Qantas A380 uncontained #2 engine failure
bear, I am now more confused. I am looking at a schematic of a Trent as I read your post and scratching my head. I have mentally inserted stators where the picture shows only the rotating wheels with blades on compressor and turbine sections. we start with compressor stages, 1 big LP fan, 8 IP rotors, 6 HP rotors (the combustion can, not shown) -- then power stages -- 1 HP turbine (wheel?) 1 IP turbing (wheel?) 5 LP turbine (wheels?) in order as the air comes in from fore to aft and exits as gloriously warm exhaust and thrust ...
Roger, normal turbine engine operation.
Do you mean the IP turbine section (1 wheel) or the IP compressor section (6 rotors)?
OK, from this I get the great big LP fan on the front is pushing air into IP faster than it can flow through the system, and this is due to an out of bounds pressure drop aft of the IP compressor section. Do I read you clearly there?
Which wheel? The HP power turbine wheel? 
Do you mean in the compressor section or the power turbine section? I am looking at the picture and you seem to have switched from compressor in the opener to the power turbine in the later passage.
I may be confusing myself, but from the picture I have I am guessing that LP shaft is "wrapped" around IP shaft is "wrapped" around HP shaft. (Nested hollow shafts might be a better way to describe that.)
Are you suggesting that things sliding for and aft due to a pressure problem are manifested in the shafts themselves migrating fore and aft? If so, would we not also see potential friction between compressor rotors and stator sections in the IP? I am assuming that the part lost and zinging through the aircraft is the IP Turbine wheel, not one of the compressor rotors. I think I understand that from these many pages of posts, but I may be utterly at sea and have missed the vagrant disc being a compressor rotor.
Sorry to come off so thick, but I am trying to understand.
[/quote]Fzz: Most interesting. Puts a grip on the stresses in the wheel[/quote]
Aye, that it did.
IP disc loads incoming air from LP into a smaller area, thus increasing the energy by compression, and a concomitant rise in T.
My view of overspeed in this case, would be a "normalizing" event that reduced the load behind the IP.
The LP overpowers the flow behind the IP, forcing it aft, and increasing its rate of rotation, since the mitigating Pressure of normal flow has diminished. (Proper airflow keeps all rotating mass in designed-for relative velocity limits)
The migration aft can force the Wheel into the Stator separating IP from HP.
Do you mean in the compressor section or the power turbine section? I am looking at the picture and you seem to have switched from compressor in the opener to the power turbine in the later passage.
This causes increased friction, with the heat of the oil fire, the wheel fails in its mount, whilst shedding blades (at this point, probably through the Stator into the HP, rather than centrifugally out the Titanium case). The damage to Hub shows a possibility of such migration.
Any Turbine (or propellor for that matter) which 'falls behind' airflow, Windmills; without a variable Blade AoA, a "flat Pitch" starts an overspeeding event. What causes the loss of Pressure in the IP cavity? Fire? With fuel, (The Oil), compression, (patent), where is the ignition? Possibly failing bearings, with unlubricated metal/metal causing a flurry of sparks? If the ensuing Fire "Blew out" the normal fires behind, there is a source of low compression behind the IP..
Are you suggesting that things sliding for and aft due to a pressure problem are manifested in the shafts themselves migrating fore and aft? If so, would we not also see potential friction between compressor rotors and stator sections in the IP? I am assuming that the part lost and zinging through the aircraft is the IP Turbine wheel, not one of the compressor rotors. I think I understand that from these many pages of posts, but I may be utterly at sea and have missed the vagrant disc being a compressor rotor.
Sorry to come off so thick, but I am trying to understand.
[/quote]Fzz: Most interesting. Puts a grip on the stresses in the wheel[/quote]
Aye, that it did.
Join Date: May 2009
Location: sfo
Age: 70
Posts: 309
Likes: 0
Received 0 Likes
on
0 Posts
LW50
The LP shaft is the longest, the IP shaft a little shorter, and the HP shaft is the shortest, since it holds the HP compressor and turbine. Does that help?
The way bearfoil was jumping around in his post had my head hurting a little as well...
Edit- you're right, it was an IP turbine let go, just as in the QF incident in SFO couple months back.
