QANTAS A380 Uncontained failure.
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TopBunk
There remains an issue with the TB international terminal and the A380. First the location is extremely tight with all wide bodies having to be towed to the gates due to the crowding. The A380s of Qantas are towed to the west wing annex area for loading and unloading with passengers bussed to the main TB terminal as I understand it. This is to be remedied this year with a complete overhaul of the terminal to accommodate the super-sized A380 and eliminate the bussing among other positive renovations.
The north runways 24R/6L and 24L/6R pose a different problem. They are too close together and too close to the taxiways for multiple operations if one of the aircraft happens to be an A-380. A plan to both widen and relocate one of the runways to balance operations, similar as to what was done on the south side was rejected. So those two runways will no doubt be used more for smaller jets, TOs and landings with the widebodies utilizing the southern runways. The western end of the southern runways was totally rebuilt to give more operational room for the A380 to taxi towards the TB terminal.
I am not a pilot, but as far as runway length goes, If you have a fully loaded, fully fueled Qantas A380 taking off on 25L, do you have enough distance left at or just before V1 to abort the TO safely if you only can use 70K (degraded) maximum thrust? It may depend on day to day changing factors, if at all. The 72K thrust may be the guarantee it is OK.
There remains an issue with the TB international terminal and the A380. First the location is extremely tight with all wide bodies having to be towed to the gates due to the crowding. The A380s of Qantas are towed to the west wing annex area for loading and unloading with passengers bussed to the main TB terminal as I understand it. This is to be remedied this year with a complete overhaul of the terminal to accommodate the super-sized A380 and eliminate the bussing among other positive renovations.
The north runways 24R/6L and 24L/6R pose a different problem. They are too close together and too close to the taxiways for multiple operations if one of the aircraft happens to be an A-380. A plan to both widen and relocate one of the runways to balance operations, similar as to what was done on the south side was rejected. So those two runways will no doubt be used more for smaller jets, TOs and landings with the widebodies utilizing the southern runways. The western end of the southern runways was totally rebuilt to give more operational room for the A380 to taxi towards the TB terminal.
I am not a pilot, but as far as runway length goes, If you have a fully loaded, fully fueled Qantas A380 taking off on 25L, do you have enough distance left at or just before V1 to abort the TO safely if you only can use 70K (degraded) maximum thrust? It may depend on day to day changing factors, if at all. The 72K thrust may be the guarantee it is OK.
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Date of that report, see link, was November 12, 2010
Airbus says bearing box failed in Rolls engine Japan Today: Japan News and Discussion
Airbus says bearing box failed in Rolls engine Japan Today: Japan News and Discussion
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Turbine D
I was referring to old engineer's comments on the bearing case. Re: T/O LAX. It is the availibility of rated thrust that allows a 380 (Gross) to take off at all from LAX?
The area between HP/IP "support structure" seems to mean to most people the diaphragm supporting the roller bearings. It isn't important either way. The roller bearings I believe are victims, not progenitors. Anyway, the bearing box is affixed one assumes with the very bolts the AD demanded be borescoped, though a borescope could not conceivably measure torque. It could present damage to the rolling surfaces and raceways, assumedly this result would give RR the go-ahead to remove the engine, or prevent further use, (grounding).
Now, if the stub pipe entered service looking as it did in the pic, I'm quite surprised. One sees random scoring on the bore's wall, a channel cut into the bore, (the supposed Q/A blunder) and fractured rim with an ugly circular wear deficit on the coupling's face. This is caused by vibration, and I'm taking wagers. The couple may have failed, though it may have stayed attached, and been uncoupled at disassemble.
The OIL FIRE is almost certainly the result of A and B, as you say.
A........High powered vibration of several expressions.
B....... Severe fatigue due Oiling issues and Raceway, ball wear caused by the combination, oil starvation and vibration. Ball bearings are a "seam", and can vibrate at their own rate, driven by vibs on either side of the support. They are not rigid, and are subject to remarkable load that can reverse several times a second. Now if the bearings wear enough, the axial travel expands, and the IPT can contact the Stator inner, and the Vanes Platform, Outer. This is not my text, but a straightforward paraphrase of the AD.
C........loss of Oil line integrity, and fire. There is no evidence of a fire in the LPT cave, and most interpretations of the fire have it in the annulus between the HPT and IPT. This could of course blow the bearings to bits (rollers), but something simpler and more mechanical is likely to have happened. No need for Occam on this one. Follow the AD, the Wear, the concern, the Burst, the Grounding, and the struggle to refit, repair, and replace. Oil Fire is merely the penultimate failure, not the cause.
Look for insidious Fan Vibration, Fan shaft IPC damage, and weakening of the area around the HPT bearing and the IPT bearing. there is a 20,000 RPM net interface between these bearings. Oil fire is patent on test, though not widely known. The fire is of course a primary suspect, but needn't be at all the procuring cause of failure, just as overspeed is unlikely, given the proximate architecture of the IPT/Stator and the almost certain instantaneous loss of IPT Blades due to Axial Drift aftward. The LPT shaft and Turbines are remarkably free of damage, or even discoloration. Had the IPT blades been lost instant, the Massive Pressure in the LPT barrel would have (and seems to have) blown everything out the bolted together LP case and the IP case separation and missing pieces of case.The HPT was intact, and prevented access to any portion of the Gas path forward of its dynamic seal. Hence the exit of everything out the visible holes in the case.
