Airline Explosion in Indonesia

[allardjd 1,853]

The last article I posted (2 posts up) has been expanded since last night. They have stated that the failed wheel is the IP turbine. The hot section of the Trent 900 has one HP stage, one IP stage and five LP stages.

 

There was a crash in Poland in the past where a turbine shaft broke, essentially decoupling the hot section from the compressor.

 

That removed the load from the turbine which then over-sped to failure. I guess that's plausible in this case, but it's still an overspeed that causes the wheel failure. The list of possible scenarios remains either a flawed wheel hub or overspeed.

 

John

[allardjd 1,853]

Airbus Says Bearing Box Failed in Rolls Engine

 

http://www.foxnews.com/world/2010/11/12/rolls-royce-explains-failure-engine/

 

The information coming out is getting more and more detailed, but I'm still left trying to understand the chain of events from a bearing box failure and oil fire to a burst turbine wheel. It's not obvious. There have been failures in the past (Russian engines on Polish-owned Russian airliners) where a bearing failure causes shaft breakage, which de-couples the power turbine from the compressor, unloading the turbine and causing massive overspeed and burst wheels. That is credible, but no one has said yet that there is a broken shaft involved here.

 

I can still only postulate two mechanisms by which a turbine wheel will burst - it's flawed, or overspeed.

 

The bearing box problem does seem to be a design issue and one R-R was already aware of.

 

Interesting that they are pulling Trent 900s from the line in Toulouse and sending them to Qantas.

 

John

 

Article excerpts - there is a lot more to the article than this...

 

An Airbus executive said Friday that Rolls-Royce has identified a faulty bearing box as the cause of the oil leak problem implicated in the midair disintegration of an engine on one of the world's largest airliners...

 

Airbus Chief Operating Officer John Leahy told reporters in Sydney that Rolls-Royce had at some point fixed the bearing box on newer versions of the massive Trent 900 engine, a model designed for the massive A380 superjumbo. He said Rolls was now fixing it on older versions.

 

The box in question contains the metal ball bearings that allow movement of the drive shaft that powers jet engines. Investigators have said they suspect that leaking oil caused a fire in the engine of a Qantas A380 that led it to disintegrate...

 

Rolls-Royce Group PLC said in an update to investors Friday that the disintegration of the engine resulted from a problem in a specific component in the Trent 900, but it did not provide details.

 

...said the new models of the Trent 900 had been redesigned to eliminate the problem of excess oil causing turbine fires. He said that Rolls-Royce was retrofitting the older versions with new parts to stop the oil leaks and computer software that would shut down an engine with leaking oil before it became at risk of disintegration.

 

Engines on the A380 malfunctioned four times before one of them disintegrated during a flight from Singapore to Sydney last week, and aviation experts have said that the earlier mishaps may hold clues to design or construction flaws.

 

Rolls-Royce said the series of checks made on the Trent 900s after last week's incident had led it to draw two key conclusions.

"First ... the issue is specific to the Trent 900," Rolls-Royce said in a statement to the London bourse. "Second, the failure was confined to a specific component in the turbine area of the engine. This caused an oil fire, which led to the release of the intermediate pressure turbine disc."

 

Airbus will take Rolls-Royce engines off the final assembly line in Toulouse, France, and send them to Qantas...

[allardjd 1,853]

Qantas A380 Was Heavily Damaged

 

http://www.avweb.com/eletter/archives/avflash/1772-full.html#203629

 

This is the meat of the article...

 

The Qantas crew whose A380 suffered an uncontained engine failure earlier this month had their hands full in getting the super jumbo back to Singapore. Shrapnel from the engine disabled one of two main hydraulic systems, hampered the fuel transfer system, punched a hole in the forward wing spar and caused a major fuel leak. The cascading nature of such failures meant the pilots couldn't dump enough fuel to bring the aircraft down to its maximum landing weight and the fuel left in the airplane was unbalanced. Flaps, slats and spoilers couldn't be fully deployed and the gear had to be dropped manually. Once it was on the ground, the anti-lock brakes didn't work and, since the damaged engine was an inboard one, there was only one left for reverse thrust (the outboard engines of A380s don't have reversers because they often overhang the grass and might be FOD damaged).

