuade the passengers that reducing the TBO would be enough to ensure their safety.

5 gear related accidents, 3 total loss fatalities worldwide in E&P since 2009, 4 of them on the same range of A/C.

Plus we have this from the AIBN...

"The nature of the catastrophic failure of the LN-OJF main rotor system indicates that the current means to detect a failure in advance are not effective."

a. Clearly we couldn't give them an absolute guarantee of no failures nor should we.
b. They won't be listening this time.

What will come out of this will be some form of industry wide initiative so that future aircraft have more reliable gearboxes.

I agree, but it depends if the outcome is
due to fatigue of use and improper overhaul/maintenance
how can you ever monitor that better?
you can only minimize the risk by decreasing TBO.

If that was new parts that leads to catastrophic failure
after less than 1 month operation time, the
issue is the qualification testing and certification at the manufacturer.

both have up until now proven insufficient as we have the bevel gear incident as well.

But even for the bevel gear incident it was introduced on all types of
Aircrafts of the type, decreased TBO, decontamination of oil
and cleaning of the part. Still CAAN approves 2 times in less than a month
extended TBO. I think that is also a main mistake.

[HeliComparator]

... Still CAAN approves 2 times in less than a month extended TBO. I think that is also a main mistake.

I'm confused - was the gearbox that ruptured the same gearbox that had a 2 times TBO extension? If not then this is a completely irelevant point. Nope, pretty sure I'm not confused!

[turboshafts]

I'm confused - was the gearbox that ruptured the same gearbox that had a 2 times TBO extension? If not then this is a completely irelevant point. Nope, pretty sure I'm not confused!
What do you mean?

It is highly unclear if gearbox is changed or not

Media reported it was changed. Was it?

Fatigue cracks in a 1 month old gearbox?

I guess we will know when the final AIBN report is released.

Until then, if you are interested in understanding the root cause
of the breakdown incident, to me its not irrelevant.

[BTC8183]

Quite often a replacement puma family mgb comes in its box without the epicyclic or accessory modules.Depending on the removed mgb epi's remaining tbo, that removed epi might be fitted to the new/overhauled mgb.

[AW009]

@ HeliComparator referring to http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-54.html#post9396103 (http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-54.html#post9396103:) :
Enrichment / irradiating of critical MRGB gears by low radioactivity and inflight measuring of the trend (grade, guantity) of abrasion under given conditons in oil flow by means of semiconductor detector(s).

[turboshafts]

Quite often a replacement puma family mgb comes in its box without the epicyclic or accessory modules.Depending on the removed mgb epi's remaining tbo, that removed epi might be fitted to the new/overhauled mgb.
Does it mean that contaminated oil from the old epi
can also come in and deteriorate in an new MGB if not
clean/flushed out sufficiently? or are there separate lubrication circuits?

[turboshafts]

Also,

Main gearbox
Main rotor assembly

Is the epicyclic module separate or included in one of those two units,
when they are changed?

[HeliComparator]

Until then, if you are interested in understanding the root cause
of the breakdown incident, to me its not irrelevant.

To me, if the point relates to equipment that was not installed on the helicopter at the time of the crash, it is totally irrelevant. What we in UK call a red herring. But if you just want to dig up dirt then perhaps it is relevant.

[turboshafts]

To me, if the point relates to equipment that was not installed on the helicopter at the time of the crash, it is totally irrelevant. What we in UK call a red herring. But if you just want to dig up dirt then perhaps it is relevant.

It is relevant to anyone who would like to understand the cause of the breakdown incident.

If you are sure that the MGB and MRH was changed at the dates claimed,
I agree its irrelevant to you.

If so may I ask how you can be sure?

[birmingham]

... so where do we go from here?

Both Puma and S92 have had catastrophic MGB problems since 2009. Then there were the non fatal bevel gear and associated problems. Ditchings due to false alarms in the back up lube systems etc. Hell it's not like the industry hasn't tried to improve this.

Todays news could hardly be worse.

If the Puma ends here does AH have enough comnercial incentive to design an "all new" replacement?

How can we ensure that redesigns don't create problems of their own?

This is now an industry in need of some serious technical leadership.

[HeliComparator]

I'm thinking of setting up a new business renting out rowing boats.

But as I've said before, helicopter flying is a bit dangerous, get over it. Using the roads, drinking and smoking, eating too much are far more dangerous. Why don't you care about that?

[turboshafts]

To me, if the point relates to equipment that was not installed on the helicopter at the time of the crash, it is totally irrelevant. What we in UK call a red herring. But if you just want to dig up dirt then perhaps it is relevant.
I agree, but that assume you have information that the gearbox was changed as claimed?

May I ask how you know that for sure?

[airsound]

UK CAA extends grounding
http://publicapps.caa.co.uk/docs/33/SafetyDirective2016003..pdf

2.2 Operators and pilots must not conduct any flight with an Airbus Helicopters EC225LP or AS332L2 helicopter.




So that now includes SAR

airsound

[birmingham]

I'm thinking of setting up a new business renting out rowing boats.

But as I've said before, helicopter flying is a bit dangerous, get over it. Using the roads, drinking and smoking, eating too much are far more dangerous. Why don't you care about that?

Thanks. It's a bit dangerous. I'm over it now.

[TommyL]

I'm thinking of setting up a new business renting out rowing boats.

But as I've said before, helicopter flying is a bit dangerous, get over it. Using the roads, drinking and smoking, eating too much are far more dangerous. Why don't you care about that?
I bet your name is Will, and next you're gonna tell us to get "our big boys pants on"...wonder if Mr. Barbier regrets that he even got out of bed that day. But then again, people like that seldom care about other peoples feelings.

Oil workers were told to put on 'big-boy pants' at safety meeting before Shetland helicopter crash | Daily Mail Online (http://www.dailymail.co.uk/news/article-2403069/Oil-workers-told-big-boy-pants-safety-meeting-Shetland-helicopter-crash.html)

If you're even a offshore helicopter pilot...some of the things you say here tells me you 're probably not...with the mockery and ridicule of peoples fear and concerns. Not a nice attitude for sure.

[robin1953]

Does anybody know what the reliability programme contains in relation to this epicyclic failure?
The reliability programme should identify individual gearbox constituent component parts that fail inspection during overhaul in the strip report.
Surely there's a failure rate of this planetary gear identified in the reliability programme, if not why not on such an important critical component as a gearbox?

[turboshafts]

CHC-sjefen: - Vi har ikke tilgang til girkassen - Bergens Tidende (http://www.bt.no/nyheter/lokalt/CHC-sjefen---Vi-har-ikke-tilgang-til-girkassen-3607349.html)

Short summary
Gearbox changed in January:

Ny girkasse i januar

- Vi følger et vedlikeholdsprogram som tilsier at girboksen etter 4400 flytimer sendes til en leverandør som utfører vedlikehold, sier Roland videre.

Girboksen på ulykkeshelikopteret ble installert i januar. Under vedlikehold blir enkelte deler utbedret, mens andre blir skiftet helt ut.

Roland vil ikke svare på om planetgiret, som ifølge Havarikommisjonen er utsatt for tretthetsbrudd, ble skiftet ut i januar.

- Jeg kan ikke gå inn på spesifikke opplysninger om de ulike delene.


English:

"We are following a maintenance program that demands that the gearbox after 4400 hours is sent to a supplier that performs maintenance, says Roland further.

The gearbox on the the accident aircraft was installed in January.
During maintenance some parts are improved, others are completely changed

Roland does not want to answer if the planetary gear, that according to AIBN
is exposed to fatigue crack, was changed in January.

- I cannot go into specific information about the different parts."



So from this it becomes clear that the "new" gearbox installed in January
also could be an old one with some changed parts, which makes it clear, to me, we are not speaking about a brand new unit.

If the same unit that was removed from LN-OJF, sent to maintenance and
sent back to CHC after the maintenance. Is not clear.

It is also not clear who is doing the maintenance. But I have my suspicions.
May it be also a matter of investigation what exactly was changed in the gearbox or not

[212man]

If the Puma ends here does AH have enough commercial incentive to design an "all new" replacement?

It's already in the pipeline: the X6, although a few years away still.
http://www.airbushelicopters.com/website/en/press/_1771.html

[loop swing]

Does it mean that contaminated oil from the old epi
can also come in and deteriorate in an new MGB if not
clean/flushed out sufficiently? or are there separate lubrication circuits?
There would be no oil "in" the epi. The oil is sprayed into the box (obviously) and drains to the sump. So, no, there would be no oil to "contaminate". Even if there was any debris in the oil, there's the oil filter and chip detectors to contend with

[GenuineHoverBug]

It is reported in the media now that the gearbox was subject to some "unkind" treatment during transport, was damaged and had to go back for repairs before the installation in January.

[AAKEE]

It is reported in the media now that the gearbox was subject to some "unkind" treatment during transport, was damaged and had to go back for repairs before the installation in January.


Do you have a link to the source ?

[n305fa]

What other methods of monitoring would you suggest?

Perhaps something "real time" like

http://www.gastops.com/products/metalscan/ms-1000/

[Miles Gustaph]

Where has the report of 'unkind treatment' come from? and seems odd that this has not been mentioned in any reports?

[HeliComparator]

When Bristow was developing its IHUMS system back in the early 90s they trialled such a full flow debris monitoring system, however it was deemed ineffective and dropped from the programme, although I can't remember exactly why.

[n305fa]

When Bristow was developing its IHUMS system back in the early 90s they trialled such a full flow debris monitoring system, however it was deemed ineffective and dropped from the programme, although I can't remember exactly why.

I also remember trials in the military in the 90s that weren't too successful by I believe the new generation kit is being used successfully on the Merlin, F35 and some other platforms.

[G0ULI]

Most of the measures to check oil quality so far amount to a slightly higher tech version of scraping the oil off the magnetic plug and rubbing it between a finger and thumb and cutting open the oil filter to check for bits of debris.

Newer methods of real time, in flight, monitoring need to be developed. Doubtless this will lead to more alarms and precautionary landings, but it is better than the alternative.

The idea of irradiating components and then monitoring filters and plugs for the build up of radioactive particles due to wear has some merit, but I'm not sure environmentalists or even passengers and crew would be entirely happy.

[n305fa]

Most of the measures to check oil quality so far amount to a slightly higher tech version of scraping the oil off the magnetic plug and rubbing it between a finger and thumb and cutting open the oil filter to check for bits of debris.

Newer methods of real time, in flight, monitoring need to be developed. Doubtless this will lead to more alarms and precautionary landings, but it is better than the alternative.

The idea of irradiating components and then monitoring filters and plugs for the build up of radioactive particles due to wear has some merit, but I'm not sure environmentalists or even passengers and crew would be entirely happy.

I don't imaging that the engineers or o/h shop would be too please with irradiated components either

[Brother]

It is also not clear who is doing the maintenance. But I have my suspicions.

