https://www.youtube.com/watch?v=2tY2HzWCvhw

China Airlines 738 fire in Okinawa. At least the Fire Services seem to have been quicker in Vegas.

And yes, people took their belongings then also.

I have been reading the FAA AD designed to prevent the type of incident which occurred to the BA 777 at Las Vegas. I found the following parts of the document interesting:


Request

Two commenters, General Electric Company and The Boeing Company, requested that we remove the “UnsafeCondition” paragraph from the AD, and reword the Summary section to resemble the Summary section of AD 2002-04-11. The commenters stated that, by their analyses, cracks in the weld joint would not develop into an uncontained failure. The commenters stated that HPCR 8-10 stage spools, P/Ns 1844M90G01 and 1844M90G02, be inspected by an enhanced inspection, similar to those parts covered in AD 2002-04-11.

Answer

We do not agree. AD 2002-04-11 was issued because of additional focused inspection procedures that had been developed by the manufacturer. Because cracks were discovered on one HPCR 8-10 spool between the 9-10 stages in the weld joint, this unsafe condition is likely to exist or develop in other products of the same type design. The unsafe condition could result in failure of the HPCR 8-10 stage spool, uncontained engine failure, and damage to the airplane. We determined that this unsafe condition requires mandatory repetitive inspections for cracks. We did not change the AD.


Well done the FAA for 'sticking to its guns'.


Inspections of the HPCR 8-10 Stage Spool

(f)(1) At the next piece-part exposure of the HPCR 8-10 stage spool after the effective date of this AD, perform a fluorescent penetrant inspection (FPI) and eddy current inspection (ECI) of the weld joint between the 9-10 stages of the HPCR 8-10 stage spool for cracks.

(2) Thereafter, perform repetitive FPIs and ECIs of the weld joint between the 9-10 stages of the HPCR 8-10 stage spool for cracks at every piece-part exposure of the HPCR 8-10 stage spool.


Presumably, this type of inspection can be performed only during major engine overhaul, with the engine removed from the aircraft? If so, will the authorities now need to consider more frequent engine overhauls?


What seems to be missing is any move to find a permanent fix for the problem such as a redesign/manufacture of a HP turbofan which does not have an inherent weakness.

http://www.pprune.org/rumours-news/5...ml#post9114090

Avionista,

Thank you for researching this and summarising key detail. You pose a critical question. I hope it will be answered.

If it is missing it means it was irrelevant, namely design wasn't in question rather perhaps the flaw in manufacturing of random nature. I am not aware of any manufacturing process on this planet that would assure 100% fail free product.

I think that fail-safe might be a more productive route for turbines -- Think how car windscreens have evolved from big lethal broken shards through regularly shaped small bits to the current 'broken but still hanging together' approach

In reply to iomapaseo:

If you watch the video, the first thing the fire appliances do is direct their jets on to the ground beneath the wing.

If you're suggesting that the engine casing should be able to retain any parts from a broken turbine breaking out, that's simply not feasible.

the speed/energy in these parts (especially at take-off power) is simply staggering, you would need something like several inches of Chobham armour backed with heavy armour plate.

If the problem is a manufacturing flaw in a small number of HP turbofans, why does the AD require repetitive inspections, ad infinitum. Surely, the replacement of any components found to be defective would suffice. The FAA, perhaps, believes the problem could develop over time in any of these HP turbofans, hence their requirement for repeated EFI/ECI scans.

I agree that nothing man-made is ever 100% reliable, but vital components should strive for a MTBF well in excess of their expected lifecycle.

I recall video footage of the testing of RR engines where this very feature is demonstrated as a test that the engine has to pass before certification.

Yes, they do strive and there is no data that would indicate this doesn't apply to this part as well. Reliability of these engines is phenomenal by any standards and this includes MTBF.

N1 only....

Failsafe is extremely difficult to imagine without numbers relating to probabilities. Tis true that some parts of a machine such as wing spars are designed with lots of margin to long life with inspections and consideration of storm encounters, damage etc. But most parts can't meet this same requirement and still maintain the total aircraft weight low enough to get off the ground.

Instead mitigation against the consequences of their failing is considered in a probalistic hazard environment.

Things like redundancy/duplication, shielding etc. are considered at the aircraft system level.

If you want to get into this kind of discussion you have to be prepared to work with probabilities and even with that you are still left with some chance of what happened in this event.

We are waiting for the investigation to reveal the causal chain so that one or two of the links can be altered to minimize a future event. Don't for minute believe you can achieve zero engine disk failures, but you can minimize some specific identified cause based on new knowledge.

The message is always the reaction to what we learn and not blame.

