KLMBlue From United States of America, joined Nov 2000, 267 posts, RR: 0 Posted (12 years 3 months 3 weeks 18 hours ago) and read 893 times:
Can a B744 or a A340 do the following?
1. Say the the two outer engines(the two farthest apart) fail. Can the two inner engines keep the airplane flying, and for how long?
2. Or the two inner engines fail, can the two outer engines keep the airplane in the air?
I know it sounds redundant asking the two different questions, but I am just wondering! Thanks in advance.
KLM
AirbusDriver From United States of America, joined Feb 2001, 255 posts, RR: 1 Reply 1, posted (12 years 3 months 3 weeks 18 hours ago) and read 865 times:
yes both can fly with any 2 engine out at max gross weight.
Baec777 From United States of America, joined Oct 1999, 1231 posts, RR: 2 Reply 2, posted (12 years 3 months 3 weeks 18 hours ago) and read 856 times:
The B747, A340 can fly with 2 engines for not so long, but they can fly for 1-2 hours during a declared emergency landing procedures until they land the plane(s).
Prebennorholm From Denmark, joined Mar 2000, 6019 posts, RR: 55 Reply 3, posted (12 years 3 months 3 weeks 17 hours ago) and read 832 times:
They will easily keep flying at low altitude on two engines only.
They will be in somewhat worse condition than a twin which beyond V1 speed actually must TAKE OFF with half of the power lost - with flaps and gear down etc.
Otherwise they wouldn't be able to climb to and cruise at high altitude where the max power is roughly one fourth due to the thin air.
Both planes have a lift to drag ratio around 20 and a power to max weight ratio around 4 at sea level. So even with only one engine operational - if it was placed on the centerline - and consequently power to weight ratio of 16, they would still be able to climb slightly. But that would depend very much on the condition of the disabled engines - what drag they would produce.
But with a light load - a lot of fuel either burned or dumped - they would both easily maintain flight on one inner engine only at low altitude.
Best regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs, Preben Norholm
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From United States of America, joined Nov 2000, 267 posts, 
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