Again, this is not my conclusion, and certainly not unsupported by the history prior to, the damage during, and the spin around the repair/refit/replace. It is what the Authority predicted, and probably with Rolls critical input. But no, we want it to be a duff piece of tube, flying in the face of enormous effort (unsuccessful) to prevent this very thing from occurring. Spline wear-vibration, oil issues. Bearing wear-vibration, oil issues, Fire-vibration-oil feeds.
The EEC, EMU. Next................
I was referring to old engineer's comments on the bearing case. Re: T/O LAX. It is the availibility of rated thrust that allows a 380 (Gross) to take off at all from LAX?
The area between HP/IP "support structure" seems to mean to most people the diaphragm supporting the roller bearings. It isn't important either way. The roller bearings I believe are victims, not progenitors. Anyway, the bearing box is affixed one assumes with the very bolts the AD demanded be borescoped, though a borescope could not conceivably measure torque. It could present damage to the rolling surfaces and raceways, assumedly this result would give RR the go-ahead to remove the engine, or prevent further use, (grounding).
Now, if the stub pipe entered service looking as it did in the pic, I'm quite surprised. One sees random scoring on the bore's wall, a channel cut into the bore, (the supposed Q/A blunder) and fractured rim with an ugly circular wear deficit on the coupling's face. This is caused by vibration, and I'm taking wagers. The couple may have failed, though it may have stayed attached, and been uncoupled at disassemble.
The OIL FIRE is almost certainly the result of A and B, as you say.
A........High powered vibration of several expressions.
B....... Severe fatigue due Oiling issues and Raceway, ball wear caused by the combination, oil starvation and vibration. Ball bearings are a "seam", and can vibrate at their own rate, driven by vibs on either side of the support. They are not rigid, and are subject to remarkable load that can reverse several times a second. Now if the bearings wear enough, the axial travel expands, and the IPT can contact the Stator inner, and the Vanes Platform, Outer. This is not my text, but a straightforward paraphrase of the AD.
C........loss of Oil line integrity, and fire. There is no evidence of a fire in the LPT cave, and most interpretations of the fire have it in the annulus between the HPT and IPT. This could of course blow the bearings to bits (rollers), but something simpler and more mechanical is likely to have happened. No need for Occam on this one. Follow the AD, the Wear, the concern, the Burst, the Grounding, and the struggle to refit, repair, and replace. Oil Fire is merely the penultimate failure, not the cause.
Look for insidious Fan Vibration, Fan shaft IPC damage, and weakening of the area around the HPT bearing and the IPT bearing. there is a 20,000 RPM net interface between these bearings. Oil fire is patent on test, though not widely known. The fire is of course a primary suspect, but needn't be at all the procuring cause of failure, just as overspeed is unlikely, given the proximate architecture of the IPT/Stator and the almost certain instantaneous loss of IPT Blades due to Axial Drift aftward. The LPT shaft and Turbines are remarkably free of damage, or even discoloration. Had the IPT blades been lost instant, the Massive Pressure in the LPT barrel would have (and seems to have) blown everything out the bolted together LP case and the IP case separation and missing pieces of case.The HPT was intact, and prevented access to any portion of the Gas path forward of its dynamic seal. Hence the exit of everything out the visible holes in the case.
Again, this is not my conclusion, and certainly not unsupported by the history prior to, the damage during, and the spin around the repair/refit/replace. It is what the Authority predicted, and probably with Rolls critical input. But no, we want it to be a duff piece of tube, flying in the face of enormous effort (unsuccessful) to prevent this very thing from occurring. Spline wear-vibration, oil issues. Bearing wear-vibration, oil issues, Fire-vibration-oil feeds.
The EEC, EMU. Next................
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I have been following this thread with interest, and have to agree with OE that turbomachinery faults can and do propagate through many levels.
QF32 brought to light the T900 issues with regard to spline wear. Helical spline coupling between compressor and turbine appears to me to be simple and ingenious - the torque generated by the turbine naturally closes the spline coupling. It is a solution conducive to modularity.
AD EASA AD 2010-0008 and its revision reveal problems with regard to IP shaft spline wear. To quote the AD, 'The shaft to coupling spline interface provides the means of controlling the turbine axial setting and wear through of the splines would permit the IP turbine to move rearwards. Rearward movement of the IP turbine would enable contact with static turbine components and would result in loss of engine performance with potential for in-flight shut down, oil migration and oil fire below the LP turbine discs prior to sufficient indication resulting in loss of LP turbine disc integrity.'
It seems an unlikely proposition that the AD and the QF32 incident are unrelated, but that is merely my own personal opinion. No matter what our engineering discipline might be, coincidences like this are rare.
From the data reproduced in ATSB preliminary report AO-2010-089, it appears that at time 02:00:22 oil temperature and pressure values begin to diverge from the recorded values for the other engines.