For instance re. inspections mandated by this AD - who keeps track of the outcome of such inspections? Boeing and GE only? Assuming there is a trend (with enough statistics), are the reliability models revisited?

flyingchanges and funfly:True it was N1, but the salient fact is that it's a BLADE (airfoil) deliberately released from the fan disk in the referenced video. All new engine models are required to endure this test; The containment for the relatively lightweight blade is established technology. But a DISC failure is several orders of magnitude worse, and containment quite impractical in a flying machine.

Inspection results are reported to the FAA and various models updated as needed. The FAA may update their AD based on any new findings.

At this point I have not seen any linkage between this event and an existing AD but I'm sure they are certainly looking at it quite closely.

This type of failure is extremely rare but the investigators not only need to find the chain of events which likely caused it but also the following chain of events which caused a lot of fuel to leak out from somewhere, probably onto the ground where it then started to vaporise and subsequently ignited.
With all the videos and other evidence they collect from various sources it may be possible to determine where the fuel exited the aircraft and where the first ignition took place. All this is amongst the myriads of things they will have to look at before trying to determine what steps may need to be taken to minimise the chances of it happening again. These processes could take days, weeks or months, or longer. Then of course there will have to be cost and safety evaluations by various parties….
It has already been mentioned by some that the seat of the fire appeared to be below and not in the aircraft and one of my thoughts is that hot brakes could have ignited it or it could have been ignited by another fire already burning in or around the engine. It may of course be difficult to tell after all the damage caused by the fire(s).

Many years ago I was told of an industrial turbine that had a disc failure probably operating in some third world country.
I was told the majority of the disc exited though the casing, out though the unit sound proofing canopy, across the site, though a fence, across a road, then it entered a house though the window 'climbed up' a rear wall, so now going vertically upwards, went through the ceilings, 1st floor and roof structure .......whereupon it finally ran out of energy

When you reject a takeoff and bring the aircraft to a halt the pilots are unable to see anything inboard of the wingtips without opening windows. They may or may not have received a left engine fire warning indication, it depends on whether the fire loop for that engine detected heat. If there was a rapidly expanding puddle of jet fuel on the tarmac that was burning and the flames were going on to the fuselage there would not be a fire indication.


I am sure the controllers were extremely busy coordinating fire services and go-arounds.However if the tower had a clear view of the aircraft would it not have been useful if the controller had told the aircraft that there was smoke and flames billowing from the left engine? Armed with that information the evacuation might have been initiated earlier.


I know that if I were to reject a takeoff, having informed ATC I was stopping I would be very grateful for any immediate feedback from ATC as to whether they could see any smoke, flames, inferno etc. Fortunately in the absence of any ATC info there was an extra flight crew member on hand to go back and see what the passengers and cabin crew could see.


If a passenger had panicked and opened door 2 left off their own bat there might have been a very different outcome. As it was what a great outcome and hats off to all concerned.

Thanks for sharing this. :ok:

Only the even numbers have memory items on the large Boeing where I work. :eek:

This can't be possible right? Surely I have that sim in the basement and am making this up. :confused:

I got the 13 items from Whip's earlier comment:

I heartily congratulate Whip on his retirement and I think our latest reduction in memory items has been since his retirement.

Some of these lists would be called profiles and maneuvers for us, we are indeed expected to know them cold.

However, things that would at one time be considered just common sense troubleshooting, like cycling a transponder, have gradually found their way into a formal non-normal checklist in the AOM (and sometimes, but not always, also in the QRH). And now, Lord help you if you don't write it in the book (or type it on the screen), send a maintenance code and maybe file an ASAP report for CYA whenever anything happens.

Remember when airline manuals only came out every year or two with a few bulletins in between to save printing costs?

Now, with pubs on tablets, revisions seem to be slipstreamed into the manuals almost constantly. At least now you don't have to look at the changes to put the new pages in, right?

Apologies for talking shop so much on a professional pilots forum but these days with events like the BA LAS RTO how you did it is as important to the feds as what you did and how it turned out.

I hope I never see a high speed RTO in the plane (but I'm sure it will be on next year's sim training ;)) however if I do, hope my coworkers watch me and make sure that we all do it right.

Ka-2b pilot, kerosene's vapour is not flammable like petrol's is. ;)

dsc810, many years ago we had a reheated Spey let go of it's HP disc and it exited at 7-0-clock, chopped through the test cell's main fuel inlet pipe, hit the floor, ran up the test cell wall like a Catherine wheel, along the ceiling, down the opposite wall and buried itself into the substantial steel test cradle. The resulting fire was spectacular and the cell out of commission for weeks. And that's with a small engine. A modern large bypass engine's disc failure is a sight to behold! :eek: