New shafts are predicted to be available mid 2014. |
The root cause is residual stresses from the manufacturing process Is hydrogen embrittlement one of the issues here? unavoidable corrosion of the bevel gear shaft |
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? 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. |
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.
I/C |
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 |
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. |
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. 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. |
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 ? |
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 |
YES, provided that all the stakeholders like the CAA, AAIB, QinetiQ and operators agree with EC's findings and proposals to allow continued flying.
|
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.
|
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."" |
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 +1 480 629 9771 (pin number is 4616121) USA 877 941 9205 (same pin) |
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! |
SASless.
I hope for all the people who are going to fly in an S92 that you do not regret your words. |
All the while
All the while, half of the 225/725 fleet continues to fly.
. |
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. |
And with this in mind:-
All the while, half of the 225/725 fleet continues to fly. |
Not flying over hostile terrain.
|
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. |
Because the solutions are not yet available.
|
Sorry HC I edited my post. If EC can break shafts at will then it also suggests that EC can avoid breaking shafts, or at least on demand. Therefore one might suggest that whatever they do to break them at will is something to avoid....?
|
HC,
As I have flown neither....I have no axe to grind. I did not have you in mind in particular....but since you leaped into the conversation....you do have to admit the significance of the problem AND the cure....has affected the 225 far worse than the 92. You can carry on with your argument about the design superiority of the 225 over the 92 with someone from Sikorsky if you wish. As to calling the 225 superior to the 92 is your opinion that does seem to be challenged by the current situation. I understand your loyalty to the 225.....as you have a lot of personal involvement in that program with your employer....thus also some sensitivity to any criticism of the 225 and EC. Neither EC or SK are without fault, just as the Certification Authorities are alsonot without fault.....and as to the 92....there was some Operator errors as well. So please don't try to trivialize the situation as you and the rest of us know it is a far more complex situation than your post would suggest. |
Pittsextra If EC can break shafts at will then it also suggests that EC can avoid breaking shafts, or at least on demand. Therefore one might suggest that whatever they do to break them at will is something to avoid....? SAS , if you want to take the line that the S92 is superior to the 225 simply because its not currently grounded, that is your prerogative but not a helpful one because by the same measure that means an R22 is equally superior to the EC225. |
Yes HC i would agree with the comments around operation otherwise one would have expected some caution around that?? However it does seem rather odd that not a single other machine even displayed a cracked shaft beyond the accident machines, and perhaps it is in fact the specific nature that is causing the real issue.
If minute 15:21 to 17:00 is any indication (in the video below) then of course one might suggest that a specific version of FADEC, in specific conditions, would fall into the operation category, especially if it relates to this:- EASA Airworthiness Directives Publishing Tool 100K hours of which CHCN looks to have been the fleet leader at 3845hrs.... |
Kind of takes you back to when the Norwegian S-61's were shucking Spindles but the UK machines were not. Ultimately it was found to be an operational issue.
HC, if you want to use Passengers Carried as the criteria.....you might be onto something....your Company Jet Rangers are carrying more passengers than the 225 fleet I bet. |
Originally Posted by SASless
(Post 7857903)
As to calling the 225 superior to the 92 is your opinion that does seem to be challenged by the current situation.
Did I miss something and they managed to stop the the Gearbox Housing feet from cracking? Did I miss something and they managed to get the Level of vibrations down to a reasonable level? Did I miss something and the S-92 meanwhile achieves the same payload/range as the EC225? (And I'm writing this not to denegrate the S-92, rather just to show how easy blunt bashing is) I understand nationalistic pride (and I'm from neither Manufacturer's County) but does the S-92 really deserve this blind defending or is the denigration of the competing model simply because you know of all the shortcomings of your national manufacturer's product and you're looking for revenge? I tried to keep out of this but your constant gleeful bashing really starts to get annoying even for the otherwise quiet reader... :ugh: And now after having vented back to lurking... |
Blind defense?
