Qantas A380 uncontained #2 engine failure
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Regarding the photo.
Maybe if you take account of the scale, it it not quite so bad. It is magnified about 5x.
And in case people have not yet realised - no,it's not a new fault. It is the same one that caused the Batam problem, as you can see from the ATSB report.
Maybe if you take account of the scale, it it not quite so bad. It is magnified about 5x.
And in case people have not yet realised - no,it's not a new fault. It is the same one that caused the Batam problem, as you can see from the ATSB report.
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Usual disclaimers apply!
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Best of luck borescoping that pipe! A 5mm oil tube, no doubt with oil residue still in situ. Probably have to use a 2.5mm scope (doubt if a 4mm will fit??). I've done enough GE90 toggle seal inspections in the past to know how difficult it can be.
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Quite a nasty problem really. No doubt RR are wondering how many more pipes have been installed in that condition, how it was manufactured, why did inspections not pick up the defect, etc.
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“Qantas doesn’t know if the (drilling issue) found on the engine on the aircraft involved on November 4 is a one off defect or a systemic problem,” he said. ” But we will find out. The inspections we are doing on all of the engines use a new 3D borescope different to the borescope used in the inspections specified in the EASA emergency airworthiness directive. There are only three of these 3D borescopes in the world and we have one of them.”
New safety defect found in Qantas A380 engines – Plane Talking
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Qantas begins legal action against RR
BBC News - Qantas begins legal action against Rolls-Royce
The carrier said its legal action allowed it "to keep all options available to the company to recover losses, as a result of the grounding of the A380 fleet and the operational constraints currently imposed on A380 services".
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Rolls Royce share price holding steady. One suspects the insurers will pay out and Rolls will instigate a review of their quality control in certain areas. Airbus (or their insurers) will also take some heat and pain,
There seems little evidence, yet, to conclude that there is a systemic problem with the Trent 900 and 1000 oil systems or overall design.
Qantas makes first move to take Rolls-Royce to court | Reuters
There seems little evidence, yet, to conclude that there is a systemic problem with the Trent 900 and 1000 oil systems or overall design.
Qantas makes first move to take Rolls-Royce to court | Reuters
Brokerage UBS estimated it may cost the airline around A$60 million in costs and lost revenue, while Macquarie estimated incremental costs of around A$20 million relating to the grounding as well as a decline in international capacity of around one percent for the first half of 2011.
DIFFICULTIES NOT YET RESOLVED
A firm estimate on the damages may still be months away as Qantas does not yet know when it can return the aircraft to service or when Rolls-Royce can fully solve the technical issues.
DIFFICULTIES NOT YET RESOLVED
A firm estimate on the damages may still be months away as Qantas does not yet know when it can return the aircraft to service or when Rolls-Royce can fully solve the technical issues.
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Looking at the pic of the tube, it must be in the region of 20mm diameter, if the 5mm is a scale reference.
Are there any other views of it?
I have a background in precision engineering inspection (not aeronautical) and from the one pic I could not tell where the manufacturing error is - too many odd angles and much material is missing. Be interesting to spend some time checking it over.
I'd also like to know how it was made. A non-concentric counter bore is actually quite hard to achieve in a turned component (assuming it's turned, of course). If it's been CNC'd there's a whole batch of tubes with the same fault... A thorough procedures audit is probably being lined up somewhere.
How is it decided that this part was damaged in service rather than during the incident?
Are there any other views of it?
I have a background in precision engineering inspection (not aeronautical) and from the one pic I could not tell where the manufacturing error is - too many odd angles and much material is missing. Be interesting to spend some time checking it over.
I'd also like to know how it was made. A non-concentric counter bore is actually quite hard to achieve in a turned component (assuming it's turned, of course). If it's been CNC'd there's a whole batch of tubes with the same fault... A thorough procedures audit is probably being lined up somewhere.
How is it decided that this part was damaged in service rather than during the incident?
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Can anyone tell me if the oil supply pressure is regulated on the Trent?
If it is a simple unregulated system, ala most turbine engines I know, then the pipe breakage would immediately show up as a drop in oil pressure. Trend monitoring, either manual or automatic, would pick this up.
