QANTAS A380 Uncontained failure.
Join Date: Dec 2010
Location: S 51 N
Age: 84
Posts: 196
Likes: 0
Received 0 Likes
on
0 Posts
limping bird
Would also like to join fchan`s question about the damaged airplane sitting at Singapore. With all the ongoing engine chats we have lost abit the trck of that part of the story.
So, what´s the status and plans for this aircraft ??
Since she held together on the accident day it seems likely that only some well thought enforcements / emergency repairs will make a flight to Toulouse no big challenge. Probably in some shorter hopps to stay at lowest possible weight.
So, what´s the status and plans for this aircraft ??
Since she held together on the accident day it seems likely that only some well thought enforcements / emergency repairs will make a flight to Toulouse no big challenge. Probably in some shorter hopps to stay at lowest possible weight.
Join Date: May 2009
Location: Australia, maybe
Posts: 559
Likes: 0
Received 0 Likes
on
0 Posts
Radken
The FADEC provides protections against the following engine malfunctions:
N1, N2 over speed, and EGT over limit
LP shaft rupture
Fan instability
Engine flameout in adverse weather conditions
Overthrust
Engine stall
(source A380 FCOM)
Do any of you know if the T972 FADEC parameters “sense” eng/nacelle/pylon fire indication, and, if warranted, autonomously shut off main fuel at the wing, while also commanding MEC fuel off to the manifolds?
N1, N2 over speed, and EGT over limit
LP shaft rupture
Fan instability
Engine flameout in adverse weather conditions
Overthrust
Engine stall
(source A380 FCOM)
Join Date: Oct 2008
Location: Melbourne, ɐıןɐɹʇsn∀
Age: 74
Posts: 81
Likes: 0
Received 0 Likes
on
0 Posts
Is she still in Singapore?
Join Date: Oct 2009
Location: Durham
Posts: 483
Likes: 0
Received 0 Likes
on
0 Posts
Radken
"your knowledge and experience about things turbine." I am a civil engineer and that is a good thing, I learned about turbines as a result of this accident. I guess the only witness acceptable to a lawyer here would be TURBINE D.
Some will say ahem..WTF does he know..Haha.. Well I can tell you that the wing structure of the A388 is really kinda strong. The miracle was that the fluids did not burn when the wing was damaged. God was certainly with that flight until the engine was shut down some hours later.
That is not say that the Qantas crew was in anyway lacking, quite the opposite.
As for the fact that it could not be shut down I know that airbus has made some soft wear changes to the control system as Trent 972 has told us. It must be remembered that this aircraft design had a priority of less mass. As an example all of the wiring looms are made from aluminum wire instead of copper.
Wojtek
Are you seeking to teach us about bearings? A grease packed bearing is cooled by energy transfer to mass. An "nm" is a nanometer, and WOW that is tight. Wojtek I are you sure they can get the metal down to that level of accuracy? I honestly cannot see any technology known so far that can do that is steel...but maybe these balls are made from ceramics. Ceramic bearings are the latest trend.
I see what you mean about "overhung" forces yes. Where the bearing is the pivot and load point for a long shaft between several bearings. Well YES...that essentially is the turbine design.
Annex
"Ref. the ongoing oil and bearing discussion. Is there somewhere a list of oils that show the maximum permissable oiltemperature for Jetengine oils ?? Is it correct to say that the Trent 900 runs at borderline oil temperatures ??"
Most of the specs are set by the the U.S. Department of Defence. MIL specs. I believe it is true to say that no other aerospace gas turbine in CIVIL avaition runs at a mean temperature of 180C. Of course as Barit has told us it depends where you measure the temperature and some have suggested that the T900 measures this at the hottest place.
196C maximum is hot. The hotter the oil the more of it escapes into a gasseous state which leads to "coking" but everytime the engineers have checked the T900 no coking has been found.
In my book the high temperature tells a tale of high energy transfers. Certainly if I was the engineer responsible for a T900 I would be taking oil samples everytime the the thing came home, no matter what time of day.
Of course this is another issue: The MBA crowd would say "excuse me!" That is a RR job, or they would say: "Hey, that will take time and cost money...no..that is a RR job...and they have that responsibility". It all depends on your company culture.
