Qantas A380 uncontained #2 engine failure
Pabellum
Given the way the info is now being used to sensationalise and may in the worst case affect (unfairly) public perception of A380- you should be careful. Unlike many on here who just want to understand what went wrong, journos have a different agenda and can't generally be trusted!
Plus your mates drinking buddy would be unimpressed I'm sure if what he said in a bar was being noted down for publication on the Internet later!
Given the way the info is now being used to sensationalise and may in the worst case affect (unfairly) public perception of A380- you should be careful. Unlike many on here who just want to understand what went wrong, journos have a different agenda and can't generally be trusted!
Plus your mates drinking buddy would be unimpressed I'm sure if what he said in a bar was being noted down for publication on the Internet later!
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Wow
This thread is fascinating. I just can't believe the amount of damage the airplane sustained. I can't wait to see the TV show Mayday's version of this incident, LOL
Thank you all for the great information.
This is my first post. I have no aviation background. I am just a former electronic tech in the Canadian armed forces with an interest for this type of epic technological sagas.
Thank you all for the great information.
This is my first post. I have no aviation background. I am just a former electronic tech in the Canadian armed forces with an interest for this type of epic technological sagas.
Nemo Me Impune Lacessit
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I do take your point JFZ90 but what I have posted has been out there for all to see and for a while now, I also discovered today that it has also been in the national press. I was the third poster on this thread.
Mates buddy will have seen it all on here and in a daily paper long before I posted, I just hadn't kept up to speed with the thread.
Mates buddy will have seen it all on here and in a daily paper long before I posted, I just hadn't kept up to speed with the thread.
"The INTRODUCER"
Slightly surprised to see the FAA issuing an AD on an aircraft which, as they point out, is not in service with any US operator. I didn't realise they ever did that. Do they just adopt all EASA ADs now as a formality?
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looks like RR, Airbus and Quantas knew all along
It looks like RR and Airbus, Quantas and the authorities knew all along about *potential* issues on those motors. It's going to be instructive to watch the insurers next actions, and whether they pay out to Quantas or not. I have a feeling that Quantas is going to be losing money this year.
Edmund
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parabellum
Thanks for that AD.
Very interesting.
Not sure how these things work. With an AD like this in general, (or even better yet specifically with regards this one), is an inspection called for immediately or after a certain number of cycles or can an inspection be delayed legally until the next routine service in the shop.
Guessing in some cases an operator could be fully compliant with certain ADs without having actually completed an inspection simply because the AD time frame/cycles/critera had not been reached.
Thanks for that AD.
Very interesting.
Not sure how these things work. With an AD like this in general, (or even better yet specifically with regards this one), is an inspection called for immediately or after a certain number of cycles or can an inspection be delayed legally until the next routine service in the shop.
Guessing in some cases an operator could be fully compliant with certain ADs without having actually completed an inspection simply because the AD time frame/cycles/critera had not been reached.
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Mrbigbird
It's up to the authority.
Qantas have never said they did the inspections before the big bang, just that they were compliant.
In this case EASA specified that engines having done more than 250 cycles had to be inspected within 150 cycles.
That's a LONG time for an A380. See Table 1 at the bottom of the AD:
http://www.channel4.com/media/c4-new...0-0008R1_1.pdf
Qantas have never said they did the inspections before the big bang, just that they were compliant.
In this case EASA specified that engines having done more than 250 cycles had to be inspected within 150 cycles.
That's a LONG time for an A380. See Table 1 at the bottom of the AD:
http://www.channel4.com/media/c4-new...0-0008R1_1.pdf
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I do not think that the coupling spline wear thing (subject of AD) is connected to bearing box oil leak which seems to have casued this recent incident. It looks to me as if some posters are thinking they are connected but I do not see the connection.
But we don't know yet that the August 2010 AD has anything to do with the thread subject incident 
and BTW there are lots of problems out there under ADs whose compliance times still assume some minor failure conditions, else we wouldn't be flying at all. So waving an AD around for extensive political discussion has little to add.
But thanks for the technical information to the poster
and BTW there are lots of problems out there under ADs whose compliance times still assume some minor failure conditions, else we wouldn't be flying at all. So waving an AD around for extensive political discussion has little to add.