N3 vibrations increased to an extremely high and non-typical value, while N1 and N2 shaft speeds slowed. N3 shaft speed increased - possibly as the EEC increased fuel demand to compensate? Is this perhaps an indication of a bearing in some severe distress?
Here in this forum we can only speculate, however we must note that the AD makes no mention of the impact upon engine bearings in the event of shaft displacement due to spline wear - it only identifies the consequences of IP shaft rearward movement that would 'enable contact with static turbine components and would result in loss of engine performance with potential for in-flight shut down, oil migration and oil fire below the LP turbine discs prior to sufficient indication resulting in loss of LP turbine disc integrity'.
Returning to the ATSB published data, we observe unusual vibrations from the aircraft body lateral accelerometer at the time of 'thrust drop' and which is coincident with N1 and N2 shaft speeds dropping to zero.
Personally, I suspect that this coincides with the time at which bearing overheat (causing increased oil temperature) and mechanical interference with static LP turbine components may have caused the IP drive arm fracture.
Furthermore, and from the data published, I suspect that that the oil fire commenced at this point because this is when EGT commenced its rise. P30 collapse resulted in a fuel shut off - but I suspect the IPT disc was already in the 'departure lounge'. If I am correct, then the oil fire had little to to do with the IPT drive arm fracture. An engine surge possibly contributed more energy to the break-up of the distressed IPT disc than the resulting oil fire that was of short duration. I seem to recall that was already suggested in this forum but I may be incorrect?
I am therefore hypothesising that the stub oil pipe failure may therefore have resulted from HP/IP bearing faliure and a consequential and excessive HP vibration. Of course, the spline wear problem may have contributed to stub pipe fatigue. There seems to be some merit in returning to the IP spline AD issue and in particular to its cause.
Of course this is all speculative hypothesis based upon information and thinking published in the public domain. Please feel free to shout me down - I'm a new guy here and won't be offended. We can only learn.
QF32 brought to light the T900 issues with regard to spline wear. Helical spline coupling between compressor and turbine appears to me to be simple and ingenious - the torque generated by the turbine naturally closes the spline coupling. It is a solution conducive to modularity.
AD EASA AD 2010-0008 and its revision reveal problems with regard to IP shaft spline wear. To quote the AD, 'The shaft to coupling spline interface provides the means of controlling the turbine axial setting and wear through of the splines would permit the IP turbine to move rearwards. Rearward movement of the IP turbine would enable contact with static turbine components and would result in loss of engine performance with potential for in-flight shut down, oil migration and oil fire below the LP turbine discs prior to sufficient indication resulting in loss of LP turbine disc integrity.'
It seems an unlikely proposition that the AD and the QF32 incident are unrelated, but that is merely my own personal opinion. No matter what our engineering discipline might be, coincidences like this are rare.
From the data reproduced in ATSB preliminary report AO-2010-089, it appears that at time 02:00:22 oil temperature and pressure values begin to diverge from the recorded values for the other engines.
N3 vibrations increased to an extremely high and non-typical value, while N1 and N2 shaft speeds slowed. N3 shaft speed increased - possibly as the EEC increased fuel demand to compensate? Is this perhaps an indication of a bearing in some severe distress?
Here in this forum we can only speculate, however we must note that the AD makes no mention of the impact upon engine bearings in the event of shaft displacement due to spline wear - it only identifies the consequences of IP shaft rearward movement that would 'enable contact with static turbine components and would result in loss of engine performance with potential for in-flight shut down, oil migration and oil fire below the LP turbine discs prior to sufficient indication resulting in loss of LP turbine disc integrity'.
Returning to the ATSB published data, we observe unusual vibrations from the aircraft body lateral accelerometer at the time of 'thrust drop' and which is coincident with N1 and N2 shaft speeds dropping to zero.
Personally, I suspect that this coincides with the time at which bearing overheat (causing increased oil temperature) and mechanical interference with static LP turbine components may have caused the IP drive arm fracture.
Furthermore, and from the data published, I suspect that that the oil fire commenced at this point because this is when EGT commenced its rise. P30 collapse resulted in a fuel shut off - but I suspect the IPT disc was already in the 'departure lounge'. If I am correct, then the oil fire had little to to do with the IPT drive arm fracture. An engine surge possibly contributed more energy to the break-up of the distressed IPT disc than the resulting oil fire that was of short duration. I seem to recall that was already suggested in this forum but I may be incorrect?
I am therefore hypothesising that the stub oil pipe failure may therefore have resulted from HP/IP bearing faliure and a consequential and excessive HP vibration. Of course, the spline wear problem may have contributed to stub pipe fatigue. There seems to be some merit in returning to the IP spline AD issue and in particular to its cause.
Of course this is all speculative hypothesis based upon information and thinking published in the public domain. Please feel free to shout me down - I'm a new guy here and won't be offended. We can only learn.