The MBAs want the planes in the air making revenue. They really do not see "the big picture". Quite often they need firm advice.
"your knowledge and experience about things turbine." I am a civil engineer and that is a good thing, I learned about turbines as a result of this accident. I guess the only witness acceptable to a lawyer here would be TURBINE D.
Some will say ahem..WTF does he know..Haha.. Well I can tell you that the wing structure of the A388 is really kinda strong. The miracle was that the fluids did not burn when the wing was damaged. God was certainly with that flight until the engine was shut down some hours later.
That is not say that the Qantas crew was in anyway lacking, quite the opposite.
As for the fact that it could not be shut down I know that airbus has made some soft wear changes to the control system as Trent 972 has told us. It must be remembered that this aircraft design had a priority of less mass. As an example all of the wiring looms are made from aluminum wire instead of copper.
Wojtek
Are you seeking to teach us about bearings? A grease packed bearing is cooled by energy transfer to mass. An "nm" is a nanometer, and WOW that is tight. Wojtek I are you sure they can get the metal down to that level of accuracy? I honestly cannot see any technology known so far that can do that is steel...but maybe these balls are made from ceramics. Ceramic bearings are the latest trend.
I see what you mean about "overhung" forces yes. Where the bearing is the pivot and load point for a long shaft between several bearings. Well YES...that essentially is the turbine design.
Annex
"Ref. the ongoing oil and bearing discussion. Is there somewhere a list of oils that show the maximum permissable oiltemperature for Jetengine oils ?? Is it correct to say that the Trent 900 runs at borderline oil temperatures ??"
Most of the specs are set by the the U.S. Department of Defence. MIL specs. I believe it is true to say that no other aerospace gas turbine in CIVIL avaition runs at a mean temperature of 180C. Of course as Barit has told us it depends where you measure the temperature and some have suggested that the T900 measures this at the hottest place.
196C maximum is hot. The hotter the oil the more of it escapes into a gasseous state which leads to "coking" but everytime the engineers have checked the T900 no coking has been found.
In my book the high temperature tells a tale of high energy transfers. Certainly if I was the engineer responsible for a T900 I would be taking oil samples everytime the the thing came home, no matter what time of day.
Of course this is another issue: The MBA crowd would say "excuse me!" That is a RR job, or they would say: "Hey, that will take time and cost money...no..that is a RR job...and they have that responsibility". It all depends on your company culture.
The MBAs want the planes in the air making revenue. They really do not see "the big picture". Quite often they need firm advice.
Join Date: Oct 2009
Location: Durham
Posts: 483
Likes: 0
Received 0 Likes
on
0 Posts
Command Environment
This will interest a lot of readers.
Love the way the customer plays with the electric seat position!
This is the way the machine is controlled from the flight deck:
YouTube - Airbus 380 Flight Deck ( Dubai Airshow )
Notice:
The airport ground maps that are stored on line on the FMS.
The reason why the reverse thrust is only on the inboard engines.
The additional computer that slides out with the display on the side.
The fact that the controls follow a similar pattern to existing Airbus products.
Love the way the customer plays with the electric seat position!
This is the way the machine is controlled from the flight deck:
YouTube - Airbus 380 Flight Deck ( Dubai Airshow )
Notice:
The airport ground maps that are stored on line on the FMS.
The reason why the reverse thrust is only on the inboard engines.
The additional computer that slides out with the display on the side.
The fact that the controls follow a similar pattern to existing Airbus products.
Last edited by DERG; 6th Feb 2011 at 09:54. Reason: additional
Join Date: Jul 2009
Location: EPWA
Age: 65
Posts: 86
Likes: 0
Received 0 Likes
on
0 Posts
Derg
bearings: i am learning from this thread rather than trying to teach anyone
even if having some experience from high precision machine tools spindles which needed the speeds and accuracies of similar range. Only the forces were somewhat different 
Accuracies: when reading the documents suggested by earlier posters (especially http://http://mdrl.mne.psu.edu/papers/bearinganalyzer.pdf ) i have learned how much the bearing testing and machining has advanced - look at data presented there.
bearings: i am learning from this thread rather than trying to teach anyone
even if having some experience from high precision machine tools spindles which needed the speeds and accuracies of similar range. Only the forces were somewhat different Accuracies: when reading the documents suggested by earlier posters (especially http://http://mdrl.mne.psu.edu/papers/bearinganalyzer.pdf ) i have learned how much the bearing testing and machining has advanced - look at data presented there
.
