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Cyclic yes I know, but that tragic accident is nevertheless unrelated to this one from a technical point of view.
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Unrelated???
The MGB failed in all 3 accidents. How on earth can you claim that they are unrelated? :rolleyes: |
What replacements are there for the EC225? A civilian AW101 or further S92s?
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Yes. Design Verification. Joking might be excused under the banner of gallows humour in this particular instance given all are well, although in no small thanks to the pilots. Fair play to the CAA but actually I'm not sure the terrain - hostile or not - cares too much when the gearbox internals are sh1tting themselves. This is going to end up as a Harvard business school case study. Eurocopter have winged it since May in a vein attempt to avoid what is now the almost certain fact that they will need to say that a design, material, manufacturing (or combination) has caused issues. The failure of the Emergency lubrication system is a sideshow. Beyond that the failure of the MGB in the 2009 crash of G-REDL suggests a more worrying attitude. In the case of REDL it was suggested in the AAIB report that the planet gear was lifed to 6600hrs in the AS332, 4400hrs in the EC225. I think I'm right in saying that the failure occured at around 3800hrs but then the manufacturer seeming to want to rely heavily on HUMS which whilst mandated what are the thresholds of the condition indicators before the operator is well over the line? Two things seem to hold true. The manufacturer in the event of a failure seems to rely very heavily on the HUMS and whilst they don't suggest it is the primary method of detecting gearbox degradation thats exactly how it seems to be spun when a EC225 ends in the sea. Beyond that as has already been said before an alarm is fine but without strict guidelines of what exactly means "no go" I'm not sure the alarm was anymore help in the case of REDL. |
Cyclic yes I know, but that tragic accident is nevertheless unrelated to this one from a technical point of view. The problem with that is you are using tech to cover up flakey mechanicals and when the technical specialisms are such that the manufactuer knows more than the authority its not hard to see how they can cloud issues. Its a very dangerous situation. |
Originally Posted by Bravo73
(Post 7486446)
Unrelated???
The MGB failed in all 3 accidents. How on earth can you claim that they are unrelated? :rolleyes: Or to make the reasoning more obvious: Do you think fixing the one issue will do anything to prevent what happened in the other case ?!. |
HC says
"For the record, Bristow downloads the HUMS data at each return to base, and an aircraft is in not despatched until the HUMS data has been checked and found to be "green". That process takes less than 5 minutes". (Could be 4 hours of data?) If correct surely it is no beyond reason to mandate this, 5 minutes v £XXm seems a good return. I presume the new data is run against legacy data, & anomaly's logged\displayed, it is still not clear why there is no way of presenting real time information even in crude form,by continuous data streaming over air. Formula 1 seems to have a fair grip on what is happening within engines, gear box & hydraulic systems, G force, steering angles, throttle & some life science for driver +++ |
Shoes pinch a bit when they are on the other foot don't they?
S92 had a head start on catastrophe, now it is 225's turn to catch up a bit, but now that the fleet has effectively been grounded this problem will be fixed and without loss of life. If the Cougar Crew had complied with the Checklist (as the Co-Pilot reminded the Captain at least twice)....what would the score have been? The accident analysis clearly demonstrated a prompt controlled ditching would have prevented the Gearbox failure that caused the uncontrolled crash into the water that proved fatal. In the North Sea events the crews DID follow the Checklist.....despite the temptation in one case of having land quit near and all turned out well. That they did because of a false report of a failure of the Emergency Lube system does not change the fact they ditched rather than continue to fly a machine with a suspected gearbox failure. We cannot say that about the one that shed its rotor head can we....and do we really know what caused that one? We know what failed....but do we know with definity what caused that to happen? Why is it we see the EC aircraft being limited to a HUMS download every three hours.....are the MGB's that susceptible to failures that such monitoring is necessary? You are quite correct I have flown neither the 225 or the 92 and that allows me to be absolutely impartial in my evaluation of the two. I never worked for Sikorsky or EC...I have not been a Company Type Captain, have not been involved in making recommendations to Management about which aircraft to buy, and have had no involvement in formulating SOP's, writing Checklists, or anything like that for an Operator for either of the two aircraft. Are you that free of bias? Face it....EC has a problem every bit as serious as Sikorsky did. Like it or not....currently your favorite helicopter is grounded as being unsafe to fly in the Commercial Market. I would suggest implying Bristow is bullet proof on this is just Whistling as you walk past the Graveyard. The fact Bristow has not had one of these events does warrant examining to see what is being done different by your Engineering staff that might not be happening elsewhere....as there might just be something there worth duplicating by other Operators. Yet....the absence of an event does not mean it cannot happen to Bristow. |
technically there does not seem to be a causal connection between the two 225 shaft failures on the one side and the 332 sun gear failure on the other side |
Congratulations to the CAA for having the balls to issue their Directive. :D
When I read the EASA AD its logic and rationale seemed to have so many holes it looked like a Swiss cheese. The CAA do not appear to be advertising their initiative by broadcasting it on their website on the pages that the media might check. It must be a difficult thing for them to do politically, in essence publically disagree with the all-powerful (but wrong) EASA bandwagon. Cannot but wonder at the pressures that may be being applied. I wonder if the general media will catch-on to what is happening? |
Originally Posted by Helinut
(Post 7486790)
I wonder if the general media will catch-on to what is happening?