Oh do tell us how you arrived at that conclusion? In case you failed reading comprehension.....or just did not read what is posted.....back up a few posts on the same page and digest what I said. Neither EC or SK are without fault, just as the Certification Authorities are also not without fault.....and as to the 92....there was some Operator errors as well. |
Originally Posted by SASless
(Post 7858501)
Blind defense?
Oh do tell us how you arrived at that conclusion? Edit: In case you failed reading comprehension.....or just did not read what is posted.....back up a few posts on the same page and digest what I said. But I considered it rather a fig leaf to somewhat disguise your rather open bashing. I sometimes use this tactic myself, you know... :E /Edit. Even though I have absolutely no relation to EC or the 225 it reached the point where it became simply too much. This is not youtube... And from other Posts of you I know you can do better. |
Yes, naughty SAS, get back in your box!
|
SAS
The only statistics that count are souls lost. In the OGP world do you know what the count is between the 235 and the 92 for mechanical failure? When you add that known critical faults were allowed to fly until a major casualty event no one can say the 92 is safer than the 235. The Sultan |
SAS The only statistics that count are souls lost. In the OGP world do you know what the count is between the 235 and the 92 for mechanical failure? When you add that known critical faults were allowed to fly until a major casualty event no one can say the 92 is safer than the 235. The Sultan |
Sultan, is the EC 235 the EC225 with the new shaft? |
SASless, I have not flown the S92 but I am involved in the EC225. As you have flown neither I doubt you would have a scooby of which I am about to speak. The EC225 is a wolf in sheeps clothing. It has its issues, before the shaft event, like the same cabin as its Puma stable mates which of course one could make a good argument to say the S92 in this respect is better. The Bears certainly love the space.
However, the EC225 is a significant technological leap forward from the S92 or indeed any other machine flying currently. Incidently, the EC175 takes another leap forward again and I have had the good fortune to fly it too. For those of us who have lived and operated with the EC225 we recognise the significant enhancements in safety and payload/range that the EC225 represents, and I say this in full knowledge that the poor old girl has thus far not cause any loss of life. I am fairly certain that such a statement cannot be said of any other helicopter in the air today. The S92 is certailny a fine ship with some good qualities for sure, but make no mistake, it is not even in the same stable as the EC225. It is one generation at least behind it. Your constant jingoistic jibes protray you as you are. Ill informed and ignorant of even the most basic facts. If I was able to give you just 15 minutes of time in the EC225 you would change your perspective forever. You are backing the wrong horse from a technological perspective. No doubt in regards to your private portfolio you are probably doing the right thing. Just don't try to hide behind your real motivation to those who know. Your opinions are poorly concieved and your arguments are thin reflections of a mind void of the advantages of facts. DB |
Originally Posted by DOUBLE BOGEY
You are backing the wrong horse from a technological perspective.
DB not having a go just expanding your point for those who have yet the pleasure to fly an EC225. Si |
Well happily the button pressing seems set to resume very soon...although it seems nobody told Bristow, or maybe after the last time they back peddled enough??
(Dow Jones) - EC225 helicopters, widely used to transport personnel and equipment to offshore oil rigs around the world, are expected to resume service within a few weeks after being grounded for nearly eight months because of engine problems, although two of its major players are not in agreement on the calendar. Most EC225 helicopters are capitalized since October 2012, after two helicopters were forced to land in the North Sea due to damage. Canadian CHC Helicopter operates 30 helicopters and fixed said Thursday expect that the resumption of flights of EC225 is "a matter of weeks," according to the approval of regulators and customers. Rival Bristow Group (BRS), however, does not expect that its ten EC225 to be allowed to fly again until the fourth quarter. Eurocopter, a subsidiary of EADS, said in recent weeks the helicopter operators and their customers have discovered the cause of the incident last year. The group is working with regulators to temporary solutions and a new design of the gearbox of the helicopter, which, according to Bristow, could take more than a year. "Eurocopter is confident that once the safety measures approved by the authorities, the first EC225 will resume full operation by the end of June [or] in mid-July 2013," said the manufacturer in a email. -Doug Cameron, Dow Jones Newswires |
When CHC resumes, or attempts to resume North Sea operations with the EC225, as they seem to be preparing for now, the question will almost certainly be raised as to why Bristow isn't following suit.
