Qantas A380 uncontained #2 engine failure
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A good bet indeed. Inconel has a long and illustrious past. There are numerous concoctions, and it is widely used. I'm not sure why the Trent would need a "special" blend, the PrattWhitney J58 used Inconel, and its T's as a low bypass turbo-jet engine were a good deal higher than Trent's.
In full burner on ground test, it sported doughnuts on a rope out 300 feet, all of it moving so fast it stayed parallel to the deck its full length. I wish I could remember some representative temps. but I don't do wiki, suffice to say it was a hot mama. This powerplant (J58) is fifty years old! As Trent's IP is Titanium, one can see why fire in its locale would be so dangerous. I really like Fzz's description of transient Temperatures and disc stress.
bear
A good bet indeed. Inconel has a long and illustrious past. There are numerous concoctions, and it is widely used. I'm not sure why the Trent would need a "special" blend, the PrattWhitney J58 used Inconel, and its T's as a low bypass turbo-jet engine were a good deal higher than Trent's.
In full burner on ground test, it sported doughnuts on a rope out 300 feet, all of it moving so fast it stayed parallel to the deck its full length. I wish I could remember some representative temps. but I don't do wiki, suffice to say it was a hot mama. This powerplant (J58) is fifty years old! As Trent's IP is Titanium, one can see why fire in its locale would be so dangerous. I really like Fzz's description of transient Temperatures and disc stress.
bear
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What number
Well, I'd still be interested to know what number each of the 20 engines classified being with possible or potential problems were. Obviously 2 & 3 have a different duty cycle to 1 & 4.
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Yes, thanks lonewolf.
I was mostly curious about whether or not there was a channel for the plane manufacturer (Airbus) to chip in with real time advice that was along the lines of "these x events together mean you should do y", something that may be out of scope for manuals/training... but the commentary that I've seen suggests that in this particular case, Airbus had little to offer in that regard.
I was mostly curious about whether or not there was a channel for the plane manufacturer (Airbus) to chip in with real time advice that was along the lines of "these x events together mean you should do y", something that may be out of scope for manuals/training... but the commentary that I've seen suggests that in this particular case, Airbus had little to offer in that regard.
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Just a guess as to HP "Nickel Alloy" : Inconel?
Its like Dural, which is a brand name of Dürener Aluminiumwerke, but used by engineers worldwide as a technical term.
Great link to the RR animated video of a journey through a Trent.
Originally Posted by bear
As Trent's IP is Titanium
Not what the little video shows ... but you may have more detailed info than the PR release.
glhcarl: thanks!
How it used to be
I was at RR Derby 50 years ago, and we always designed turbine discs and blades using nickel alloys that did not yet exist. Well, if you didn't, your engine was out of date by the time it took to the air. I assume alloy development and "aiming off" still occurs.
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Satcom
Lonewolf
For at least since 1996 with the arrival of the B777, all this type of communication is done by satfone. If you have not used it, it is exactly as clear as any landbased phone. The days of calling base by radio or HF are long gone from long haul airplanes.
I endorse your clear explanation of prioritising and the timeless validity of the dictum "aviate navigate communicate"
Coireall
Sorry for repeating what was said in #1330 and #1331
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.
For at least since 1996 with the arrival of the B777, all this type of communication is done by satfone. If you have not used it, it is exactly as clear as any landbased phone. The days of calling base by radio or HF are long gone from long haul airplanes.
I endorse your clear explanation of prioritising and the timeless validity of the dictum "aviate navigate communicate"
Coireall
Sorry for repeating what was said in #1330 and #1331
damage to LPT visible in ATSB photo
The ATSB update section dated 22 November includes this picture of the removed Low Pressure Turbine.
Coireall
Thanks, since the case in question is seriously long haul -- A380.
My follow on question would be: would you consider Southwest Airlines to be a long haul airline, or is that closer to a "regional" given how they operate? I don't think they do much transocean work, and some of my most current info and understanding (before finding these forums) are based on friends and relations who work at Southwest .. but now that I think about it, that info is pretty old as well.