The Gearbox overhaul was performed by Heli One

[Pablo332]

I bet your name is Will, and next you're gonna tell us to get "our big boys pants on"...wonder if Mr. Barbier regrets that he even got out of bed that day. But then again, people like that seldom care about other peoples feelings.

Oil workers were told to put on 'big-boy pants' at safety meeting before Shetland helicopter crash | Daily Mail Online (http://www.dailymail.co.uk/news/article-2403069/Oil-workers-told-big-boy-pants-safety-meeting-Shetland-helicopter-crash.html)

If you're even a offshore helicopter pilot...some of the things you say here tells me you 're probably not...with the mockery and ridicule of peoples fear and concerns. Not a nice attitude for sure.
Good old Chris and Will sensible voices in a world of confusion, anyone know what they are doing now?

[212man]

If you're even a offshore helicopter pilot...some of the things you say here tells me you 're probably not...with the mockery and ridicule of peoples fear and concerns. Not a nice attitude for sure.

Well he's not anymore, as he's retired, but he was for about 30 years if that counts! He knows a thing or two about the Puma family too....

[albatross]

Perhaps the better term to use may be "overhauled" vs "new" gearbox.
It would, perhaps, avoid much confusion.

[GenuineHoverBug]

Where has the report of 'unkind treatment' come from? and seems odd that this has not been mentioned in any reports?

It is here http://www.tu.no/artikler/hovedgirboksen-var-skadet-matte-tilbake-pa-verksted-for-den-ble-montert-i-ulykkeshelikopteret/347805 . Unfortunately in Norwegian, but usually quite reliable.

[HeliComparator]

If you're even a offshore helicopter pilot...some of the things you say here tells me you 're probably not...with the mockery and ridicule of peoples fear and concerns. Not a nice attitude for sure.

I'm a retired helicopter pilot so I can say what I like, which is great. Let's be clear, I dedicated quite a bit of my career to flight safety projects and enhancements. All based on science and rationality even bearing in mind the hefty dose of human factors that goes with any flight safety project.

So if you have any questions about flight safety on the EC225 (which I flew since it first came to the N Sea, until I retired in 2013) I'll be happy to try to answer them. However if you are going to come on here making foolish, hysterical and ill-informed statements designed to whip up fear, you are going to get the respect you deserve which is not a lot.


Flight safety should be based on fact and science, not who can wail and sob the loudest.

[GenuineHoverBug]

The Gearbox overhaul was performed by Heli One

What is your source for that?

[auroraborealis90]

https://www.easa.europa.eu/newsroom-and-events/news/update-regarding-crash-norwegian-helicopter-29-april-2016
Following a report by the Norwegian accident investigators on 1 June 2016, EASA has decided to prohibit all flights by the Airbus Helicopters H225 LP and AS332 L2 helicopters as a precautionary measure and until further information is available.

[HeliComparator]

What is your source for that?


Well as I understand it, all MGBs on CHC aircraft are overhauled at HeliOne. Whereas Bristow uses Power by the Hour and thus the boxes are overhauled at the factory.

[GenuineHoverBug]

Well as I understand it, all MGBs on CHC aircraft are overhauled at HeliOne. Whereas Bristow uses Power by the Hour and thus the boxes are overhauled at the factory.

That may well be, but there are rules and there are sometimes exceptions.

[as365n4]

https://www.easa.europa.eu/newsroom-...-29-april-2016
Following a report by the Norwegian accident investigators on 1 June 2016, EASA has decided to prohibit all flights by the Airbus Helicopters H225 LP and AS332 L2 helicopters as a precautionary measure and until further information is available.

Sorry, but this is bollocks! You should have read the AD 2016-0103-E and there is not a single word in regards of a suspension of TC or similar! Just a replacement of Attachment Fittings etc..

[212man]

EASA has decided to prohibit all flights by the Airbus Helicopters H225 LP and AS332 L2 helicopters as a precautionary measure and until further information is available.

Sorry, but this is bollocks! You should have read the AD 2016-0103-E and there is not a single word in regards of a suspension of TC or similar! Just a replacement of Attachment Fittings etc..

Not suspending TC but prohibiting flights - maybe it's semantics.

[CertGuy]

It is AD 2016-0104-E. It just got released. 2016-0103-E is the link that is (incorrectly) linked in the EASA newsroom article.

[HeliComparator]

Not suspending TC but prohibiting flights - maybe it's semantics.

Its very confusing because the news item on the EASA web site talks about prohibiting further flight for the time being - see our AD. But the linked-to AD just talks about checking the suspension bar fittings. Where is the definitive instruction to ground the fleet?

[wigglyamp]

https://publicapps.caa.co.uk/docs/33/SafetyDirective2016003..pdf and
http://publicapps.caa.co.uk/docs/33/20160602EASAAD20160104E.pdf

[HeliComparator]

Yes but that is the UK CAA. The question was about whether EASA had grounded all flights which they said they had in their press release, but not in the AD published today.

Edit: Ah ok thanks, different AD. The press release links to the wrong AD.

[helicrazi]

Easa has now published, but confusingly has grounded 225 and L2, but is allowing the 225 to fly for SAR etc but not the L2... confused...

[Capot]

The AD (Emergency Airworthiness Directive AD No.: 2016-0104-E) (http://publicapps.caa.co.uk/docs/33/20160602EASAAD20160104E.pdf) landed in my Inbox just now.

The grounding of the AS 332 L2 and EC 225 LP helicopter fleet is because;

a second preliminary report from the investigation board indicated metallurgical findings of fatigue and surface degradation in the outer race of a second stage planet gear of the MGB epi-cyclic module. At this time, it cannot be determined if this is a contributing causal factor or subsequent failure from another initiating factor.

but

Pursuant to Art.1 (2) (a) of Regulation (EC) 2016/2008, the requirement of paragraph (1) of this AD does not apply to EC 225 LP helicopters while carrying out military, customs, police, search and rescue, firefighting, coastguard or similar activities or services.

Now Article 1.2 of EC 216/2008 (pity about the '2016' typo in the AD; is the omission of AS 332 L2 just the same sloppiness? I wouldn't know) says;

This Regulation shall not apply when products, parts, appliances, personnel and organisations referred to in paragraph 1 are engaged in military, customs, police, or similar services. The Member States shall undertake to ensure that such services have due regard as far as practicable to the objectives of this Regulation.

which explains the exclusion, but it seems to me that this Article is badly thought out. Apart from military, most of the other categories are operated commercially in some if not all EU States, and should, I would have thought, be grounded just like other operators, for exactly the same reason, danger to crew, passengers and the population beneath them.

I don't know if in the UK the CAA has made any pronouncements; perhaps they have or will do so to fulfil their responsibility under that Article. Maybe each State will do that; maybe they'll even co-ordinate their response.

[HeliComparator]

which explains the exclusion, but it seems to me that this Article is badly thought out. Apart from military, most of the other categories are operated commercially in some if not all EU States, and should, I would have thought, be grounded just like other operators, for exactly the same reason, danger to crew, passengers and the population beneath them.


No I'd say it is well thought out. Whether or not it is commercial is irelevant. The grounding is precautionary and nothing has changed since last month before the accident. If you were bobbing about in a cold ocean or stranded up a mountain having a heart attack, you would be very happy to be rescued by an EC225 regardless of a 1 in a million risk that the rotors might fall off.

The flight crews who were happy to fly the 225 for years before the accident will almost certainly still be, for the purposes of saving life. There is already an elevated risk from being a SAR pilot, compared to an "airline" helicopter pilot.

[helicrazi]

But doesn't the CAA ban stop all SAR activity? I stand to be corrected...

[ukv1145]

I would suggest that the statement in the EASA AD reference SAR/military/police operations is simply acknowledging/reminding that these operations are carried out under the authority of the NAA of the country involved, and are not subject to EASA regulations. Therefore it is up to the NAA to decide on an approptiate action. Note: SAR training is carried out under Public Transport regulations and therefore prohibited by the EASA AD.

[HeliComparator]

@helicrazi: It would do if there were any EC225s flying SAR in the UK / G-reg but as far as I know there aren't.

[helicrazi]

@HeliComparator: good point, well made.

Next question, why allow 225's and not L2's?

[Capot]

I don't know if in the UK the CAA has made any pronouncements;Well, I would have known if I had read the thread a bit more carefully.

The CAA said;

2 Compliance/Action to be Taken

2.1 The Civil Aviation Authority (CAA), in exercise of its powers under article 15 of the Air Navigation Order 2009, directs operators of any Airbus Helicopters EC225LP or AS332L2 helicopter which is:

a) registered in the United Kingdom; or

b) flying in the United Kingdom or in the neighbourhood of an offshore location.

to comply with the requirements set out in paragraph 2.2.

2.2 Operators and pilots must not conduct any flight with an Airbus Helicopters EC225LP or AS332L2 helicopter.

(a) and (b), and 2.2 seem to me to prohibit all UK-registered aircraft of the types listed, regardless of their role, from being flown anywhere, as well as prohibiting flights by non-UK aircraft of those types in UK airspace. So it's only the military who can keep flying, if indeed they have any.

So, the answer to Helicrazi is yes, SAR is banned, or would be if there were any operators with these helicopters.

And to the second question, the CAA bans both, and (partly because of that) I suspect the EASA AD is simply sloppy drafting, as per everything else EASA produces. But there may be a good reason, I wouldn't know.

[HeliComparator]

@HeliComparator: good point, well made.

Next question, why allow 225's and not L2's?

Yea well not that good a point - there are of course AS332L2s flying SAR aren't there? (Jigsaw) or rather, were. Or am I out of date?

[helicrazi]

HeliComparator:

You are correct, there are L2's servicing the Babcock SAR contract, which is why I don't understand EASA allowing 225's to continue, but not L2's.

Of course with the CAA blanket ban across all roles, then it wouldn't matter anyway.

[HeliComparator]

HeliComparator:

You are correct, there are L2's servicing the Babcock SAR contract, which is why I don't understand EASA allowing 225's to continue, but not L2's.

Of course with the CAA blanket ban across all roles, then it wouldn't matter anyway.
I see your point. Could it be as simple as a typo? Maybe they forgot to add "or AS332L2" to that para? Presumably it was done in a bit of a rush.

[MichiScholz]

Can anybody explain the differece between these types, regarding to the MGB/ rotor Head or connection to the fuselage?

[krypton_john]

Apologies if this has already been posted...

EC225 Main Rotor Head and Main Gear Box Design - Aerossurance (http://aerossurance.com/news/ec225-main-rotor-mgb-design/)

[HeliComparator]

Can anybody explain the differece between these types, regarding to the MGB/ rotor Head or connection to the fuselage?
MGB and mounting very similar in basic principle, but the devil is in the detail and inside there are major differences in materials etc. Although the L and L1 are identical I think? The AS332L and L1 had a head with conventional bearings, the L2 and 225 have no conventional bearings in the head, just elastomeric thingies (multilayered blobs of rubber and metal discs). More blades on the 225.

