Qantas A380 uncontained #2 engine failure
Join Date: Jan 2006
Location: LPFL
Age: 60
Posts: 83
Likes: 0
Received 0 Likes
on
0 Posts
Just an SLF, and read all posts from start of thread, but the parallel coming to my mind is BA712, the BOAC 707 at LHR in 1968 where a bit of the compressor of No 2 was ejected and severed a fuel pipe causing a fire. Also the United DC10 at Sioux City where a bit of ejected engine disc had the extremely bad luck to knock out all the hydraulics.
My point is to get a view from the experts whether the people on QF32 were just a lot luckier in the way their engine disintegrated. Or is it the case that technology on the A380 (and its engines) is so far ahead of 707s and DC10s - in other words, while uncontained engine failures on A380s are not ideal, they're just so much more robust, better designed etc. that you're not comparing like with like vis a vis BA712/Sioux UAL DC10.
Hope that's not too daft an observation and thanks for the opportunity to comment.
(EDIT - ugh! Just read stepwilk's post above. Sorry if I've annoyed anyone with my post.)
My point is to get a view from the experts whether the people on QF32 were just a lot luckier in the way their engine disintegrated. Or is it the case that technology on the A380 (and its engines) is so far ahead of 707s and DC10s - in other words, while uncontained engine failures on A380s are not ideal, they're just so much more robust, better designed etc. that you're not comparing like with like vis a vis BA712/Sioux UAL DC10.
Hope that's not too daft an observation and thanks for the opportunity to comment.
(EDIT - ugh! Just read stepwilk's post above. Sorry if I've annoyed anyone with my post.)
Some pertinent technical questions from folks like
fdr & barit1
e.g.
Highly technical answers regarding shaft separation and overspeed, are best handled in Tech Section and not appropriate to confuse R&N armchair designers.
The overspeed issue has two competing ingredients
* the compressed (spring) gas pressure aft of the compressors and already destined for the turbines
* the enertia of the turbine spools as well as their gas loads pushing a seperated rotor into the stationary vanes
there other equally significant design effects which I won't get into here
The simple answer to Barit1 question is No
The HPT will likely overspeed by a factor of two in about 1 sec
The IPT in about 2 sec
and the LPT in about 4 sec
I'll bow out of the discussion now and the only reason I even answered was because several posts continued along the same line.
PS fdr there are lots of data sources on uncontained discs but forget about using statistics with the regulators
pps, we probably shouldn't even be talking about overspeed in this A380 thread since overtemp at constant speed is still under investigation as well
fdr & barit1
e.g.
Highly technical answers regarding shaft separation and overspeed, are best handled in Tech Section and not appropriate to confuse R&N armchair designers.
The overspeed issue has two competing ingredients
* the compressed (spring) gas pressure aft of the compressors and already destined for the turbines
* the enertia of the turbine spools as well as their gas loads pushing a seperated rotor into the stationary vanes
there other equally significant design effects which I won't get into here
The simple answer to Barit1 question is No
The HPT will likely overspeed by a factor of two in about 1 sec
The IPT in about 2 sec
and the LPT in about 4 sec
I'll bow out of the discussion now and the only reason I even answered was because several posts continued along the same line.
PS fdr there are lots of data sources on uncontained discs but forget about using statistics with the regulators
pps, we probably shouldn't even be talking about overspeed in this A380 thread since overtemp at constant speed is still under investigation as well
Join Date: Sep 2010
Location: Double Oak, Texas
Age: 71
Posts: 180
Likes: 0
Received 0 Likes
on
0 Posts
Neptunus Rex....
Yes, but wouldn't you prefer the professional boys and girls of recent historic events, like water landings, this flight, etc...... wouldn't you prefer to get more of these high caliber crews manning the perfectly servicable CFIT flights? Make some hoo-ha over the non-injury events.....maybe it will spur the few professional putzes out there.
All this hoo-ha over an engine failure, albeit dramatic, which was handled extremely professionally by an experienced and well trained Qantas Crew, without any injury to the hundreds of people on board. Bravo Zulu.
I am far more concerned about the recent spate of fatal accidents in which perfectly serviceable airliners were flown into the ground, or into the sea, by supposedly experienced crews.
I am far more concerned about the recent spate of fatal accidents in which perfectly serviceable airliners were flown into the ground, or into the sea, by supposedly experienced crews.
Join Date: Jan 2008
Location: London
Age: 68
Posts: 1,269
Likes: 0
Received 0 Likes
on
0 Posts
Seems the investigators are looking for a specific metal component.
They have asked the local population to turn in all found debris (obviously) but specifically referred to one metallic component. The article (in Dutch) does not give a description of the component.
NOS Nieuws - Qantas vraagt hulp inwoners Batam
They have asked the local population to turn in all found debris (obviously) but specifically referred to one metallic component. The article (in Dutch) does not give a description of the component.
