Qantas A380 uncontained #2 engine failure
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Bearfoil - Many ADs make reference to possible outcomes to justify their application. The spline wear AD refers to excessive axial movement leading to possible non containment. This is what could happen if the AD is not accomplished.
The reverse is not necessarily true. Hence a non contained IP turbine will not inevitably be caused by a spline problem.
And speaking of splines, do we all realise that the fancy parabolic splines are a GE patent? Reference is made therein to a 1981 RR patent from Bristol, but I can't get my head around it.
The reverse is not necessarily true. Hence a non contained IP turbine will not inevitably be caused by a spline problem.
And speaking of splines, do we all realise that the fancy parabolic splines are a GE patent? Reference is made therein to a 1981 RR patent from Bristol, but I can't get my head around it.
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CAAAD
This AD also is a follow-on to an EASA AD. To be honest, you should include the reference to possible OIL FIRE. You seem to take a rather ambiguous approach to regulations, apologizing for them? I take them at face value. They are written as a Last Ditch curative, hence the specificity of their language. Last Ditch because they are composed with the input of the Manufacturer, who generally has more knowledge and experience. (The FAA is required to ask for Public comment as well).
I read them at face value, as they are intended.
cheers bear
This AD also is a follow-on to an EASA AD. To be honest, you should include the reference to possible OIL FIRE. You seem to take a rather ambiguous approach to regulations, apologizing for them? I take them at face value. They are written as a Last Ditch curative, hence the specificity of their language. Last Ditch because they are composed with the input of the Manufacturer, who generally has more knowledge and experience. (The FAA is required to ask for Public comment as well).
I read them at face value, as they are intended.
cheers bear
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Bearfoil
I have a question concerning the IPT rotor and its fastening to the IP shaft. If I see it correctly, the rotor is joined to the shaft by a series of bolts joining the drive arm of the disc to a corresponding flange on the end of the IP shaft. A dual set of roller bearings is positioned between the IP shaft and the bore of the disc. Is this correct? If so, referring to the ATSB AO-2010-089 preliminary report, look at Figure 15 on page 21. A partially remaining section of the drive arm (1/2 bolt hole) would suggest the drive arm is bent 180 degrees opposite from where it should be. Assuming this rupture and bending took place during the failure event and not after (exiting the engine or crashing to earth), how could this be? I can't see it happening if the disc moved rearward easily and it is hard envision if the disc moved forward, except for the first 90 degrees of the bending. I know there are quite a few other components in that area that might account for the final 90 degrees of bending. Your thoughts?
Turbine D
I have a question concerning the IPT rotor and its fastening to the IP shaft. If I see it correctly, the rotor is joined to the shaft by a series of bolts joining the drive arm of the disc to a corresponding flange on the end of the IP shaft. A dual set of roller bearings is positioned between the IP shaft and the bore of the disc. Is this correct? If so, referring to the ATSB AO-2010-089 preliminary report, look at Figure 15 on page 21. A partially remaining section of the drive arm (1/2 bolt hole) would suggest the drive arm is bent 180 degrees opposite from where it should be. Assuming this rupture and bending took place during the failure event and not after (exiting the engine or crashing to earth), how could this be? I can't see it happening if the disc moved rearward easily and it is hard envision if the disc moved forward, except for the first 90 degrees of the bending. I know there are quite a few other components in that area that might account for the final 90 degrees of bending. Your thoughts?
Turbine D
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I identified the 180 degree aspect as a "folding over" of the drive arm in a previous post. My guess is that it is due "explosion" from the forward shaft area of the IP(T) join.
If plastic from heat, the Disc would show this signature in a blast from the front side of its Hub. The "Resistance" to the energy from such a blast would be the High Pressure contents of the IP LP cavity (Piston) area, plus the mechanical obstacle of the Stator ring just aft the IP Disc. It is pure and simple guesswork, and only that.........
Beyond this, the "flattening over" of the Drive Arm metal may have been amplified by contact with the mounting base of the Stator assembly, from which it may have rebounded, and with the impetus of Highly energetic Gas Path, thrown forward and "Out" after disintegration.
Rgds. bear
If plastic from heat, the Disc would show this signature in a blast from the front side of its Hub. The "Resistance" to the energy from such a blast would be the High Pressure contents of the IP LP cavity (Piston) area, plus the mechanical obstacle of the Stator ring just aft the IP Disc. It is pure and simple guesswork, and only that.........
Beyond this, the "flattening over" of the Drive Arm metal may have been amplified by contact with the mounting base of the Stator assembly, from which it may have rebounded, and with the impetus of Highly energetic Gas Path, thrown forward and "Out" after disintegration.
Rgds. bear
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Northen Krestal, THANKS for the link to the supervising CKA interview.
Some REALLY fascinating reading!
One outake.......
Uh, oh....near the start of the published interview,the CKA was quoted using the the word.....engine explosion.
That will probably generate some discussion here.
Some REALLY fascinating reading!
One outake.......
Its one of those things that because we had five of us on the flight deck – of course there are lessons to be learned but I think on the day we did absolutely everything. In hindsight I don’t think any of us would have done anything differently. Questions were asked ‘why did we spend so long in the air’? But we had to spend that time in the air to determine the state of the aircraft and it took that long to do that. I think we made the right decision to keep everyone on the aircraft. We had the contingency to evacuate the aeroplane at any moment if things deteriorated. We had fire services in attendance. Certainly we had an engine we couldn’t shut down and that engine continued to run for another five hours before the fire services drowned it with fire retardant.
