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A380 engine failure - Qantas

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A380 engine failure - Qantas

Old 14th Nov 2010, 13:59
  #61 (permalink)  
 
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No connection to 74 engines. Qantas push 'em hard because of the route lengths and TO weights. Always were hard on engines.

RR knew of a fault with T970s back in summer 2009. They made a modification to engines on the line at Toulouse. They notifed Euro Cert Authority and they decided to monitor and not to stop operation.

Of the 80 T970 units in service over half already had the newer design. Qantas was left out of the information loop.

The rest is now history.
Quite a concise summary.

My bold above contains an important nugget if true.

To me a "fault" should be identified to a user along with a corrective action program under "continued airworthiness"

OTOH a design improvement to meet a design goal (e.g. time on wing etc.) may simply be an option available to the organization doing the maintenance. One way to tell the difference is to review what was told to the cert authority that approved the change.
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Old 14th Nov 2010, 15:34
  #62 (permalink)  
 
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If I read this right, QF's 747/RB211 IPT uncontained failure is because "Qantas push 'em hard". Is this an acceptable way of life in the commercial airline industry? If engines are run within certified parameter limits, how many uncontained (read shrapnel) failures should be expected?

In my experience in the industry, the only acceptable number was zero, and a huge effort expended toward this goal. "Pushing them hard" was NO excuse!
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Old 14th Nov 2010, 15:42
  #63 (permalink)  
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barit1

If, as suspected, the failure in the 972 is due abuse (pushed 'em hard), a new set of parameters in affixing blame rear their head.

The extra 2k POT have to be certificated, and maintained differently, or at least "via AD". If the extra thrust was adhered to (this is a software limit), no abnormal or premature seal wear can happen, by design, engineering, manufacture, or use.

Identification and disclosure of the problem, with an addressed reg by the authority leaves Qantas off the hook, responsibility wise, but not on the fiscal end, No?

edit: this being tech log, I'll bring up a material issue re: vibration. The bearing oil seals are flexible, and subject to distortion, within limits, to acommodate transient movement of the rim. Given a Climb thrust, at its top, and most heat filled iteration, with attendant relaxation of the seal, its elastic rating becomes critical. With time, does it relax its pressure and resultant "sealing capability?" Oil migration is containment critical?

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Old 14th Nov 2010, 16:14
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Inasmuch as the failure occurred during climb, perhaps at MCL thrust, which is no greater than MCT:

Is MCT for the 972 greater than for the 970? If so, I'd expect deterioration to be a bit faster, an economic issue.

But NOT a safety issue.
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Old 14th Nov 2010, 18:29
  #65 (permalink)  
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Precisely that. Compliance = "Safety". It would be encouraging to note somewhere in the Industry that mere COMPLIANCE is a baseline, a minimum, to be enhanced with volitional programs. Who calculates "wiggle room"? "You", "no, You", "no, Him". One can dream.

(Off thread) In racing, one can push too hard a little engine, or get out the checkbook and install a larger one: more power, more fuel, more power in reserve. Of course the rules (In Aviation, Money), control the specifyin'.

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Old 15th Nov 2010, 12:35
  #66 (permalink)  
 
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"But NOT a safety issue."

Of course it's a safety issue. If an engine is not cooling properly it evaporates the oil, dries up the bearing and bingo the engine explodes.
The temperature rise is not linear. This happens exponentially. If any fault is to be assigned here it is firmly at the door of EASA. They were advised of the problem and elected to monitor rather than halt operations.
Thank God the Qantas crew were tip top and thank God the three missiles exiting the engine did no more damage than occured. BARIT you really do need to read up on basic physics, or alternatively, steer clear of energy based concepts.
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Old 15th Nov 2010, 13:49
  #67 (permalink)  
 
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Once again:

There are certified, published operational limits. As long as ALL these limits are observed, the engine should run fine at MCT until fuel is exhausted. Is oil temperature not one of these limits?

A bit more background: For almost a decade, I carted a hi-bypass fan around the world, with a portable instrumentation data package, conducting cell correlation tests at airline facilities. The engine had some tired and obsolete hardware, and so was not airworthy; but for comparative performance purposes, it was stable and an ideal transfer standard.

I ran the engine per a test plan THAT IGNORED ALL T/O TIME LIMITS.

EGT, speed, oil pressure/temp. etc. limits were observed, but OFTEN I spent 30 minutes or so, continuously above MCT, at various T/O ratings. THERE WAS NEVER A SAFETY ISSUE with this operation schedule. The only failures my team incurred were when some customer-supplied equipment broke.

If a Trent would be at risk in this sort of operation, I have to question the design standards employed.