 

The heavy, significantly disabled aircraft needed virtually all of the 13,123 feet of available runway. The whole wing might have to be replaced and the aircraft is expected to be out of commission for months.

[allardjd 1,853]

Rolls-Royce to replace leaking engines on A380s

 

http://flightaware.com/news/ap/Official-to-AP-RollsRoyce-replacing-A380-engines/2241

 

It appears from this that R-R will remove affected engines, swapping in a new one to get the affected AC flying again, but then will swap the original engine back after refurbishment and update to the new design. There is little new technical information in this, although the statement...

 

"Investigators say leaking oil caught fire in the Qantas engine on Nov. 4 and heated metal parts, causing them to disintegrate..."

 

...provides the first tenuous explanation of how an oil fire could cause a burst turbine wheel and, in my opinion, it's still a pretty thin explanation.

 

There is some concern over the number of engines available as spares. Some will come off the A380 line in Toulouse - they've already said that. That raises the spectre of delivery delays for the A380s. Much depends on the turn-around time to rebuild a removed engine.

 

John

[allardjd 1,853]

Up to 40 Trent 900s may need replacement

 

http://my.earthlink.net/article/top?guid=20101117/fff4199d-6e97-489a-8f18-7e90299e1d4b

 

John

[allardjd 1,853]

Drama in the cockpit: Qantas crew faced 54 alarms

 

http://news.yahoo.com/s/ap/20101118/ap_on_bi_ge/superjumbo_woes_22

 

This is the best article I've seen yet describing the effects of the event, however it doesn' mention the loss of control of #1 engine - the inability to adjust power or even to shut it down once on the ground. Keep that in mind and add that to the list of other problems described.

 

The longitudinal imbalance it describes is positively chilling.

 

The paragraph below, near the bottom of the article, captures the essence of this event to a tee - though engine failures may and will occur, failures of a nature that jeopardize other systems, structures and components beyond the affected engine itself must be made so improbable as to be virtually impossible.

 

However, Michael Barr, who teaches aviation safety at the University of Southern California, said a commercial plane can't be designed with certainty to withstand a spray of shrapnel, which can inflict damage anywhere. The proper focus, he said, should be on determining what caused the engine to fail and fixing that problem.

 

John

[MarkJones 0]

Must have been "interesting" watching all those warning messages come up on your aeroplane that a second ago was working just fine...

If something can happen, it will. It's only a matter of when...

[Aidan 1]

Wasn't even Qantas' fault, all Rolls Royce.

Qantas remains the safest airline round town :001_th_smiles89:

[IcedUpPitotTube 0]

It's the modern version of Aeroperu flight 603... but even worse! 54 alarms... wow. Probably the first one was "engine surge." Pilots are like uh-oh but not that freaked out. Then comes engine fire, and captain says," Okay declare an emergency, I have the airplane." Then finally, hydraulic system failure. Pilots were probably thinking "We're screwed." Quite amazing that the pilots were not bowled over by the alarms and actually landed relatively safely.

Wasn't hydraulic system failure by debris solved when United Airlines flight 232 crashed? I thought the airline industry would know better than to put a tube in direct line of an explosion...

[hurricanemk1c 195]

Yes, UA232 had a fan blade fracture - but sometimes you have to put the hydraulic lines in certain places - unfortunatly, JAL123 had it's tail blown off with all the hydraulics inside.

In the A380, I believe the only place to put the lines is the leading edge - the trailing edge has flaps and the centre has great big fuel tanks (I could be wrong....)

[allardjd 1,853]

UA 232 had a fan disk disk failure, much more serious than a fan blade failure. In the case of that one, it was found that the disk had an inherent metallurgical flaw that escaped detection. It was determined to not be a design problem with the engine, but rather a single flawed part that could have - should have - been spotted and replaced. Stains from dye penetrant were found on the fracture surfaces indicating that at least one dye-penetrant test should have revealed a crack, but for some reason it was overlooked. For the engine maker, if you're going to have engine failures, that's the kind of cause you'd like to have found by the investigators.