But thanks for the technical information to the poster
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The trail of failure was not instant. This is a conclusion, and made without evidence. It is informed speculation, nothing more.
This engine is built like a battleship; stresses within can be understood mathematically, but seldom viscerally. Any "Spline Wear" may have had a few different causes. It is best guess territory. Alan Joyce declares "Oil where it shouldn't be". Fine, but he is reporting this, it is not to be taken as a new development. It is most likely oil seepage was patent. Like any massive powerplant, there are "parameters" of service.
The AD specifies a timeline for "Deferrable Maintenance". All this means is that the timetable for inspection/mitigation is decided by the authority. Their work is also a "best guess". In hindsight, the affected serial numbers would have been grounded and repaired/refit immediately.
So back to spline wear and lubrication issues. There has to be a "New Duck" at play to cause such rapid degradation of machined surfaces, and the logical culprit is lack of sufficient lubrication. "Oil where it shouldn't be" implies "Lack of oil where it should be". The bearings restrain a finely balanced Shaft/Wheel combination, and any rogue wear would rapidly compromise the connection, causing imbalance and harmful vibration: "The more it wears, the faster it wears." and worse. Normal strain gets abnormal, etc. The status of the assembly at disintegration, (the millisecond prior) would most likely show an unbelievably "box of rocks", needing to escape.
If the bearings disintegrated, the resultant imbalance would throw the Disc off like a mosquito, if they seized, a different type of failure would have evolved, perhaps to include a scrub of the splines and wicked overspeed. I think overspeed and heat damage was the cause, with a bold contribution of bearing failure. This overspeed would be a result of unspooling from the Shaft, the Blades still being present. As the Wheel migrates instantly into the face of the stator, Blade loss is complete, instantaneous, and clean. The vertical fractures to me show a hub failure, not a disc failure, per se. IMO
This engine is built like a battleship; stresses within can be understood mathematically, but seldom viscerally. Any "Spline Wear" may have had a few different causes. It is best guess territory. Alan Joyce declares "Oil where it shouldn't be". Fine, but he is reporting this, it is not to be taken as a new development. It is most likely oil seepage was patent. Like any massive powerplant, there are "parameters" of service.
The AD specifies a timeline for "Deferrable Maintenance". All this means is that the timetable for inspection/mitigation is decided by the authority. Their work is also a "best guess". In hindsight, the affected serial numbers would have been grounded and repaired/refit immediately.
So back to spline wear and lubrication issues. There has to be a "New Duck" at play to cause such rapid degradation of machined surfaces, and the logical culprit is lack of sufficient lubrication. "Oil where it shouldn't be" implies "Lack of oil where it should be". The bearings restrain a finely balanced Shaft/Wheel combination, and any rogue wear would rapidly compromise the connection, causing imbalance and harmful vibration: "The more it wears, the faster it wears." and worse. Normal strain gets abnormal, etc. The status of the assembly at disintegration, (the millisecond prior) would most likely show an unbelievably "box of rocks", needing to escape.
If the bearings disintegrated, the resultant imbalance would throw the Disc off like a mosquito, if they seized, a different type of failure would have evolved, perhaps to include a scrub of the splines and wicked overspeed. I think overspeed and heat damage was the cause, with a bold contribution of bearing failure. This overspeed would be a result of unspooling from the Shaft, the Blades still being present. As the Wheel migrates instantly into the face of the stator, Blade loss is complete, instantaneous, and clean. The vertical fractures to me show a hub failure, not a disc failure, per se. IMO
More Scuttlebutt from the Antipodes ( unverifiable source)
1. Bus #2 is supposedly automatically powered by Bus #1 in the event of Engine #2 failure - didn't happen.
2. Buses #3 & #4 will supposedly power Bus #2 in the even that the auto transfer from Bus #1 fails - didn't happen.
3. After some time the RAT deployed for no apparent reason, locking out (as a load-shedding function) some still functioning services.
4. One of the frequently recurring messages warned of the aircraft approaching the aft C of G limit (the procedure calls for transferring fuel forward), the next message advised of fwd transfer pumps being u/s. This sequence occurred repeatedly.
5. Apparently landing/approach speeds are obtained from the FMS, but there weren't anywhere near sufficient fields to load all the defects for speed corrections - the crew loaded what they thought were the most critical ones.