Join Date: Oct 2009
Location: Durham
Posts: 483
Likes: 0
Received 0 Likes
on
0 Posts
WojtekSz
Yes we are all learning ALL of us are. Including RR and Airbus.
We ALL learned from this accident!
Your English is excellent! Please repost that link: the link will not connect for me! Thank you.
Join Date: Jul 2009
Location: EPWA
Age: 65
Posts: 86
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: Oct 2009
Location: Durham
Posts: 483
Likes: 0
Received 0 Likes
on
0 Posts
Yup see the issue
"The results are repeatable to the 100 nm level
and may be used to identify bearing characteristics"Thats 10 to power negative 7 (metres). That's achievable!
10 to power negative 9 is developing in "nano engineering"
As yet not in public domain.
Look up "micro" and "nano".
Join Date: Jul 2009
Location: EPWA
Age: 65
Posts: 86
Likes: 0
Received 0 Likes
on
0 Posts
yeah, i know there is some difference between micro and nano - i was boring holes to micrometer tolerances
still we are discussing the accuracy of balls and the track: overall bearing characteristic may be 100nm which is still only 0,1um but selecting the roller balls can be easily done to better tolerances.
to picture what is 1 nm = the increase of the OD of the 10mm steel ball heated by 1C !
still we are discussing the accuracy of balls and the track: overall bearing characteristic may be 100nm which is still only 0,1um but selecting the roller balls can be easily done to better tolerances.
to picture what is 1 nm = the increase of the OD of the 10mm steel ball heated by 1C !
Join Date: Jul 2009
Location: EPWA
Age: 65
Posts: 86
Likes: 0
Received 0 Likes
on
0 Posts
Derg
i believe the problem is actually not the bearings but the structure supporting the bearings - forces, temperatures and vibrations do significantly impair bearings geometry and hence the behaviour. The conditions are far from ideal. Rough environment calls for tougher solutions with wider spec tolerances so bigger ball diameters. I am sure RR must know it from their experience!
The splines are eaten neither by temperature nor nominal forces - must be significant uncontained forces from vibrations induced by parasitic resonance. Check the engine vibrations signature depicted in Fig 1of your link http://www.robots.ox.ac.uk/~davidc/pubs/ieeeaerospace.pdf - this does look like asking for bad resonance to happen.
But overall - watch the name: David Cliffton. Yes, he works on 'novelty detection' but to my feeling he will get it right. Both links from your post #328 are worth really careful reading. Thanks for research and posting them
i believe the problem is actually not the bearings but the structure supporting the bearings - forces, temperatures and vibrations do significantly impair bearings geometry and hence the behaviour. The conditions are far from ideal. Rough environment calls for tougher solutions with wider spec tolerances so bigger ball diameters. I am sure RR must know it from their experience!
The splines are eaten neither by temperature nor nominal forces - must be significant uncontained forces from vibrations induced by parasitic resonance. Check the engine vibrations signature depicted in Fig 1of your link http://www.robots.ox.ac.uk/~davidc/pubs/ieeeaerospace.pdf - this does look like asking for bad resonance to happen.
But overall - watch the name: David Cliffton. Yes, he works on 'novelty detection' but to my feeling he will get it right. Both links from your post #328 are worth really careful reading. Thanks for research and posting them
Join Date: Oct 2009
Location: Durham
Posts: 483
Likes: 0
Received 0 Likes
on
0 Posts
Probabilities
OK Woj I checked out this guy....
"His related research has resulted in patented early-warning systems for the jet engines of the Eurofighter, Airbus A380, and Boeing 787 Dreamliner, and for manufacturing processes that build such engines. He provides consultancy in machine learning to Rolls-Royce PLC and Oxford BioSignals Ltd., a university spin-out company."