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Howdy there. Big G. I think I'll have to take responsibility for the comment about the Fire being of insufficient length and ferocity to "Melt" the DA. I also have opined on the surge as the cause (one of) the IPT disc's erratic spin, a contributory factor in its loss, and I thank you for the support. I have held from the beginning that mechanical slip and effaced wheels causing great friction heat did in the Drive Arm, the Stator, and of course ultimately the IPWheel. Ingenious Helical Splineage?? Oh yeah, but remember, what screws in, also screws out. The bearings were not mentioned in the AD because technically they ARE 'Static Turbine Components', and were therefore covered in Rolls' expression of potential catastrophic failure. Not really non disclosure, 'not really'.
My conclusion had everything to do with the AD, a document that was rather suddenly abandoned in favor of a "may have intiated events that caused...." reported by RR through the ATSB.
Pray, what can be said about Vibration, the mother of this blast??
Howdy there. Big G. I think I'll have to take responsibility for the comment about the Fire being of insufficient length and ferocity to "Melt" the DA. I also have opined on the surge as the cause (one of) the IPT disc's erratic spin, a contributory factor in its loss, and I thank you for the support. I have held from the beginning that mechanical slip and effaced wheels causing great friction heat did in the Drive Arm, the Stator, and of course ultimately the IPWheel. Ingenious Helical Splineage?? Oh yeah, but remember, what screws in, also screws out. The bearings were not mentioned in the AD because technically they ARE 'Static Turbine Components', and were therefore covered in Rolls' expression of potential catastrophic failure. Not really non disclosure, 'not really'.
My conclusion had everything to do with the AD, a document that was rather suddenly abandoned in favor of a "may have intiated events that caused...." reported by RR through the ATSB.
Pray, what can be said about Vibration, the mother of this blast??
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Bearfoil & BigG22
I think we are all parked pretty much in the same corner. Although RR avows there is no connection between spline wear and what happened, it may be a brave statement. One of the things that is least predictable is extraneous vibrations that can develop, particularly those that develop in the torque field. The old saying "the best laid plans of mice and men often go astray" happens more often than not when it comes to vibration. You can do all sorts of testing and analysis, but an unpredicted and unanalyzed vibration could creep in over time and affect a component/components somewhere. I don't discount the potential that spline wear could have create vibration somewhere else in the engine, like tubes or fittings, bearings/bearing support structures, the stub pipe, the plenum or even fastening devises in the torque field, including the disc power drive arm to IP shaft flange bolt holes and bolts. For instance, the bolt holes are very critical in a torque field, and generally treated with significant multipliers of stress to deal with vibration and fatigue. What if some unusual vibration or harmonics entered the equation? Is premature spline wear something you anticipate and analyze for in terms of vibrational effects? Was this anticipated in the margins provided? This is the "A leads to B" I've talked about. The experts with all of the pieces and data have to figure this out. "The spline problem has nothing to do with this engine failure" (RR statement), well I say, "Never Say Never" until all the cards are face up on the table. At this point, all the cards aren't face up on the table. Lets hope they will be, because root cause/causes of failures are only fixed by identifying them and not denying they existed at all. Oil fire and BANG are obvious, A and B are not so obvious. I don't have the answers, not seeing all the face up cards, but RR should.
I think we are all parked pretty much in the same corner. Although RR avows there is no connection between spline wear and what happened, it may be a brave statement. One of the things that is least predictable is extraneous vibrations that can develop, particularly those that develop in the torque field. The old saying "the best laid plans of mice and men often go astray" happens more often than not when it comes to vibration. You can do all sorts of testing and analysis, but an unpredicted and unanalyzed vibration could creep in over time and affect a component/components somewhere. I don't discount the potential that spline wear could have create vibration somewhere else in the engine, like tubes or fittings, bearings/bearing support structures, the stub pipe, the plenum or even fastening devises in the torque field, including the disc power drive arm to IP shaft flange bolt holes and bolts. For instance, the bolt holes are very critical in a torque field, and generally treated with significant multipliers of stress to deal with vibration and fatigue. What if some unusual vibration or harmonics entered the equation? Is premature spline wear something you anticipate and analyze for in terms of vibrational effects? Was this anticipated in the margins provided? This is the "A leads to B" I've talked about. The experts with all of the pieces and data have to figure this out. "The spline problem has nothing to do with this engine failure" (RR statement), well I say, "Never Say Never" until all the cards are face up on the table. At this point, all the cards aren't face up on the table. Lets hope they will be, because root cause/causes of failures are only fixed by identifying them and not denying they existed at all. Oil fire and BANG are obvious, A and B are not so obvious. I don't have the answers, not seeing all the face up cards, but RR should.
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I do have access to the answers, as do others. The problem of the splines was identified in test. The characteristics of the vibration that caused this particular event were identified in test. It is a tramp, a harmonic, and not an insignificant one. The LP Shaft impinges through vibration on the IP Shaft. Chronic oil loss was ignored in test. All this plus an oil fire in test was documented. Shaft relationships were identified as troublesome due to proximity and vibration of two of the three shafts relative to the third. There was no "Oh my goodness, what a surprise". This engine was fielded too quickly, and without the customary care and sticklers for Proof that is ordinarily so much a part of RR. This includes all the 9's, not just the 72. I am just about through with this thread, it has been a laborious march, and the answers are dangling on the stage. I am no prophet, but as I have said before, this story has very long legs, and it is far from over. This entire event has no chance of containment, just like the IP Wheel. It has barely begun. It is entering the world of Industrial intrigue, politics and corporate survival, IMO.
