Qantas A380 uncontained #2 engine failure
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John W Lewis,
Maybe read some more of the thread first?
This is an engine issue.
What's more, it's an uncontained engine failure issue.
Such failures tend to leave a mess behind.... every time.
Some of those 'messes' have led to aircraft being lost.
In this case not even a single life was lost.
You can be assured everybody concerned is already crawling all over that aircraft, and has already pulled out all the drawings in case there are any lesson to be learned, rather than just closing a stable door....
Remarks such are yours are futile... we've all been there long before you.
CJ
Maybe read some more of the thread first?
This is an engine issue.
What's more, it's an uncontained engine failure issue.
Such failures tend to leave a mess behind.... every time.
Some of those 'messes' have led to aircraft being lost.
In this case not even a single life was lost.
You can be assured everybody concerned is already crawling all over that aircraft, and has already pulled out all the drawings in case there are any lesson to be learned, rather than just closing a stable door....
Remarks such are yours are futile... we've all been there long before you.
CJ
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JWL:
Engines will fail, but an uncontained failure such as this is an UNACCEPTABLE failure mode. The industry will bring very great pressure to bear on R-R (just as they have on GE, P&W etc) to stop such uncontained failures. The consequences of a burst disc will always be severe and somewhat hard to quantify.
That said, Airbus is reviewing this case and will, I'm sure do whatever is feasible to mitigate the loss of systems etc.
BTW, if you could find and compare engine failure statistics between airliner engines vs general aviation engines, you'd be VERY impressed with how reliable the Trent, GE90, PW4000 ... are.
(BTW: My father soloed in 1930 behind a watercooled Curtiss OX-5 - WWI surplus. His average flight time between forced landings was 50 hrs.
)
Engines will fail. If the failure of this one has exposed deeper problems with the management of emergencies on the A380, then surely these need to be investigated before continuing to operate this type. I am dismayed to read that Qantas intend to resume limited operation of their A380s tomorrow, 2010-11-27.
That said, Airbus is reviewing this case and will, I'm sure do whatever is feasible to mitigate the loss of systems etc.
BTW, if you could find and compare engine failure statistics between airliner engines vs general aviation engines, you'd be VERY impressed with how reliable the Trent, GE90, PW4000 ... are.
(BTW: My father soloed in 1930 behind a watercooled Curtiss OX-5 - WWI surplus. His average flight time between forced landings was 50 hrs.
)
I'm not at liberty to discuss its identity, but it was an advanced military machine.
FWIW, I believe the GEnx (748, 787) has differential contrarotating bearings.
I note the Trent has a frame/bearing box situated between the HPT and IPT. It seems to me that has the effect of negating the synergistic vortex exiting the HPT blades into the opposite-rotation IPT.
Perhaps someone can tell/show us what these radial struts (aerodynamic static structures) between the HPT & IPT look like....
Perhaps someone can tell/show us what these radial struts (aerodynamic static structures) between the HPT & IPT look like....
Didn't the Pegasus, as fitted to the Harrier have contrarotating shafts??? Is there a Harrier expert in the house???
I seem to recall it needed some clever technology to cope with high g loads.
Intershaft bearings? No idea.
John W Lewis
Rest assured that your concerns will be investigated and addressed by the professional investigating teams and show up in their final report.
Today's issue is; what is the quickest way of addressing going forward risk and getting planes back in the air on a predicatable schedule.
The chatter that one reads on the internet only reflects what's in the heads of those doing the chattering
As a late comer to this thread, and a lapsed private pilot with probably far less experience than almost everyone here, I am nevertheless surprised to see that this thread is still focussing on the engine failure on the Qantas A380.
The implications of some of the things that I am hearing about this flight are far more serious than an engine failure.
There are a large number of messages on this thread, and I have not read them all. However, on the first few pages there were observations from the photographs of the aircraft shortly after landing. These related to the continued running of the no 1 engine and the position of slats and undercarriage doors. Have the implications of these points been discussed and resolved? Is there, perhaps, another thread on which they are being discussed?
The implications of some of the things that I am hearing about this flight are far more serious than an engine failure.
There are a large number of messages on this thread, and I have not read them all. However, on the first few pages there were observations from the photographs of the aircraft shortly after landing. These related to the continued running of the no 1 engine and the position of slats and undercarriage doors. Have the implications of these points been discussed and resolved? Is there, perhaps, another thread on which they are being discussed?
Today's issue is; what is the quickest way of addressing going forward risk and getting planes back in the air on a predicatable schedule.
The chatter that one reads on the internet only reflects what's in the heads of those doing the chattering
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http://www.pprune.org/members/274091-john-w-lewis
1. read all the posts as most of us did..
2. run your search engine for the posts that you dont understand...
3. then start asking you questions in http://www.pprune.org/spectators-bal...ers-corner-52/
cheers
1. read all the posts as most of us did..
2. run your search engine for the posts that you dont understand...
3. then start asking you questions in http://www.pprune.org/spectators-bal...ers-corner-52/
cheers
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JFZ90:
I'm sure the GE, P&W, & R-R field reps on the LH Hamburg shop floor already know about each others' jetmotors; the industrials have already been espionaged. 
My interest is purely personal - I've been out of the loop long enough that I couldn't make a meaningful contribution to innovative design.
Why would these stators be of particular interest, apart from industrial espionage if they are of novel design of course?