NOS Nieuws - Qantas vraagt hulp inwoners Batam
Join Date: Mar 2008
Location: jordan
Posts: 41
Likes: 0
Received 0 Likes
on
0 Posts
Qantas 747-400s are powered by Rolls Royce RB211 engines not Trents. This is with the exception of the 400ER's and the 3 ugly sisters (always assuming that the Ugly Sisters are still in the fleet that is) which are CF6 powered.
You will find that the Trent 900 modelnumber begins with RB211-......
You will find that the Trent 900 modelnumber begins with RB211-......
Join Date: Jul 2007
Location: London
Age: 63
Posts: 15
Likes: 0
Received 0 Likes
on
0 Posts
Trent 900 - a number of versions
The difference between the Trent 970 and 972 is of note.
Nonetheless, it seems RR has certificated other versions of the Trent 900 that offer even more thrust. Those engines are presumably aimed at future versions of the A380.
Does seem to imply that the Trent 900 design should be robust enough to cope with whatever Qantas is doing with it.
Nonetheless, it seems RR has certificated other versions of the Trent 900 that offer even more thrust. Those engines are presumably aimed at future versions of the A380.
Does seem to imply that the Trent 900 design should be robust enough to cope with whatever Qantas is doing with it.
You mention, as some others have, that there is an overtemp condition under constant speed. What is running overtemp
Since a recovered disk piece is now in the hands of the ATSB they would already know the difference between an overtemp or overspeed condition.
So watch carefully for a news release or find some pictures of the cavity where the disk ran
Join Date: Jul 2006
Location: Brisbane, Oz
Age: 82
Posts: 46
Likes: 0
Received 0 Likes
on
0 Posts
On gliders, & optional donks
Dear Lemain, (post 479, 101106 2000 ?TC)
Quote: “With powerful power plants and aircraft that don't glide well”
As an old banger-driver, as well as a new Porshe-cockpit driver, and also a glider instructor (ret), please understand that the glide ratio of your average late model very-efficient RPT device, what-ever it's size, is far better (i.e. they have a higher L/D ratio) that most of the gliders that populated the skies for the last 80 years or so, while enabling the training of innumerable pilots by them flying innumerable miles.
As I have said to innumerable zero-aeronatics-aware-but-media-scared SLFs in the past, *every* aircraft ever built is a glider. Some of them are excellent & highly efficient gliders, and a few of them are actually self launching gliders. There are a few large self launchers. Some are very large - gliders, like the A-380.
At top of descent every RPT A/c is a glider for the next 20-25 mins or so, and the engines are only spooled/spun up (increase(s) power) so the crew can quickly abort the landing if necessary. To increase power and yet go down you need to increase drag, but that is for lesson #2.
Thus endeth the TIF* briefing.
Could all non-professional aviators please leave by the rear door, and proceed to the sound-proof room with the glass wall, where they can read all they like, and maybe learn a little.
Thank you.
*Trial Introductory Flight
Oh: and would all retired-professional aviators (like me) please proceed to the back rows and shut up in future?
Thank you.
(I’ll try)
p.s Sorry Lemain. I needed a trigger comment to get this concept out there. Yes. most piston A/c glide like bricks (think 1:5), just like a glider with the spoilers out & up. Take the (dead) prop off and they’d be not bad gliders, sometimes.
Quote: “With powerful power plants and aircraft that don't glide well”
As an old banger-driver, as well as a new Porshe-cockpit driver, and also a glider instructor (ret), please understand that the glide ratio of your average late model very-efficient RPT device, what-ever it's size, is far better (i.e. they have a higher L/D ratio) that most of the gliders that populated the skies for the last 80 years or so, while enabling the training of innumerable pilots by them flying innumerable miles.
As I have said to innumerable zero-aeronatics-aware-but-media-scared SLFs in the past, *every* aircraft ever built is a glider. Some of them are excellent & highly efficient gliders, and a few of them are actually self launching gliders. There are a few large self launchers. Some are very large - gliders, like the A-380.
At top of descent every RPT A/c is a glider for the next 20-25 mins or so, and the engines are only spooled/spun up (increase(s) power) so the crew can quickly abort the landing if necessary. To increase power and yet go down you need to increase drag, but that is for lesson #2.
Thus endeth the TIF* briefing.
Could all non-professional aviators please leave by the rear door, and proceed to the sound-proof room with the glass wall, where they can read all they like, and maybe learn a little.
Thank you.
*Trial Introductory Flight
Oh: and would all retired-professional aviators (like me) please proceed to the back rows and shut up in future?
Thank you.
(I’ll try
) p.s Sorry Lemain. I needed a trigger comment to get this concept out there. Yes. most piston A/c glide like bricks (think 1:5), just like a glider with the spoilers out & up. Take the (dead) prop off and they’d be not bad gliders, sometimes.