 

The Qantas Trent 900 had a disk failure too, but further back, in the hot section. That turbine has 1 HP, 1 IP and 5 LP stages behind the burners. It was the IP that went, unleashing three heavy segments of about 120 degrees of arc each - that's a typical wheel burst.

 

When a wheel bursts, the pieces are large, heavy and have serious kinetic energy. Armoring the engine and nearby things is nearly impossible against that kind of heavy, high-energy projectile.

 

Certification requirements for aircraft only assume one "large fragment" and designers must prove that redundant systems will carry the day in that event. In the light of this accident, that requirement might need to be looked at again, but it's a Pandora's Box.

 

A better policy is to assure that the engines cannot eject heavy, high energy fragments. Easy? Certainly not, but neither is making a wing and the systems it contains immune to one or more one hundred pound, sharp-edged axe-heads travelling at several hundred feet per second.

 

Burst turbine wheels are the most potentially destructive ejecta that can result from a catastrophic engine casualty. It's relatively uncommon, but when it happens it has the capability to do extreme damage to everything in the path(s). One mechanism by which a wheel burst can occur is by a shaft failure that uncouples the turbine from it's load - the compressor section in the case of jet engines. Still being driven by the burner exhausts but free of it's load, the turbine accelerates well beyond its design speed in a heartbeat and centrifugal force tears the weakest wheel apart. It's not clear yet if that was the mechanism for this failure or not.

 

As far as I know there have still been no further details from R-R explaining how an oil fire leads to a wheel failure.

- - - - - - - - - - - - - - - - -

Interesting items in the news today relative to this event...

 

1) Airbus says its delivery schedules are likely to be affected and that they will incur additional costs as a result. They plan to seek damages from Rolls-Royce. That one came from the Airbus CEO.

 

2) The damage to the Qantas wing components included a ruptured or severed fuel pipe near one of the wing tanks that resulted in a very large fuel leak.

 

John

 

EDIT: I just found this... there are some very impressive photos and diagrams detailing the damage; don't miss Figure 8, the severed fuel pipe. It's worth noting that none of these images are of the engine itself - this is all collateral damage to other things.

 

http://blogs.crikey.com.au/planetalking/2010/11/17/the-anatomy-of-the-airbus-a380-qf32-near-disaster/

 

JDA

[allardjd 1,853]

Qantas to return A380s to service

 

http://my.earthlink.net/article/int?guid=20101122/bd107c84-d25f-43bd-bbea-86fceb6ba8a4

 

"...will resume flying some of its A380 superjumbos this weekend..."

 

"...two of Qantas' existing fleet of six Airbus superjumbos would be brought back into service, flying between Sydney and London via Singapore. Two more A380s that the airline will take delivery of before Christmas would begin taking passengers as soon as they are ready."

 

"...keeping its direct A380 flights from Australia to Los Angeles suspended because they use the maximum amount of engine thrust, which adds stress to the engines."

 

"We are voluntarily reducing the thrust of the aircraft, and making sure that we don't operate out of LA until we have sufficient information going forward about the performance of engines as we put them back into service..."

[allardjd 1,853]

Qantas A380 returns to air after engine blowout

 

http://my.earthlink.net/article/top?guid=20101127/47c9d16c-33a4-42b3-99fa-6d1184178310

 

A Qantas A380 carrying more than 450 passengers, including the airline's chief executive, took to the skies Saturday in the first flight by one of its superjumbos since a midair engine explosion three weeks ago...

 

Qantas says it will eventually pursue compensation from Rolls-Royce for the failure and losses from grounding its fleet...

[Aidan 1]

Heres an email Alan Joyce sent to Frequent Flyer Members:

Dear Mrs Sandri,

I am pleased to advise that Qantas will resume A380 services, commencing with an initial A380 service to London via Singapore on Saturday 27 November.

We have undertaken a rigorous inspection program in conjunction with Rolls Royce and Airbus to ensure the fleet is ready to return to service.

We always put safety first, and we continue to take a conservative approach to the reintroduction of the A380 fleet. So we will initially operate the A380 between Australia and the United Kingdom. As more A380s come into service, we will assess when and how best to deploy them.

I want to assure you that we have full confidence in our A380 aircraft fleet, and will not fly any individual aircraft unless we are completely sure that it is safe to do so.