[T28B]

Apologies if this has already been posted...

EC225 Main Rotor Head and Main Gear Box Design - Aerossurance (http://aerossurance.com/news/ec225-main-rotor-mgb-design/) It was posted in about page 31 of this thread, which is now a page 56+.

[n305fa]

MGB and mounting very similar in basic principle, but the devil is in the detail and inside there are major differences in materials etc. Although the L and L1 are identical I think? The AS332L and L1 had a head with conventional bearings, the L2 and 225 have no conventional bearings in the head, just elastomeric thingies (multilayered blobs of rubber and metal discs). More blades on the 225.

The L2 and the 225 share the same epicyclic module which is different for the L and L1, the 332L2 and 225 have two stages of eight gears, not sure of the L and L1 have 7 or 9 gears per stage. The main module for the L2 and 225 are basically the same configuration with material changes to the gears of the 225 main module to take account of the higher power/operations temps. The L2 has a conical housing on top of the epicyclic with two races of ball bearings to take the lift loads, the 225 has a flared housing with two rows of inclined roller bearings to take the lift loads. The 225 also has the EM lube system

[Thorond0r]

Babcock has grounded all 225's and that includes the EC-MCR, the brand new, one and only SAR 225 operated by Inaer Spain

[roscoe1]

Super Puma Crash Was Gearbox Failure - Unexpected AIBN Preliminary Report Released - Oil and Gas News (http://www.oilandgaspeople.com/news/8696/super-puma-crash-was-gearbox-failure-unexpected-aibn-preliminary-report-released/)

[wdew]

End of speculation.

[Outwest]

Indeed. Call all the hard working AIBN investigators tomorrow morning and ask them to start their summer holiday. Tell 'em an internet publication has solved things for you. Actually quit the whole branch, what a waste of tax payer's money. Same all over Europe. I bet hundreds of millions would be saved over the becoming years if we all just let the media tell us what went wrong.??????

The media is reporting what the AIBN reported, even included the actual report so how is that wrong with what the others posted.

I would say wdew is referring to all the speculation that this was a sus bar failure, and it appears that the AIBN has ended that speculation. I, and some others like Mitchaa had said that from the beginning....

[OMONEZ]

Only for idiots like you. I have never seen such a cover up by an Authority.
Note book's need to get hands on. EPI no chance if they did the correct actions. I Knew/ know both the people that made those errors in Miri and REDL. 1 is due an Alloute 3 plus a hangar to the team. The other was not welcome to return.

[Max Power 3503e]

Case closed..

[OMONEZ]

When it suits you. 32 years on the Sa330J AS 332L / L1 / L2 First course on the EC225 LP
Retired now at 55.
Moderator Outwest loc: LOS
This member from his posts has never been close any puma aircraft.

[Satcomm]

[QUOTEOnly for idiots like you. I have never seen such a cover up by an Authority.
Note book's need to get hands on. EPI no chance if they did the correct actions. I Knew/ know both the people that made those errors in Miri and REDL.[/QUOTE]

Not going to comment on the idiot thing but what would you suspect they are covering up? Why would you have such a hard time believing this is a MGB/EPI failure?

[TeeS]

I may be confused but isn't roscoe's link to a news report with a headline stating 'Super Puma crash was gearbox failure' - the actual AIBN report doesn't say anything of the sort, it just says:

Recent metallurgical findings have revealed features strongly consistent with fatigue in the outer race of a second stage planet gear in the epicyclic module of the MGB. It cannot be ruled out that this signifies a possible safety issue that can affect other MGBs of the same type. The nature of the catastrophic failure of the LN-OJF main rotor system indicates that the current means to detect a failure in advance are not effective. - which is what we already knew?

TeeS

[OMONEZ]

Don't call me am Idiot. I have Been type rated on the 225 longer than any one, 21 st July 2005. I never said it was not a EPI or Main Module failure. The rubbish I have read on his site is shocking. Read the report it is all bollocks. POSSIBLE!!!!!!!!!!!!!!!!! Now retired Ill be happy to see the norge early retirement that we pay for cancelled.

[letmein]

EASA:
At this time, it cannot be determined if this is a contributing causal factor or subsequent failure from another initiating factor. Pending further investigation to determine the root cause(s)….[..]

I'd say it's far from case closed..the Oil and Gas news is going out on a limb here by stating that:
Chillingly the report states that fatigue was the cause of the gearbox failure

[OMONEZ]

Well . Back track.

[lynnx]

I can,t help but feel this site would be much more "Professional" if we just stuck to the "Rumours" and stopped slagging each other off.

[TommyL]

Professional Pilots board....sure doesn't resemble anything like it. I have a feeling that for a couple of persons here, the "retirement" might not have been a voluntary thing...

[Satcomm]

OMONEZ, I was not calling you an idiot. I was just saying that I was not going to comment on you calling everyone on here an idiots ... Turns out we may have one more peanut in the gallery.

Anyway, was just trying to figure out your stance on the topic. Seemed like your first post "EPI no chance .... " suggested to me that you did not believe it was an EPI failure. But now your second post suggests that you may actually agree with the EPI/MGB failure.

Number of years on type does not impress most engineers. Think 99% would agree that we have all worked with guys that, well, you wonder how they ever got where they are. Again, not suggesting this is you, you obviously seem very level headed.

[AW009]

One of the two big questions is, would FAA react analogue to EASA?
The other is, how will all the EASA non-member states - but being in relationship to EASA - react?

https://www.easa.europa.eu/easa-and-you/international-cooperation/easa-by-country/maphttp://https://www.easa.europa.eu/easa-and-you/international-cooperation/easa-by-country/map (https://www.easa.europa.eu/easa-and-you/international-cooperation/easa-by-country/maphttp://)

https://www.easa.europa.eu/easa-and-you/international-cooperation/easa-by-country/map
https://www.easa.europa.eu/easa-and-you/international-cooperation/easa-by-country/maphttps://www.easa.europa.eu/easa-and-you/international-cooperation/easa-by-country/map

[Nadar]

@OMONEZ (http://www.pprune.org/members/320311-omonez) I recognize most of the words you write as English, but the sentences might as well be Chinese to me - I don't understand what you're trying to say.

@lynnx (http://www.pprune.org/members/316525-lynnx) A strongly agree even though I'm not a pilot. Pilot or not, the endless "fighting" about who's right is pointless. I read this thread to get ideas/theories/viewpoints on what might have gone wrong, not to watch people tell other's they are wrong. To do the latter there are thousands of other internet forums I could read.

@TommyL (http://www.pprune.org/members/267538-tommyl):D

[whoknows idont]

I mean what the actual hell are you waffling on about, you can barely string a sentence together. If you want to be taken seriously, construct a well written response in the English language that we can all understand. You're coming across like a crazed buffoon.

Thank you, Mitchaa. You just reestablished a bit of my confidence in my English skills. Relieved to read that everybody else couldn't´t make sense of it either... :ok:

[DOUBLE BOGEY]

Mitchaa, obviously the subject matter of this thread is very serious but.... Your response to OMENEZs "Agressive, paranoid poetry" made me piss myself laughing. Thanks for lightening the mood somewhat!

[bigglesbutler]

Mitchaa, thank you I though it was just me and that my mind was finally gone, I am glad I'm not the only one unable to decode OMONEZ.

Si

[birmingham]

Professional Pilots board....sure doesn't resemble anything like it. I have a feeling that for a couple of persons here, the "retirement" might not have been a voluntary thing...
☺☺☺ well said!

[ARRAKIS]

Is the MGB on the military variant (i.e. EC725/H225M) exactly the same as on the EC225/H225?

A.

[HeliComparator]

Anyway let's be clear amongst all the squabbling, the report implies suspicion about a planet gear break-up but doesn't categorically state it. So the press item is misrepresenting somewhat. However, clearly enough evidence to convince EASA. Worrying...

[Variable Load]

Mitchaa, obviously the subject matter of this thread is very serious but.... Your response to OMENEZs "Agressive, paranoid poetry" made me piss myself laughing. Thanks for lightening the mood somewhat!

Ditto. I really wanted to find a "Like" button somewhere!

[nowherespecial]

In case any of you haven't seen this EAD yet: (apologies for cack copy paste)

F L I G H T P R O H I B I T I O N
Manufacturer(s):
Airbus Helicopters (formerly Eurocopter, Eurocopter France, Aerospatiale)

Applicability:
AS 332 L2 and EC 225 LP helicopters, all manufacturer serial numbers.

Reason:
Following a fatal accident that occurred in Norway to an EC 225 LP helicopter, indicating in-flight detachment of the main rotor hub from the main gearbox (MGB), EASA issued Emergency AD 2016-0089-E to require, as a precautionary measure, the accomplishment of one-time inspections. Investigation is on-going to identify the root cause of this accident.

The review of the data reported in accomplishing AD 2016-0089-E, revealed installation findings for the MGB upper deck fittings of the three MBG suspension bars. Prompted by these findings, EASA issued superseding AD 2016-0103-E for further inspection and replacement instructions for correct installation of the MGB suspension bars and attachment fittings.

Soon after EASA AD 2016-0103-E was issued, a second preliminary report from the investigation board indicated metallurgical findings of fatigue and surface degradation in the outer race of a second stage planet gear of the MGB epi-cyclic module. At this time, it cannot be determined if this is a contributing causal factor or subsequent failure from another initiating factor.

Pending further investigation to determine the root cause(s) of the reported damage, and development of mitigating measures by Airbus Helicopters, EASA has decided, as an additional precautionary measure, to temporarily ground the fleet.

For the reason described above, this AD prohibits flight of the AS 332 L2 and EC 225 LP helicopters .
Required Action(s) and Compliance Time(s):

Required as indicated, unless accomplished previously.
(1) From the effective date of this AD, do not operate any AS 332 L2 and EC 225 LP helicopter, except as specified in paragraph (2) of this AD.
(2) A single ferry flight without passengers is allowed to a maintenance location where the helicopter grounding, as required by paragraph (1) of this AD, can be accomplished in adequate storage conditions.

Note: Pursuant to Art.1 (2) (a) of Regulation (EC) 2016/2008, the requirement of paragraph (1) of this AD does not apply to EC 225 LP helicopters while carrying out military, customs, police, search and rescue, firefighting, coastguard or similar activities or services.

[Magjam]

In case any of you haven't seen this EAD yet: (apologies for cack copy paste)

So EASA have not grounded 225 SAR but the operators have.

Wrong, the Norwegian CAA (http://www.luftfartstilsynet.no/incoming/16-05616-9_SAFETY_AND_OPERATIONAL_DIRECTIVE_-_Airbus_Helicopters_EC225LP_and_AS332L2_-_Limi_1170234_3_0.pdf/BINARY/16-05616-9%20SAFETY%20AND%20OPERATIONAL%20DIRECTIVE%20-%20Airbus%20Helicopters%20EC225LP%20and%20AS332L2%20-%20Limi%201170234_3_0.pdf) and UK (http://publicapps.caa.co.uk/docs/33/SafetyDirective2016003..pdf) CAA have.