The way bearfoil was jumping around in his post had my head hurting a little as well...
Edit- you're right, it was an IP turbine let go, just as in the QF incident in SFO couple months back.
sb, I understand that dimensionally, the picture makes that clear. I am guessing from the sketch that inside out "wrapping" is a correct description. (A tube --LP shaft -- inside a tube of larger dia -- IP shaft-- inside a tube of larger dia -- HP shaft) with the round bits attached at appropriate places to mount the shafts and to fit between the stationary bits of the engine.
I am trying to figure out where in the flow the pressure discontinuity bear is talking about would happen, and can't yet. But if the IP turbine wheel is where the friction/fire/movement occurred, then maybe what he is suggesting is that the pressure diff problem causes the IP compressor section to migrate aft, that being on the same shaft as IP turbine makes the IP turbine wheel move aft, (or the same with HP compressor and turbine) and thus make contact with a stationary bit that it wasn't meant to, hence friction, and so on. The fog is lifting slightly ...
I am trying to figure out where in the flow the pressure discontinuity bear is talking about would happen, and can't yet. But if the IP turbine wheel is where the friction/fire/movement occurred, then maybe what he is suggesting is that the pressure diff problem causes the IP compressor section to migrate aft, that being on the same shaft as IP turbine makes the IP turbine wheel move aft, (or the same with HP compressor and turbine) and thus make contact with a stationary bit that it wasn't meant to, hence friction, and so on. The fog is lifting slightly ...
Guest
Posts: n/a
My get was IP Wheel loss from the git. Right? The AD mentions with oil problems a concomitant wear in splines of the IP/Shaft join. This was to be assessed at each special inspex? A couple fail is what causes the migration, in the sense that the aft tendency of the airflow 'pushes' the wheel past its limit (geographically), to cause a very significant trail of failure. imo.
I think there is that much Ti in the Trent, Lonewolf, but most of it is left on the shop floor after machining, or in the slurry if a water cut?
bear
I think there is that much Ti in the Trent, Lonewolf, but most of it is left on the shop floor after machining, or in the slurry if a water cut?
bear
Bear.....
At that point a rampie with an unfamiliar tool in hand looks up the lady's skirt, and declares "What, exactly, am I looking for?
I would. But maybe I am naive.
Nevertheless, your post seems to be very disparaging of the gentlemen and ladies of the International Licensed Aircraft Engineering community.
If I have misunderstood you, then ignore the above.
Thanks sb and bear, it makes a little more sense now.
@ Turin, agree with your points in general. I suspect you are aware of what the required degree of engine disassembly is, if any, before inspectors can get a good look at the potential problem area. Might be "on the ramp" or at a higher level of maintenance. Depends on how a given maintenance facility is organized and equipped.
@ Turin, agree with your points in general. I suspect you are aware of what the required degree of engine disassembly is, if any, before inspectors can get a good look at the potential problem area. Might be "on the ramp" or at a higher level of maintenance. Depends on how a given maintenance facility is organized and equipped.
Warning to all browsers
There is a great amount of mis-information let alone mis-understandings rattling around in this thread from a technical standpoint over the last few days. I strongly suggest that the technical stuff get sorted out somewhere else and we concentrate more on new released information like inspections, repairs and anything that the ATSB, Airbus or RR choose to share.
The leaked stuff is not really cause and effect stuff but more along the line of what needs to get repaired, so lets leave it at that.
There is a great amount of mis-information let alone mis-understandings rattling around in this thread from a technical standpoint over the last few days. I strongly suggest that the technical stuff get sorted out somewhere else and we concentrate more on new released information like inspections, repairs and anything that the ATSB, Airbus or RR choose to share.
The leaked stuff is not really cause and effect stuff but more along the line of what needs to get repaired, so lets leave it at that.
Guest
Posts: n/a
TURIN
No disrespect intended, I merely make the point that this close hauled inspection may be better accomplished in the barn.
