Qantas A380 uncontained #2 engine failure
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Annoted cutaway of RB-211 at Flightglobal Flight Archive... not quite 'Trent' --
IP turbine disc 51 in cutaway.
Just an aside, the 'spline' (past? problem) as in curvic coupling (60 in cutaway) ?
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IP turbine disc 51 in cutaway.
Just an aside, the 'spline' (past? problem) as in curvic coupling (60 in cutaway) ?
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BTW- On my last QF a380 flight I noticed what appeared to be a pitot like nozzle / exhaust on the bottom of the engine. During taxi it appeared to vent smoke, but not continuously. Anybody know what this is for?
Thanks!
Thanks!
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For the crowd who have not yet made a study of words with multiple meanings.
bear: to carry, or support, a verb
bearing: carrying, the act of, a gerund
bearing: a direction, a heading
bearing: a surface made to reduce the friction of discrepant motion, a noun
As: roller, needle, ball, friction, etc. Also defined by type of action: as in Thrust.
Unless there have been leaps made in the pursuit of frictionless propulsion, some sort of element exists to suspend a rotating mass in the TRENT. Likewise, to provide a mass against which Newton's third force may impinge, to create THRUST, a face of stationery Metal must be provided.
Too many bearings? Not if one considers the need for each one.
Pictures, Diagrams, Schematics. Excellent to have a picture to refer to in the discussion, I have no talent with computers; this may explain why I use too many words. Some form of compensation, I suppose. I'll work on it.
on we go, then. (NOT Titanium, I so stipulate!! The picture is acceptable)
bearfoil
bear: to carry, or support, a verb
bearing: carrying, the act of, a gerund
bearing: a direction, a heading
bearing: a surface made to reduce the friction of discrepant motion, a noun
As: roller, needle, ball, friction, etc. Also defined by type of action: as in Thrust.
Unless there have been leaps made in the pursuit of frictionless propulsion, some sort of element exists to suspend a rotating mass in the TRENT. Likewise, to provide a mass against which Newton's third force may impinge, to create THRUST, a face of stationery Metal must be provided.
Too many bearings? Not if one considers the need for each one.
Pictures, Diagrams, Schematics. Excellent to have a picture to refer to in the discussion, I have no talent with computers; this may explain why I use too many words. Some form of compensation, I suppose. I'll work on it.
on we go, then. (NOT Titanium, I so stipulate!! The picture is acceptable)
bearfoil
I assume the "Too many bearings" remarks are linked to some previous gaff posting.
Please can someone post a link or quote of the offending remarks? It sounds amusing.
PS Bear - if you can you post your reference to RR stating their engines run "cooler", it maybe possible to put it in context. It is likely to be a reference to the temperature margins RR can play with to tailor durability vs performance of a given engine design. It won't mean the temps are necessarily "cool" as such.
Please can someone post a link or quote of the offending remarks? It sounds amusing.
PS Bear - if you can you post your reference to RR stating their engines run "cooler", it maybe possible to put it in context. It is likely to be a reference to the temperature margins RR can play with to tailor durability vs performance of a given engine design. It won't mean the temps are necessarily "cool" as such.
Last edited by JFZ90; 26th Nov 2010 at 18:50.
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Not too many bearings.
Each shaft has one and only one ball (thrust bearing) and as many roller bearings as are required for shaft stability (shaft whip or whirl). So the slender inner shafts have a centre bearing as well as one near each end. In this case the centre bearings are thrust bearings.
Very good article in Flight International about the Trent 800 September 1996 can be downloaded free, gratis and for nothing from flightglobal.
Each shaft has one and only one ball (thrust bearing) and as many roller bearings as are required for shaft stability (shaft whip or whirl). So the slender inner shafts have a centre bearing as well as one near each end. In this case the centre bearings are thrust bearings.
Very good article in Flight International about the Trent 800 September 1996 can be downloaded free, gratis and for nothing from flightglobal.
Last edited by firstfloor; 26th Nov 2010 at 20:18.
I assume the "Too many bearings" remarks are linked to some previous gaff posting.