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A very interesting and troubling piece of information, indeed. Things like this can't be ignored. Speed to market is one thing, but ...... Stick around, it will be interesting as the future unfolds.
A very interesting and troubling piece of information, indeed. Things like this can't be ignored. Speed to market is one thing, but ...... Stick around, it will be interesting as the future unfolds.
A very interesting and troubling piece of information, indeed. Things like this can't be ignored. Speed to market is one thing, but ...... Stick around, it will be interesting as the future unfolds.
This after market management is what's known as "continued airworthiness" and as such must be perfomed based on data and analysis by the certificate holder to the satisfaction of the regulatory authority.
It is not the intent to satsify the nay-sayers and in many cases the general public can submit their own comments to the docket for consideration. Meanwhile the present course is to satisfy the emergency AD notice
The typical course of problems like this is to tweak the interim corrective action programs as additional data is received and until a closing action is decided upon and effected. There have been far bigger problems than this in aviation including the B747 fuse pin problem and the various uncommanded reverser problems.
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Sorry, "Far bigger problems than this" ?? I thought no one knew what happened yet. Very odd take on things, and dare I say, Premature??
Turbine D
Yes, I think parked in the same place. Good company, regards.......
Turbine D
Yes, I think parked in the same place. Good company, regards.......
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ref. digging mud??
Quite some commotion in progress since my last entry!! However I have meanwhile detected that this report I linked was not the only one, no there is a whole wave of similar sounding news reports. The origin however, seems to be the report issued by associated press on Nov, 12 right after the Airbus CEO spoke in Australia.
So far firstfloor and Turbine D I agree in what you posted, most unlikely the CEO was - knowingly - talking hard facts about the QF 32 failure.
However, have to ask the question: How did he come to the conclusion to mouth something so serious as a cause of failure in public, if not some information about this possible problem area was known to him ???
Turbine D
Those bolted joines that are subject to boroscopic evaluation have to be those connections between the Modules 2, 3 and 4 - s.a. RR-brochure > gasturbines_tcm92-4977.pdf - sorry I have no working link. One of these bolts is visible in that Trent 900 cutaway I posted a while ago just on top of the Nr. 2 ball bearing.
My question about the decolouringf the disk fragment and the obvious lack of wear or damage to the side of the disk that was supposed to have slammed into the rearward structure and the nozzle guide vane ring was triggered by
lomopaseo
quote: However, once again I would urge you to forget about the significance of friction once the failure scenario has started. At the speeds that turbo machinery runs the interface conditions in a contact environment is nothing but molten metal.
Okay if friction is no player in the game and also no obvious marks about a "fluid bearing" neither in the bore nor at the circumferential crack in the drive arm, and also no mark of contact at least on the recovered part of the disk, what is left as explanation for the disk failure?? Overspeed/ overstress and a plain "ductile fracture" as explained in the ATSB report ??? Here the engineers are demanded !! Its just a conclusion !
Assisted by what?? Look at Fig. 13 of the ATSB report, enlarge it a bit and check the visible rear side of the nozzle guide vanes of the IP turbine. Its there well visible, just some shiny or dark marking, probable contact on break up ? and the gas channels at - as I consider it - normal performance colouration. There is no Oil, there is no oil soot, there is just plain metal !! Wasn´t that the side where that feroscious -blowtorch like - oilfire had to have its devastating work done ??
Hard to believe !!
Still I am thinking of the hottest place of that oilfire more foreward, seen the damage from inside outward on the remains of the bottom section aft cowling.Wasn´t there nearby not that Inner Gear Box witha connection to the ring in front of ball bearing Nr. 3 ??
Finally, the "spline wear" AD is still in force, as is the restriction to 75 takeoffs with power settings at 540 Psi at P30!! Why that ??
Obviously the oil tube is a contributing cause but the real problem still excists and is not identified to the public. Looks like someone tries the old game of "sectioned information and selected truth" Okay, Okay, if at the end the case is sober and no one gets hurt, but meanwhile ?? how long will it take to be really back on the safe side of the game ??
So far firstfloor and Turbine D I agree in what you posted, most unlikely the CEO was - knowingly - talking hard facts about the QF 32 failure.
However, have to ask the question: How did he come to the conclusion to mouth something so serious as a cause of failure in public, if not some information about this possible problem area was known to him ???
Turbine D
Those bolted joines that are subject to boroscopic evaluation have to be those connections between the Modules 2, 3 and 4 - s.a. RR-brochure > gasturbines_tcm92-4977.pdf - sorry I have no working link. One of these bolts is visible in that Trent 900 cutaway I posted a while ago just on top of the Nr. 2 ball bearing.
