PPRuNe Forums - View Single Post - Cross controls on a 747 or other big jet/turbo prop
Old 17th Jan 2006, 10:50
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FlightDetent

Only half a speed-brake
 
Join Date: Apr 2003
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Re: Cross controls on a 747 or other big jet/turbo prop

For swept wing aircraft it is not an approved manouevre. And, anyhow, it is a life saving manouevre (cannot spell it, sorry) for a single but for twins and more you are not supposed to need it because you use the rudder to compensate for the failed engine and keep flying. If attempted, due to much larger rudder authority (constructed to compensate the yawing moment with failed engine) I can imagine the resulting attitude would be much wierder than with full rudder on the aircraft I flew for my PPL. Draw a diagram of a relative wind over a swept wing A/C under cross controlled conditions, think of the leeward side of the fuselage and high lift devices shielded also by the lowered upwind wing and I really think it may depart controlled flight. So no-no. Even if it wouldn't, if the cricitcal engine for that condition failed you would have the sky on your tail. It is all exactly the same. On SE one has a safe emergency site chosen all the time. On ME, you make sure to steer well clear of all situations that you cannot recover from with a failed engine.

Yours,
FD
(the un-real)
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