I would have loved to see some real close ups of the suspect bearing compartment for the RR900 to get an idea of exactly what the fire impinged on. Alas all I could see were just row after row of bearings hence the throw away glib statement, nothing more meant so let's move on
Looking at the bearings - its a clever piece of design.
The counter rotating parts don't actually have any interfacing parts e.g. via any bearings - the IP and HP shafts are only attached to the casing, not each other. The IP and LP shafts do contact each other via a bearing but they rotate the same way.
Hence its seems the "three shaft engines with a counter rotating stage have higher bearing speeds than twin shaft"=Internet Myth.
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NOT a myth. The Trent may not have contrarotating intershaft bearings, but I have worked on an engine that DID. I was astounded by the differential speeds, but there it is!
NOT a myth. The Trent may not have contrarotating intershaft bearings, but I have worked on an engine that DID. I was astounded by the differential speeds, but there it is!
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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.
FWIW, I believe the GEnx (748, 787) has differential contrarotating bearings.
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Surprised that this thread is still about engine issues
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 things that I am hearing relate to major difficulties with many of the aircraft systems as a consequence of the engine failure including: a huge workload in dealing with system messages; failure of systems for fuel dumping and cross-feeding; failure of hydraulic systems, etc., etc..
My understanding is that it was extremely fortunate that additional and very experienced pilots were on board this flight. Also it is my understanding that the situation deteriorated to the extent that they felt the need to land the aircraft not only because the trapping of fuel in tanks in the tail section was causing the C of G to move continually aft, but eventually because they risked losing lateral control of the aircraft due to the inability to cross-feed fuel.
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.
If there is any truth in any of this, then it indicates a need for the study of the implications for the safety: certainly, of existing A380s; probably, of the A380 in general; and, possibly, of all Airbus aircraft. If there are possible major safety concerns in operating this type of aircraft, then it seems most unlikely that Airbus will put a stop to their operation. So who will: the authorities, the airlines or the pilots?
If there are no problems to be investigated, then these detailed "rumours" are coming from somewhere!
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 things that I am hearing relate to major difficulties with many of the aircraft systems as a consequence of the engine failure including: a huge workload in dealing with system messages; failure of systems for fuel dumping and cross-feeding; failure of hydraulic systems, etc., etc..
My understanding is that it was extremely fortunate that additional and very experienced pilots were on board this flight. Also it is my understanding that the situation deteriorated to the extent that they felt the need to land the aircraft not only because the trapping of fuel in tanks in the tail section was causing the C of G to move continually aft, but eventually because they risked losing lateral control of the aircraft due to the inability to cross-feed fuel.
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.
If there is any truth in any of this, then it indicates a need for the study of the implications for the safety: certainly, of existing A380s; probably, of the A380 in general; and, possibly, of all Airbus aircraft. If there are possible major safety concerns in operating this type of aircraft, then it seems most unlikely that Airbus will put a stop to their operation. So who will: the authorities, the airlines or the pilots?
If there are no problems to be investigated, then these detailed "rumours" are coming from somewhere!
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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....
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PW F100 ?
Pedant : Counter/rotating is different than Contra/rotating?
JFZ90 I heartily apologize; the RollsRoyce Trent data I nicked from a Puff brochure. It very definitely referred to the TRENT's development as having made possible some diminution of ambient heat surrounding shafts, bearings, etc. If you demand proof, I will seek it out. Other than a "Paraphrase" of the brochure's text, the data is accurate, and even though a sales pitch, it needs be a valid claim. No numbers were included. Some things I accept at Face.
At long last, a picture of what "Aft Migration" may have accomplished, and a glimmer of the Splines face(s).
cheers, bear
Pedant : Counter/rotating is different than Contra/rotating?
JFZ90 I heartily apologize; the RollsRoyce Trent data I nicked from a Puff brochure. It very definitely referred to the TRENT's development as having made possible some diminution of ambient heat surrounding shafts, bearings, etc. If you demand proof, I will seek it out. Other than a "Paraphrase" of the brochure's text, the data is accurate, and even though a sales pitch, it needs be a valid claim. No numbers were included. Some things I accept at Face.
At long last, a picture of what "Aft Migration" may have accomplished, and a glimmer of the Splines face(s).
cheers, bear