He is employed as a full time "line" lecturer and teaches under grad basic math and post grad Bayesian math. I see he also has a strong interest in the medical field so I would guess this failure annoyed him from a moral viewpoint. A vocational person, for sure.
He also works as a consultant to RR.
In his paper
"Bayesian Extreme Value Statistics for Novelty Detection" in your link you posted the clue to this failure is very clear:
"An engine-specific approach to novelty detection has been
shown to be possible, in which the characteristics of data
from individual engines is learned – this often provides
better performance than generic “fleet-wide” models of
normality [21,22], in correctly identifying behaviour that is
abnormal for that engine, while minimising the number of
false-positive alarms generated."
In other words engines inherently are DIFFERENT. They are unique and they are seeking the normative values. Unfortunately there are not a lot of T900s around. T972s even less. They did not have enough DATA SETS. Clue number 1.
Now it is easy to quote sections of a paper to make a biased claim and I urge all readers to read the whole paper to make their judgement of just WTF is going on here, excuse me.[/LEFT]
"Future research will include the application of the technique
to vibration phase, and to non-vibration data sets, such as
“performance parameters” (engine temperatures, pressures,
etc.), which have previously been used with off-line density estimation
approaches [23]".
Well that about wraps it up. RR were running with this without the full data. The "novelty" threshold was set too high to minimise false alarms.
Basically they were taking a big risk.
I make it clear that the responsibility DOES NOT not rest with Mr. David A Clifton.
We will just see how long this post remains on this site. Some of us want the full picture.
"His related research has resulted in patented early-warning systems for the jet engines of the Eurofighter, Airbus A380, and Boeing 787 Dreamliner, and for manufacturing processes that build such engines. He provides consultancy in machine learning to Rolls-Royce PLC and Oxford BioSignals Ltd., a university spin-out company."
He is employed as a full time "line" lecturer and teaches under grad basic math and post grad Bayesian math. I see he also has a strong interest in the medical field so I would guess this failure annoyed him from a moral viewpoint. A vocational person, for sure.
He also works as a consultant to RR.
In his paper
"Bayesian Extreme Value Statistics for Novelty Detection" in your link you posted the clue to this failure is very clear:
"An engine-specific approach to novelty detection has been
shown to be possible, in which the characteristics of data
from individual engines is learned – this often provides
better performance than generic “fleet-wide” models of
normality [21,22], in correctly identifying behaviour that is
abnormal for that engine, while minimising the number of
false-positive alarms generated."
In other words engines inherently are DIFFERENT. They are unique and they are seeking the normative values. Unfortunately there are not a lot of T900s around. T972s even less. They did not have enough DATA SETS. Clue number 1.
Now it is easy to quote sections of a paper to make a biased claim and I urge all readers to read the whole paper to make their judgement of just WTF is going on here, excuse me.[/LEFT]
"Future research will include the application of the technique
to vibration phase, and to non-vibration data sets, such as
“performance parameters” (engine temperatures, pressures,
etc.), which have previously been used with off-line density estimation
approaches [23]".
Well that about wraps it up. RR were running with this without the full data. The "novelty" threshold was set too high to minimise false alarms.
Basically they were taking a big risk.
I make it clear that the responsibility DOES NOT not rest with Mr. David A Clifton.
We will just see how long this post remains on this site. Some of us want the full picture.
Join Date: Jul 2009
Location: EPWA
Age: 65
Posts: 86
Likes: 0
Received 0 Likes
on
0 Posts
Derg:
look also at the second article mentioned: http://www.eng.ox.ac.uk/samp/pubs/clifton_transfer.pdf and check fig 2.2 referring to trent 900 engine with data "...constructed from 200 hours of flight data recorded over a period of one month."
So the data is there BUT look at the width of the red band in the middle or rev range and at the high end. Over there there is practically no chance to detect anything viable!
i would suggest that all of us interested in turbine engines monitoring read carefully both of these articles - luckily to all of us you have been able to dug out and publish links to such extremely valuable reading. It looks like a good peek under the hood of RR maintenance program
look also at the second article mentioned: http://www.eng.ox.ac.uk/samp/pubs/clifton_transfer.pdf and check fig 2.2 referring to trent 900 engine with data "...constructed from 200 hours of flight data recorded over a period of one month."