Other... I notice a potential adversarial proclivity here recently, and if the fault is mine, I will stop; I admit to being outspoken, and occasionally in territory where I am a tad bit lower than the threshold. I do think this is Rumours and News, for pilots mainly, and those generally who make/made a living of it. I am no boffin, never will be. I am a pilot, and given to chest out shoulders back bluster, on occasion. I rather dislike being told what to discuss, and when. Maybe that's just me.....
bear
No disrespect intended, I merely make the point that this close hauled inspection may be better accomplished in the barn.
Other... I notice a potential adversarial proclivity here recently, and if the fault is mine, I will stop; I admit to being outspoken, and occasionally in territory where I am a tad bit lower than the threshold. I do think this is Rumours and News, for pilots mainly, and those generally who make/made a living of it. I am no boffin, never will be. I am a pilot, and given to chest out shoulders back bluster, on occasion. I rather dislike being told what to discuss, and when. Maybe that's just me.....
bear
Join Date: Nov 2010
Location: Tarmac
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Live interaction with Airbus/Qantas?
It has been mentioned that the aircraft generated a series of error messages that would have been received by Qantas and I also suspect Airbus (via satellite).
Is there any chance for pilots to receive advice or information in real time from Qantas (or more generally, the airline that "owns" the plane) or Airbus on how to handle the situation?
Or do the systems that receive the messages live via satellite have insufficient programming to allow any extra live assistance to be made available?
I would imagine that any such interaction between the airline/Airbus would need to be via the control tower. If that interaction was present, would it be welcome or just another unwanted distraction from the job at hand?
Or is the utility of such interaction dependent on other information (such as how much fuel is in each tank, etc) that is not relayed back via satellite?
Is there any chance for pilots to receive advice or information in real time from Qantas (or more generally, the airline that "owns" the plane) or Airbus on how to handle the situation?
Or do the systems that receive the messages live via satellite have insufficient programming to allow any extra live assistance to be made available?
I would imagine that any such interaction between the airline/Airbus would need to be via the control tower. If that interaction was present, would it be welcome or just another unwanted distraction from the job at hand?
Or is the utility of such interaction dependent on other information (such as how much fuel is in each tank, etc) that is not relayed back via satellite?
No worries Bear, keep up the good work.
I think I may have made an assumption that due to the frequency of these inspections, major dismantling of the engine would not be required. Wondeful things shuftyscopes.
I think I may have made an assumption that due to the frequency of these inspections, major dismantling of the engine would not be required. Wondeful things shuftyscopes.
Join Date: Mar 2010
Location: overthehillsandmountains
Posts: 140
Likes: 0
Received 0 Likes
on
0 Posts
live interaction
erlanger, the essence is in the "live", i.e. voice communication.
Sure they had the possibility to talk to and get advice from Qantas engineering.
I'm not so sure about talking live to Airbus. Someone please enlighten us ...
As for communicating with these people via the tower, I don't think so.
Sure they had the possibility to talk to and get advice from Qantas engineering.
I'm not so sure about talking live to Airbus. Someone please enlighten us ...
As for communicating with these people via the tower, I don't think so.
erlanger:
Part of what pilots do is handle situations. The planes flying today have a lot of systems information loaded onboard, and available at the pilot's console to use when they are handling a situation.
Already discussed in this thread is the large number of alerts, (50 or more) and actions to be taken, that cued up in the pilot's displays regarding symptoms of what is wrong, and steps to follow as remedy.
Given the number of systems that ran into problems when the engine turbine disc came off, they had to spend some time prioritizing and dealing with those alerts while they flew the plane and made decisions on what to do next. You can safely assume that in the process of doing that, there was likely some communication with the airline when time and cockpit task loading permitted.
Aviate, navigate, communicate, in that priority order.
I can't think of an airline in operation that would not have an admin frequency at the operating base that allows a flight crew to communicate via radio to the company (be it for admin, ops, scheduling, or maintenance issues) without having to go through the tower. There are typically multpile radios available to the flight crew to use.
The question is, are you in range? In this case, as the aircraft headed back to the originating airfield, yes, they were probably never out of range. (UHF/VHF ranges (very rough) 50-100 miles, depending on various factors).
