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Qantas A380 uncontained #2 engine failure

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Qantas A380 uncontained #2 engine failure

Old 6th Nov 2010, 22:24
  #561 (permalink)  
 
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Quote:
So half of the Qantas fleet require an engine change upon inspection.
None of the 11 Singapore aircraft - we have yet to hear of any of the 3 Lufthansa.

Would any resident mathematician/statistician like to work out the odds that this could be a simply random coincidence?
Maybe you need to check the engine types... there might be a (significant?) difference
The AD refers to all Marks, All serial numbers.
It may be that there is a particular Mark used by Qantas - that would be very significant if so.
A 2.7% chance of it being coincidental - is the converse that it is over 97% likely that it is not?

So quite likely it is either related to a particular engine Mark or alternatively related to a (Qantas) procedure.

(it could be the inspection procedure!)
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Old 6th Nov 2010, 22:29
  #562 (permalink)  
 
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iskyfly

Apparently the Blue hydraulic system was changed to electro-hydraulic actuators. So still three systems.
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Old 6th Nov 2010, 22:29
  #563 (permalink)  
 
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Several posts on the first page have links to photographs that appear to show smoke residues on the forward part of the panel that broke off. Is this an indication of fire in the compression stages, upstream of the combustion and later stages. Or is their some other explanation?

Could a lubrication failure lead to an oil fire and seizure of some bearings, leading on to fractures, freeing of power turbines, overspeed and disintegration?
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Old 6th Nov 2010, 22:43
  #564 (permalink)  
 
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Apparently the Blue hydraulic system was changed to electro-hydraulic actuators. So still three systems.
pumps or actuators?
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Old 6th Nov 2010, 22:55
  #565 (permalink)  
 
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iskyfly

Take a look:

http://www.fzt.haw-hamburg.de/pers/S...t_Controls.pdf
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Old 6th Nov 2010, 22:56
  #566 (permalink)  
 
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@ BillS

Negative,

3 engines are in use:

1) Engine Alliance (EA) GP7270 used by Emirates & Air France

2) Rolls-Royce Trent 970/B used by Singapore Airlines & Lufthansa

3) Rolls-Royce Trent 972/B used by Qantas

Korean has the EA on order and Malaysian the Trent 970.


The Trent 972 is a slightly powerfull version of the Trent 970
From post #217. So yes it does appear that QANTAS use a different model of the Trent 900. Maybe significant, maybe not.
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Old 6th Nov 2010, 23:01
  #567 (permalink)  
 
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970/B vs 972/B

Dual ground: Oh ####, all my calculation work for nought ! #### but thanks!
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Old 6th Nov 2010, 23:08
  #568 (permalink)  
 
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Looks like pumps to me. Not very effective if the system is empty.
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Old 6th Nov 2010, 23:14
  #569 (permalink)  
 
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Originally Posted by iskyfly View Post
Am I to understand that there are only 2 hydraulic systems on the A380?
Only two pure hydraulic, but also two hydraulic-electrical systems behind them for backup. The latter systems are new on the 380 I think - with previous airbus models having 3 hydraulic.

I've also seen these systems referred to as "hydro-electrical" - which could get awfully confusing to an EE...
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Old 6th Nov 2010, 23:19
  #570 (permalink)  
 
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Originally Posted by Gegenbeispiel
Dual ground: Oh ####, all my calculation work for nought ! #### but thanks!
Not for nought at all!

If the issue is just with one engine mark, that is very significant for RR and Airbus!
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Old 6th Nov 2010, 23:28
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Bear in mind that I just culled this information from an earlier post. I have no way of knowing how accurate this is. No disrespect meant to the original poster, just that I haven't verified it.
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Old 6th Nov 2010, 23:28
  #572 (permalink)  
 
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BillS...

It does appear QF use a slightly different model #. Not necessarily too significant... it might just be a (slight) thrust rating increase, and can be reversed, or at least "points" to where the problem might lie. Or it's not relevant at all...

Just remember Kegworth with regard to this aspect

NoD
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Old 6th Nov 2010, 23:35
  #573 (permalink)  
 
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@ Morrissey

Thanks for your response. It all sounds very probable and I take your words as your own opinion, nothing else.

I'm sure it must have been stressful for all involved and it's interesting to read how others dealt with it.

I did speculate that the landing would be fast and I have to commend the pilots, not only for their flying, but for keeping the passengers informed and calm.
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Old 7th Nov 2010, 00:39
  #574 (permalink)  
VFD
 
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It does appear QF use a slightly different model #. Not necessarily too significant... it might just be a (slight) thrust rating increase, and can be reversed, or at least "points" to where the problem might lie. Or it's not relevant at all...
I pulled up Rolls pdf with a google search and for what it has to say is that there is a significant increase in take off thrust with a 5 minute limit on the 972 vs the 970. All the other numbers looked the same.