So the data is there BUT look at the width of the red band in the middle or rev range and at the high end. Over there there is practically no chance to detect anything viable!
i would suggest that all of us interested in turbine engines monitoring read carefully both of these articles - luckily to all of us you have been able to dug out and publish links to such extremely valuable reading. It looks like a good peek under the hood of RR maintenance program
Last edited by WojtekSz; 7th Feb 2011 at 09:09. Reason: it must be red instead of blue band ;)
Join Date: Oct 2009
Location: Durham
Posts: 483
Likes: 0
Received 0 Likes
on
0 Posts
thank you!
Woj
Yes I missed that..thank you for taking me back to that link.
There is specific data in this link about the T900 testing programme.
At last we are getting close to some answers..thank you!
Yes Yes..
this document!
http://www.eng.ox.ac.uk/samp/pubs/clifton_transfer.pdf
Yes I missed that..thank you for taking me back to that link.
There is specific data in this link about the T900 testing programme.
At last we are getting close to some answers..thank you!
Yes Yes..
this document!
http://www.eng.ox.ac.uk/samp/pubs/clifton_transfer.pdf
Join Date: Oct 2009
Location: Durham
Posts: 483
Likes: 0
Received 0 Likes
on
0 Posts
Test Data T900
Yes Woj I see exactly. That's one HELL of a wobble!
If readers would open the above link and go to page 14.
The graph of amplitude on the LP shaft.
(inches per second amplitude vs shaft speed %)
Redlines are upper and lower recorded movement in inches per sec.
Blue line is the mean...the average.
Context: THIS IS DATA FROM THE T900
This is IN FLIGHT data from 200 hours of testing.
Think we can assume this would be a T970, maybe, but we don't know the airframe it was fixed on.
The graph tells us that when the throttle is set to 61% we have:
A wobble of between 0,42 inches and 1.20 inches per second WOW!
It has been pointed out that is OK. I hope TURBINE D can help us out here.
To many of you the consequences of this will be self evident.
Most of the data in this document uses the T500 as the source. But there are several references to the T900 and T1000 in the document which is worth reading very carefully.
Then we have the additional uncertainty of data for the T972 as used in the Qantas.
If readers would open the above link and go to page 14.
The graph of amplitude on the LP shaft.
(inches per second amplitude vs shaft speed %)
Redlines are upper and lower recorded movement in inches per sec.
Blue line is the mean...the average.
Context: THIS IS DATA FROM THE T900
This is IN FLIGHT data from 200 hours of testing.
Think we can assume this would be a T970, maybe, but we don't know the airframe it was fixed on.
The graph tells us that when the throttle is set to 61% we have:
A wobble of between 0,42 inches and 1.20 inches per second WOW!
It has been pointed out that is OK. I hope TURBINE D can help us out here.
To many of you the consequences of this will be self evident.
Most of the data in this document uses the T500 as the source. But there are several references to the T900 and T1000 in the document which is worth reading very carefully.
Then we have the additional uncertainty of data for the T972 as used in the Qantas.
Last edited by DERG; 7th Feb 2011 at 18:38. Reason: additional
Join Date: Oct 2009
Location: Durham
Posts: 483
Likes: 0
Received 0 Likes
on
0 Posts
Hiya
Thanks. In a word NO. 
This stuff takes some ploughing through.
So you say that the "amplitude" is accn? So that should be seconds (-2)?
If so the graph is not labelled properly. That axis is velocty...s to (-1)
So you say the actual distance covered in the wobble is the reciprocal?
Regards
P.S. This is just one of the THREE transmission shafts in this T900 turbine. I can see why SKF wanted no part of this.
You know what....The MBA courses love statistics...easy way to try and justify BS. No joke. Really ANNOYS me!
I just wish this guy and his supervisor would STAY in the medical field.
This stuff takes some ploughing through.So you say that the "amplitude" is accn? So that should be seconds (-2)?
If so the graph is not labelled properly. That axis is velocty...s to (-1)
So you say the actual distance covered in the wobble is the reciprocal?