The CEO of Bristow has made it plain that he won't allow operations to resume until all the safety issues pertaining to the gearbox have been resolved and he's absolutely correct. I'm not going to risk being the first to reveal that while an intelligent plan has been devised to allow the existing shaft to continue in service, there is still another matter which has to be properly addressed. Bristow has never compromised on safety in my experience and I'm glad that Mr. Chiles is at the helm to continue that tradition. I've no doubt that shortly another little matter will become public knowledge and that it will most likely cause another delay. |
Something new coming out about the EM Lub not "working under certain circumstances" I heard......even though it is supposed to be fixed.
|
No. 2582-S-00
Revision 0 2013-05-24 Page 1/3 This document is available on the internet: www.eurocopter.com/techpub SAFETY INFORMATION NOTICE SUBJECT: GENERAL EC225/EC725 Main Gearbox Technical Investigation Update, Proposed Improved Safety Measures and EC225 Roadmap for the complete Return-to-Service AIRCRAFT CONCERNED Version(s) Civil Military EC225 LP EC725 AP Introduction In 2012 two EC225 helicopters made controlled water landings in the North Sea. In both incidents, the bevel gear shaft which drives the MGB oil pumps cracked and ruptured after several further flying hours. This rupture resulted in loss of oil pressure necessary for the MGB lubrication and along with an indicated failure of the emergency lubrication system (EMLUB) resulted in a checklist action to land immediately. Subsequent to the two events, protective measures were approved by EASA to permit those helicopters fitted with similar shafts to continue flying. These measures have been implemented by a number of operators representing approximately 50% of the affected fleet. Since the second event, in October 2012, approximately 100 EC225/EC725 and some Super Puma helicopters with similar shafts have continued to fly and these helicopters have flown approximately 20 000 flight hours without any crack incident. The aim of this Safety Information Notice is to update you with more detail on the technical investigation of the EC225/EC725 Main Gear Box (MGB) events. In addition, we will present some new safety measures and provide a roadmap to facilitate a common baseline for planning purposes. For some EC225/EC725 operators that are currently flying, these new measures will simplify the operation and support of their aircraft. They will also lift some restrictions for the operators’ aircraft which are equipped with the Health and Usage Monitoring System (HUMS). The EUROCOPTER technical investigation has now determined the root causes of the crack initiation and the characteristics of the subsequent crack propagation. Further safety measures are now being proposed by EUROCOPTER in order to support the aircraft currently in flight and to allow the suspended fleet to safely return to flight, starting in June/July 2013. These safety measures and their implementation are described below. In the longer term, all affected shafts in the EC225/EC725 fleet will be replaced by new shafts. These new shafts will have a modified design to eliminate any risk of crack initiation. For the attention of No. 2582-S-00 Revision 0 2013-05-24 Page 2/3 This document is available on the internet: www.eurocopter.com/techpub Technical Investigation The technical investigation has identified a combination of three root causes of crack initiation: - Active corrosion in localised areas of the shaft; - Reduced fatigue strength due to residual stresses inherent in the welding process; and - Reduced fatigue strength due to stress “hot spots”. As a result of identifying these root causes, we are able to propose: - Additional Safety measures designed to significantly reduce the risk of crack initiation. - New Safety measures, easier to apply than the current ones which in the unlikely event that a crack is initiated provide warning and prevent failure. For those operators not flying, our recommendation is that these measures should be implemented as part of a return to service safety case. These new safety measures are detailed below. New Safety Measures A number of new safety measures are being discussed with the regulatory authorities. These include: - Introduction of a shaft cleaning procedure which removes the presence of mud generated by the wear of the splines and thus the localised humid environment on the shaft, thereby significantly reducing the possibility of active corrosion and the likelihood of crack initiation. - Replacement of one of the main gearbox oil jet pipes to provide permanent shaft cleaning and improved splines lubrication. - Introduction of an ultrasonic non-destructive inspection (NDI) as an alternative to the current eddy current procedure. This NDI procedure, significantly faster to apply compared to the Eddy Current NDI ensures that crack initiation