One pilot can talk to tower (or other Air Traffic Control site) for flight specific topics and needs, while the other pilot can talk to the company regarding whatever issue is pressing, and can't wait for after landing. A serious maintenance/materiel issue (like the malfunction we have discussed in this thread) is a case where talking to the company while airborne would likely be done when the flying priority has been stabilized. The more unusual the malfunction, the more likely it is that crew will call on ground based assistance in handling the situation. A further advantage of being able to do this is that when the aircrew advises the company that their plane is returning to base, damaged or otherwise unserviceable, someone in the company can begin the process (in parallel to the recovery efforts) of taking care of the hundreds of passengers, and get them to where they wanted to go in the first place.
Does that answer your question in re talking to tower?
Is there any chance for pilots to receive advice or information in real time from Qantas (or more generally, the airline that "owns" the plane) or Airbus on how to handle the situation?
The planes flying today have a lot of systems information loaded onboard, and available at the pilot's console to use when they are handling a situation. Already discussed in this thread is the large number of alerts, (50 or more) and actions to be taken, that cued up in the pilot's displays regarding symptoms of what is wrong, and steps to follow as remedy.
Given the number of systems that ran into problems when the engine turbine disc came off, they had to spend some time prioritizing and dealing with those alerts while they flew the plane and made decisions on what to do next. You can safely assume that in the process of doing that, there was likely some communication with the airline when time and cockpit task loading permitted.
Aviate, navigate, communicate, in that priority order.
I would imagine that any such interaction between the airline/Airbus would need to be via the control tower. If that interaction was present, would it be welcome or just another unwanted distraction from the job at hand?
The question is, are you in range? In this case, as the aircraft headed back to the originating airfield, yes, they were probably never out of range. (UHF/VHF ranges (very rough) 50-100 miles, depending on various factors).
One pilot can talk to tower (or other Air Traffic Control site) for flight specific topics and needs, while the other pilot can talk to the company regarding whatever issue is pressing, and can't wait for after landing. A serious maintenance/materiel issue (like the malfunction we have discussed in this thread) is a case where talking to the company while airborne would likely be done when the flying priority has been stabilized. The more unusual the malfunction, the more likely it is that crew will call on ground based assistance in handling the situation. A further advantage of being able to do this is that when the aircrew advises the company that their plane is returning to base, damaged or otherwise unserviceable, someone in the company can begin the process (in parallel to the recovery efforts) of taking care of the hundreds of passengers, and get them to where they wanted to go in the first place.
Does that answer your question in re talking to tower?
BusyB. Thanks for that, I am a bit out of date.
Curious: do all airlines, large and small, use Satphone, or just the major lines?
Curious: do all airlines, large and small, use Satphone, or just the major lines?
Join Date: Jan 2006
Location: Georgia, USA
Posts: 454
Likes: 0
Received 0 Likes
on
0 Posts
This little video should answer a lot of the questions asked about the Material Used, the Tempatures experanced and the RPM's turned by the RR Trent engine:
Rolls-Royce: Journey Through A Jet Engine
Rolls-Royce: Journey Through A Jet Engine
Last edited by glhcarl; 23rd Nov 2010 at 20:54.
Join Date: Mar 2002
Location: Canada
Posts: 690
Likes: 0
Received 0 Likes
on
0 Posts
The PW4000 is having problems too: PW4000 AD Just Released
The proposal for this AD was published 5 months ago.
The proposal for this AD was published 5 months ago.
This AD results from one report of a repaired No. 3 bearing oil pressure tube that cracked and caused an engine in-flight shutdown, one report of a test cell event, and seven reports since 2007, of repaired No. 3 bearing oil pressure tubes found cracked that led to unscheduled engine removals. We are issuing this AD to prevent cracking of No. 3 bearing oil pressure tubes, which could result in internal oil fire, failure of the high-pressure turbine disks, uncontained engine failure, and damage to the airplane.
Join Date: Mar 1999
Location: Australia
Posts: 19
Likes: 0
Received 0 Likes
on
0 Posts
glhcarl
Great link to the RR animated video of a journey through a Trent.
It also identifies that the materials in the turbine area are Nickel Alloy.
It only mentions Titanium in the cold section of the Low/IP compressors.
It also identifies that the materials in the turbine area are Nickel Alloy.
It only mentions Titanium in the cold section of the Low/IP compressors.