North Sea heli ditching: Oct 2012

[SASless]

New shafts are predicted to be available mid 2014.

October 2012 till June 2014.....no big deal they say?

[Lonewolf_50]

The root cause is residual stresses from the manufacturing process

Ok, if these stresses come from the welding process, can they be baked out, or do they need to change the process? (I relaize the answer to that may not be available from our readership. I am not as familiar with welding aviation steel alloys as I am simpler structures, and so am asking for informational purposes).

Is hydrogen embrittlement one of the issues here?

unavoidable corrosion of the bevel gear shaft

I am trying to parse the term "unavoidable corrosion" of a steel shaft. There a loads of ways to prevent corrosion. Hmmmm.

[riff_raff]

Ok, if these stresses come from the welding process, can they be baked out, or do they need to change the process? (I relaize the answer to that may not be available from our readership. I am not as familiar with welding aviation steel alloys as I am simpler structures, and so am asking for informational purposes).

Is hydrogen embrittlement one of the issues here?

Lonewolf_50-

The EB weld is performed after carburize/temper of the bevel gear teeth, so it would be difficult to thermally stress relieve the weld HAZ without affecting the tooth case properties. However, it may be possible to perform some mechanical type of stress relief post welding using vibratory stress relief or controlled shot peening. If they are not already doing so, EC should use controlled preheating & postheating in their EB welding process. This will help minimize any residual stress in the weld HAZ created by asymmetrical heating/cooling around the weld circumference as the weld is being produced.

Like you, I was also puzzled by the article's comment about "unavoidable corrosion". I don't think hydrogen embrittlement is a concern since the EB welding is performed in a vacuum chamber. In modern aerospace manufacturing, there is no such thing as "unavoidable corrosion" when it comes to something like a flight critical component inside a rotorcraft transmission. First of all, there should not have been any corrosion present on the part after manufacturing since this would be cause for rejection. Second, if there were the potential for surface corrosion to occur during the component's service life it should theoretically not have produced a fracture failure. Flight critical components like this bevel gear should be included in the propulsion system fracture control plan, which would include a fracture analysis that takes into account the effect of surface flaws from corrosion. Either the author of the article misspoke, or maybe EC needs to take another look at their fracture control plan for this particular aircraft.

[Ian Corrigible]

Originally Posted by Pittsextra

when you have a CEO coming out with comments like ..."corrosion....and other things" and "very specific set of circumstances" it will be interesting to see how the story gets spun for the punters at the HSSG.

Interestingly timed perspective from Boeing on root cause analysis:

It is possible we will never know the root cause. It is not uncommon not to have found the single root cause. So industry best practice is to look at all the potential causes and address all of them.

I/C

[DOUBLE BOGEY]

PITTS,

How are you now aware of of such a venerable collective as the HSSG???? What could you possibly understand of their functions and role in a situation such as this?

Now I know who/ what you really are your drivel is finally exposed for what it is worth. Bias, self interested rubbish.

Come clean.....if you dare! Or must I compromise my own INTSEC and finally "Out" you?

DB

[gasax]

Really simple DB - tens of thousands of us are aware of the HSSG and its propaganda.

Its entire approach has been to try and tell the workforce that modern helicopters are much safer than of old - inspite of the accident figures clearly showing that is not the case.

Any organisation which is prepared to 'overlook' incident figures to spin a story that suites their needs, shnould be kept at very much more than arms length. Indeed if there were such a concept as 'natural justice' bad things would be happening to these masters of spin.

[Pittsextra]

DB a lot of sudden angst.

I’m not sure it takes any detective work to follow the “venerable collective as the HSSG”… Its all over YouTube. Here is a link:-

StepChangeInSafety - YouTube

You can even watch the part where around minute 28:50 you can see how earnings transcript quotes from Bristow CEO re: the EC225’s return as the press filling column inches.

That’s what I call “spin”.

See it for yourself via this link.

Helicopter Safety Event - Q&A Panel led by Les Linklater - YouTube

When the CEO comes out and attributes at least part of the problem to “other things” if you do believe it is a valid quote can you be surprised by the reaction to it given the machine is in service?

Eurocopter develops ?interim fix? for EC225 issue - News - Shephard

No doubt in the coming weeks there will be some formal reporting on this and then we will see. Good luck.

[Offshorebear]

Step Change latest ;

Eurocopter has recreated the conditions for cracks to occur in the main gearbox vertical shaft. The crack propagation rate has also been verified using bench testing on eight different main gearbox vertical shafts.
From Eurocopter perspectives, the most probable cause is a specific combination of factors, the main ones being a specific combination of residual stress and corrosion of the vertical shaft.

Will you guys be happy to fly them on the basis of that ?