Likely would not change the outcome, unless the crew shut down #2 immediately; but would be a valuable clue in sorting out the origin of the failure.
If it is a simple unregulated system, ala most turbine engines I know, then the pipe breakage would immediately show up as a drop in oil pressure. Trend monitoring, either manual or automatic, would pick this up.
Likely would not change the outcome, unless the crew shut down #2 immediately; but would be a valuable clue in sorting out the origin of the failure.
Barit1
The more fancy you get with this kind of trend monitoring the less conclusive it is.
The oil systems have many leakage paths like overboard breathers etc. Thus some perfectly safe engines leak even more than the engine that is not safe (false positives). The key is the type and location of the leak. The worst leak is wet oil (not just fumes) directly into a rotor disk cavity.
More than just RR has had this problem. The solutions are typically problem specific (based on data). The surprise here was that the result didn't seem to be forewarned by previous data (or was it?).
However armed with the latest information the going forward approach would be obvious and hindsight truly a lesson learned for all manufacturers and users.
To me the part defect should not be unexpected, however we shouldn't have expected the surprise result without a clue beforehand (FAR/JAR 33.75)
Can anyone tell me if the oil supply pressure is regulated on the Trent?
If it is a simple unregulated system, ala most turbine engines I know, then the pipe breakage would immediately show up as a drop in oil pressure. Trend monitoring, either manual or automatic, would pick this up.
Likely would not change the outcome, unless the crew shut down #2 immediately; but would be a valuable clue in sorting out the origin of the failure.
If it is a simple unregulated system, ala most turbine engines I know, then the pipe breakage would immediately show up as a drop in oil pressure. Trend monitoring, either manual or automatic, would pick this up.
Likely would not change the outcome, unless the crew shut down #2 immediately; but would be a valuable clue in sorting out the origin of the failure.
The oil systems have many leakage paths like overboard breathers etc. Thus some perfectly safe engines leak even more than the engine that is not safe (false positives). The key is the type and location of the leak. The worst leak is wet oil (not just fumes) directly into a rotor disk cavity.
More than just RR has had this problem. The solutions are typically problem specific (based on data). The surprise here was that the result didn't seem to be forewarned by previous data (or was it?).
However armed with the latest information the going forward approach would be obvious and hindsight truly a lesson learned for all manufacturers and users.
To me the part defect should not be unexpected, however we shouldn't have expected the surprise result without a clue beforehand (FAR/JAR 33.75)
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Having read the AD, it appears that a relaxation of wear limits occurred for the splines. The splines were to be assessed at "crown", a wear of 2.15 mm was to be the trigger for strip and rebuild. As built, the Spline crown is 2.65 mm. When Crown diminished to .5mm, down she comes. At some point, EASA was convinced the "Wear" values could be "Meaned", allowing some wear resistant splines to proxy for what had been a non negotiable "off the wing" event. This extended the "service" of the Splines on the wing, and may have been responsible for November 4, perhaps.
This stub pipe appears to be approx 15 mm in diameter, so the bits lost off the end were perhaps 3-4 mm in size. These bits cannot in my opinion have caused the emergency. Left to roam in a bearing box is not desirable, but oil flow, seal integrity, and bearing misalignment, causing Spline wear signify a degradation over time. The IP is thought to have migrated aft, to do this, the thrust duty of the integrated bearing was compromised, I think. Again I note the soot on the LP Shaft. The report will make some great reading imo.
bear
This stub pipe appears to be approx 15 mm in diameter, so the bits lost off the end were perhaps 3-4 mm in size. These bits cannot in my opinion have caused the emergency. Left to roam in a bearing box is not desirable, but oil flow, seal integrity, and bearing misalignment, causing Spline wear signify a degradation over time. The IP is thought to have migrated aft, to do this, the thrust duty of the integrated bearing was compromised, I think. Again I note the soot on the LP Shaft. The report will make some great reading imo.
bear
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Iomapaseo
I was in full agreement until the last paragraph. The Safety Assessment called for by FAR 33.75 is not easy to do . If it were we would never have any unpleasant surprises. In general the discipline is a pretty good coarse filter and certainly better than nothing.