Join Date: Dec 2007
Location: Hampshire
Age: 74
Posts: 64
Likes: 0
Received 0 Likes
on
0 Posts
A Possible Mode of Failure?
I need to reassure any RR engine men who might have time to read PPRUNE that the following is pure conjecture… but it is based on some historic experience.
I find it interesting that the photographs, firstly of a piece of disk resting in the back of somebody’s van (Post 42), and secondly of another piece that presumably has been found after the appeal by the authorities in Indonesia (Post 588), show a disk that has lost its turbine blades. I don’t think that they are the same piece, but I am open to correction.
The question that arises is: when did the turbine blades separate from the disk? Was that separation after the disk had departed from the engine, or did the blades (or possibly, some of the blades) come out of the disk whilst the disk was more or less still in the engine?
It is extremely hard to imagine that the fir tree roots would let go under ‘normal’ circumstances. However, if the disk had been subjected to a high over temperature, possibly as a result of an oil fire, then its metallurgical properties might be compromised such that it softened, or maybe ‘crept’, and this resulted in the fir trees no longer holding the blades. If some of the blades departed sooner than their neighbours, then there would be a severe imbalance at 12,000 rpm or so, and this might precipitate the departure of the disk, taking various other components with it as it left.
The AD refers to “wear on the abutment faces of the splines on the IP shaft rigid coupling”. This interface “provides the means of controlling the turbine axial setting and wear through of the splines would permit the IP turbine to move rearwards” If this movement resulted in damage to the bearing chamber oil seals, and there was an oil leak, then it is possible that an oil fire might ensue. A stoichiometric mix of oil and the hot air around the turbine face could give a very nice torch of flame that might have played on the disk, and led to its unzipping.
Any movement resulting from the IP coupling wear presumably is measurable; or possibly there only has to be a small amount of movement for there to be observable excessive wear on one of the bearing chamber seals. Measuring the movement, or looking for such seal wear, probably is relatively easy if one knows where to go though the boroscope holes, and possibly this is why the SQ and LH engines, and (most of), the remaining QF engines, have been cleared for continued operation relatively quickly.
I again emphasise that the postulated failure mechanism is pure conjecture on my part, and I have no inside track on the investigation.
I find it interesting that the photographs, firstly of a piece of disk resting in the back of somebody’s van (Post 42), and secondly of another piece that presumably has been found after the appeal by the authorities in Indonesia (Post 588), show a disk that has lost its turbine blades. I don’t think that they are the same piece, but I am open to correction.
The question that arises is: when did the turbine blades separate from the disk? Was that separation after the disk had departed from the engine, or did the blades (or possibly, some of the blades) come out of the disk whilst the disk was more or less still in the engine?
It is extremely hard to imagine that the fir tree roots would let go under ‘normal’ circumstances. However, if the disk had been subjected to a high over temperature, possibly as a result of an oil fire, then its metallurgical properties might be compromised such that it softened, or maybe ‘crept’, and this resulted in the fir trees no longer holding the blades. If some of the blades departed sooner than their neighbours, then there would be a severe imbalance at 12,000 rpm or so, and this might precipitate the departure of the disk, taking various other components with it as it left.
The AD refers to “wear on the abutment faces of the splines on the IP shaft rigid coupling”. This interface “provides the means of controlling the turbine axial setting and wear through of the splines would permit the IP turbine to move rearwards” If this movement resulted in damage to the bearing chamber oil seals, and there was an oil leak, then it is possible that an oil fire might ensue. A stoichiometric mix of oil and the hot air around the turbine face could give a very nice torch of flame that might have played on the disk, and led to its unzipping.
Any movement resulting from the IP coupling wear presumably is measurable; or possibly there only has to be a small amount of movement for there to be observable excessive wear on one of the bearing chamber seals. Measuring the movement, or looking for such seal wear, probably is relatively easy if one knows where to go though the boroscope holes, and possibly this is why the SQ and LH engines, and (most of), the remaining QF engines, have been cleared for continued operation relatively quickly.
I again emphasise that the postulated failure mechanism is pure conjecture on my part, and I have no inside track on the investigation.
Join Date: Jul 2006
Location: Brisbane, Oz
Age: 82
Posts: 46
Likes: 0
Received 0 Likes
on
0 Posts
Still gliding
@ Enkei . . . your "Oh, one minor niggle: not just increase drag. Decreasing lift also works, does it not?" . . . is covered in lesson three. 
By then you are (just) on your way to 1st solo (hopefully,) when you will become an authority on >all< things aeronautical.
(Said in jest, but highly recommended to all frustrated drivers. Doesn't cost too much, gets it out of your system, and you can read stuff like this with a measure of understanding and sympathy.)