[nowherespecial]

Angry reply Magjam, are you tired? Amended.

[Cows getting bigger]

My reading of the various directives is:

UK/Norway has grounded both the L2 and LP - no concessions. This prohibition includes overflight by any third country operator. EASA says you can do a single ferry flight and continue SAR.

As part of ongoing investigations, significant anomalies have been identified in both MGB suspension bars/fittings and planetary gear.

Are there any operators still flying the 225L2/LP outside of UK/Norway?

[AW009]

Should we restart the thread with Adam & Eve and discuss the difference and the sense between an 'AD' and a 'SD', the differences betwee jurisdictions and competences of EASA CAA N and CAA UK and should we also discuss the meaning of 'PP' in the abbrevation of 'PPRuNe'?
:ugh:

[212man]

Note: Pursuant to Art.1 (2) (a) of Regulation (EC) 2016/2008, the requirement of paragraph (1) of this AD does not apply to EC 225 LP helicopters while carrying out military, customs, police, search and rescue, firefighting, coastguard or similar activities or services.

Interesting to note that EASA has added additional roles in this notice that are not actually listed in the referenced article (other than as 'similar'):

This Regulation shall not apply when products, parts,
appliances, personnel and organisations referred to in paragraph
1 are engaged in military, customs, police, or similar
services. The Member States shall undertake to ensure that such
services have due regard as far as practicable to the objectives of
this Regulation

[ukv1145]

As previously stated, EASA do not have jurisdiction over State operations such as SAR/Military etc. The NAA of the state involved will make a ruling on this, as the UK and Norwegian CAA have.
The wording on the EASA document is irrelevant to these ops (albeit with a possible mistake of missing the L2).

[turboshafts]

Are there any operators still flying the 225L2/LP outside of UK/Norway?

These are the civilian operators I know

Airtelis Switzerland

SonAir Spain


Could be others as well?

Not referring to police or military

[212man]

I understand that they do not have Operational jurisdiction - hence in the UK there is CAP999 for guidance, and a national SAR AOC - but surely a civil registered aircraft on an EASA TC being maintained under EASA Part 145 and Part M will be subject to an Airworthiness Directive?

[Nige321]

I'll try again as my last post got lost in the noise...

The new interim report shows a picture of a second-stage planetry gear. Although it's not mentioned in the text, the caption notes that 3x of the rollers are missing...

How? How do they escape? Or were they never fitted...??

[ukv1145]

@212man. You would think so I know, and it really is semantics as the CAA have introduced the flight ban for all ops, however whilst on SAR ops (not training) the aircraft is technically maintained under the old BCAR system and a different Certificate of Release to Service (CRS) (CAA rather than EASA) must be issued. There is a CAA derogation in place to cover this situation.

[MichiScholz]

@nige321 as you can see in the picture of the planetary gear there was much stress on the gears so they become ovalized - thats a possibilty how such a roller can escape from the bearing.

[Pablo332]

Or they could have exited via the loading slot on the inner race?

[AW009]

Again my questions to the community:



Would FAA react analogue to EASA?
How will all the EASA non-member states - but being in relationship to EASA - react?
How will military of the EASA memberstates react?
How will military of EASA non-member states react?
Are there any of those reactions already known?
If yes, by which states?
What is the reaction?

In commercial aviations?
In military aviations?

Thanks ahead

P.S.: Please see https://www.easa.europa.eu/easa-and-you/international-cooperation/easa-by-country/map (https://www.easa.europa.eu/easa-and-you/international-cooperation/easa-by-country/map)

[n305fa]

Or they could have exited via the loading slot on the inner race?

The only way the rollers can get out of an installed planet gear is if the outer race either brakes, deforms or is pulled off the inner race. Getting them out of the loading slot in the inner race can only be done with the inner race, rollers and cages rotated 90 degrees to the outer race.

The outer race is part of a sphere and the rollers are barrel shaped which allows the gear to "self align"

[Pablo332]

Sad they can’t even get the map of the world right. I’m voting out.

[Pablo332]

The only way the rollers can get out of an installed planet gear is if the outer race either brakes, deforms or is pulled off the inner race. Getting them out of the loading slot in the inner race can only be done with the inner race, rollers and cages rotated 90 degrees to the outer race.

The outer race is part of a sphere and the rollers are barrel shaped which allows the gear to "self align"
I think during this incident a considerable amount of miss alignment took place.

[212man]

EASA EAD now corrected to include L2:
Note: Pursuant to Art.1 (2) (a) of Regulation (EC) 2016/2008, the requirement of paragraph (1) of this AD does not apply to AS 332 L2 and EC 225 LP helicopters while carrying out military, customs, police, search and rescue, firefighting, coastguard or similar activities or services.

[Nige321]

http://i86.servimg.com/u/f86/11/94/64/62/gears210.jpg

There's the gear bottom-right.
You're trying to say that that gear distorted enough to release 3 rollers, from 2 different places, then snapped back into its former shape, all without any damage...??!

[turboshafts]

I am looking back in the Super Puma gearbox overhaul history.

For the A332 L1 MGB it is written about the TBO which is 3000 hours.

It was yesterday said on the press conference by CHC
that the TBO on MGB is 4400 hours on the EC225.


Why is the TBO MGB longer with the EC225 than the L1?

[Scuffers]

more than possible once the case broke, only have to go to ~20 degree's to 'free' the rollers, ie. more than likely to have happened during the event

the cracked gear (bottom left) looks like it was caused by the event too, as it the distortion of the gear, rather than fatigue.

can't tell from these what the root cause of the failure were, could have been anything from a big chip/bit floating round the box or the failure of one of the rods then placing a massive angular load on the epicyclic.

None of this is the smoking gun.

[lynnx]

Looking at the picture provided by nige123 (and the aib) - if the LH lower gear is missing ALL its bearings and is still intact .... the fact that the RH one has only 3 missing would be a bonus whatever its failure mode!
Who can say what goes on during a catastrophic event of this size?
I think we are still looking at a chicken and egg.

[Scuffers]

one interesting thing to note, looking at the gear teeth themselves, they look remarkably un-damaged, if the primary cause was trash in the box, you would expect to see some evidence of this in tooth damage.

[Cyclic Hotline]

The FAA has now issued an Emergency Airworthiness Directive prohibiting further flight on AS332L2 and EC225LP.

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/e8afb3f556876b0b86257fc7006d82e2/$FILE/2016-12-51_Emergency.pdf

[AW009]

Up to now the first (German) military reaction to CAA N and CAA UK, EASA and FAA and their AD, SD and EAD:
(see Absturz eines "Superpuma": Bundeswehr setzt Flüge mit VIP-Hubschraubern aus - SPIEGEL ONLINE (http://www.spiegel.de/politik/deutschland/absturz-eines-superpuma-bundeswehr-setzt-fluege-mit-vip-hubschraubern-aus-a-1095845.html))
’Crash of SUPER PUMA: [German] Bundeswehr suspends flights of governmental helicopters’:ooh:

[buzz66]

So now we have a possible scenario of why the Epicyclic blew apart.
I always maintained a Sus Bar or Foot will not cause the Gearbox to separate.

But I also don't see the Planet wear causing the event. It became a weak point for sure. If the Sus Bar letting go did cause enough gear stress for the Epicyclic to fail is really doesn't matter does it......EITHER scenario on it's own or together will result in total destruction of the Machine and everyone in it.

What can't be ignored regardless of what the cause, is the fact it was never detected by HUMS, CHIPS, FDR, CVR, SOAP, ENGINEERS, PILOTS
Whatever failed first it gave no warning at all!

Why the Gear Race wear was not picked up in a SOAP sample, is also a mystery. Surely SOAP samples are taken as part of the normal Maintenance Program.

HUMS is clearly inadequate in detecting detecting early bearing wear issues in the Epicyclic. With multiple Gears with the same tooth count rotating on the same plane it's not doesn't surprise. A Tooth defect is a different story.
I'm sure the HUMS actual values, learning values, component step change, ETC were all looked at in great detail. You might find now they know which component is worn they can take another closer look at the HUMS Data and actually spot the wear. If if they did,was the Relevant Data significantly above the Noise to fix by reducing the trigger levels on the those Accelerometers. I think not.

If the Conical housing failed then surely that can only happen if it was badly treated at some stage, same could be said for the Sus Bars or Gearbox itself.

The speed of the occurrence with no warning remains the most disturbing thing whatever the finding and it's getting harder and harder to walk away from

[riff_raff]

From what I read there was a fracture thru the rim of an output stage planet gear that originated at a spall on the spherical roller bearing outer race surface. Normally, bearing race surface spalls are fairly benign events that propagate slowly, and do not result in a rapid catastrophic failure. They also produce ferrous debris which is quickly and easily picked up by a lube oil magnetic chip detector. On the other hand, fractures thru a gear rim (as opposed to thru a gear tooth) are almost always catastrophic and tend to propagate fairly rapidly. This is one reason rotorcraft drivetrain gears use an L2 reliability rate for tooth bending fatigue, while rolling element bearings can safely use an L10 reliability rate for contact fatigue.

One thing I noticed looking at this cross section of the gearbox (http://s1340.photobucket.com/user/FBav/media/225-coupeBTP.jpg.html) is how thin the rim section of the output stage planet gear is. This type of planet gear and bearing configuration having a thin rim without adequate radial stiffness can present a fatigue issue. The planet gear is subject to fairly large opposing inward radial forces twice per rev, from the mesh contacts at the ring gear and sun gear. Basically this means the planet gear rim gets squashed into a slightly oval shape twice per revolution. In my opinion, based simply on what I see in the drawing, it seems like the planet gear rim could have been made a bit thicker. Since this gear is a fracture critical component, I'd think this particular condition of crack propagation from a race surface spall would be a case considered in the fracture analysis.

There is one other thing that seems a bit strange to me based on what I read. If the planet gear rim fracture initiated at a spall in the race surface, there should have been enough ferrous debris generated by the early spall formation to be picked up by a chip detector long before it became a problem. Once again, looking at the cross section drawing of the gearbox linked above, there is an oil tray below the planetary stages. I wonder if the shape of this tray, combined with swirling motion imparted to the return oil flow by windage from the close proximity rotating components, effectively trapped the ferrous debris above the tray and prevented it from reaching the chip detector in the sump.

I'd just like to state the comments above are all just speculation on my part, and I admit to having no detailed knowledge of the design of the gearbox in question.:rolleyes:

[OnePerRev]

riff raff and buzz66, you are both spot on.
Failure to detect sufficiently is the one bold claim made in the preliminary report.


