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Qantas A380 uncontained #2 engine failure

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Qantas A380 uncontained #2 engine failure

Old 10th Dec 2010, 15:42
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Overview ...

As the concerns from the FD, the fire crew and the available engineering information is brought to a conclusion, it speaks volumes for the value of CRM ground and air, systems redundacy in the most extreme of circumstances, and the whole system to bring about an outcome which resulted in no injuries.

Engineering holes in this instance were blocked by other layers, including the baseline engineering itself, the co-operation with the fire crew on the ground prevented another... that is the value of CRM.

When I first reviewed this thread, and thought of my own aircraft type I believed this would have been a hull loss, what I have read since is an education in more ways than one.
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Old 10th Dec 2010, 16:46
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I hadn't read anything about wing replacement?

Edit: OK, I see this has already been queried!
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Old 10th Dec 2010, 17:39
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Herald Sun = utter tabloid garbage!

You only have to LISTEN to the audio to see(hear?) clearly that Capt Evans and the rest of QF32 fight crew were not 'gripped by fear' but calm professionals working their way methodically through a complex problem...

Kudos to the crew as well for keeping the passengers informed - that it was going to take a while to get them on the ground.

If only the trains operators in the UK could be that upfront - they usually love letting people guess what leaves/snow/strikes/maintenance is gonna strand them overnight....
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Old 10th Dec 2010, 18:06
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Just a thought, but how beneficial can it be to listen (read) one poster's critique of other posters, while he ignores the topic.?

Perhaps he should be less oblique, and more specific?

DirtWalk. What is that?

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Old 10th Dec 2010, 19:44
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First Floor

The engine on Qantas and SAI aircraft are maintained under a RR program known as "Total Care". Don't know if this is the case at Lufthansa. Nevertheless, RR assumes complete responsibility for the welfare of engines under the program for the duration of the contract. Both Pratt and GE have similar programs with their customers. It is a win-win situation if carried out properly. There is variation as to the content of each program as they are derived based on individual customer needs. The program usually includes real time engine monitoring and recommendation when corrective action is required, implementation of all appropriate AD's or other notifications, replacement of parts deemed necessary to be replaced and of course, major servicing and overhaul. When an engine goes out of service for a period of time, a replacement engine is usually provided. This is all done based on a set cost per engine flight hour.

It would seem to me that the engine manufacture is responsible for all the above costs. For this to all work correctly, there is one additional requirement: Good Communications and Trust coupled with back and forth sharing of all pertinent data and observations between both parties. Something didn't work right here.

The compensation in question is that of the operator's loss in operational revenue, the cost of repair of the damaged aircraft, the replacement of the damaged engine and other considerations such as lack of replacement engines. Today's UK Financial Times estimated the damages could be as much as $500M.

Qantas is solely responsible to make the decision to fly or not based on data and information at hand, safety first. Remember, their engines are different than either SAI's or Lufthansa's in that they are operating a higher thrust model. An apple to apple comparison is not valid. The extra 2,000 Lbs. of thrust must come from somewhere, no doubt higher operating temperatures at maximum thrust.

At any rate, this makes for interesting discussions.

Turbine D
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Old 10th Dec 2010, 20:48
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At any rate, this makes for interesting discussions.
Err.....................
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Old 10th Dec 2010, 21:10
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Turbine D:
...Remember, their (Qantas) engines are different than either SAI's or Lufthansa's in that they are operating a higher thrust model. An apple to apple comparison is not valid. The extra 2,000 Lbs. of thrust must come from somewhere, no doubt higher operating temperatures at maximum thrust.
True, but there's more to the equation.

A 72K engine operated in cooler airports, with longer runways (and thus more reduced/derated ops) will run cooler than a 70K machine in hotter/higher climes, w/ more rated-thrust ops.

So the negotiated lease cost per EFH will take all these factors into consideration - it's to both parties' benefit. There will also likely be some consideration for excess fuel burn.
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Old 10th Dec 2010, 21:17
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barit1

Very good point and well taken! The other thing is, Qantas may not use full thrust on every takeoff depending on various factors.

Turbine D
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Old 10th Dec 2010, 21:38
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glad rag

I am referring to the financial compensation issues.