6. The crew commenced an approach NOT because they'd sorted out all the problems but because they were very worried about the way-out-of-tolerance and steadily worsening lateral imbalance.
7. The aircraft stopped with just over 100 metres or runway left, brakes temps climbed to 900C and fuel pouring out of the ruptured tank. Unable to shutdown #1 engine (as previously mentioned) but elected not to evacuate as the fire services were attending in great numbers.
8. The other comment from the source of the above (who was on the flight deck) was that the aeroplane did many things they simply didn't understand and/or failed to operate as expected.
1. Bus #2 is supposedly automatically powered by Bus #1 in the event of Engine #2 failure - didn't happen.
2. Buses #3 & #4 will supposedly power Bus #2 in the even that the auto transfer from Bus #1 fails - didn't happen.
3. After some time the RAT deployed for no apparent reason, locking out (as a load-shedding function) some still functioning services.
4. One of the frequently recurring messages warned of the aircraft approaching the aft C of G limit (the procedure calls for transferring fuel forward), the next message advised of fwd transfer pumps being u/s. This sequence occurred repeatedly.
5. Apparently landing/approach speeds are obtained from the FMS, but there weren't anywhere near sufficient fields to load all the defects for speed corrections - the crew loaded what they thought were the most critical ones.
6. The crew commenced an approach NOT because they'd sorted out all the problems but because they were very worried about the way-out-of-tolerance and steadily worsening lateral imbalance.
7. The aircraft stopped with just over 100 metres or runway left, brakes temps climbed to 900C and fuel pouring out of the ruptured tank. Unable to shutdown #1 engine (as previously mentioned) but elected not to evacuate as the fire services were attending in great numbers.
8. The other comment from the source of the above (who was on the flight deck) was that the aeroplane did many things they simply didn't understand and/or failed to operate as expected.
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Why loss of HYD sys and Electric control of Engine 1 LP and HP shut off valves
It would seem much investigation is required apart from the Engine failure.
1/ Why the loss of a HYD system? I thought that there are HYD valves that sense a rapid loss of fluid and automatically shut off to stop any more fluid loss. Something learnt from Sioux City accident, priority shut off valves?
2/ The EBHAs that power the spoilers in the event of HYD fluid loss appear not to have operated, at least one, as seen on YouTube.
3/ On ALTN braking, loss of LEHGS. I believe another self contained HYD sys to self activate in the event of HYD sys loss that didn't work?
4/ Why is the electrical wiring controlling #1 engine contained within the # 2 engine. Sioux City showed the aviation world the disastrous consequences of having controlling systems route together.
1/ Why the loss of a HYD system? I thought that there are HYD valves that sense a rapid loss of fluid and automatically shut off to stop any more fluid loss. Something learnt from Sioux City accident, priority shut off valves?
2/ The EBHAs that power the spoilers in the event of HYD fluid loss appear not to have operated, at least one, as seen on YouTube.
3/ On ALTN braking, loss of LEHGS. I believe another self contained HYD sys to self activate in the event of HYD sys loss that didn't work?
4/ Why is the electrical wiring controlling #1 engine contained within the # 2 engine. Sioux City showed the aviation world the disastrous consequences of having controlling systems route together.
Last edited by Capt Groper; 14th Nov 2010 at 15:46.
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Contrarotating (counterrotating?) shafts
#1 UPside: A stator vane stage (nozzle guide vanes) can be eliminated, less weight, higher cycle efficiency.
#1 DOWNside: If differential (intershaft) bearings are involved, Very high bearing speeds (seal speeds too).
#1 DOWNside: If differential (intershaft) bearings are involved, Very high bearing speeds (seal speeds too).
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My guess would be that contra-rotating shafts (+ compressors and turbines!) also mitigate the additional structural problems resulting from hanging a few huge gyroscopes under a wing.
CJ
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My guess would be that contra-rotating shafts (+ compressors and turbines!) also mitigate the additional structural problems resulting from hanging a few huge gyroscopes under a wing.
CJ
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kwateow, sorry EBHAs then.
Sorry EBHAs (not EHAs) for SPLRs 5 & 6. But I thought that EBHAs are to work the same as EHAs when the normal HYD sys fails? The HYD fluid must have emptied from the actuators self contained reservoir and not a closed system as first thought.
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