The gear design does not account for a rim fracture as a design point, relies on this mode to simply never show up. An overtorque test is the standard used, but that would not consider degradation of raceway over time, just tooth bending primarily. Other factors could still include mis-assembly leading to uneven load share (although at least two planets have the cracks. Worse, there may not be enough control of planet load share. We really speculate without knowing details, but fatigue can still happen in a matter of hours if loads are unusually high. In that case - would we not expect severe loads to be picked up by the HUMS? I said early on that I suspect that we have multiple failed oppurtunities that would have prevented this. We have an idea on two, details will follow, but it will take a couple months anyway. Urgency to report initially is about maintaining fleet safety. Only urgency now is money, and the investigators are not losing any, so they are not the ones in a hurry. We won't be seeing more tidbits until someone inside the investigation leaks it. Until then, we rumor anyway.

[AW009]

To summarize: It seems useless, hypothetical and philosophical to discuss about chicken and egg, if the chicken turns out to be a cuckoo! The rest is ’PPRu’ and entirely worth reading, because the crash of LN-OJF for sure will become a crucial experience for future helicopter technics and design.

[roscoe1]

Can anyone explain to me why the EASA and FAA directives cover the 225LP and the 332L2 but not the 332L1 and none of the short Puma variants, the civil version being now called the H215C1e? I know the MRH is different on the 332L1 but is the main transmission the same? Between the many variants and the Airbus model name changes it is difficult to know what some of the differences are. I am an engineer/mechanic and may become involved with the short Pumas. Thanks.

[Twist & Shout]

roscoe1

I believe the MRGB changed significantly after the L1.
Further, I understand the L2 and EC225 MRGBs are substantially the same design as each other. Hence in this, and the previous grounding, the L2 and 225s were grounded, but the earlier variants continue/continued to fly.

[AW009]

@ Roscoe1, @all: placeholder text:
You soon get a technical explanation and reference documents to MRGB.:).

[Fatigue]

So the MRGB was changed from the L1 version, is this now the same gearbox that is in the 175???

[AW009]

Because I'm not particularly familiar with the development of the SUPER PUMA I browsed a bit in the Web and found the following interesting documents


https://www.stepchangeinsafety.net/sites/default/files/news/1566.pdf



Probe into EC225 North Sea Ditching Centers on Gearbox | Business Aviation News: Aviation International News (http://www.ainonline.com/aviation-news/business-aviation/2012-05-22/probe-ec225-north-sea-ditching-centers-gearbox)
Probe into EC225 North Sea Ditching Centers on Gearbox | Business Aviation News: Aviation International News (http://www.ainonline.com/aviation-news/business-aviation/2012-05-22/probe-ec225-north-sea-ditching-centers-gearbox)

Accordingly, are existing three different (bevel gear?) shafts for Super PUMA series AS332L, L1, L2 and H225:


In the L, L1 and L2 models is (was) "Shaft 1" of original design installed.



For the H225 model was "Shaft 2" developed and installed



In the course of product care, maintenance and overhaul "Shaft 2" as retrofit could also be installed in the L, L1 and L2 models.



However, "Shaft 1" can not be installed in the H225 model.



As one of the results of the Aircraft Accident Investigations of Ditching of G-REDW and of G-CHCN a change in the manufacturing process of specific batches of "Shaft 2" was thought to be the cause.



Since 2012 and the groundings, L, L1 and L2 aircraft are re-fitted with ‘Shaft 1”, the original design of shaft which had accumulated 4.5 million flight hours without obviousely corresponding incidents or accidents



New evidence is coming to light which suggests that the scopes of the problems associated with ’Shaft 2’ are wider. Use of aircraft which feature this shaft is not supported by the aircraft operators and is also not permitted by the CAA of UK since the incidents and accidents of 2012.



H225 remained grounded till development, evaluation, production and availability of ’Shaft 3’ was successful in 2013 and all H225 were equipped / retrofitted with ’Shaft 3’.

The big question is now: Are there new evidences given, that ’Shaft 3’ might be one of the multiple causes of latest accident in Norway?

In this case all helicopters being equipped with ’Shaft 3’ must be grounded and those might be besides the already grounded H225 and AS 332L2, due to overhauls of MRGB, a majority of AS332L1 and AS 332L worldwide!

With regret and the wishing of a competent and happy knack in tackling the various problems of the PUMA / PUMA SUPER series it is no longer done.

Too much has accumulated over the decades at the "Design Approval Holder" AIRBUS Helicopters France and it seems to me more likely to go to "To be, or not to be, that is the question”.

The "shaft problem" and/or the total MRGB problem might result in the desaster that the majority of the approx. 800 PUMA / SUPER PUMA operated worldwide is multiple affected.:rolleyes:

[Never Fretter]

So the MRGB was changed from the L1 version, is this now the same gearbox that is in the 175???

Are there new evidences given, that ’Shaft 3’ might be one of the multiple causes of latest accident in Norway?

The simple answer to both is is no.

[Pablo332]

The simple answer to both is is no.
+1 No please no more X files.

[Gusteo]

What can't be ignored regardless of what the cause, is the fact it was never detected by HUMS, CHIPS, FDR, CVR, SOAP, ENGINEERS, PILOTS
Whatever failed first it gave no warning at all!

I am not an expert on the Super Puma but have friends flying them. I agree with Buzz66 on the fact that there was no warning thus no pilots reaction time to this accident. This is a major set back in confidence on the platform for both pilots and passengers whatever the outcome of the investigation.

[AW009]

@Never Fretter (http://www.pprune.org/members/441030-never-fretter), @Pablo332 (http://www.pprune.org/members/292168-pablo332): Do You both definitely know, that the bevel gear and its shaft was 100% o.k.?
Then you might know more as AIBN!
Or are you AIBN?!

[albatross]

Please everybody play nice as we go round and round this mulberry bush!
Frankly I, myself, am getting rather dizzy.

[Pablo332]

@Never Fretter (http://www.pprune.org/members/441030-never-fretter), @Pablo332 (http://www.pprune.org/members/292168-pablo332): Do You both definitely know, that the bevel gear and its shaft was 100% o.k.?
Then you might know more as AIBN!
Or are you AIBN?!
I’m absolutely sure I know considerably less than the people of the AIBN. That’s why I fully concur with their current avenues of investigation.

[jimf671]

... ... You're trying to say that that gear distorted enough to release 3 rollers, from 2 different places, then snapped back into its former shape, all without any damage...??!


Would not surprise me. It would be interesting to know the material used. I expect that will feature in AIBN reports in due course. (I am a former automotive gear design guy.)

[Never Fretter]

AW009 I'm pretty sure on this I know more than you;)

[dascanio]

@Never Fretter (http://www.pprune.org/members/441030-never-fretter), @Pablo332 (http://www.pprune.org/members/292168-pablo332): Do You both definitely know, that the bevel gear and its shaft was 100% o.k.?
Then you might know more as AIBN!
Or are you AIBN?!

No, @AW009, They don't, BUT YOU ARE NOT AIBN, as well!
we need, as a whole industry, a serious investigation, not self appointed experts.
Besides, the issue of the bevel gear has been discussed in other long threads, and your "x files" are not, in fact, the end of that story. You should do your homework better, and read AAIB accidents reports, AH SINs, ADs, introduced interim modifications and redesigned gear description, on this topic.

Another thing: do you really need to use "AW009" nick? You know, for me, working in AW, now Leonardo, it is a bit annoying that a glorious name is associated to such posts...

[Satcomm]

AW009,

@Never Fretter, @Pablo332: Do You both definitely know, that the bevel gear and its shaft was 100% o.k.?

Why do you not get it??? It is the only thing that Airbus has 100% verified. After 48 hours, they stated that this was NOT a repeat of the issue that caused the 2012 ditchings. In which, they were talking about the bevel gear and its shaft. That is about the only thing that has been confirmed at this point.

[lowfat]

seems some of you need to see this

https://www.youtube.com/watch?v=iJKZPbf_kPI

and
https://www.youtube.com/watch?v=oD4jKBOIBwc



its about the new vertical shaft

[Diversification]

The refurbishing of the grarbox, and probably the epicyclic gears too, makes me think of old stories about bad spare parts being resold as new. The husband of by secretiry died as pilot in an accident over the North Sea when a bolt broke making the plane lose its vertical stabilser.

Is there a system with numbering of each part in a gearbox which would certify that old parts are not saved and reused several times instead of new parts.

[Never Fretter]

The refurbishing of the grarbox, and probably the epicyclic gears too, makes me think of old stories about bad spare parts being resold as new. The husband of by secretiry died as pilot in an accident over the North Sea when a bolt broke making the plane lose its vertical stabilser.

Is there a system with numbering of each part in a gearbox which would certify that old parts are not saved and reused several times instead of new parts.

Again, simple answer: yes

[birmingham]

agreed. Indeed there is more than one.

Diversification; There is no way that a company of HS/CHC's standing operating a contract for Statoil would knowingly use old parts (unless part of a fully approved refurbishment program with full traceability). There is an outside chance it would happen without their knowledge but so many systems and checks are there it is next to impossible. There have been a number of statements made about maintenance and we haven't yet had the report. But the standards these guys work to are the highest in the world. We should certainly give them more than the benefit of the doubt until some evidence is produced. I don't know any more than anybody else but I would be very surprised if they weren't entirely exonerated.

[Lonewolf_50]

agreed. Indeed there is more than one.

Diversification; There is no way that a company of HS/CHC's standing operating a contract for Statoil would knowingly use old parts (unless part of a fully approved refurbishment program with full traceability). There is an outside chance it would happen without their knowledge but so many systems and checks are there it is next to impossible. There have been a number of statements made about maintenance and we haven't yet had the report. But the standards these guys work to are the highest in the world. We should certainly give them more than the benefit of the doubt until some evidence is produced. I don't know any more than anybody else but I would be very surprised if they weren't entirely exonerated.
birmingham: who did the overhaul? (CHC or Heli-One (http://heli-one.ca/), the company referred to in this thread). I would expect that item by item documentation of critical dynamic components is part of an overhaul contract's paperwork and audit trail. This is the kind of stuff a QC or QA department must review/verify before calling the overhaul complete / satisfactory / up to standards.

[OnePerRev]

The problem with the bevel shaft affecting the planet theory is that it would probably affect first stage. Not to say it didn't end up that way, we don't know. First stage sun was worn uneven. About the only thing that one could logically speculate to be related.
Could also be a general local starvation of oil in the epicyclic module. Clogged passage could do that.
To me, looks like gears ran very hot and discolored.
Chip detector won't work without oil return flow.

[Lonewolf_50]

The problem with the bevel shaft affecting the planet theory is that it would probably affect first stage. Not to say it didn't end up that way, we don't know. First stage sun was worn uneven. About the only thing that one could logically speculate to be related.
Could also be a general local starvation of oil in the epicyclic module. Clogged passage could do that.
To me, looks like gears ran very hot and discolored.
Chip detector won't work without oil return flow.
But if oil return flow stops, doesn't the cockpit get an indication? Temps going up?