My interest is purely personal - I've been out of the loop long enough that I couldn't make a meaningful contribution to innovative design.
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Thread drift is such fun!
Originally Posted by Dr Illitout
Didn't the Pegasus, as fitted to the Harrier have contrarotating shafts??? Is there a Harrier expert in the house???
I've had a look at some simplified Pegasus drawings and cutaways and can't see any intershaft bearings, The tubular centre shaft is very fat and rigid, thanks to the plentiful space within the Orpheus on which the Pegasus is based.
Please email if you'd like copies of the drawings.
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Didn't the Pegasus, as fitted to the Harrier have contrarotating shafts??? Is there a Harrier expert in the house???
Pegasus Mk101 to 107
No3 Bearing in the Pegasus is the one, the inner race is fitted to the LP shaft and the outer race is part of the oil tube ( part of the M09, HP2 turbine) which is which is inserted into the HPC rotor centre front on the HPC. The rear of the tube is held in place by the HPT hub at the rear of the HP2 turbine.
No1 and 4 bearing support the LP shaft.
No2 bearing supports the front of the HPC.
Shaft speeds are:
HP 11,000 rpm
LP 6,500 rpm
Pegasus Mk107 had a 2a bearing which supported the front of the LP shaft when the LPC module was removed.
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JFZ90
In looking at your generously donated pic of the TRENT, it is clear that, as you say, the HP and IP shafts do not touch. Except: The bearings that support them both seem to efface, or their respective race makes contact in the box that contains them both. Either inner or outer race must have discrepant radial velocity, or there is missing a line denoting a supporting Steel web that isolates one from the other, No?
bearfoil
In looking at your generously donated pic of the TRENT, it is clear that, as you say, the HP and IP shafts do not touch. Except: The bearings that support them both seem to efface, or their respective race makes contact in the box that contains them both. Either inner or outer race must have discrepant radial velocity, or there is missing a line denoting a supporting Steel web that isolates one from the other, No?
bearfoil
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The HPT & IPT bearings appear to be supported by static structure (outlined in black, between the HPT and IPT wheels). This is most likely a series of short struts through the gas path, secured to the outer case, and on the inner end secured to a large baffle or diaphragm. The bearing box is at the center of this; static outer bearing rings (or races) in that housing, and the inner races on the rotor shafts.
(My prior question was regarding the number, shape, etc. of those struts)
(My prior question was regarding the number, shape, etc. of those struts)
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barit 1
Yes, I see. May I direct your attention to the "pocket" (seen in section only) that surrounds the aft bearing on three sides? It is comprised of the Shaft on one side, the "Fin" of the IPT, and an "L" shaped "ring" ? The Turbine appears sandwiched in between these shaft/shaft sections. It is in this portion of the Wheel/Shaft mate that I percieve the "Splines" to be located. Showing the Wheel as separate in this view, there can assumedly be no other way to locate the Joint. This is then where the accelerated wear must have occurred, and seemingly the only avenue for Oil to escape.
Am I making sense here?
Yes, I see. May I direct your attention to the "pocket" (seen in section only) that surrounds the aft bearing on three sides? It is comprised of the Shaft on one side, the "Fin" of the IPT, and an "L" shaped "ring" ? The Turbine appears sandwiched in between these shaft/shaft sections. It is in this portion of the Wheel/Shaft mate that I percieve the "Splines" to be located. Showing the Wheel as separate in this view, there can assumedly be no other way to locate the Joint. This is then where the accelerated wear must have occurred, and seemingly the only avenue for Oil to escape.
Am I making sense here?
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Bear - No, not making sense.
The illustration is what we engineers call a diagram intended to explain the bearing system. It is not a general arrangement and is not intended to show details of clearances, oilways and so on.
Even so, it seems to me to show that the bearing outer races are fixed to the bearing housing and do not rotate, and the inner races are attached to their respective shafts.
I would agree with you that Rolls Royce are probably the finest engineers in the world, but I doubt that even they would be able to put a splined joint in the complex geometry of the turbine hub area.
Aren't the splines refered to in the AD at the compressor end of the shaft?
IP Turbine Disc would then be secured to shaft system by curvic coupling.
We need a rather more detailed drawing of the general area, or a copy of the RR Service Bulletin
The illustration is what we engineers call a diagram intended to explain the bearing system. It is not a general arrangement and is not intended to show details of clearances, oilways and so on.
Even so, it seems to me to show that the bearing outer races are fixed to the bearing housing and do not rotate, and the inner races are attached to their respective shafts.
I would agree with you that Rolls Royce are probably the finest engineers in the world, but I doubt that even they would be able to put a splined joint in the complex geometry of the turbine hub area.
Aren't the splines refered to in the AD at the compressor end of the shaft?
IP Turbine Disc would then be secured to shaft system by curvic coupling.
We need a rather more detailed drawing of the general area, or a copy of the RR Service Bulletin
Last edited by CAAAD; 28th Nov 2010 at 08:58. Reason: Address
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Sky News - take it as you will - is reporting that the presence of the extra crew members on board played a significant role in bringing the situation under control. Quite what that infers, I'm not sure.
More bang for your buck
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Similar article in the Sunday Times which suggests that there were so many alarms activated that 2 pilots might not have been able to cope with the workload, or that it would have taken them so long that it could have led to disaster.