My question about the decolouringf the disk fragment and the obvious lack of wear or damage to the side of the disk that was supposed to have slammed into the rearward structure and the nozzle guide vane ring was triggered by
lomopaseo
quote: However, once again I would urge you to forget about the significance of friction once the failure scenario has started. At the speeds that turbo machinery runs the interface conditions in a contact environment is nothing but molten metal.
Okay if friction is no player in the game and also no obvious marks about a "fluid bearing" neither in the bore nor at the circumferential crack in the drive arm, and also no mark of contact at least on the recovered part of the disk, what is left as explanation for the disk failure?? Overspeed/ overstress and a plain "ductile fracture" as explained in the ATSB report ??? Here the engineers are demanded !! Its just a conclusion !
Assisted by what?? Look at Fig. 13 of the ATSB report, enlarge it a bit and check the visible rear side of the nozzle guide vanes of the IP turbine. Its there well visible, just some shiny or dark marking, probable contact on break up ? and the gas channels at - as I consider it - normal performance colouration. There is no Oil, there is no oil soot, there is just plain metal !! Wasn´t that the side where that feroscious -blowtorch like - oilfire had to have its devastating work done ??
Hard to believe !!
Still I am thinking of the hottest place of that oilfire more foreward, seen the damage from inside outward on the remains of the bottom section aft cowling.Wasn´t there nearby not that Inner Gear Box witha connection to the ring in front of ball bearing Nr. 3 ??
Finally, the "spline wear" AD is still in force, as is the restriction to 75 takeoffs with power settings at 540 Psi at P30!! Why that ??
Obviously the oil tube is a contributing cause but the real problem still excists and is not identified to the public. Looks like someone tries the old game of "sectioned information and selected truth" Okay, Okay, if at the end the case is sober and no one gets hurt, but meanwhile ?? how long will it take to be really back on the safe side of the game ??
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Annex14
Howdy. The AD is the Gorilla in the living room. Eventually, and ironically, RR and EASA will have to merge reality with prior work. It won't go away, and the liability can never be diminished. Ever.
In the Broad view, time is running out on the program. Fewer and fewer of the principals are adhering to "Let's wait and see". Or, more laughably, "Let's wait for the final report". Any rush to Nirvana will be roundly criticized, but the patience of the entire Aviation landscape will get thin.
There is a reason for intensified scrutiny. There is a reason for the borescope. There is also, like white on rice, the need to strip and bare the insufficencies, which perforce will cost the community untold money. We are witnessing the underside of what is wrong with the too cozy relationships between the Authority and the Manufacturer/Operator.
I think there will be a "fix". The question is obviously, is there room for it inside the confines of the certificate?? The "Back in the Air, what a relief" has to do with a system that hadn't any part in the cascade of cause, the fingered "Stub Pipe", around which there is no AD. There is only an emergency directive. While the audience is fixed on OIL, the "modules" are switched. Presto.
Can this feint be pulled off?? Only if it is not a feint, but as RR and all would have it, merely a duff piece of metal tube.
Hiding in plain sight has gotten orders of magnitude more difficult than days of old. This is a good thing; all the artifacts, fossils and tricks are uncovered to enhance Safety. Disclosure is a very good thing, always. It is sadly predictable that keeping secrets and hiding is getting ever more difficult, bummer............
Howdy. The AD is the Gorilla in the living room. Eventually, and ironically, RR and EASA will have to merge reality with prior work. It won't go away, and the liability can never be diminished. Ever.
In the Broad view, time is running out on the program. Fewer and fewer of the principals are adhering to "Let's wait and see". Or, more laughably, "Let's wait for the final report". Any rush to Nirvana will be roundly criticized, but the patience of the entire Aviation landscape will get thin.
There is a reason for intensified scrutiny. There is a reason for the borescope. There is also, like white on rice, the need to strip and bare the insufficencies, which perforce will cost the community untold money. We are witnessing the underside of what is wrong with the too cozy relationships between the Authority and the Manufacturer/Operator.
I think there will be a "fix". The question is obviously, is there room for it inside the confines of the certificate?? The "Back in the Air, what a relief" has to do with a system that hadn't any part in the cascade of cause, the fingered "Stub Pipe", around which there is no AD. There is only an emergency directive. While the audience is fixed on OIL, the "modules" are switched. Presto.
Can this feint be pulled off?? Only if it is not a feint, but as RR and all would have it, merely a duff piece of metal tube.
Hiding in plain sight has gotten orders of magnitude more difficult than days of old. This is a good thing; all the artifacts, fossils and tricks are uncovered to enhance Safety. Disclosure is a very good thing, always. It is sadly predictable that keeping secrets and hiding is getting ever more difficult, bummer............
Last edited by bearfoil; 4th Jan 2011 at 18:54.
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Annex writes:
Those bolted joines that are subject to boroscopic evaluation have to be those connections between the Modules 2, 3 and 4 - s.a. RR-brochure > gasturbines_tcm92-4977.pdf - sorry I have no working link. One of these bolts is visible in that Trent 900 cutaway I posted a while ago just on top of the Nr. 2 ball bearing.