Qantas has six A380s in its fleet, and is scheduled to take delivery of two new A380s before the end of this year, and a further two next year. With our fleet of more than 250 aircraft, we are able to maintain a full international and domestic network, so you can book and fly with us with confidence.

I want to thank you for your loyalty and patience. On behalf of all of us at Qantas we deeply regret any inconvenience. We look forward to welcoming you warmly when next you fly.

ALAN JOYCE

Qantas Chief Executive Officer

[allardjd 1,853]

Interesting - thanks for posting. I get the impression that Qantas tries very hard to be a class act and this is the kind of thing that shows that. If you're someone who flies Qanatas twenty times a year, receiving this kind of thing may help to restore the warm fuzzies.

 

I'm thinking his letter to Rolls Royce will have a different tone.

 

John

[allardjd 1,853]

A380 engines may have manufacturing fault

 

http://my.earthlink.net/article/top?guid=20101201/d8f19436-4186-4f5f-aca9-6f78af490f0f\

 

There's not really all that much new here, though the words, "...manufacturing defect..." are used with respect to Trent 900 engines. That's been suggested already, but this seems to be more statement of fact than conjecture. The two most significant points in this article are...

 

1) The Australian Transoprt Safety Bureau, acting on a recommendation from R-R, has issued a "safety recommendation" to perform another inspection for a specific manufacturing defect. I presume that body has no authority over Lufthansa or Singapore Airlines, but it seems reasonable to assume that similar measures are being pursued through the responsible authorities for those Trent 900 powered A380 operators.

 

2) There's finally a little more detail about the nature of the problem, which is being called a, "...misaligned oil pipe counter-boring..." which may lead to an engine fire such as has already caused severe damage in one aircraft with an affected engine.

 

John

[allardjd 1,853]

Qantas launches court action over Rolls-Royce A380 engines

 

http://www.smh.com.au/travel/travel-news/qantas-launches-court-action-over-rollsroyce-a380-engines-20101202-18hie.html

 

Qantas has increased pressure on Rolls-Royce to reach a commercial settlement over problems caused by the manufacturer's A380 superjumbo engines by launching a court action.

 

The airline issued a statement today saying it had filed a statement of claim and was granted an injunction by the Federal Court of Australia to ensure the company can pursue legal action against Rolls-Royce in Australia, particularly under the Trade Practices Act, if a commercial settlement is not possible.

 

It is believed the costs incurred by the grounding of aircraft could be $100 million.

 

- - - - - - - - - - - - - - - -

The article also has two interesting photos I hadn't seen yet. One shows another view of some of the damage to the Qantas AC. The other is a very good photo of a mis-machined oil pipe end, illustrating not only the off-center counter-bore, but also a failed section with fatigue cracking.

[allardjd 1,853]

Investigators blame A380 failure on oil fire

 

http://my.earthlink.net/article/top?guid=20101202/5fe5d5bb-c7a1-4a9d-807f-89c8e8f42b8d

 

There's not very much new here - a little more definitive description of the location of the fault is one thing that is a bit expanded from what I've seen up to now.

 

There is an indication of a differing opinion between the Australian Transport Safety Board, who says more inspections are warranted and the European Aviation Safety Administration, who seem to think that what they've decreed already is enough.

Everything else is pretty much a re-hash. All involved had better hope there isn't another one. It will damage R-R, Airbus, the airline involved and the safety agencies.

 

This kind of failure cannot be allowed to happen in flight. Describing 50 + lb. pieces of turbine wheel as "shrapnel", as this article does, is like calling Tenerife a "mishap" - it kind of understates things.

 

John

[allardjd 1,853]

Qantas Pilots Saved Crippled Airbus, Investigator Says

 

http://www.nytimes.com/reuters/2010/12/03/world/international-us-qantas-a380-pilots.html?_r=1

 

Good article. It was fortunate that there were additional qualified A380 pilots aboard and that must have been a great help in the cockpit managing all the damage and the automated systems reactions to the damage.

