Critical engine question

J

jackbo

For turbofan powered airplanes, what constitutes the critical engine? I think it is the upwind one as they have no real difference in thrust. Is that correct?

I'm think of the differences between centerline thrust like a DC-9 or CRJ, then the A320 or 757, and then the 747 with more than 2 engines.

Just curious on how they determine critical for type rides with "critical engine failure."

Thanks to all.
 

typhoonpilot

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The critical engine in a jet aircraft at or below Vr is the most outboard upwind engine because of the combined effect of assymetric thrust and weathervaning making control of the aircraft on the runway more difficult. After Vr ( once airborne ) the critical engine is the most outboard downwind engine because of the combined effects of assymetric thrust and crosswind induced drift making extended centerline tracking difficult.


TP
 

320AV8R

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The critical engine is the one you need most when it's not running..:rolleyes:
 
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1stCivDiv

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Wrong thread..

Shouldn't this thread have started under Training vs. Major Interview board? Just a thought...
 
C

Chuck Yogourt

If it is an engine that is meant to keep the bird flying, it is critical. Doesn't really matter where it is on the frame. Just a thought from an old buzzard.
 

donger

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Chuck Yogourt said:
If it is an engine that is meant to keep the bird flying, it is critical. Doesn't really matter where it is on the frame. Just a thought from an old buzzard.
Right place if s/he is anticipating answering this question in an interview
 
J

jackbo

1stCivDiv said:
Shouldn't this thread have started under Training vs. Major Interview board? Just a thought...
I posted it here to ask people who fly the equipment so I will understand the subject better and help me if it comes up in an interview. Sorry if you are too narrow minded to realize that.



typhoonpilot said:
The critical engine in a jet aircraft at or below Vr is the most outboard upwind engine because of the combined effect of assymetric thrust and weathervaning making control of the aircraft on the runway more difficult. After Vr ( once airborne ) the critical engine is the most outboard downwind engine because of the combined effects of assymetric thrust and crosswind induced drift making extended centerline tracking difficult.
Thank you for your answer. I appreciate it.
 

1stCivDiv

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Hey bro, you could lump 80% of the threads on this board in here using your rationale. I was just making a suggestion, no need to start tossing stones... :cool:
 

TIS

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typhoonpilot said:
The critical engine in a jet aircraft at or below Vr is the most outboard upwind engine because of the combined effect of assymetric thrust and weathervaning making control of the aircraft on the runway more difficult.
That depends on the jet. A Hawker 700 weathervanes AWAY from the wind while the 800 weathervanes INTO the wind. It has to do with the fact that on the 800 the nosegear doors are retracted, eliminating a point of leverage on the nose, and the fact that its tail is 18% larger in terms of surface area, adding leverage area to the tail. Go figure, but it's true!

A more correct statement is to follow the definition - the engine whose failure most adversely affects control. That wll vary from airplane to airplane and also by circumsatance.

TIS
 
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