[gulliBell]

@Lonewolf_50: I don't know the 225, but I don't know of any helicopter with an indicating system that senses oil return flow (or oil supply flow for that matter, whether that be in an engine or gearbox).

Oil temperature, where a thermocouple is inserted into an oil flow line or sump somewhere, obviously requires oil to be in the system for the probe to measure the oil temperature. If oil system volume is decreasing you should see an increase in temperature as the available oil is spending less time cooling down before it's heated up again. But you need to be looking at the gauge, I don't think there is an oil high temp warning on a CWP?

And oil supply pressure, usually on the output of the integral oil pump/s built into or on the gearbox (or engine). Oil pressure should be dual function, low pressure switch and pressure transmitter. Without oil you might not see a high temperature indication, but you should see a low oil pressure indication, and a low oil pressure warning on the CWP.

If there is an anomaly in the oil flow circuit somewhere (such as a blocked oil jet), you might only get a slight increase in the oil temperature indication, but still within the normal range.

I guess most people here know all this anyway.

[TowerDog]

. on the fact that there was no warning thus no pilots reaction time to this accident.

No sh!t.
If the pilots had any kind of warning it would have taken them 30-40 seconds to do an emergency descent and put down on any kind of surface, rock or sea. If the rotor departed 5 or 10 feet before landing they would all have had a good chance of surviving the madness.
Timing is everything.

[riff_raff]

....The gear design does not account for a rim fracture as a design point, relies on this mode to simply never show up. An overtorque test is the standard used, but that would not consider degradation of raceway over time, just tooth bending primarily....

Good point. Gear rim fractures are most likely to initiate at the tooth root fillet surfaces where tensile stress is concentrated. With current design practice, the gear rim section under the root fillets is made thick enough (typically >1.25 times the tooth whole depth) so that any fracture initiated at the fillet propagates thru the adjacent tooth rather than through the rim. Loss of a single tooth is preferable to failure of the rim structure.

Here is a good read (https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwiQ2KfGppDNAhVPU1IKHWK3AK4Q5TUICQ&url=http%3A%2F%2Fwww.geartechnology.com%2Fissues%2F0911%2Fmi gnot.pdf&bvm=bv.123664746,d.amc&psig=AFQjCNFpgM9vkPROsGbq2htpJfE0nrMmGw&ust=1465195955650876) on the situation with a thin section planet gear supported by a spherical roller bearing, if anyone is interested.

[AW009]

@dascanio, @Never Fretter, @Pablo332 & @Satcomm:

By http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-60.html#post9398712 I have put into the discussion facts to bevel gear and shaft and no rumor or trolling!

Furthermore I simply asked „The big question is now: Are there new evidences given, that ’Shaft 3’ might be one of the multiple causes of latest accident in Norway?“

One of the facts is that first stage sun was worn uneven. It is a further fact that a problem with the bevel shaft is affecting at minimum the first stage of planet gear, not to say it will end up that way!

So, why are you trying to piss on my feet without any facts and evidences?

AH did exclude without any evidence the bevel gear and shaft problematic within the first 48 hours after the accident and also created a lot of other stories, which proofed to be nonsense.

I am of the opinion 'A liar will not be believed even when he speaks the truth. This spirit runs like a red thread through the history of (Super) PUMA, NH-90, AH-TIGER, A400M, EUROFIGHTER, EUROHAWK and the UAV-Scenario” and I have already told this in http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-51.html#post9393708

@dascanio: Maybe I was involved in my forty-five years carriere in military and commercial aviations in more AAIB as you dream? As a consultant I am engaged in a project which doesn’t allow me to use “H120“ or “B505X“ as a nick, otherwise my client would become a little bit angry.:p

[henra]

The refurbishing of the grarbox, and probably the epicyclic gears too, makes me think of old stories about bad spare parts being resold as new. The husband of by secretiry died as pilot in an accident over the North Sea when a bolt broke making the plane lose its vertical stabilser.


I think this issue has been mostly rectified at least in the 'civilised' parts of the world. What I do wonder is if while changing/disassembling the MGB a mishandling could cause damage to the outer race of a bearing/epicyclic gear?
Roller bearings are normally very robust when running and very fragile against shocks while being static. Could a ding while changing/disassembling/handling the MGB cause a small damage/dent in the race that then started to propagate? How is this prevented, especially in such a combined design with hardened surfaces on both sides (inner and outer side)?

[dascanio]

@dascanio, @Never Fretter, @Pablo332 & @Satcomm:

By http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-60.html#post9398712 I have put into the discussion facts to bevel gear and shaft and no rumor or trolling!

Furthermore I simply asked „The big question is now: Are there new evidences given, that ’Shaft 3’ might be one of the multiple causes of latest accident in Norway?“

One of the facts is that first stage sun was worn uneven. It is a further fact that a problem with the bevel shaft is affecting at minimum the first stage of planet gear, not to say it will end up that way!

So, why are you trying to piss on my feet without any facts and evidences?

AH did exclude without any evidence the bevel gear and shaft problematic within the first 48 hours after the accident and also created a lot of other stories, which proofed to be nonsense.

I am of the opinion 'A liar will not be believed even when he speaks the truth. This spirit runs like a red thread through the history of (Super) PUMA, NH-90, AH-TIGER, A400M, EUROFIGHTER, EUROHAWK and the UAV-Scenario” and I have already told this in http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-51.html#post9393708

@dascanio: Maybe I was involved in my forty-five years carriere in military and commercial aviations in more AAIB as you dream? As a consultant I am engaged in a project which doesn’t allow me to use “H120“ or “B505X“ as a nick, otherwise my client would become a little bit angry.:p

@AW009: unfortunately you are mistaken. The sun gear extremely worn you are referring to is, actually, the SECOND stage sun gear, that is integral with the first stage planet carrier. The first stage sun gear is driven by the bevel shaft, but is below, and is not integral with the bevel shaft. Therefore, you are looking, ref AIBN report of the 27th, pic 5, to the a second stage component, i.e. The sun, actually.
A failure of the bevel shaft, as evidenced in the previous accidents, causes immediate loss of power to the pumps, and is identified by zero oil pressure, I imagine this is the reason why AH said almost immediately this is not the same situation as the previous two (2012) accidents.
Therefore my previous comments; besides riff raff in one of his previous posts, attached a cross section of the gearbox that is quite self explaining

I still think that a serious and thorough investigation is under way, and should be respectful for the victims that the investigators are left doing their job.
Regards

[AW009]

@dascanio: Thank you for your prompt reaction. You are very right with your theory, but did you regard, if there is a dislining inside the MRGB due to bevel gear shaft and its axle, in praxis the damage in the epicyclic modules is increasing by the grade of dislining. This is meaning that the upper module of epicyclic and its sun gear will be the first “to say good bye”!

Also regards to Cascina Costa di Samarate or to Swidnik

[Praet]

*deleted* Sorry

[zalt]

AW009 it is trolling to raise unsubstantiated and inaccurate accusations in the form of a question and then ignore the correct answer! Even more so to be demanding extensive evidence from others, while you continue to churn out irrelevant and unjustified sanctimonious nonsense.

[Satcomm]

Zalt, I agree 100%.

[Satcomm]

gulliBell,

@Lonewolf_50: I don't know the 225, but I don't know of any helicopter with an indicating system that senses oil return flow (or oil supply flow for that matter, whether that be in an engine or gearbox).

The only aircraft that I know of that does the above is the S92, however, only for the input modules. My understanding is, the left MGB oil pump is responsible for scavenging the left input and the right MGB oil pump for scavenging the right input. Basically there is a vacuum switch in the oil return from the modules and if the vacuum is lost then the cockpit gets an indication that the left or right pump has failed. If ignored, there will be a rise in oil temp with an eventual over temp of that input. Pretty sure standard procedures are to reduce power to the effected side until landing. Again, this is only for the inputs, anything inside the MGB module itself would have no indication.

[turboshafts]

Hi,

the systems for an aircraft has to be fault-proof

the same is valid for the maintenance

I assume that the gearbox is test driven (as claimed) to the extent
that any damage due to the mistreatment could be indentified.

However, I have found something interesting.

With respect to the LN-OPG accident, I have read the report again
to understand a bit more further the strategy of the ongoing investigation.

It is written explicitly in the report, that gearboxes are interchanged
between helicopters in the fleet. The same is said for the engines.
After overhaul they could be mounted on any aircraft of the type (per my understanding).

so that leads me to the following point.
even in the LN-OPG accident, the maintenance history was investigated.
And from there it was reported that during MGB overhaul it was also
found pitting on the inside surface of the planetary gears. But the gearbox was still
rebuilt as it was claimed to be not of influence on the operation (as claimed in report)
Even this gearbox was testdriven and found faultproof.

The LN-OPG accident was however due to the splined part of the bendix input shaft breaking and engine overreving.

Now, with respect to the findings in the investigation of that accident I find it hard to understand that the TBO was increased from 3000 hours on the L1 to 4400 hours on the EC225?

If pitting could be found and reinstalled and put to service.
How come that they react so stringent to the fact that it is fatigue cracks on the current gearsets of the EC225?

If pitting occurs on any gear, it means that the surface is not holding up.
could be many reasons for that. but in all engineering, we know as well
that a surface that pits, might also develop hair thin, stochastic cracks in the surface finish that eventually will lead to fatigue cracks.

sorry to say, that it is found that the gears have fatiuge cracks, doesn not give me the impression that a solution is found, when in 1997 the gears with pitting could be rebuilt without any concern.

Is the maintenance program fault-proof for the ec225? as it was for the L1?

with all do respect, for those involved in the maintenance, design, flight etc.
this is not an attack on the job you made.

i just want to ask a question.

would the disasters have happened if the TBO was 2500 hours?

I have read the report of the Cougar S92 accident as well.
1 out of 16 detrimental factors that lead to the accident was that a metal particle
was found in the gearbox during overhaul, not deemed of importance
and the gearbox was rebuilt.

Was fatigue cracks one of many factors that could ultimately
be traced to the fact that a more stringent maintenance could
have avoided the accident?

I think it´s a fair time to open that discussion

[Gusteo]

No sh!t.
If the pilots had any kind of warning it would have taken them 30-40 seconds to do an emergency descent and put down on any kind of surface, rock or sea. If the rotor departed 5 or 10 feet before landing they would all have had a good chance of surviving the madness.
Timing is everything.
I understand from reports, that the CVFDR had only about 2 seconds of recording of the incident and the aircraft crashed. I don't believe any mayday calls were made. This I feel is what makes this accident so scary. There was nothing the aircrew could have done to survive.

[Brother]

Towerdog

If the pilots had any kind of warning it would have taken them 30-40 seconds to do an emergency descent and put down on any kind of surface, rock or sea. If the rotor departed 5 or 10 feet before landing they would all have had a good chance of surviving the madness. Timing is everything.

But of course they didn't because the whole MRH departed, so your point is?

