Re: Are Two Engine 757 & 767 Jets Dangerous?

Date:         13 Dec 96 04:26:01 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
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>In both El Al and China Air cases, two engines on the same side separated
>from the wing, not just lost power. United 811 lost power but the engines
>still hang on. A pilot friend told me, El Al was marginally recoverable
>from simulator study in the investigation, had the pilots knew the engines
>were gone.

True, but how much did physical separation of the engines damage the
ability of the plane to stay airborne in the first two cases?  The
wing was damaged -- debris from the separation of #3 is what caused
#4 to depart the airframe -- but was there substantial aerodynamic
damage to the wing surfaces?

In the case of United 811, while the engines remained, their presence
might have made matters worse since a large, windmilling turbofan adds
significant drag.  There was damage to the right wing and horizontal
stablizer, plus the vertical stabilizer, though I suspect this damage
was not as severe as in the El Al and China Air crashes.

>How heavy was UA 811?

>From the NTSB report:

    The maximum calculated takeoff weight for flight 811 was 706,000
    pounds.  The flight plan data showed an actual takeoff weight of
    697,000 pounds.

The aircraft's MGTOW was 734,000 lbs, so takeoff was at about 95% of
the maximum.  However, the accident occured as the aircraft was
climbing between FL 220 and FL 230, by which time considerable fuel
weight would have been burned off.

Karl Swartz	|Home
Moderator of sci.aeronautics.airliners -- Unix/network work pays the bills