So with flex/assumed temp take offs not too sure how often they get into the range above the thrust of a 970 with a 972.
You may be on to something.
Not sure if there are any other internal differences in the engines. Maybe they are just pushing the limits of the design with the higher thrust rating.

VFD
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Old 7th Nov 2010, 00:58
  #575 (permalink)  
 
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Many are saying that the IP turbine will overspeed if disconnected from the compressor and I can see a transient overspeed in a very short interval after decoupling.

But once the IP compressor is no longer being driven, compression and resultant exhaust flow will be pretty much limited to what the HP can stuff into the cans and I would think that there would not be that much gas flow to drive the IP turbine, especially with the many stages of the IP compressor simply freewheeling.

So either:
  1. the IP overspeed happens near instantaneously on decoupling
  2. the HP gas flow is sufficient to overspeed the decoupled IP turbine
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Old 7th Nov 2010, 01:04
  #576 (permalink)  
 
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Originally Posted by infrequentflyer789
Only two pure hydraulic, but also two hydraulic-electrical systems behind them for backup. The latter systems are new on the 380 I think - with previous airbus models having 3 hydraulic.

I've also seen these systems referred to as "hydro-electrical" - which could get awfully confusing to an EE...
The A380/787 are moving towards what I have been taught as more electric aircraft.

That is removing all the 'typical' engine driven hydraulic pumps and coloured systems (Blue, Green & Yellow for Concorde) with local electric motors powering local hydraulic pumps for flaps, slats, flying controls etc.

The use of electric motors powering flaps and slats was rejected due to the much higher probability of a mechanical system jamming vs a hydraulic one.

Apparently this 'contained' system of individual electrical motors and pumps gives weight savings and increased redundancy.

Unfortunately I cannot remember anymore details on all the MEA stuff I learn't!
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Old 7th Nov 2010, 01:16
  #577 (permalink)  
 
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A380 Uncontained Engine Failure

just a guy from detroit here....not a journalist....just a newbie stickin my head in (pardon me please) looking at the photo of the #2 engine with the fire soot marks ahead of the combustion chamber of the engine, is there any possibility that this engine was reverse thrusting in flight? I believe i've seen posts where the #2 is one of the two engines that have reversers on the A380. BTW , the crew and all involved did a helluva job limping her home
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Old 7th Nov 2010, 01:16
  #578 (permalink)  
fdr
 
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stats...

Hydro4.0

the current probability considered for this type of failure event is 10e-7. The event in itself does not constitute a catastrophic event - the certification requirements require the manufacturer to demonstrate a 1 in 20 case. All in all it has to be shown that an event like this ending in a catastrophe is less than 10e-9.
FAR/CS Part 21, 33, and FAA AC33.3, AC33.7 have various criteria for design standards for turbine discs, in relation to burst requirements to be evaluated. I have no reference to hand that shows a statistical probability in respect of the disc, except under part 25 Subpart E, where it is possibly inferred in 25.905(d) (1) and (2). The earlier references relate the certification requirements to overspeed loads, and related creep/burst modes. (Failure of the disc at the inner bore would be interesting from a hoop stress analysis following a material or machining defect, rather than a radial shear overload, IMHO).

can you provide your reference for the stated disc rupture statistical value? PM is fine. I have been working on a helicopter STC and failure mode analysis using monte carlo simulation, but do not have any regulatory precedent to hand.

AC20.128A provides: "Fuel tank penetration leak paths should be determined and evaluated for hazards during flight and ground phases of operation. If fuel spills into the airstream away from the airplane no additional protection is needed. Additional protection should be considered if fuel could spill, drain or migrate into areas housing ignition sources, such as engine or APU inlets or wheel wells. Damage to adjacent systems, wiring etc., should be evaluated regarding the potential that an uncontained fragment will create both an ignition source and fuel source. Wheel brakes may be considered as an ignition source during takeoff and initial climb. Protection of the wheel wells may be provided by airflow discharging from gaps or openings, preventing entry of fuel, a ventilation rate precluding a combustible mixture or other provisions indicated in ~~ 23.863 and 25.863". Which is what the system did.

Similar analysis methodolgies:

Aerospace Industries Association Rotor Integrity Subcommittee, “The Development of Anomaly Distributions for Aircraft Engine Titanium Disk Alloys,” Proceedings of the 38th Structures, Structural Dynamics, and Ma- terials Conference, AIAA, Reston, VA, 1997, pp. 2543–2553.