Regards
P.S. This is just one of the THREE transmission shafts in this T900 turbine. I can see why SKF wanted no part of this.
You know what....The MBA courses love statistics...easy way to try and justify BS. No joke. Really ANNOYS me!
I just wish this guy and his supervisor would STAY in the medical field.
Last edited by DERG; 7th Feb 2011 at 18:41. Reason: correction
Guest
Posts: n/a
WojtekSz
The Supporting Structure of the Bearings and its shortcomings are well known, they are addressed by RR themselves, I believe. The IPT Case containing the IPT Disc and the LP/NGVs with Platform are supported by a center bore that is itself part of the Casing. These are ten Radial and hollow struts that are fastened to the Case with special fasteners (bolts). The AD does address the chronic loosening of these bolts, and requires their re-torquing at specific intervals. "Re-Torquing", "Borescoping", "Oil Inspections"; these are known "Palliatives". Palliative in the sense of treatment, not cure. The underlying consideration for the life of this powerplant is the rehabilitation back to profiles certified in its original certificate.
The squishy part is determining, and by whom, what constitutes Safety in pursuance of keeping this engine on wing. I can simply repeat that the cause of the chronic wear and shortened life of this machine is and was known. It is Vibration, and resonance; a "novelty" dependent on whom one asks. The core bores, bearings, and webs are subject to not additional stress, but normal stress that was unaddressed. It may be pedantic, but I think it is accurate. It is not a mystery, it never was. The engine landed on wing early, with insufficient test and a lurking problem that cannot be controlled given present design, not insofar as adherence to the certificate is involved. Decisions made about the future of the TRENT are forthcoming. Replacing moving mass every three hundred cycles may treat the disease, but it won't cure it.
The Supporting Structure of the Bearings and its shortcomings are well known, they are addressed by RR themselves, I believe. The IPT Case containing the IPT Disc and the LP/NGVs with Platform are supported by a center bore that is itself part of the Casing. These are ten Radial and hollow struts that are fastened to the Case with special fasteners (bolts). The AD does address the chronic loosening of these bolts, and requires their re-torquing at specific intervals. "Re-Torquing", "Borescoping", "Oil Inspections"; these are known "Palliatives". Palliative in the sense of treatment, not cure. The underlying consideration for the life of this powerplant is the rehabilitation back to profiles certified in its original certificate.
The squishy part is determining, and by whom, what constitutes Safety in pursuance of keeping this engine on wing. I can simply repeat that the cause of the chronic wear and shortened life of this machine is and was known. It is Vibration, and resonance; a "novelty" dependent on whom one asks. The core bores, bearings, and webs are subject to not additional stress, but normal stress that was unaddressed. It may be pedantic, but I think it is accurate. It is not a mystery, it never was. The engine landed on wing early, with insufficient test and a lurking problem that cannot be controlled given present design, not insofar as adherence to the certificate is involved. Decisions made about the future of the TRENT are forthcoming. Replacing moving mass every three hundred cycles may treat the disease, but it won't cure it.
Join Date: Oct 2009
Location: Durham
Posts: 483
Likes: 0
Received 0 Likes
on
0 Posts
Bear - TURBINE D
I believe RR estimated that the T972 in use with Qantas had a life of 70 cycles only. Yes only 70 cycles Good move on the Qantas management to take the "power by the hour" deal.
Does anyone have a link to the data plots from this accident engine please...I have lost the link. They were available but cannot find them.
TURBINE D can you help us out with this wobble stuff. Thanks.
Does anyone have a link to the data plots from this accident engine please...I have lost the link. They were available but cannot find them.
TURBINE D can you help us out with this wobble stuff. Thanks.
Last edited by DERG; 7th Feb 2011 at 18:39.
Join Date: Dec 2010
Location: Middle America
Age: 84
Posts: 1,167
Likes: 0
Received 0 Likes
on
0 Posts
Data Plots
Here is the link to the #2 engine data plots, they are at the very end of the report.
http://www.atsb.gov.au/media/2888854...ort.pdf#page=0
http://www.atsb.gov.au/media/2888854...ort.pdf#page=0