Restrictions imposed on Super Puma helicopter The Civil Aviation Authority (CAA) has banned the use over sea of helicopters similar to one which ditched off Shetland. The CAA order applies to all Super Puma EC225s and some AS332s, except those involved in "life-saving" operations. The manufacturer has ordered extra safety checks in an attempt to prevent a repeat of the incident. An air accident report on Monday's ditching said it was caused by a serious gearbox failure. All 19 men on board the Super Puma EC 225 survived. Continue reading the main story “ Start Quote I understand that Eurocopter has to rebuild confidence in our company. Two ditchings are two too many” Derek Sharples Eurocopter executive vice president Eurocopter said gearboxes should be monitored more closely and at more regular intervals. The French company said Monday's problem was similar to one which caused a helicopter to ditch in the North Sea in May. It said all its efforts were now being devoted to fully understanding the root cause of the failure. Eurocopter executive vice president Derek Sharples told the BBC Scotland news website: "I understand that Eurocopter has to rebuild confidence in our company. "Eurocopter has issued a new set of measures to reassure operators, crew and passengers that the aircraft is safe to fly. With these measures we seek to eliminate any reoccurence. "We understand these concerns and take them seriously. Two ditchings are two too many." Investigators found a failure in the lubrication system of the helicopter which ditched near Fair Isle. A special bulletin issued by the Air Accidents Investigation Branch (AAIB) said the main and standby oil pumps were not working. Shaft crack All those on board the Super Puma EC 225 were rescued safely after it ditched during a flight from Aberdeen to the West Phoenix rig, west of Shetland.The AAIB report suggests that the helicopter came close to being involved in a much more serious incident on Monday. The bulletin said a 360 degree crack was found on the bevel gear vertical shaft of the helicopter. This crack prevented the oil pump gears from being driven. The AAIB said the European Aviation Safety Agency (EASA) and the manufacturer were urgently reviewing the effectiveness and scope of an airworthiness directive previously issued for this helicopter type. Flights by other aircraft of the same type have been halted. 'Growing concern' BBC Scotland has also learned that two North Sea search and rescue Super Pumas operated by BP have been restricted to "life-saving" operations only in the wake of the incident. These are rescuing people from the water, and "life and death" medical evacuation cases. BP said it was looking at bringing in Sikorsky aircraft to provide temporary cover while the industry examines the evidence from the CHC-operated Super Puma ditching. Balpa, the union which represents professional pilots, said there was now "growing concern" amongst pilots and offshore workers. 'Saving lives' Willie Wallace, regional industrial officer with the Unite union, said: "We clearly have a problem with the gearbox components on these particular helicopters. "The manufacturer Eurocopter has ordered safety checks and said that 'two ditchings is two too many'. "We agree. We cannot rely on luck to keep saving lives." The crew of another Super Puma helicopter ditched in the North Sea in May after a gearbox failure. All 14 passengers and crew involved in that incident, about 30 miles east of Aberdeen, were rescued. A special meeting of the industry's helicopter safety group is due in Aberdeen on Thursday afternoon. http://news.bbcimg.co.uk/media/image..._puma_oct3.jpg http://news.bbcimg.co.uk/media/image...opthree624.jpg |
Don't forget this Bristows Puma ditch
That no one knows the circumstances of. http://www.pprune.org/rotorheads/486...ex-g-pumi.html |
I was a bit disappointed by the Eurocopter man on the telly last night saying that the EC225 is a very safe helicopter. What do you expect him to say? He has to say that to one and all, it's his priority! |
Well done to the crew of CHCN on a job well done!