Turbine D
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Old 10th Dec 2010, 22:22
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Barit1 writes:
A 72K engine operated in cooler airports, with longer runways (and thus more reduced/derated ops) will run cooler than a 70K machine in hotter/higher climes, w/ more rated-thrust ops.
I have been led to assume that - except for thrust rating - the t900 and the t972 are identical.

What would make the t972 run cooler than the t900 at the same thrust?


Cheers!
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Old 10th Dec 2010, 23:26
  #1791 (permalink)  
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I too believe the engines are identical. More power from the same powerplant is not free, it is not even cheap. A drop in MTOW and rated Thrust is what the "Old" 972's are doing these days, Yes? The New "C"'s?? Dunno.

The Emergency software mod is not a "Fix". It senses high temps earlier than previous program, and allows (theoretically) a quicker roll back. The idea is to save the Engine prior to "Burst", not to eliminate the cause of OverHeat, or hobbled oiling. Assumedly, the failChain still exists, for no data that has been released addresses this.

"Replacing a Module"??? CEOSpeak for "Mind your own Business??"

bear, all respect to all.
 
Old 11th Dec 2010, 00:46
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I agree the 970 and 972 are the same engine. The difference is the "turning up the wick" on the 972 verses the 970 at max thrust.

The higher thrust comes at the expense of higher temperatures, pressures and stress if nothing changes.

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Old 11th Dec 2010, 01:25
  #1793 (permalink)  
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The Shed, The Shop, and the Boardroom.

Early in WWII, a new airframe was developed in the US and provided to the British for service in Europe. It was a DOG. Low altitude, crap power, and a resultant lack of agility. It was called the "Apache", and had an American engine, an Allison? Same mill that tractored the P-40 around the Pacific.

Later on, much later, after several iterations and a re-engined North American airframe with a Belly Tank, it could bird dog the Bombers all the way to Berlin. It had the Range, the Guns, and the Belly for some fight that allowed the big bombs to hobble the Nozzies.

The Airframe was North American, the Engine? Rolls Royce. Each September I drive, fly, or hitchhike to Stead Field to listen to the magic that prevented my family from having to learn German. It is that simple, American Aluminum and English Iron. Mustang.

The engineering is still there, the double RR in blue, and the Fan is in a shroud now, but the machine, the machine. What goes wrong? What ails us? Our legacy of hard won supremacy in manufacturing is overseen now by imposters. Lawyers, Accountants, Public Relations Frozen Smiley Face, etc. Some one came into possession of the keys to the Shed, the Shop, and the Boardroom. Someone needs to buy a position in the Firm, and kick some Ass.

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Old 11th Dec 2010, 01:32
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rottenray:
What would make the t972 run cooler than the t900 at the same thrust?
All else being equal (same PA, same OAT...) the 72K machine at max TO will run hotter than the 70K machine at max TO. But that's not the point.

Different operators have different route systems - Different airfields, departing at different time of day, thus different ambient conditions; Different stage lengths, different payloads, thus more/less opportunity for derated or flex TO thrust; ad. inf. This eventually equates to AVERAGE TGT/EGT at takeoff. Makes no difference what the nameplate says; the 72K machine departing SEA for SYD will run cooler than a 70K machine leaving MEX for MAD. The proof is left to the student.

This translates to different severity in the overall route structure. One needs to understand all these elements to predict the average shop visit rate for the engine fleet, and that translates to maintenance cost. If R-R (or CFMI or P&W etc) are providing such maintenance-by-the-hour, the individual airline severity is essential to know.

EDIT: The operator will generally choose his nameplate thrust based on worst-case conditions; his scheduled departure from Riyadh may be 0300 local for coolest OAT, but he needs to take into account a 9 hr delay (40+C) and he needs the extra performance to avoid offloading payload. So he buys the T972, even if he only uses it 1-2 time a year.

Last edited by barit1; 11th Dec 2010 at 01:47.
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Old 11th Dec 2010, 01:56
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No quarrel re the other limits, bear, but in practice, turbine gas temperature is the parameter that makes the deterioration clock run faster or slower.

In a well-designed machine, bearings seem to last forever; fan/compressor airfoils too unless subjected to FOD or an erosive environment; combustors might need attention; but HPT airfoils are often the limiting factor.
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Old 11th Dec 2010, 03:15
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Barit1 writes:
The proof is left to the student.
Thanks for your in-depth explanation - once again, I've learned something here by asking a question.