Another thought: would commuters use satphone, or rely on more old fashioned VHF type radios for comms with parent company Ops/Scheds, etcetera?
I've used some Satcom links in my day, but that was mostly military stuff. I had a few interesting conversationswith some SPECOPS folks on Iridium (which as I peek about appears to be alive and well and part of the Satphone family) ... conversations that don't belong on this forum, or probably any other.
Thanks, since the case in question is seriously long haul -- A380.
My follow on question would be: would you consider Southwest Airlines to be a long haul airline, or is that closer to a "regional" given how they operate? I don't think they do much transocean work, and some of my most current info and understanding (before finding these forums) are based on friends and relations who work at Southwest .. but now that I think about it, that info is pretty old as well.
Another thought: would commuters use satphone, or rely on more old fashioned VHF type radios for comms with parent company Ops/Scheds, etcetera?
I've used some Satcom links in my day, but that was mostly military stuff. I had a few interesting conversationswith some SPECOPS folks on Iridium (which as I peek about appears to be alive and well and part of the Satphone family) ... conversations that don't belong on this forum, or probably any other.
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Lonewolf 50:
SWA will have an international operation if/when ATA becomes a part of them. Historically, SWA has operated only within the 48 continental states. ARINC has complete VHF coverage of the U.S., at least at jet levels. And, direct company VHF comm is usually available near stations or maintenance bases. In any case, ARINC can link them with the company.
No sat comm for domestic in the "Lower 48;" it is unnecessary and expensive.
SWA will have an international operation if/when ATA becomes a part of them. Historically, SWA has operated only within the 48 continental states. ARINC has complete VHF coverage of the U.S., at least at jet levels. And, direct company VHF comm is usually available near stations or maintenance bases. In any case, ARINC can link them with the company.
No sat comm for domestic in the "Lower 48;" it is unnecessary and expensive.
Gracias, amigo!
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EASA (AD) originally established a "wear schedule", for inspections of the crest of the shaft splines. The crest (new) is 2.65mm, wear at .5mm or less meant off wing upgrade. At a later date (?) EASA revised the wear limit from "worst case" to "averaged", allowing more worn shafts to stay on the wing longer. This allowed some accelerated wear to be "buffered" by splines on the shaft that had less wear. In September, FAA issued its AD, the main difference was the language, where EASA framed the possible failure as everything up to (but not mentioning) "uncontained", FAA incorporated the word into theirs, "Possible uncontained failure and damage to a/c," etc.
Some observations. The wear is patently too rapid, hence the AD, and possible replacement of major parts well before normal O/H. What is the wear having to do with the "Fire"? The AD mentions wear leading to aft migration of IPdisc, contact with "Stationery" engine parts, and engine damage (leading to "Uncontained" shed per FAA). If this is the concern of the AD, at what point is the fire addressed? The lubrication/wear process is unclear to me. We seem to be entertaining two separate failure causes.
If the aft migration causes the explosion, was the fire incidental? No mention of fire is apparent to me in my reading of the AD, at least insofar as causative of wear and migration, which is the fear of excess wear addressed by both ADs. Is it that oil leakage causes the wear over time?
Fire is an immediate and emergent event, yet the wear issue is satisfied by AD one year prior, addressing inspections only? If the fire possibility is AD'ed, why is the fix without change to alert in cockpit and shutdown not presented? The AD specifically addresses the lack of warning of engine (catastrophic) failure, as a direct and possible contribution to explosion.
The remedy, by inference of prior AD is to provide a system of warning of imminent engine failure which may abruptly lead to explosive uncontainment, I see no evidence in the emergency AD of requirements for such an alert. If the spline issue is at the 'off wing point', a new Shaft is needed, not just a "module". I am getting the feeling that RR is doing more than merely changing out a duff part, (although the part number is present in original AD). This part number is identical to the part being "replaced". So it is not a re-design, it is an overhaul by original spec, but with accelerated schedule. It is most unfortunate RR has stopped talking.