Lowfat I believe that PUMI was an unplanned ditching of a perfectly serviceable helicopter due to poor handling. No Gearbox issues, hence irrelevant in this discussion apart from the ditching aspect (which was not planned), and evacuation process... similar to the Bond ETAP 'ditching'. |
The problem with effectively grounding the EC225, even with the EC enhanced monitoring is that there will have to be a very solid reason to rescind the grounding. Without some concrete assurances that this problem is somehow fixed (with a new shaft?) which could take a long time, the EC225 could be having a long rest. In this instance, I think that increased oversight would have been better than a grounding.
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Increased oversight in terms of what?
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"Oversight" can only be maintained by the HUMS being downloaded within every 3 hours of TOTAL running time, airborne and non-airborne. However I don't believe that we should be flying again until the emlube is made not only 100% reliable, which it is, but that the problem of false warning of emlube failure gets convincingly sorted out.
IMHO the present shaft has to be replaced with the older type which used different processes and techniques to join the bevel gear to the shaft. That will obviously take a long time to achieve. The French told our bosses that it can't be done, but I don't understand why. It has to be done! With these provisos, I'll feel comfortable to fly again while a replacement for the existing shaft is being produced and tested. However our passengers will understandably need a lot of convincing. |
With these provisos, I'll feel comfortable to fly again while a replacement for the existing shaft is being produced and tested. However our passengers will understandably need a lot of convincing. |
Pitts
Increased HUMS downloads as Colibri says, not much else can be done. The 3 hour downloads should be sufficient to show the beginnings of propagation if past experience is anything to go by. Now that it is grounded, what action can be taken to rescind the grounding? New shaft? Design, test, manufacture and install; 1 year? If it is 1 year, there are not enough spare 332Ls with functioning MGBs or S-92s around to make up the deficit. The oil companies will be looking for a way to not continue to pay the operators, who won't be making enough revenue to pay the banks. How long before some jobs may have to go? |
This is what the passengers are being told/briefed:
G-CHCN ditching incident - Step Change in Safety http://www.stepchangeinsafety.net/te...setFileID=1562 |
If it is 1 year, there are not enough spare 332Ls with functioning MGBs or S-92s around to make up the deficit. The oil companies will be looking for a way to not continue to pay the operators, who won't be making enough revenue to pay the banks. How long before some jobs may have to go? |
false warning of emlube failure gets convincingly sorted out. "EMLuBe Fail(ed to fix the problem) - Ditch" then in fact it is working properly, If I were writing the software, I might well decide to not have a host of different error messages when the conclusion is the same. |
Just out of interest - how many Aberdeen aircraft does this affect (all 3 operators)?
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As it stands, that message from the StepChange website is out of date. If I understand the effect of the CAA Operational Directive, it will prevent the use of any UK-Reg Pumas and variants offshore, if they have the relevant part number shaft.
The "Step Change" party line is really just the view of the offshore installation operators. It is clear they wanted Puma shuttles to resume with limited restrictions. I wonder whether this will change, in the light of the CAA action? |
Is relying on HUMS acceptable?
CAP 753 (8.3) states that HUMS must detect no less than 70% of failure modes that it is directly monitoring. The oil pump shaft is not directly monitored so presumably the rate of detection may be less than 70%. At what percentage do you say the risk is mitigated and it's OK to fly? Can EC or an operator demonstrate 225 HUMS will always give an early warning of impending failure? |
Originally Posted by Helinut
(Post 7487270)
As it stands, that message from the StepChange website is out of date. If I understand the effect of the CAA Operational Directive, it will prevent the use of any UK-Reg Pumas and variants offshore, if they have the relevant part number shaft.
The "Step Change" party line is really just the view of the offshore installation operators. It is clear they wanted Puma shuttles to resume with limited restrictions. I wonder whether this will change, in the light of the CAA action? Why is the EC225 still suspended? The helicopter operators took the decision to continue to suspend the EC225 until further guarantees can be provided on its safety. Independent of this, the UK aviation regulator, the Civil Aviation Authority (CAA) has since issued an operational directive forbidding its use for offshore transport. This continued suspension of the EC225 is fully supported by the Helicopter Safety Steering Group and the trade unions. |
Exactly the point Sanus. You have answered the question yourself.