[bigglesbutler]

My point of view has always been, I would rather fly the EC225 with one known problem, that we can monitor/manage, than the Tiger. That said the Tiger (AS332L) is a reliable old girl and we know her intimately, both flying and maintaining it, I just prefer the 225.

From an engineering point of view EC can now make the shaft fail on command, so they know the problem and can then design a fix. That gives me comfort that they have found the problem and also have had their data ratified by several outside agencies.

In short the answer to your question is, Yes I would be happy to fly the 225 with the remedial actions going on. That and I know our engineers will go above and beyond the EC directive to satisfy themselves the aircraft is serviceable. The only question is how long it will take to get them going again.

Si

[Colibri49]

YES, provided that all the stakeholders like the CAA, AAIB, QinetiQ and operators agree with EC's findings and proposals to allow continued flying.

[riff_raff]

Assuming the corrective actions proposed are implemented, I would have no problem being a passenger on this model aircraft. No aircraft design is perfectly safe, and every system of every aircraft presents some potential for failure, however remote that potential may be. The problems that present a real hazard are the ones that are unanticipated or unforeseen. A known potential failure mode that has been characterized through extensive analysis and testing, has been addressed with engineering and manufacturing process changes, and whose recurrence is now actively being monitored for in service, presents no unacceptable level of risk. At least in my humble opinion.

[landeverywhere]

EC225 grounding hits revenue and profit at Eurocopter

"However, a temporary fix to the issue could be delivered to operators within the next three to four weeks, according to a disclosure by one EC225 customer."

furthermore:

"ERA believes a permanent fix to the cracking issue afflicting the type's bevel gear vertical shaft may be nine to 12 months away, but highlights the proposed interim solution which involved cockpit warning lights linked to the helicopter's health-monitoring system. It anticipates receipt of these retrofit kits in the next "three to four weeks", it says. However, it notes: "It is unclear whether such a case will meet the requirements of certain companies and/or unions.""

[Pittsextra]

Bristow Group reported its 2013 Q4 results yesterday and had the following statement on the 225:-


UPDATE ON EC225 OPERATIONS
Recently, Eurocopter, the manufacturer of the EC225 Super Puma aircraft, has indicated that they have determined the root causes of the gear shaft failure in the EC225, which are being reviewed by airworthiness authorities and independent third parties. The definitive solution to the problem will be a redesign of the gear shaft which could take more than a year to complete. However, interim solutions are under consideration, including minor aircraft modifications and new maintenance/operating procedures for mitigating shaft failure and enhancing early detection, which could result in Bristow's return to revenue service for the EC225 aircraft in the third quarter of our fiscal year 2014.
The current situation will continue until the necessary modifications are made to the EC225 fleet, the airworthiness regulators remove the operating restrictions, and we are confident that the interim modifications will allow us to operate the aircraft safely. Until then, this situation could have a material adverse effect on our future business, financial condition and results of operations.

I guess that means the "no commercial pressure" elements can be put to bed...

The conference call, which will no doubt have a lot of Q&A around the EC225 can be listened to at 1500hrs (UK) today (23rd May 2013) by dialling the following numbers:-

International [phone] (pin number is 4616121)
USA 877 941 9205 (same pin)

[SASless]

All the while....the s-92 carries on.

I suppose those who lauded the 225 over the 92 might find this news to be a bit embarrassing.....or should anyway!

[Fareastdriver]

SASless.
I hope for all the people who are going to fly in an S92 that you do not regret your words.

[HeliHenri]

All the while

All the while, half of the 225/725 fleet continues to fly.
.

[HeliComparator]

Unfortunate rather than embarrassing. The EC225 is a fantastic aircraft which unfortunately has a problem with one of its thousands of components - albeit an important one. The S92, although better these days, is of poor design in many areas and has a number of problems. Fortunately for the 92 none of these has been quite critical enough to ground the fleet, though it has come close.

So crow while you can SAS but history will show which is the better aircraft long term. And by the way, since you have flown neither of these aircraft and I have flown both, I am not sure your opinion is of value, based as it is only on nationalistic prejudice.

There, I bit, which is of course what you were hoping for.

[Pittsextra]

And with this in mind:-

All the while, half of the 225/725 fleet continues to fly.

...allied to the "corrosion, residual stress, other things and very specific set of circumstances" highlighted over a month ago by Eurocopters out going CEO, one wonders on what basis this flying continues...

[HeliComparator]

Not flying over hostile terrain.

[Pittsextra]

sure but never the less.... if you can use known solutions to mitigate the risk why wouldn't you?

Edited to add:- by which I mean if EC can now break shafts at will and the CEO comments regarding "other things, specific set of circumstances" suggests that the breakage is beyond the shafts material properties and one of operation and/or specification of the type.