That said, it still concerns me that the bottom-line FWSOV seems now to be an optional (functional) extra. In my (ancient) day(s) it was the fundamental bottom line. 'When all else fails . . .'
[YOU! Old grub! Shuffle your a*se to the rear row. NOW!
SaH!)
By then you are (just) on your way to 1st solo (hopefully,) when you will become an authority on >all< things aeronautical.
(Said in jest, but highly recommended to all frustrated drivers. Doesn't cost too much, gets it out of your system, and you can read stuff like this with a measure of understanding and sympathy.)
That said, it still concerns me that the bottom-line FWSOV seems now to be an optional (functional) extra. In my (ancient) day(s) it was the fundamental bottom line. 'When all else fails . . .'
[YOU! Old grub! Shuffle your a*se to the rear row. NOW!
SaH!)
Join Date: Jan 2008
Location: UK
Age: 69
Posts: 292
Likes: 0
Received 0 Likes
on
0 Posts
JenCluse
Hmmm... I have more flying experience than you might think -- but not jets. I think you've missed the point (got carried away with the rhetoric, eh?) that a dead-stick on a big jet is very dangerous. If the world was a tarmac runway it would be no problem. Anyone could do it. But it isn't, and a big jet takes time to stop, and wind-shear is unpredictable. Jolly difficult -- particularly without full control and a lot of luck needed, as well as skill and nerve. Been there.
Don't dis everyone off as uninformed -- read, listen, and discuss -- dis when it is nonsense (plenty of that on the Internet) but put brain in gear before foot in mouth.
Don't dis everyone off as uninformed -- read, listen, and discuss -- dis when it is nonsense (plenty of that on the Internet) but put brain in gear before foot in mouth.
Trent 970/Trent 972:
Could it be that both are one and the same engine but subject to a different maintenance regime?
For example, I had good experience of the General Electric CF6-50C2. The basic engine would normally produce about 4,000 lbs of extra thrust above its guaranteed minimum. If an operator wanted to make use of this extra thrust benefit for performance purposes, then that operator could opt to go for the C2B option.
This was fine and it meant that they could operate, for example, at higher operating weights but the downside was that since the engine was now on a different maintenance cycle, then components were going to have to be changed more often.
I was told that the only modification to the engine was to change the "plate" on the engine which took about five minutes to do.
If this has nothing whatsoever to do with the case in hand then I apologise in advance!
Could it be that both are one and the same engine but subject to a different maintenance regime?
For example, I had good experience of the General Electric CF6-50C2. The basic engine would normally produce about 4,000 lbs of extra thrust above its guaranteed minimum. If an operator wanted to make use of this extra thrust benefit for performance purposes, then that operator could opt to go for the C2B option.
This was fine and it meant that they could operate, for example, at higher operating weights but the downside was that since the engine was now on a different maintenance cycle, then components were going to have to be changed more often.
I was told that the only modification to the engine was to change the "plate" on the engine which took about five minutes to do.
If this has nothing whatsoever to do with the case in hand then I apologise in advance!
Join Date: Nov 2007
Location: UK
Posts: 15
Likes: 0
Received 0 Likes
on
0 Posts
A tadge more than just changing a data plate,or did miss the point? The engine would operate at a new set of parameters so FMC software would need to be changed etc bit like chipping your car.
fflyingdog:
I bow to your superior and more up-to-date knowledge.
However, it could just be that the basic engine has not changed. Perhaps I should have said it was only a plate change plus some different electronics?
In my day, we didn't have to worry about FMS, FADEC etc etc (although we did have dual auto-throttles) because we still had a human being called a Flight Engineer and he was the best piece of kit that a captain could ever have when the world was unravelling around you.
Not only that, but he could buy beer which is more than FMS, FADEC etc etc can do and his conversation was also usually more illuminating than 58 ICAM messages!
I bow to your superior and more up-to-date knowledge.
However, it could just be that the basic engine has not changed. Perhaps I should have said it was only a plate change plus some different electronics?
In my day, we didn't have to worry about FMS, FADEC etc etc (although we did have dual auto-throttles) because we still had a human being called a Flight Engineer and he was the best piece of kit that a captain could ever have when the world was unravelling around you.
Not only that, but he could buy beer which is more than FMS, FADEC etc etc can do and his conversation was also usually more illuminating than 58 ICAM messages!
Join Date: Nov 2010
Location: CE
Posts: 86
Likes: 0
Received 0 Likes
on
0 Posts
QUOTE: ''The engine would operate at a new set of parameters so FMC software would need to be changed etc bit like chipping your car.''
In the case of the Trent series of engines all that is needed is a new DEP (Data Entry Plug) fitting to the EEC. This plug carries all the relevant info for the new rating requirements.
In the case of the Trent series of engines all that is needed is a new DEP (Data Entry Plug) fitting to the EEC. This plug carries all the relevant info for the new rating requirements.