That will probably generate some discussion here.
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Northern Kestrel - Thanks for the link to the RAeS interview with Captain David Evans, Qantas Senior Check Captain, who was Supervising Check Captain on the flight. In the interview he answers many of the questions raised on this thread. I would earnestly recommend everyone to read it and at the same time listen to the soundtrack because there are aspects that come over better verbally.
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Thank you to NorthernKestrel for the link to that interview--it was fascinating.
I'm only an interested piece of SLF but think that one link answers most of the questions posed earlier about whether the crew spent too much time with checklists, whether they should have landed earlier and whether they should have used the evacuation slides.
I recommend that interview to everyone.
Bob
I'm only an interested piece of SLF but think that one link answers most of the questions posed earlier about whether the crew spent too much time with checklists, whether they should have landed earlier and whether they should have used the evacuation slides.
I recommend that interview to everyone.
Bob
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Turbine D
In addition to the Drive Arm bolting to the IP Shaft, there is a piece of (A disc) of L shaped flange which impinges the bearing, creating a "sandwich" at the attachment. This may be serving as a heat "Sink" adding to problems of heat dissipation in Climb?
again, just guesswork
In addition to the Drive Arm bolting to the IP Shaft, there is a piece of (A disc) of L shaped flange which impinges the bearing, creating a "sandwich" at the attachment. This may be serving as a heat "Sink" adding to problems of heat dissipation in Climb?
again, just guesswork
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Thanks Old Engineer for your answer and also to PBL and lomapaseo,
Well I hope we'll get more info about how partially was the wing structure affected (i.e. how reduced was its resistance to loads)
Would you guys think a general guide in the QRH, as you OE suggested, could tell the pilots about the probability of how bad the wing should be affected, depending on what the pilot sees (wing + engine) (I know it won't be precise) ?
This would give pilots some more situation awareness before taking the decision to stay airborne to handle problems or decide it might be wiser to start an approach for an (emergency) landing
cheers
Well I hope we'll get more info about how partially was the wing structure affected (i.e. how reduced was its resistance to loads)
Would you guys think a general guide in the QRH, as you OE suggested, could tell the pilots about the probability of how bad the wing should be affected, depending on what the pilot sees (wing + engine) (I know it won't be precise) ?
This would give pilots some more situation awareness before taking the decision to stay airborne to handle problems or decide it might be wiser to start an approach for an (emergency) landing
cheers
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Bearfoil
I see what you are saying relative to the additional flange. I should have been clearer in my original post to have said that the forward of the two bearings is the rear HP shaft bearing that is turning in the opposite direction (due to the counter-rotation feature of this engine).
Turbine D
I see what you are saying relative to the additional flange. I should have been clearer in my original post to have said that the forward of the two bearings is the rear HP shaft bearing that is turning in the opposite direction (due to the counter-rotation feature of this engine).
Turbine D
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Turbine D
I take note of your reference to "rupture" of the Disc; if you agree, I will use your term for Heat/Friction/Pressure failure instead of 'explosion'. The kerfuffel re: this word is distracting. If the splines have failed relative to the AD's portent, I do not envision a "smoothe" transition aft of the IP Wheel. At best, perhaps a stuttering and rapid, oscillatory transition aft, not a "migration". If an excess of swirl combustants from the Shaft's interface with the HP bearing/Shaft foci, (due to "Oil Fire"?), This may have been sufficient in and of itself to part the Drive Arm from its join with the Shaft Flange.
I've yet to read your reference, I will. I also think you sit upon a vastly greater fund of knowledge than I. You asking questions for clarification of me tells me this is so. Just "musing".
Your reference to the HPT bearing? Is that an invitation to discuss what may have been the results of loss of lubrication? Cooling? (Oil Related)? Unclear to me.
regards bear
bear
I take note of your reference to "rupture" of the Disc; if you agree, I will use your term for Heat/Friction/Pressure failure instead of 'explosion'. The kerfuffel re: this word is distracting. If the splines have failed relative to the AD's portent, I do not envision a "smoothe" transition aft of the IP Wheel. At best, perhaps a stuttering and rapid, oscillatory transition aft, not a "migration". If an excess of swirl combustants from the Shaft's interface with the HP bearing/Shaft foci, (due to "Oil Fire"?), This may have been sufficient in and of itself to part the Drive Arm from its join with the Shaft Flange.
I've yet to read your reference, I will. I also think you sit upon a vastly greater fund of knowledge than I. You asking questions for clarification of me tells me this is so. Just "musing".
Your reference to the HPT bearing? Is that an invitation to discuss what may have been the results of loss of lubrication? Cooling? (Oil Related)? Unclear to me.
regards bear
bear
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As mentioned before, the interview really does answer a lot of questions that were asked here.
It is clear to me that based on the information they had the crew made the right decisions regarding length of time in the air and the decision not to use the slides.
It also made it clear that the standard crew of 3 was adequate for this situation.
It is clear to me that based on the information they had the crew made the right decisions regarding length of time in the air and the decision not to use the slides.
It also made it clear that the standard crew of 3 was adequate for this situation.
A new update has been published by the ATSB.
News:
Qantas appears to have been extremely unlucky.
Turbine D
News:
Qantas appears to have been extremely unlucky.
Turbine D
Always like to work with data rather than imagination.
I don't see this as "luck"
My thoughts initially go to infant mortality rather than a wear out mode.
But of course the on-going inspection covers both. I wonder what the final fix will be ?
I'm not a fan of software changes for this except on a temporary basis
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I wonder what the final fix will be ?