Question for 747 / A340 Pilots

[Ex1900Driver]

Hi everyone... I have a quick question for all you 747 and A340 pilot out there. Is there a critical engine on a 747 and/or the A340?
I have been told there is although which one and why was not explained.
Thanks in advance for the help.
GC

 

[Diesel]

read flying the big jets and try not to stare out the window behind the interviewers.... From what i hear it's very tough.

Did you get a call?

 

[Cpt. Underpants]

I believe it's the #4 on both - something to with rudder offset, composite construction (of the rudder) variable rates of contraction/expansion of the composite surfaces and a natural predisposition to favour one's right foot. No B-S.

Personally, it's doesn't make a rats' difference on the A340 (I have about 3000 pic on type) but with the 744 I found either outboard just as challenging (7000 pic).

When is your interview...CX?

 

[Ex1900Driver]

Thanks for the information everyone! No I don't have an interview although I want to be ready just in case...

I think my rather limited experience considering the variety of people looking for work isn't going to be enough to get me in. Oh well. Doesn't hurt to try though.
GC

 

[Freddie Spencer]

Didn't know the -340 had engines, thought they were just hair-dryers.

 

[UpNDownGuy]

All things being equal, on a 4-engine jet it's the upwind, outboard engine.

 

[typhoonpilot]

Didn't know the -340 had engines, thought they were just hair-dryers.

That is true of the A340-300, the A340-500 and -600 actually look like they have real engines.

On to the actual question, if I could figure out how to post a link I would. The answer is on PPrune's technical forum from a thread titled, " Eng. Failure in a Crosswind " dated 13 November 2001. I'll summarise though:

The critical engine on a jet aircraft before Vr is the most outboard upwind engine due to the combined effect of assymetric thrust and weathervaning tendencies which make control on the runway difficult.

After Vr, or more accurately, once airborne, the critical engine is the most outboard downwind engine because of the combined effect of assymetric thrust and crosswind induced drift making extended centerline tracking more difficult.

In essence think about this as if you are taking off in a maximum permissable crosswind. You will need to use rudder to correct for weathervaning while on the runway. If you lost the upwind engine you now need just that much more rudder and may not have enough ( under the most extreme conditions ) to keep tracking the centerline. After liftoff we don't generally use rudder to keep tracking the centerline, but we are in a crab. If we lose the most downwind engine the airplane starts heading off the extended centerline. Use rudder to correct but even in the best case situation you will have deviated from the extended centerline and may continue drifting downwind. That becomes an issue if you leave the protected splay area that guarantees obstacle clearance while in the intial climb.


Hope that helps,


Typhoonpilot

 

[UpNDownGuy]

You're right...

Typhoon, your reply was much more accurate. I'm going to SVT tomorrow, and I'm in the "V1 cut" mindset, so I answered the question pre-V1. You're correct in that the critical engine changes after liftoff.

 

[FN FAL]

Wasn't there a critical injun in that commercial where he would be riding on a horse and see a landfill and a tear would come out his eye?

 

[FN FAL]

ooops, I'm sorry, I spoke out of place. That commercial had props in it.