[Apprentice Yoda]

Hi,

the systems for an aircraft has to be fool-proof

the same is valid for the manintenance


There are some pretty creative fools out there

[birmingham]

Lonewolf_50 I have no idea who did this particular installation sorry

[RVDT]

If oil system volume is decreasing you should see an increase in temperature as the available oil is spending less time cooling down before it's heated up again.

???? Just the same as it spends less time heating up again? Common misconception and wives tale.

Low volume where the oil reservoir is integral i.e. a gearbox will actually run cooler as the oil visits the cooler more in a given time period.

Bell 206 overfilled due to people misunderstanding the correct level in the MGB is a classic example.

[Lonewolf_50]

With respect to the LN-OPG accident, I have read the report again to understand a bit more further the strategy of the ongoing investigation. It is written explicitly in the report, that gearboxes are interchanged between helicopters in the fleet. The same is said for the engines. After overhaul they could be mounted on any aircraft of the type (per my understanding). The ability to replace major components (like gear boxes and engines) is a desirable design feature for a variety of customers. Modularity does not, by itself, lead to gear boxes or engines failing. (I am not sure what point you are trying to make with that observation). Your reference to that accident led me to the very thorough report AIBN did for that accident: it was interesting from a lot of angles. (Thank you!) Your question on "what if" regarding TBO differences (higher or lower) probably can't be answered definitively without being able to account for the health of the fleet overall, and how frequently this family of main gear boxes have to be removed before the TBO due to various removal criteria.

[gulliBell]

@RVDT: What I said at #1217 is what is taught in flight training based on manufacturer supplied training material. Not common misconception and wives tale. If you're losing oil volume the oil temperature should rise slightly. We are not ones to teach something other than what the manufacturer espouses.

[Diversification]

Birmingham wrote in #1213
Diversification; There is no way that a company of HS/CHC's standing operating a contract for Statoil would knowingly use old parts (unless part of a fully approved refurbishment program with full traceability). There is an outside chance it would happen without their knowledge but so many systems and checks are there it is next to impossible. There have been a number of statements made about maintenance and we haven't yet had the report. But the standards these guys work to are the highest in the world. We should certainly give them more than the benefit of the doubt until some evidence is produced. I don't know any more than anybody else but I would be very surprised if they weren't entirely exonerated.

After reading of the AIBN report about LN-OPG dated 2001 it is clear to me that at that time (2001) the procedures applied for quality control of some parts made by Eurocopter and their suppliers in France as well as by HS in their own refurbishing of gear boxes. One can only hope that the findings in that report from AIBN had a major impact and was followed up later.

[turboshafts]

Except it wasn't increased to 4400hrs it was reduced to 2000hrs.

If that is the case, it´s good.

But it is truly stated in an interview with the CEO Arne Roland after CHC last week press conference that they follow a maintenance program where the gearbox at 4400 hours is sent to overhaul

here is the article
CHC-sjefen: - Vi har ikke tilgang til girkassen - Bergens Tidende (http://www.bt.no/nyheter/lokalt/CHC-sjefen---Vi-har-ikke-tilgang-til-girkassen-3607349.html?xtor=RSS-2)

However, in the interview with NRK, BT or TU
he refuse to tell how many flying hours the gearbox had before the accident.

The main point he made several times is that CHC does not have access to the gearbox and is sent to an external supplier for overhaul.
He refuse to say where and who is doing the overhaul.

In the topic here it was mentioned that the overhaul is done by Heli-One
and is 100% owned by CHC.

Both Heli-One and CHC Headquarters are at Sola Airport in Norway.

[turboshafts]

CHC-sjefen: - Vi har ikke tilgang til girkassen - Bergens Tidende (http://www.bt.no/nyheter/lokalt/CHC-sjefen---Vi-har-ikke-tilgang-til-girkassen-3607349.html?xtor=RSS-2)

Ny girkasse i januar

- Vi følger et vedlikeholdsprogram som tilsier at girboksen etter 4400 flytimer sendes til en leverandør som utfører vedlikehold, sier Roland videre.

Girboksen på ulykkeshelikopteret ble installert i januar. Under vedlikehold blir enkelte deler utbedret, mens andre blir skiftet helt ut.

Roland vil ikke svare på om planetgiret, som ifølge Havarikommisjonen er utsatt for tretthetsbrudd, ble skiftet ut i januar.

- Jeg kan ikke gå inn på spesifikke opplysninger om de ulike delene.

Directly translated to English by me:

New gearbox in January

- We follow a maintenance program that says that the gearbox
after 4400 flying hours is shipped to a supplier that perform maintenance, says Roland further.

The gearbox on the accident helicopter was installed in January.
During maintenance some parts are refurbished, some are completely replaced.

Roland does not want to answer, if the planetary gear, that according to the Accidentboard is subject to fatigue cracks, was replaced in January.

- I can not go into specific information about the different parts.

[MrSnuggles]

Some news from the investigation, not previously mentioned in this thread:

Spricka funnen i kraschade helikopterns rotorväxel | Ny Teknik (http://www.nyteknik.se/fordon/spricka-funnen-i-kraschade-helikopterns-rotorvaxel-6577737)

Utredarna i den norska haverikommissionen som granskar vad som gick snett i den norska helikopterolyckan den 29 april har upptäckt en utmattningspricka i ett av kugghjulen som ingår i huvudrotorns växel. Det uppger myndigheten i en första rapport om händelsen. Det finns också andra tecken på metallurgiska utmattningsproblem.

My translation:

The investigators in AIBN, who studies what went wrong in the Norwegian helicopter accident the 29th of April, have discovered a fatigue crack in one of the wheels in the main rotor gear box. AIBN states this in the first report about the accident. There are also other indications of problems of metal fatigue.

[Nadar]

The investigators in AIBN, who studies what went wrong in the Norwegian helicopter accident the 29th of April, have discovered a fatigue crack in one of the wheels in the main rotor gear box. AIBN states this in the first report about the accident. There are also other indications of problems of metal fatigue.
This is already known, is described in the latest preliminary report (http://www.aibn.no/Luftfart/Undersokelser/16-286?iid=19958&pid=SHT-Report-Attachments.Native-InnerFile-File&attach=1), and has been discussed here extensively.

[Colibri49]

I haven't looked at this topic for a few weeks, so hopefully I'm not about to repeat something which might already have been raised by others. As someone with thousands of hours flying the EC225, I know that there is a chip detector spring-loaded toggle switch above the pilots' heads. Moving it one way tests all chip detectors, both for the engines and gearbox. While holding the switch against its spring you see in sequence "Chip1" for engine 1, "Chip2" for engine 2 and "Chip" for the gearbox, all showing on the VMS display panel. This test gets done before every flight. Moving it the other way in flight would put a high voltage electric pulse through the very smallest (hair fine) metal particles on the detectors and burn them off.


Two such "fuzz burns" are allowed in flight, after which if it's a gearbox "Chip" warning a landing must be made as soon as possible e.g. on the nearest available helideck offshore. I've only ever had a "Chip 1" in flight and I brought engine 1 back to idle in the cruise, to minimise further possible damage. The particle was found to be negligible and the engine was returned to service.


With the removal of the magnets from the gearbox after the REDL disaster, I would hope that the slightest particles from wear or spalling in the epicyclic gears at the top of the gearbox would be detected long before any risk could arise. But this doesn't seem to have been the case in Norway. Yet photographic evidence and some opinions suggest that there was wear. In which case why weren't particles being detected during several hours of flight before the rotor head came off? As for missing roller bearings in one of the planet gears, is the metal of the gear-wheels elastic enough to allow rollers to escape during violent deformation of all components?


I still feel on balance that the cause was detachment of one of the gearbox suspension rods, for as yet unknown reasons. Sudden shattering of gearbox internal components without any prior signs of wear seems beyond belief.

[Harry the Hun]

Super Pumas Finished in North Sea - Oil and Gas News (http://www.oilandgaspeople.com/news/8771/super-pumas-finished-in-north-sea/)

[turboshafts]

I haven't looked at this topic for a few weeks, so hopefully I'm not about to repeat something which might already have been raised by others. As someone with thousands of hours flying the EC225, I know that there is a chip detector spring-loaded toggle switch above the pilots' heads. Moving it one way tests all chip detectors, both for the engines and gearbox. While holding the switch against its spring you see in sequence "Chip1" for engine 1, "Chip2" for engine 2 and "Chip" for the gearbox, all showing on the VMS display panel. This test gets done before every flight. Moving it the other way in flight would put a high voltage electric pulse through the very smallest (hair fine) metal particles on the detectors and burn them off.


Two such "fuzz burns" are allowed in flight, after which if it's a gearbox "Chip" warning a landing must be made as soon as possible e.g. on the nearest available helideck offshore. I've only ever had a "Chip 1" in flight and I brought engine 1 back to idle in the cruise, to minimise further possible damage. The particle was found to be negligible and the engine was returned to service.


With the removal of the magnets from the gearbox after the REDL disaster, I would hope that the slightest particles from wear or spalling in the epicyclic gears at the top of the gearbox would be detected long before any risk could arise. But this doesn't seem to have been the case in Norway. Yet photographic evidence and some opinions suggest that there was wear. In which case why weren't particles being detected during several hours of flight before the rotor head came off? As for missing roller bearings in one of the planet gears, is the metal of the gear-wheels elastic enough to allow rollers to escape during violent deformation of all components?


I still feel on balance that the cause was detachment of one of the gearbox suspension rods, for as yet unknown reasons. Sudden shattering of gearbox internal components without any prior signs of wear seems beyond belief.

what we do know is this:
TURØY - Helikopteret avbrøt flygning tre dager før ulykken (http://www.nettavisen.no/nyheter/helikopteret-avbrt-flygning-tre-dager-fr-ulykken/3423219437.html)

There where some "indication lamp" that was providing several messages
in the days before the accident causing the flight to be canceled and the
helicopter to return to base immediately.
After that it was also occuring during test flights, after which
a "component" was changed

if this is coupled to detecting metal particles is too early to say
and purely speculation without having the first hand info.

In which case why weren't particles being detected during several hours of flight before the rotor head came off?

It could be days before, hours or it could be minutes.

Until we know the facts it is impossible to answer that question.

Still to me the last conclusion in your post is a bit too soon.

My personal opinion is that 3 rollers missing from the planetary gear isnt
enough to kill the gearbox even if the roller would get stuck between the carrier and the sun gear.

but it would probably cause surface deterioration that would significantly accelerate the wear on all components in the gearbox.

some signs of wear can be seen on the components. some other components look to be damaged upon impact. The rollers are inserted by squeezing
the outer ring on normal bearings.
if you squeeze a ring gear it will break, so probably there are other methods
of installing the rollers without squeezing the outer ring, and thus
it must also be possible that the rollers can escape.
but honestly i find that as well not very probable.