(Footnote: Oh, yes, one time when "my" engine was being ground-shipped, the lorry driver took a shortcut - and bashed the engine into a rr overpass! )
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Old 15th Nov 2010, 16:44
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Trent Design Issues

That much is clear: there ARE design issues. I am ALMOST certain that engine performance anomalies were evident before this event occurred. The way this aircraft was punted out from London only to turn back over Poland itself tells a tale.

The way forward is to bring back flight engineers. Now before all of you call me every name under the sun please consider the following... This aircarft had no less than FIVE fully qualified operators on the flight deck when this emergency happened.

Two of the hydraulic systems were disabled, the fuel transfer system was buggered and the machine needed all of the runway to finally stop. I suggest that if only TWO were on the flight deck the outcome may have been very different.

Now tell me if the cost of a flight engineers salary would threaten the commercial success of this aircraft.
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Old 15th Nov 2010, 18:00
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Now tell me if the cost of a flight engineers salary would threaten the commercial success of this aircraft.
How on earth did we manage to morph this technical discussion into a flight engineers pay
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Old 15th Nov 2010, 20:50
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DERG

"Two of the hydraulic systems were disabled"

Then why did the spoilers powered by the Yellow hydraulic system deploy?
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Old 15th Nov 2010, 21:58
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DON'T argue with him, unless you wish a torrent of invective!
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Old 16th Nov 2010, 08:19
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Are you serious?

Maybe because the little tubes in that system were intact, moreover maybe the little wires to the pumps and valves were not severed by a whacking great 25kg lump that was exploded out of the engine case?
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Old 16th Nov 2010, 08:41
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Hi Derg,

Two of the hydraulic systems were disabled,
We don't think so because:

"The A380 incorporates two rather than three Eaton Corporation hydraulic systems with an increased hydraulic pressure of 5,000lb/inČ instead of a standard 3,000psi."
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Old 16th Nov 2010, 09:48
  #74 (permalink)  
 
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Hiya Rudder

Thanks for the info.

Not sure if that helps me sleep at night though!
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Old 2nd Dec 2010, 15:59
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Safety Recommendation Ao-2010-089-ar-012

NTSB advice. see above

Miele Washing Machines need to teach Rolls Roycle how to counter bore fluid lines in nickel steel.

God knows what other parts this particular workshop flung out. Someone needs to send Rolls Royce Quality staff for a mandatory eye test.

What a way to destroy a company reputation. What a waste! Thank God Qantas saved the day.

Now for litigation in court.
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Old 2nd Dec 2010, 19:04
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Reminds one, somewhat, of UA232.

Except in that case, UA had a known-high-time piece of hardware, with a known vulnerability, and they placed in back into service with only a cursory inspection.

The present case is a newly-made piece, fresh from the vendor, passed with only cursory inspection.

The open question: How is this event different from QF74 31 Aug, or from the Trent 1000 testbench failure?
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Old 2nd Dec 2010, 21:10
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Quote: Reminds one, somewhat, of UA232.

The UA 232 fan disk failure occurred with about 5 hrs. of usable life left before mandatory removal and disposal. The disk was ~ 20 years in service. The defect that caused the ultimate failure was detectable but missed during its last UA shop inspection. The defect was present in other fan disks that were sliced from the same billet. Thirty or more years ago there wasn't the sophistication in inspection methods and this was a critical rotating part, highly inspected with the best techniques of the day.

The tube is not really viewed as a critical component and as such doesn't receive as much attention.

The 1000 test stand failure was probably the result of a different cause than the 900 failure, but certainly demonstrated what can happen when oil accumulates in the wrong area of a hot turbine.
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Old 2nd Dec 2010, 22:48
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The tube is not really viewed as a critical component and as such doesn't receive as much attention.
This speaks for itself. Oil fires almost always lead to major damage. Who can possibly decide the oil tube isn't critical?
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Old 3rd Dec 2010, 00:48
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This speaks for itself. Oil fires almost always lead to major damage. Who can possibly decide the oil tube isn't critical?
The designer, who applies for a design certificate.

If the regulator pops the question the answer is "we got it covered"

I suspect that this is about to change
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Old 3rd Dec 2010, 00:57
  #80 (permalink)  
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Anticipating Bankruptcy and dissolution, Pan American was soft pedalling maintenance. UAL took possession of some very clapped out airframes. There was a memo after 232 pranged that claimed Pan Am had actually id'ed the fracture, but sent the engine back into service prior to UAL's next check. The memo disappeared.

This is a Rumours site, after all.

Has anybody else wondered why the end of the Stub pipe has such intricate architecture? It resembles the female end of a line coupling. The bell coving at the tip suggests to me a male end misjoined. Is this a Line couple or a suck tube. If the latter, why the ring/land, and shoulder wear, not to mention the coving wear at the entrance to the tube?

From the image it looks one heckuva lot more like in-service wear from incorrect connection, than a degraded inlet aperture of a simple line/scavenge.

bear

Last edited by bearfoil; 3rd Dec 2010 at 01:08.
 

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