Having "Found" the problem, what is it? What is the fix? Once again, as with the TRENT 700 and 777, we are to be satisfied with fixes to problems that address unknown causes? A redesigned FOHE to mitigate "unknown" fuel characteristics which are as yet still "Unknown"?
It would be nice to know the nature of wear between shaft and Disc, and why it is unacceptably rapid. Plugged Oil vanes, or Design problem?
Relative to the first paragraph above, it would seem the EASA's relaxing of the inspection standard from "worst" to "averaging" may have contributed to the failure on November 4th. If there is another way to see it, let me know.
bear
Some observations. The wear is patently too rapid, hence the AD, and possible replacement of major parts well before normal O/H. What is the wear having to do with the "Fire"? The AD mentions wear leading to aft migration of IPdisc, contact with "Stationery" engine parts, and engine damage (leading to "Uncontained" shed per FAA). If this is the concern of the AD, at what point is the fire addressed? The lubrication/wear process is unclear to me. We seem to be entertaining two separate failure causes.
If the aft migration causes the explosion, was the fire incidental? No mention of fire is apparent to me in my reading of the AD, at least insofar as causative of wear and migration, which is the fear of excess wear addressed by both ADs. Is it that oil leakage causes the wear over time?
Fire is an immediate and emergent event, yet the wear issue is satisfied by AD one year prior, addressing inspections only? If the fire possibility is AD'ed, why is the fix without change to alert in cockpit and shutdown not presented? The AD specifically addresses the lack of warning of engine (catastrophic) failure, as a direct and possible contribution to explosion.
The remedy, by inference of prior AD is to provide a system of warning of imminent engine failure which may abruptly lead to explosive uncontainment, I see no evidence in the emergency AD of requirements for such an alert. If the spline issue is at the 'off wing point', a new Shaft is needed, not just a "module". I am getting the feeling that RR is doing more than merely changing out a duff part, (although the part number is present in original AD). This part number is identical to the part being "replaced". So it is not a re-design, it is an overhaul by original spec, but with accelerated schedule. It is most unfortunate RR has stopped talking.
Having "Found" the problem, what is it? What is the fix? Once again, as with the TRENT 700 and 777, we are to be satisfied with fixes to problems that address unknown causes? A redesigned FOHE to mitigate "unknown" fuel characteristics which are as yet still "Unknown"?
It would be nice to know the nature of wear between shaft and Disc, and why it is unacceptably rapid. Plugged Oil vanes, or Design problem?
Relative to the first paragraph above, it would seem the EASA's relaxing of the inspection standard from "worst" to "averaging" may have contributed to the failure on November 4th. If there is another way to see it, let me know.
bear
Last edited by bearfoil; 24th Nov 2010 at 23:16.
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Bearfoil;
Having hoisted by "cynical" facade, I would venture that the answer to the question you have raised is, "Because the manufacturer decided that this was the expedient action to take", and the regulator decided that they weren't competent to dispute.
So, that is the way things are done - or isn't it?
mm43
Having hoisted by "cynical" facade, I would venture that the answer to the question you have raised is, "Because the manufacturer decided that this was the expedient action to take", and the regulator decided that they weren't competent to dispute.
So, that is the way things are done - or isn't it?
mm43
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Bearfoil said
I think you will find they are still taking, just not to the public. It is clear that the investigation has a long way to go and there is really no point in anyone (including RR) guessing the outcome.
So the situation is now that flight operations continue subject to certain constraints. And I think that these constraints cover ALL Trent 900's - even the newer modified ones?
Does anyone have a diagram of the parts in question - to make sense of the AD's?
It is most unfortunate RR has stopped talking.
So the situation is now that flight operations continue subject to certain constraints. And I think that these constraints cover ALL Trent 900's - even the newer modified ones?
Does anyone have a diagram of the parts in question - to make sense of the AD's?