I guess a part of the analysis is to predict/simulate if there was shearing of the gearbox during rotation. There are many methods to do this
could be a reason that AIBN was doing extensive search for parts in the area
after the accident.

I guess as well there are pilot voice recorder readings to say
how eventual indications lamps or error messages was interpreted during the flight before the accident

[SASless]

Would it be more accurate to say "...without any signs of wear being detected by the Aircraft systems or Engineering surveillance procedures..."?



I haven't looked at this topic for a few weeks, so hopefully I'm not about to repeat something which might already have been raised by others. As someone with thousands of hours flying the EC225, I know that there is a chip detector spring-loaded toggle switch above the pilots' heads. Moving it one way tests all chip detectors, both for the engines and gearbox. While holding the switch against its spring you see in sequence "Chip1" for engine 1, "Chip2" for engine 2 and "Chip" for the gearbox, all showing on the VMS display panel. This test gets done before every flight. Moving it the other way in flight would put a high voltage electric pulse through the very smallest (hair fine) metal particles on the detectors and burn them off.


Two such "fuzz burns" are allowed in flight, after which if it's a gearbox "Chip" warning a landing must be made as soon as possible e.g. on the nearest available helideck offshore. I've only ever had a "Chip 1" in flight and I brought engine 1 back to idle in the cruise, to minimise further possible damage. The particle was found to be negligible and the engine was returned to service.


With the removal of the magnets from the gearbox after the REDL disaster, I would hope that the slightest particles from wear or spalling in the epicyclic gears at the top of the gearbox would be detected long before any risk could arise. But this doesn't seem to have been the case in Norway. Yet photographic evidence and some opinions suggest that there was wear. In which case why weren't particles being detected during several hours of flight before the rotor head came off? As for missing roller bearings in one of the planet gears, is the metal of the gear-wheels elastic enough to allow rollers to escape during violent deformation of all components?


I still feel on balance that the cause was detachment of one of the gearbox suspension rods, for as yet unknown reasons. Sudden shattering of gearbox internal components without any prior signs of wear seems beyond belief.

[HeliComparator]

I know that there is a chip detector spring-loaded toggle switch above the pilots' heads. Moving it one way tests all chip detectors, both for the engines and gearbox. While holding the switch against its spring you see in sequence "Chip1" for engine 1, "Chip2" for engine 2 and "Chip" for the gearbox, all showing on the VMS display panel. This test gets done before every flight. Moving it the other way in flight would put a high voltage electric pulse through the very smallest (hair fine) metal particles on the detectors and burn them off.

With the removal of the magnets from the gearbox after the REDL disaster, I would hope that the slightest particles from wear or spalling in the epicyclic gears at the top of the gearbox would be detected long before any risk could arise. But this doesn't seem to have been the case in Norway. Yet photographic evidence and some opinions suggest that there was wear. In which case why weren't particles being detected during several hours of flight before the rotor head came off? As for missing roller bearings in one of the planet gears, is the metal of the gear-wheels elastic enough to allow rollers to escape during violent deformation of all components?
.


Well just to be picky, not "high voltage pulse" since the "chip" will be making a short circuit, across which it is very difficult to generate a "high voltage". In fact is a measured dose of charge (set current for a set time) such that a small chip will be vapourised, a larger chip won't be.


I presume that the body of the chip detector has a high-ish value resistor across it and the test procedure checks that this resistance is in circuit. Open circuit (wires disconnected) would therefore not give a good test, and of course a short circuit (chip present) would leave the light permanently on. A bit like the fire detection system in reverse!

[HeliComparator]

There where some "indication lamp" that was providing several messages
in the days before the accident causing the flight to be canceled and the
helicopter to return to base immediately.
After that it was also occuring during test flights, after which
a "component" was changed




This was said to be an engine gov warning light -according to rumour anyway.

[Nadar]

I'm not sure that the missing rollers are significant, it's very hard to imagine those falling out prior to the accident without being noticed in some way. I'm not sure they can escape while in one piece. To me it's by far most likely that they disappeared during the break up or ground impact.

When it comes to how the bearings are put together, I'd guess that they shrink the inner roller surface by cooling it down.

[HeliComparator]

So here we are, 5 weeks or so after the crash. Suggestions coming out of AAIBN about metal fatigue in a planet gear even though the proper metallurgical examination has not been carried out yet. All clever and tricky stuff.

And yet on some of the basics such as the maintenance history, component hours, history of HUMS data, in fact anything that could reflect on things Norwegian, they are strangely silent even though this info must surely be readily available just a day or two after the accident. Why the secrecy? Is there a rat to be smelled out?

[Self loading bear]

The rollers can exit easily when gears have left the carrier wheel
(I.e. after the epicyclic has been torn apart)
when cage and core rotate 30 degrees out of plane with race the first rollers can leave the cage.
see how they are put together.
https://youtu.be/ZvZfgVP-nvA

SLB

[buzz66]

Well just to be picky, not "high voltage pulse" since the "chip" will be making a short circuit, across which it is very difficult to generate a "high voltage". In fact is a measured dose of charge (set current for a set time) such that a small chip will be vapourised, a larger chip won't be.


I presume that the body of the chip detector has a high-ish value resistor across it and the test procedure checks that this resistance is in circuit. Open circuit (wires disconnected) would therefore not give a good test, and of course a short circuit (chip present) would leave the light permanently on. A bit like the fire detection system in reverse!
Some Aircraft like the S76 also use a set of contacts on the Chip Detector relay to latch and hold the Chip light on. Not sure if this aircraft is a latch hold circuit or not.
Fire Detectors use an Integrity Resistor to prevent False Fire Warnings. Chip detectors do NOT have any Integrity resistors.
Test resistors are used on Fire Bottle, Winch Cut, ETC type Squibs to limit the current during integrity test.

[buzz66]

This was said to be an engine gov warning light -according to rumour anyway.
GOV light is a common defect on this Aircraft and is almost always an Electronic Bleed Valve.
I am willing to bet the Component change was a Bleed Valve

[SASless]

HC,


...in fact anything that could reflect on things Norwegian, they are strangely silent....


Conspiracy Theory a Hobby of yours now days since you have retired?

[letmein]

from HC:
And yet on some of the basics such as the maintenance history, component hours, history of HUMS data, in fact anything that could reflect on things Norwegian, they are strangely silent even though this info must surely be readily available just a day or two after the accident

Also: Status of front suspension bar (missing or not), status of front attachment area - pins missing?, holding pin?, front bracket damage?

.....crickets.

[riff_raff]

I haven't looked at this topic for a few weeks, so hopefully I'm not about to repeat something which might already have been raised by others. As someone with thousands of hours flying the EC225, I know that there is a chip detector spring-loaded toggle switch above the pilots' heads. Moving it one way tests all chip detectors, both for the engines and gearbox. While holding the switch against its spring you see in sequence "Chip1" for engine 1, "Chip2" for engine 2 and "Chip" for the gearbox, all showing on the VMS display panel. This test gets done before every flight. Moving it the other way in flight would put a high voltage electric pulse through the very smallest (hair fine) metal particles on the detectors and burn them off. Two such "fuzz burns" are allowed in flight, after which if it's a gearbox "Chip" warning a landing must be made as soon as possible e.g. on the nearest available helideck offshore. I've only ever had a "Chip 1" in flight and I brought engine 1 back to idle in the cruise, to minimise further possible damage. The particle was found to be negligible and the engine was returned to service. With the removal of the magnets from the gearbox after the REDL disaster, I would hope that the slightest particles from wear or spalling in the epicyclic gears at the top of the gearbox would be detected long before any risk could arise. But this doesn't seem to have been the case in Norway. Yet photographic evidence and some opinions suggest that there was wear. In which case why weren't particles being detected during several hours of flight before the rotor head came off?

Lube oil magnetic chip detectors with fuzz suppression circuitry (http://www.vibro-meter.com/index.cfm/aerospace/oil_debris/fuzz_suppression_systems) have been standard practice with aircraft engines/gearboxes for many years. The chip detector has magnetic sensor rings with a short gap between them. When enough ferrous metal debris accumulates to bridge the gap it closes a circuit that signals a potential fault. Some systems automatically perform one or two burn-off cycles prior to sending a warning signal.

The ability to distinguish between harmless "nuisance" debris (or fuzz) and larger debris that indicates a more serious problem is very important. Every engine and gearbox continually generates nuisance debris throughout its life from metal surface contacts in rolling element bearings/gears/splines/etc. Bearings/gears/splines tend to generate a greater amount of nuisance debris when new, and much less after they have been run-in.

The sensing end of a magnetic chip detector is commonly positioned so that it has maximum exposure to the passing lube oil flow, and ideally in a location where the denser ferrous metal debris particles naturally tend to separate from the oil flow. Chip detectors are often positioned inside (the upstream side) of a filter screen at the oil pump pick-ups (http://www.allenaircraft.com/products/chip_detectors.html), which further helps to separate debris particles in the lube oil flow. The advantage of this filter screen and chip detector arrangement is makes things easier for techs to perform an inspection after there is an indication from the chip detector. They can first remove the chip detector to see exactly what size/shape of debris has accumulated on the magnet rings. They can also remove the filter screen to look for larger debris.

[HeliComparator]

Fire Detectors use an Integrity Resistor to prevent False Fire Warnings. Chip detectors do NOT have any Integrity resistors.
Test resistors are used on Fire Bottle, Winch Cut, ETC type Squibs to limit the current during integrity test.

I don't think you can be right about the resistors. If no resistors, what does the chip detector test function do?

Perhaps you are thinking about resistors in series? I am thinking about a resistor in parallel within the body of the detector.

[RVDT]

The chip detector has magnetic sensor rings with a short gap between them.

Which is all fine until the detector loses some of it's magnetism.

Some maintenance procedures call up regular checking with a "test piece".

A surprising number of maintenance manuals don't.

Just saying.

[CTR]

"I am thinking about a resistor in parallel within the body of the detector."


Most chip detectors on newer rotorcraft incorporate resistors in parallel with the detector circuit to provide an indication of an open circuit. Without this function a broken wire to the detector would not be identified in flight.

[HeliComparator]

"I am thinking about a resistor in parallel within the body of the detector."


Most chip detectors on newer rotorcraft incorporate resistors in parallel with the detector circuit to provide an indication of an open circuit. Without this function a broken wire to the detector would not be identified in flight.
Eggzacary.

(Or on the ground, either)

[henra]

HC,
Conspiracy Theory a Hobby of yours now days since you have retired?

Possibly. But he is spot on insofar as we are still lacking the most basic and easy to obtain information. The silence is deafening...

[SASless]

Tis not their job to satisfy your hunger for information...I am sure they will get around to reporting all that information when they put out a more substantive Preliminary/Interim Report.

[HeliComparator]

Tis not their job to satisfy your hunger for information...I am sure they will get around to reporting all that information when they put out a more substantive Preliminary/Interim Report.
This is true. However it is interesting to note what information has been leaked / drip fed, and what info has been withheld.