“Advisory Circular—Damage Tolerance for High Energy Turbine En- gine Rotors,” Federal Aviation Administration, Rept. AC 33.14-1, U.S. Dept. of Transportation, Washington, DC, Jan. 2001.
Almroth, P. (2008). 638103 IN718: Creep model. Internal report 1CS75032. Siemens Industrial Turbomachinery AB, Finspång, Sweden.

Andersson, R. (2004). GTX100 version A: Heat transfer data and transient scaling factors for the turbine rotor at DPO conditions. Internal report T10C 76/03. Siemens Industrial Turbomachinery AB, Finspång, Sweden.

Blom, G., Enger, J., Englund, G., Grandell, J., Holst, L. (2005). Sannolikhetsteori och statistikteori med tillämpningar (Fifth Ed.). Lund: Studentlitteratur.

Booker, M. K., Booker, B. L. P. (1980). Analysis of available creep and creep‐rupture data for commercial heat‐treated alloy 718. Report ORNL/TM‐7134. Oak Ridge National Laboratory, Oak Ridge, USA.

Bykov, V. (1998). Turbine rotor 2D cooling & MIT analysis. Internal report TR010. ABB Uniturbo, Moscow, Russia.

Dahlberg, T., Ekberg, A. (2003). Failure fracture fatigue an introduction. Lund: Studentlitteratur.

Enright, M. P., and Frangopol, D. M., “Failure Time Prediction of Dete- riorating Fail-Safe Structures,” Journal of Structural Engineering, Vol. 124, No. 12, 1998, pp. 1448–1457.

Enright, M. P., Millwater, H. R., and Huyse, L. (2006). Adaptive Optimal Sampling Methodology for Reliability Prediction of Series Systems AIAA JOURNAL Vol. 44, No. 3, March 2006.

Enright, M. P., Huyse, L., McClung, R. C., and Millwater, H. R, “Probabilistic methodology for Life Prediction of Aircraft Turbine Rotors,” Proceedings of the 9th Biennial ASCE Aerospace Division International Conference on Engineering, Construction and Operations in Challenging Environments (Earth & Space 2004), edited by R. B. Malla and A. Maji, American Society of Civil Engineers, Reston, VA, 2004, pp. 453–460.

Leverant, G. R., McClung, R. C., Millwater, H. R., and Enright, M. P, “A New Tool for Design and Certification of Aircraft Turbine Rotors,” Journal of Engineering for Gas Turbines and Power, Vol. 126, No. 1, 2003, pp. 155–159.

Lindgren, H. (2006). GTX100 version A: 2D axisymmetric LCF life assessment and contact load calculation of the turbine rotor. Internal report GRC 68/04. Siemens Industrial Turbomachinery AB, Finspång, Sweden.

Montgomery, D. C. (2005). Introduction to statistical quality control (Fifth Ed.). Hoboken, NJ: John Wiley & Sons Inc.

Myers, R. H. (1995). Response surface methodology: process and product optimization using designed experiments. New York, NY: John Wiley & Sons Inc.

Nikolaidis, E., Chiocel, D. M., Singhal, S. (2008). Engineering design reliability applications for aerospace, automotive and ship industries. Boca Raton: CRC Press.

Nilsson, F. (2008). Probabilistic methods in solid mechanics. Department of solid mechanics, Kungliga tekniska högskolan, Stockholm, Sweden.

Petukhovsky, M. (1998). Turbine clearances calculation. Internal report TR012. ABB Uniturbo, Moscow, Russia.

Last edited by fdr; 7th Nov 2010 at 01:55.
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Old 7th Nov 2010, 01:38
  #579 (permalink)  
fdr
 
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RBF:
So either:
the IP overspeed happens near instantaneously on decoupling
the HP gas flow is sufficient to overspeed the decoupled IP turbine
An overspeed would be a transient event. The structure certification is required to show that an overspeed:

"Section 33.27(c)(2)(v) states that rotor structural integrity must be demonstrated at: “105% of the highest speed that would result from failure of the most critical component or system in a representative installation of the engine.” This single component may not necessarily be in the rotor itself; instead, it may be some part of another engine sub-system that, upon failure, could cause a rotor overspeed. Examples of such components might include certain key elements of the engine control system and its related sensors. A failure modes effect analysis (FMEA) or other similar engineering assessment would generally be required to identify such components". (AC 33.27-1, AC 33-2B, AC 33-3 )...


FDR
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Old 7th Nov 2010, 01:47
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Looks like pumps to me. Not very effective if the system is empty.
The EBHA units are self-contained hydraulically, so control is still possible with hydraulic failure. (And even electrical/engine failure cases, given use of RAT etc)
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