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-   -   744/340 double eng failure (https://www.pprune.org/questions/166075-744-340-double-eng-failure.html)

president 7th Mar 2005 16:29

744/340 double eng failure
 
Hi

After I read about the BA 744 that continued to destination on 3 engines I came up with a few questions. Can someone tell me what would happend if they had to shut down one more engine. Would the aircraft be able to fly on the remaining 2 engines and perform a normal approach/landing? I could imagine an approach with a lower flap setting to create less drag or what...? Or would it even fly :eek:

My second question is what a 4 engine aircraft is capable of in case of double engine failure after v1? I know a twin can continue on 1 engine but it is hard to believe an A340-2/300 at MTOW actually lifting off on 2 engines. I cannot find any info on the reguations concerning that scenario.

I hope you can answer my question ;)


President

Mad (Flt) Scientist 7th Mar 2005 16:39

FAR 25.123(c) contains en route flightpath requirements for three or four engined planes for a two engine inoperative case.

FAR 25.121 is the one engine inoperative climb requirements section; although (obviously) it only addresses OEI cases, there is implied margin for four-engined aircraft in that it requires an additional flightpath angle of approximately 0.5% for four engined aircraft after engine failure, compared to a twin after losing one engine.

Rainboe 7th Mar 2005 17:54

The B747 is no problem to fly with two engines out in the worst condition- ie on one side. It is periodically practised in the simulator. If it happened in the cruise, the resulting drift down altitude is pretty seriously compromised-some 17,000' at max top of climb weight up to mid 20,000s' at more typical cruise weights. A diversion would then be recommended.
It is known that a 747 will fly on one- not very well, but it is surviveable.
Large aeroplanes do not use limited flap landing settings- it can create more of a problem stopping. Twins do.

jc2354 7th Mar 2005 18:14

1982, a British Airways B-747 with 247 passengers and 16 crew members was enroute from Kuala Lumpur, Malasia to Perth, Australia. Because of volcano ash, not only did they loose 2 engines, progressively they lost ALL engines. Eventually, 3 engines were restarted and the plane landed in Jakarta.

Here is a link to a very brief synopsis:
http://www.nw.faa.gov/releases/volash.html

Old Smokey 8th Mar 2005 02:27

I believe that the 2 Engines Inoperative case has been well covered here in consideration of the En-Route, and Handling capability cases.

Mad (Flt) Scientist has correctly indicated that only OEI (One Engine Inoperative) is considered for 2,3, and 4 engined aircraft at the Takeoff phase, with the 4 engined aircraft requiring an additional 0.5% OEI Climb Gradient compared to the 2 engined aircraft. So, the question arises, "Does this incremental 0.5% capability allow for a second engine failure at Takeoff?" - ABSOLUTELY NOT! In short, you're dead. The El Al B747 double engine failure on Takeoff accident amply demonstrates this. If the 4 engined aircraft were taking off at a weight well under typical takeoff weights, there MIGHT be a fighting chance of survival, and at typical weights, fuel cannot be dumped fast enough to make it possible.

So, which aircraft is the safest? Consider this -

(1) A 4 engined aircraft has twice the probability of engine failure as does a twin,

(2) A 4 engined aircraft in normal all engine operations has much less performance reserve than does a twin (see (3) below), thus requiring much longer application of high thrust levels, increasing cumulative engine stress, rendering them more likely to suffer engine failure.

(3) The One Engine Inoperative (OEI) performance for a 2 or 4 engined aircraft is APPROXIMATELY the same (slightly in the 4 engined aircraft's favour) at Takeoff. That is, the twin achieves the same on 1 engine as does the quad on 3 engines. Now, in the 99.999% of cases where an engine does not fail on Takeoff, the twin is operating with 200% of the thrust required, whilst the quad is operating with only 133% of the thrust required. Thus for normal operations (the 99.999% case), the twin has a huge excess of performance compared to the 4 engined aircraft.

For me, I'll stick to twins. I'll opt for the aircraft giving me the greatest performance reserve on 99.999% of my flights, whilst offering perfectly acceptable performance on the other 1 or 2 days of my career that I lose an engine. There's no jealousy here, I've flown 1,2,3, and 4 engined aircraft, and I know when I feel the safest.

Regards,

Old Smokey

R8TED THRUST 8th Mar 2005 03:56

The B-744 will easily fly with one engine out and continue to destination faster than an airbus on 4 as for two out it will still perform nicely but due to lower alt and fuel it is then time to divert.

Cheers

411A 8th Mar 2005 06:26

In short, you're dead...well, maybe
 
SV had a very nasty incident some years ago, Old Smokey, wherein an -SP departing at MTOW ex-JED suffered an uncontained failure of number two at two hundred AGL, bits of which entered number one, and lit up the number one fire handle.
The F/E, thinking he was doing OK (but clearly was not) pulled the number one fire pull handle...and presto, two engines at 400 agl.

I knew the Captain quite well, and he managed to descend slightly, clean up, and climb very slowly, dump, and return for landing.

Crew co-ordination went out the window, but nonetheless, all survived.

They were very lucky.

Omark44 8th Mar 2005 08:25

The EL Al didn't crash beacause it lost two engines, it crashed, after a fair time airborne, because they lost their flying controls.

For two engines inoperative on a B744 the flap setting becomes Flap25, not the usual Flap30

Phil Squares 8th Mar 2005 11:23

IIRC, the EL AL crashed because of the leading edge assymetry when they were directed to reduce speed. Had they kept their speed up and landed with no flaps, they would have been in a much better position.