Those bolted joines that are subject to boroscopic evaluation have to be those connections between the Modules 2, 3 and 4 - s.a. RR-brochure > gasturbines_tcm92-4977.pdf - sorry I have no working link. One of these bolts is visible in that Trent 900 cutaway I posted a while ago just on top of the Nr. 2 ball bearing.
Cheers!
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lomapaseo
Here is another "told you so" to think about....
Joerg Handwerg, a spokesman for the pilots’ union for Lufthansa said that minor problems are routine for any jet engine, but it is possible that the issues were an indication that regulators did not adequately check the engine before approving it for commercial use.
“When you see we have a problem with not just one of these engines but several then it points towards that we have a problem in the certification process,” Handwerg said. Why Lufthansa is check-fly, check-fly, etc.?
So, the Trent 900 engine was certified as being airworthy and then the certification of the Airbus A380 began with the Trent engines. So in this aircraft certification process, how many engines do you think would be acceptable to come of wing due to "technical problems"? 5, 10, 20, 25, 30? I am not referring to planned removals. I think the true number would surprise you. Maybe this is where Airbus Chief Operating Officer, John Leahy had information the general public didn't.
Technical problems with the engines, lets fix them, starting with the ones sitting at Airbus?? What about the ones flying? Humm.
Now the RR lawyers are in charge of the business, settle with Qantas and Airbus as to damages while not admitting to or denying anything was the fault of RR. Isn't that the way business is done these days?? Sure is! Too Bad!!!
I suspect a lot of "I told you so" just like the ones that we are still waiting for predicting that all kinds of aircraft would eventually fall out of the sky from eating the icelandic dust of a year ago.
Joerg Handwerg, a spokesman for the pilots’ union for Lufthansa said that minor problems are routine for any jet engine, but it is possible that the issues were an indication that regulators did not adequately check the engine before approving it for commercial use.
“When you see we have a problem with not just one of these engines but several then it points towards that we have a problem in the certification process,” Handwerg said. Why Lufthansa is check-fly, check-fly, etc.?
So, the Trent 900 engine was certified as being airworthy and then the certification of the Airbus A380 began with the Trent engines. So in this aircraft certification process, how many engines do you think would be acceptable to come of wing due to "technical problems"? 5, 10, 20, 25, 30? I am not referring to planned removals. I think the true number would surprise you. Maybe this is where Airbus Chief Operating Officer, John Leahy had information the general public didn't.
Technical problems with the engines, lets fix them, starting with the ones sitting at Airbus?? What about the ones flying? Humm.
Now the RR lawyers are in charge of the business, settle with Qantas and Airbus as to damages while not admitting to or denying anything was the fault of RR. Isn't that the way business is done these days?? Sure is! Too Bad!!!
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Turbine D
Lufty has been quiet since the outset, and I hadn't seen Herr Joerg's comment. LuftTek has the marbles, the action they have taken/acceded to will speak volumes when they speak, I'd say. Qantas by now has a thick jacket on the 9 and RR's "unusual" timetable. A shiny newbie gets re-engined prior to one that takes off and dodges a bullet?? I'm watching for action around the AD's. Something is amiss when a flying operator is passed over when the AD's call for such draconian levels of inspections, and repair, rebuild, re-new. Is there anything in the "C" model that stretches the Certificate to fit it?? What can be so attractive about a rebuild when it doesn't satisfy its own Certificate and retains so many limitations?? The DEP/EEC has new programming, and what good is the extra 2000 pounds when all it gets one is trouble and sanctions?? Speaks volumes about what might be wrong with the 900 as well. It isn't the Oil, and it isn't the DEP, Coupled shafts have issues, can RR design/build a new engine to wear the 900 livery, spec sheet and maintain the certificate?? EASA and ROLLS are in a corner. Qantas has some challenges as the result of the Burst, but just because the situation paints them the victim, money is way off, and how to recoup their position?? Haven't heard from Mr. Joyce recently.
Time to break the huddle and line-up??
Lufty has been quiet since the outset, and I hadn't seen Herr Joerg's comment. LuftTek has the marbles, the action they have taken/acceded to will speak volumes when they speak, I'd say. Qantas by now has a thick jacket on the 9 and RR's "unusual" timetable. A shiny newbie gets re-engined prior to one that takes off and dodges a bullet?? I'm watching for action around the AD's. Something is amiss when a flying operator is passed over when the AD's call for such draconian levels of inspections, and repair, rebuild, re-new. Is there anything in the "C" model that stretches the Certificate to fit it?? What can be so attractive about a rebuild when it doesn't satisfy its own Certificate and retains so many limitations?? The DEP/EEC has new programming, and what good is the extra 2000 pounds when all it gets one is trouble and sanctions?? Speaks volumes about what might be wrong with the 900 as well. It isn't the Oil, and it isn't the DEP, Coupled shafts have issues, can RR design/build a new engine to wear the 900 livery, spec sheet and maintain the certificate?? EASA and ROLLS are in a corner. Qantas has some challenges as the result of the Burst, but just because the situation paints them the victim, money is way off, and how to recoup their position?? Haven't heard from Mr. Joyce recently.
Time to break the huddle and line-up??
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Annex14
You are correct, that is the nozzle vane that sits behind the HPT rotor, it is a hot gas path at that point and the vanes are air-cooled. They are no doubt coated to prevent oxidation/sulfidation and the brownish color is the deposit left by the fuel that has been burned in the combustor. There would be no soot from oil burning it would be completely consumed because of the gas path temperature (~ 1800℉). The vanes are not the problem, it is the plenum chamber directly under these vanes that you can not see that is the problem. As you would move down that plenum towards engine centerline, the HPT/HPC rear roller bear sits, supported by the end of the plenum.Just slightly rearward sits the IPT/IPC rear roller bearing. If there was an oil fire in this plenum, it could cause it to rupture exposing the front face of the disc near the bore. The plenum is (or should be) under positive pressure from the cooling air that has passed through the nozzle vanes. the vanes didn't see the oil at all.
In one of the press releases or media briefings by the ASTB, they talked about the disc and the fact that it showed both melting and molten metal splatter on the rear surface of the disc. I think I mentioned that the light grey area next to the bore was just that. When something is spinning at 7-8K rpms, the metal spreads out into a film (usually a combination of metal and metallic oxide). Also, look at the recovered nozzle vane photo in the ASTB report. They note a coating on the surface of the airfoils they intended to examine. That to could be a molten metal deposit film as well. I believe the disc broke free from the bolt holes when the power drive arm broke at that location. Once free, it was able to rotate to whatever speed the HPT gas flow could drive it and remember the N3 was 98% at its peak. At this point it would be stretching. They will be able to determine this by dimensional measurements taken on this recovered section. So it moved back contacting the Stg. 1 LPT nozzle, not blade to vane but blade to the inner nozzle band forward overhang. Look at the vane photo again, the inner forward overhang is gone, not there. The other possibility is what Bearfoil proposes. No matter which, the disc over-sped. It all happened in a couple of seconds. Mostly everything went out including the Stg. 1 nozzle vanes, very little went back through the LPT which is what you would expect if the disc didn't burst.
Assisted by what?? Look at Fig. 13 of the ATSB report, enlarge it a bit and check the visible rear side of the nozzle guide vanes of the IP turbine. Its there well visible, just some shiny or dark marking, probable contact on break up ? and the gas channels at - as I consider it - normal performance colouration. There is no Oil, there is no oil soot, there is just plain metal !! Wasn´t that the side where that feroscious -blowtorch like - oilfire had to have its devastating work done ??
Hard to believe !!
Hard to believe !!
Okay if friction is no player in the game and also no obvious marks about a "fluid bearing" neither in the bore nor at the circumferential crack in the drive arm, and also no mark of contact at least on the recovered part of the disk, what is left as explanation for the disk failure?? Overspeed/ over-stress and a plain "ductile fracture" as explained in the ATSB report ??? Here the engineers are demanded !! Its just a conclusion !
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Just so nobody goes away with the idea that Rolls Royce is the only one with engine problems. In the news today is this.
But back on subject, it seems to me that the only way to know if the C engine still has a design issue is if it comes back on the USA west coast routes with restrictions imposed on 72k takeoffs. This restriction has so far only been mentioned in the infamous Qantas affidavit.
GE says it is working with the carrier, after local reports from Angola said that TAAG grounded its three 777-200ERs after another incident on 23 December involving a GE90.
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DERG
There also seems to be some confusion on market share and market leader when it comes to the Trent 800 & Boeing 777. RR, in the brochure for this engine states that they are the market leader at a 41% market share. In that there are only two engines offered, one being a RR, how can you be the leader at 41% share? I think the same disclaimer is on the back page.
Turbine D
There also seems to be some confusion on market share and market leader when it comes to the Trent 800 & Boeing 777. RR, in the brochure for this engine states that they are the market leader at a 41% market share. In that there are only two engines offered, one being a RR, how can you be the leader at 41% share? I think the same disclaimer is on the back page.
Turbine D
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Turbine D
Thanks for your comments. Those tremendous gas and thermo dynamics inherent in a running jet engine are always good for surprise, I assume.
Ref. that statement of Cpt. Handwerg, VC - the union of the LH pilots - is indeed amazing, I´ve read it too. But knowing their reluctance to go public with company related insider data, this is a clear sighn that the pilots and technicians At DLH see a potential problem.Will have a close watch what else they might release in this case.
firstfloor
There is thread in Rumors & News about that TAAG-incident on Dec, 6 . The flight returned to Lisbon with vibrations in one engine. On its way back parts - engine ?? - fell onto cars in southern Portugal.
Jo
Ref. that statement of Cpt. Handwerg, VC - the union of the LH pilots - is indeed amazing, I´ve read it too. But knowing their reluctance to go public with company related insider data, this is a clear sighn that the pilots and technicians At DLH see a potential problem.Will have a close watch what else they might release in this case.
firstfloor
There is thread in Rumors & News about that TAAG-incident on Dec, 6 . The flight returned to Lisbon with vibrations in one engine. On its way back parts - engine ?? - fell onto cars in southern Portugal.
Jo