And we fought long and hard to retain the rigour of European Requirements. So there is no such thing as JAR 33.75. It is JAR E, or in this case I believe something called CS-E 515.
bearfoil - Could you please state in simple terms the failure progression you are postulating? Your thoughts are very interesting but I sometimes have difficulty in following them.
Do you think there was not an oil fire?
I was in full agreement until the last paragraph. The Safety Assessment called for by FAR 33.75 is not easy to do . If it were we would never have any unpleasant surprises. In general the discipline is a pretty good coarse filter and certainly better than nothing.
And we fought long and hard to retain the rigour of European Requirements. So there is no such thing as JAR 33.75. It is JAR E, or in this case I believe something called CS-E 515.
bearfoil - Could you please state in simple terms the failure progression you are postulating? Your thoughts are very interesting but I sometimes have difficulty in following them.
Do you think there was not an oil fire?
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bearfoil - Could you please state in simple terms the failure progression you are postulating? Your thoughts are very interesting but I sometimes have difficulty in following them.
Last edited by firstfloor; 2nd Dec 2010 at 18:53.
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I find it strange that posts including:
'Balance discs', forward & rearward gas loads, 'axial bearing thrust control' among other more obscure topics are tolerated on Rumours & News.
Whereas, mention of a composite fuselage (the future of aviation, no kidding) suffering fire damage and not complying with FAA requirements, is sent to Tech Log.
What is happening now to the 787 affects us ALL. Please don't hide it away.
.
'Balance discs', forward & rearward gas loads, 'axial bearing thrust control' among other more obscure topics are tolerated on Rumours & News.
Whereas, mention of a composite fuselage (the future of aviation, no kidding) suffering fire damage and not complying with FAA requirements, is sent to Tech Log.
What is happening now to the 787 affects us ALL. Please don't hide it away.
.
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Old Engineer...
The Trent engines powering the A380 however are NOT new engines, they are newer iterations of the RB211 which was a product of the late 1960's
The Trent engines have been around since 1990.
In other news, methinks legions of barristers, probably more than enough to sort thru multiple cascading serious legal issues (that number is 2
) are lining along the trough for a feeding frenzy.
The situation of problems in a newly designed engine essential for an newly introduced airframe has occurred before. We have to go back about 40 years. It is the 747 and its PW engine. The details are in "Wide-Body ... The Triumph of the 747", by Clive Irving, publisher Morrow, 1992. You'd want to look in Ch 17, "The Ink and Iced Water Men."
The Trent engines have been around since 1990.
In other news, methinks legions of barristers, probably more than enough to sort thru multiple cascading serious legal issues (that number is 2
) are lining along the trough for a feeding frenzy.
CAAAD
Of course you are right about the exact specification JAR-E etc.
And yes I would agree about it not being an exact or easy to do.
But where would we be without such a requirement? Should we simply tell the public that life's a bitch and some engineering mistakes are gonna really knock your socks off?
We must have regulations that ensure that the best safety processes are followed. The idea is to enforce that lessons learned are really adopted in design practices overseen by a regulation and should the argument be placed forward that it's too difficult in some area then at least there should be a fall back to a "prime reliable" approach that forces a specific attention to detail a least equivalent to the design, and maintainence controls placed on a rotor disk itself.
Don't misunderstand, I'm not saying they did it wrong, I'm simply saying that we must ensure that everybody does it better in the future.
I was in full agreement until the last paragraph. The Safety Assessment called for by FAR 33.75 is not easy to do . If it were we would never have any unpleasant surprises. In general the discipline is a pretty good coarse filter and certainly better than nothing.
And yes I would agree about it not being an exact or easy to do.
But where would we be without such a requirement? Should we simply tell the public that life's a bitch and some engineering mistakes are gonna really knock your socks off?
We must have regulations that ensure that the best safety processes are followed. The idea is to enforce that lessons learned are really adopted in design practices overseen by a regulation and should the argument be placed forward that it's too difficult in some area then at least there should be a fall back to a "prime reliable" approach that forces a specific attention to detail a least equivalent to the design, and maintainence controls placed on a rotor disk itself.
Don't misunderstand, I'm not saying they did it wrong, I'm simply saying that we must ensure that everybody does it better in the future.