18-Wheeler 8th Mar 2005 12:46


IIRC, the EL AL crashed because of the leading edge assymetry when they were directed to reduce speed. Had they kept their speed up and landed with no flaps, they would have been in a much better position.
If they'd used the alternate system correctly, they would not have lost control.
It's the one switch in a 747 Classic that'll kill you - The Alternate Leading Edge Arm switch.

LE's FIRST, THEN the TE's.

Rainboe 8th Mar 2005 13:11

Omark, BA 744 standard landing is 25. 30 is only used in CAT 3 or when very tight landing distance available.

sky330 8th Mar 2005 13:40

Most of what have been said for 744 apply to a340 as well as it is the regulation for 4-engines aircraft.

My company quite often trained in the sim., engine failure, dumping and return for landing, go-around in very short final, and second engine failure at power application.

No problem at max. landing weight, IF you do it correctly, and there is an escape path as your climb rate is very low. At max take-off weight or just after take-off, like already said,... rest in peace.

My 2 cents.

TheOddOne 8th Mar 2005 14:04

In the late 80's a Continental 747 departing LGW suffered stall on nos 1 & 2 engines due xwind, just after V1. Managed to get airborne. The F/E was dumping fuel even as the a/c was still on the roll & before rotation. The a/c just cleared Russ Hill 2 miles to the W then disappeared from view, whereupon the controller hit the crash alarm. The altitude readout on RADAR was showing 002 for a while; a cheer apparently went up when it read 003. The a/c returned & made an overweight landing. The rumour that twigs were found in the undercarriage are unfounded as they had the gear up before they got to the hill.

So, yes, you CAN depart after V1 & before Vr with a 747 with 2 out on the same side.

Cheers,
TOO

sicknote 8th Mar 2005 14:57

For a one or 2-eng inop landing an A340 uses flap 3 rather than flap full.

Omark44 8th Mar 2005 22:52

BA are probably out there on their own then Rainboe? I think QF gave up 25 flap landing after BKK.

Would BA land on 27 at Bombay on 25 Flap? At Nairobi I'd certainly want to bring everything to a standstill as soon as possible, given the state of the runway!

Rainboe 9th Mar 2005 07:54

Omark, I think all of us use 25 at BOM- I always do as a frequent visitor. It is well within the performance figures and stopping has never been a problem there. If the runway was monsoon-like, I think most people would go for 30.
Back in the early 80s on the Classic, we uniquely had several incidents of flap sections falling off. Boeing came over to see why only we were suffering and questioned why we were doing standard 30 landings instead of 25 when 30 should be used for certain failures. We went over to 25 and have been there ever since. When you look at the performance table, there is very little difference. For fatigue reasons and comfort, I think 25 is the better option- it doesn't rattle as much!

Flyer01 9th Mar 2005 12:38

KLM is standard 25

A Comfy Chair 10th Mar 2005 14:18

TOO, WRT the double engine failure on takeoff scenario... yes, it can fly away from the ground, IF flown accurately, and more important, it isn't a terrain critical takeoff!!!

I'd like to see a successful takeoff like that from high altitude, or where there is rising terrain at the end of the runway. At max weight, I don't think it'd work quite that well.

lomapaseo 10th Mar 2005 14:50


In the late 80's a Continental 747 departing LGW suffered stall on nos 1 & 2 engines due xwind, just after V1. Managed to get airborne. The F/E was dumping fuel even as the a/c was still on the roll & before rotation. The a/c just cleared Russ Hill 2 miles to the W then disappeared from view, whereupon the controller hit the crash alarm. The altitude readout on RADAR was showing 002 for a while; a cheer apparently went up when it read 003. The a/c returned & made an overweight landing. The rumour that twigs were found in the undercarriage are unfounded as they had the gear up before they got to the hill.

So, yes, you CAN depart after V1 & before Vr with a 747 with 2 out on the same side.
Not correct



.... as the main wheels left the runway No. 4 engine surged
... see www.fromtheflightdeck.com for the.
video. The video clearly shows that the engine never regained thrust.

The aircraft was allowed to pitch up 22 deg which is 11 degrees greater than recommended. There is some evidence that the No.1 engine surged temporarily so that thrust was fully recovered in 2-3 seconds.

Fuel dumping began shortly after the engine failure (in the air) and continued for some 40 min.s until the required landing weight was achieved..

However there are instances where a B747 has taken off successfully with two engines out on one side after reaching Vr, it all seems to depend on weight and performance for the day.

TheOddOne 11th Mar 2005 00:37

lomapaseo,

I must apologise for an inaccurate posting here, not something I like to do. I'm afraid that this story has become somewhat distorted from alleged eyewitness accounts over the years. However, there is little doubt that at an early stage in the flight, 2 engines were inop, though as the video shows, one of them is on the downwind side.

I'm having great difficulty locating either the AAIB or NTSB official reports. I'll certainly attempt to chase up the AAIB report because I want to get it straight in my own mind, what really happened.

Theground appears to be closer than you might expect because the contour immediately after takeoff slopes upward towards Russ Hill, just to the west of the airport.

I'm still of the view that a crosswind was a major contributory factor in this incident; I understand that a number of changes werer made at Gatwick as a result, so it did some good.

Thanks again for putting me straight!

Cheers,
TheOddOne


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