 

It seems that the computer provides "fields" where the aircrew can enter out-of-spec, unavailable or other anomolous items for the computer to take into account when it calculates things like approach speed, landing distance, etc. In this case, there was more broken than the there were fields to enter it so they had to pick and choose what they entered into the available fields. They chose those things they thought would have the greatest effect and omitted the ones that seemed less critical. I've seen this referenced before and it is mentioned again here, a little. I guess they guessed right.

 

Several articles have commented on the fact that they ended up using almost all the available runway and toasted the brakes and tires, but a couple of earlier ones, including an early statement from Qantas, did say they "modulated" the braking toward the end, electing to stop as close to the emergency vehicles as possible. The implication is that they could have stopped a little shorter than they actually did.

 

John

[allardjd 1,853]

Rolls-Royce lawyers no-show at compensation court hearing

 

http://atwonline.com/aircraft-engines-components/news/rolls-royce-lawyers-no-show-compensation-court-hearing-1208

 

...the engine maker’s lawyers failed to show up at an Australian Federal Court hearing to discuss a compensation claim for the grounding of the airline’s Airbus A380 fleet...

 

Qantas’s seventh A380...required one Trent 972 engine changed because it was a “Mod A” with the faulty stub pipe thought responsible for the Nov. 4 incident... Qantas confirmed to ATW that it refused to accept the latest A380...until the “Mod C” engine was fitted....

 

...Qantas filed a...statement of claim in the federal court to negotiate a commercial settlement with Rolls-Royce over loss of earnings—which could run more than $100 million by some estimates—from the grounding of its A380 fleet. Repairs to the aircraft alone could be $70 million. Rolls-Royce countered and filed an application to suppress aspects of the claim but the judge declined because no lawyers for the engine maker showed up in court."

[stu7708 244]

Just found an interesting interview with one of the guys on the flight deck that day.

http://www.aerosocietychannel.com/aerospace-insight/2010/12/exclusive-qantas-qf32-flight-from-the-cockpit/

An interesting read, plus some shots from the cockpit taken while limping back to Singapore.

[allardjd 1,853]

Good post - good stuff.

 

Two new points for me in there are...

 

1) The #1 engine ran (at power, not idle) for five hours on the ground before finally being shut down by gagging it with water from fire hoses.

 

2) It took an hour to get an airstair out to the AC and another hour to get everyone off through one door.

 

That was an incredibly gutsy call to keep everyone aboard. Deplaning using the slides with an engine running, fuel leaking, hot brakes and fire-fighting materials being sprayed around would have made the 3 Stooges look like a team of efficiency experts and someone would surely have gotten hurt or worse. That seems in hindsight to have been a wise decision but must have been a gut-wrencher at the time.

 

If a fire had broken out it was going to be a bad situation no matter what, but though much is being made of the hot brakes and the presence of spilled fuel, I suspect that the brakes were cooled quickly with fire hoses and that particular hazard didn't exist for very long after they stopped rolling.

 

The longitudinal cg issues are probably being understated here a little, but it seems clear that's what drove landing when they did, even though they were still about 100,000 lbs above the max landing weight for the A380. That's a situation that was getting worse over time and I think they decided that they needed to get the wheels on terra firma before the cg went much further aft.

 

The crew performed brilliantly. They were fortunate to have five well-qualified people in the cockpit and CRM appears to have been used to good effect. The other factor in their favor was good weather - if this had been at night in IMC it might have been a lot more difficult.

 

One of the things that is going to get a lot of attention in the background is that computer response to serious casualties. This is the third event I've heard of recently where the computer almost literally overwhelmed the crew with redundant, contradictory or useless information and in some cases, took away some things that did not need to be shut down. The software will get better and better and events like this, unfortunately, are one of the things that roots out the issues that need to be corrected. They will be and the planes will get better as a result. It's fortunate that the price of this particular knowledge did not have to be paid in blood as is sometimes the case.

 

John

[stu7708 244]

...would have made the 3 Stooges look like a team of efficiency experts...

Nice comparison.. gave me a good laugh

[allardjd 1,853]

Qantas to resume A380 flights to Los Angeles

 

http://flightaware.com/news/ap/Qantas-to-resume-A380-flights-to-Los-Angeles/3417

[mutley 4,495]

Sunday is the day then, no operating restrictions so fingers crossed