Bearfoil writes:
Someone needs to buy a position in the Firm, and kick some Ass.
One of the most cogent and concise statements I've read regarding commercial aviation in this wonderful age of low cost. Could be applied to a lot of other industry as well.


Turbine writes:
The other thing is, Qantas may not use full thrust on every takeoff depending on various factors.
On this particular flight, they were apparently light and didn't use "full thrust" according to the interview with the senior check captain.

ASChan: Can you take us through the sequence of events as they happened?
DE: We departed normally, the aeroplane was relatively light and consequently used a relatively low thrust setting for departure. (link to article)
Now - please take this question in the way I intend it. Had it been a MTOW flight with full TO thrust, could the failure have happened earlier?


Cheers!
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Old 11th Dec 2010, 05:04
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Qantas, like most if not all operators only use as much thrust as required for that specific takeoff without creating a limiting situation at any time. They use what is called Flex Thrust [airbus] or Assumed Temp [boeing] to calculate what would be the minimum thrust required to achieve a safe takeoff. Obviously, the less weight you have at takeoff on a specific runway, the less thrust required. If this flight was departing for LHR instead of SYD the BRW would have been considerably higher requiring a higher thrust setting & much closer to the max certified thrust of 72,000 LB. This higher weight could have brought about a totally different outcome to what eventuated, especially when you take into account that the previous two sectors were WSSS to EGLL & return.

To the best of my knowledge the TRENT 900 is capable of Thrust limits of 80,000 LB which could be bought by any Airline as required, at a price from RR. Each Airline only buys the certification needed & this certification is limited by a simple selection by RR with the computers. As QF only operate the engine at 72,000 LB the engine is already operating 10% below it's maximum design limits. The reason for the possible higher certification limits is to cater for the freighter & future stretch should this ever happen.

Hope this helps.

P B

Last edited by PACIFIC BARON; 11th Dec 2010 at 05:16.
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Old 11th Dec 2010, 06:03
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P BARON

"80,000 LB which could be bought by any Airline as required..."

The engine may well be certified to that thrust but an airline can't buy it unless Airbus is offering it.

I believe those higher thrusts would only be needed for (later) higher MTOW versions: pax or freighter.
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Old 11th Dec 2010, 06:36
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@ barit1

No quarrel re the other limits, bear, but in practice, turbine gas temperature is the parameter that makes the deterioration clock run faster or slower.

In a well-designed machine, bearings seem to last forever; fan/compressor airfoils too unless subjected to FOD or an erosive environment; combustors might need attention; but HPT airfoils are often the limiting factor.
I'd like to add, IMHO, that the deterioration clock in this LP spline coupling is running full bore whenever the thrust is running at full bore. In that case, if temperature is proportional to thrust, the spline clock is going to run at something like the the square of the thrust used, since the strength of the splines go down as the temperature goes up. Some authorities also say that the fatigue susceptibility gones up as well, with temperature. One could argue that we are dealing with the cube of the thrust with fatigue involved, if not worse.

For worse, I can see how we can get to the 4th power of the thrust, by adding in spline wear proportional to thrust, resulting in coupling-generated additional heat above the local engine ambient in turn proportional to the wear. The 4th power of adding 2000 pounds thrust to the same wt of engine has got to be at least 10%. If you were already fatigue-limited in spline life, 10% could have a real disproportionate effect on spline life. There has to be some explanation of what is happening to these particular splines in this application.

Somewhere I have read that the goal for AC turbine engines is 7 yrs (3000 cycles) between overhauls. Does that mean 7 yrs on the wing, or is the current AD for for 400 cycle inspection of splines previously new (or on later inspection found substantially undamaged-- I forget the wording) less than an overhaul? Certainly the inspection of just this item requires removal of the rear turbine section with rear shaft attached, at a minimum. I'd assume the engine has to come off and go to the hangar for this, not to mention stripping any plumbing that crosses this joint. Is this being considered more like an oil change than an engine overhaul? Looking at six of these, minimum, before 3000 cycles right now. Did I mis-read something or has the borescope been made that can inspect splines?

OE
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Old 11th Dec 2010, 09:12
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Line check result?

I wonder what was the outcome of the line check on the PIC? and the training captain check?
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