This failure of the defective part is known and at the moment has an apparent return period of 6 months in the UK fleet. Apparently the HUMS has only a relatively small chance of preventive detection, so the frequency of further undetected failures is pretty significant if the affected aircraft continue to fly. Its only a satisfactory resolution, if you are happy with a reasonable prospect of North Sea "controlled" ditching, in the winter months. We have been very lucky so far, that the outcomes have not involved injury or worse. What is the conditional probability of benign conditions in a North Sea winter? It gives the expression "wing and a prayer" new resonance. B73 - thanks for pointing me at the second link. However, is it not less to do with the aircraft type/variant but more with the gearbox shaft batch part number/method of manufacture? |
Originally Posted by 902Jon
(Post 7487263)
Just out of interest - how many Aberdeen aircraft does this affect (all 3 operators)?
The return to flying will see an additional one AS332L1 and eight AS332L2 aircraft amongst the three Aberdeen-based operators. So, in essence, the CAA directive effects all but 9 Super Pumas in ABZ. |
I wonder what the time scale is for going back to original design shafts on the L and L2 models. I also wonder if it is possible to rework the existing new design shafts which are in service now or will EC have to start from scratch. I assume it takes a long time to make a shaft due to the manufacturing, chemical treatment and ageing processes involved so the North Sea (and other areas) is probably in for a lengthy disruption.
The loss of a significant proportion of O & G helicopter support worldwide is bound to cause serious concern at the highest levels of the oil companies management and governments. |
To think all those S-61's that got flogged off for junk prices!:(
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Originally Posted by Helinut
(Post 7487299)
B73 - thanks for pointing me at the second link. However, is it not less to do with the aircraft type/variant but more with the gearbox shaft batch part number/method of manufacture?
Why are some Super Pumas flying and others not? The difference is down to a certain type of component – the main gearbox vertical shaft. For ease, these have been labelled below as shafts 1 and 2. Type of shaft.......Can be fitted in.......What is it?.........Approved for use? “Shaft 1”......L, L1 and L2 models........This is the original design of shaft. Has accumulated 4.5 million flight hours without incident......Yes “Shaft 2”...... L, L1, L2 and EC225 L, L1 and L2 aircraft can be fitter with either Shaft 1 or Shaft 2 If not already so, these will now be re-fitted with shaft 1 in order to be fly again. All EC225s feature shaft 2 and cannot be fitted with Shaft 1........... A change in the manufacturing process of specific batches of Shaft 2 was originally thought to be the cause of the G-REDW ditching in May. New evidence is coming to light which suggests that the scope 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 no currently permitted by the CAA. |
I thought the EC225 fleet leader has nearly 40K hours accumulated?
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40,000 hours???? It was only certified in 2004 so that would mean the aircraft flying something in the order of 13 hours a day, every day, for the last 8 years.
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First introduction a little bit less than 8 years ago so the answer is : no
G-TIGC, a 332L from Bristow for sale (up to now...) is 30 years old with about 34000 Hrs TT. . |
Not far shy of 10,000 hrs on one NS 225 that I know of
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As of December 2011 there were two aircraft with 9K hours, so current EC225 fleet leader is likely to be at ~10K.
I/C |
I'm just using Eurocopters own data:-
Puma helicopter, super puma - Eurocopter helicopters - Eurocopter, an EADS company which says:- The EC225 has evolved from the vast experience accumulated by some 100 Super Puma operators; some 900 helicopters have been ordered in 52 countries. The in-service Super Puma fleet has logged more than 4,4-million hours and the fleet leader has flown 39,300 hours. One assumes therefore that they are now being clever with the mix and match of types. |
Not really, to be fair. The 'in-service Super Puma fleet' includes all the various variants of the AS332 and the EC225. (The EC225 is, in essence, an AS332 L3).
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ha yes but Bravo I think we are seeing that some Super Puma's are more Super than others...
One truely wonders how that approach was used in the approval process. Over simplification no doubt but do you just take AS332L2 then say you've ran the new gearbox on a rig for X hours and therefore we are good to go with the EC225? The focus on the emergency gearbox cooling system is all well and good but remember thats just the short term fix if you have one type of in flight issue. As has been said before when parts of the gearbox are departing through the fuselage a cooling system isn't going to save you. The only real solution short term is limit the torque of the 225 to protect the gearbox that it has and for the manufacturer to give a strict limits on checks. Although one might note that in the case of REDL the suggestion was that existing detection methods wouldn't have provided further indication of issues. Now I know the failures are different but with no explaination why a 3000hr gearbox shat itself which was lifed to 6000hrs and with 2 further gearbox issues in 2012 I think an engineering solution is needed not just a software update and the responsibility dumped on the operator or worse maintenance for the operator. Would you want that on your conscious? |
The only real solution short term is limit the torque of the 225 to protect the gearbox |
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