should be identified before flight. The periodicity of this inspection procedure is under discussion with the authorities and is expected to be set to permit approximately 8-10 hours flight between inspections. - Certification of a HUMS based in-flight shaft monitoring system. When fitted, this system will consist of an on-board cockpit amber warning to signal in-flight if vibration levels that indicate the presence of a crack. In the event of a warning, the aircraft will continue to safely operate for sufficient flight time to permit the pilot to return to base or perform a normal landing. Although subject to approval by the authorities, we anticipate that a flight time of two (2) hours will be allowed following the initiation of an in-flight warning. The shaft cleaning maintenance procedure is expected to be available in June 2013. This procedure will require draining the MGB but does not require any new or special tools, skills, parts or consumables. The replacement oil jet is currently being procured and is expected to be available from June 2013. The process for performing the ultrasonic NDI inspection will be published beginning of June 2013. EUROCOPTER training for your ultrasonic NDI inspectors will commence from 10th June. Planning is currently underway. EUROCOPTER is studying how best to meet operator needs for additional qualified resources for these inspections. The ultrasonic NDI inspection will require a standard ultrasonic test set and endoscope available at your facilities, along with specific probes which EUROCOPTER will provide. Certification of the HUMS based in-flight shaft monitoring system is expected by beginning of June 2013. Parts ordering and aircraft modification can commence from June 2013, when the Service Bulletin is expected to be issued. No. 2582-S-00 Revision 0 2013-05-24 Page 3/3 This document is available on the internet: www.eurocopter.com/techpub For aircraft equipped with HUMS, our aim is that the on-board shaft monitoring will in itself be sufficient to enable the authorities to lift the flight restrictions over hostile terrain. For aircraft not equipped with HUMS, our aim is that the ultrasonic NDI procedure will become an alternative to the current eddy current procedure. The classification of which safety measures are mandatory and which are recommended is currently under discussion with the authorities. New Shaft Definition In addition to these additional safety measures, the long term solution to prevent crack recurrence is to redesign the shaft. The redesigned shaft is expected to be certified in 2014. Production will commence in parallel with the certification process. Production will be increased to a maximum rate to permit fleet retrofit to commence from the third quarter of 2014. All newly delivered aircraft will be fitted with the new shafts. The retrofit of the shafts in-service is expected to be conducted during the scheduled MGB overhaul, meaning that the safety measures will be in-place until then. We are working hard to decrease the retrofit lead times and we will inform you regularly on the improvements made. Additional Information Whilst not key contributors to the ditching root causes, the investigation unearthed some additional issues and associated solutions: - The emergency lubrication (EMLUB) system operated correctly but indicated failure due to a wiring problem. As a first step the wiring on all aircraft has now been corrected. Further improvements are now planned to enhance the effectiveness of the system. It will mainly consist of a glycol pump improvement and more precise periodic maintenance. Detailed information on the EMLUB modifications will be published in an ALERT SERVICE BULLETIN and a Safety Information Notice next week. - The crash position indicator operated as designed, but it was not described in the Flight Manual. An update to the Flight Manual has been implemented. Way Ahead The EUROCOPTER investigation methodology (root cause analysis) is currently being validated by the airworthiness authorities and verified by an independent specialist, Shainin Engineering. At the same time the crack propagation investigation is being independently assessed by the Georgia Technology Research Institute (GTRI). Current discussions with the airworthiness authorities lead us to conclude that all approvals and validations should be completed by June 2013. In this case EUROCOPTER estimates that the first helicopters will be ready to return-to-service by the end of June/July 2013. This Safety Information Notice will be updated in the first half of June, in order to describe in details the new measures, and to allow you to better understand how the measures are linked and how they can be used. |
225 return to service
:rolleyes:
:ok: The crash position indicator operated as designed, but it was not described in the Flight Manual. An update to the Flight Manual has been implemented. |
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