Re: A 777 with four engines.

Date:         29 Jul 98 00:29:29 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
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>> Does anybody know of a case where a plane was controlled successfully using
>> asymmetric control of the engines?
>
>AA DC-10 over Windsor, Ontario, in the early 1980s? The basic problem was
>similar to that of the THY DC-10 just a little later: ie loss of the aft
>cargo door and damage to the cabin floor and, as a consequence, to the
>controls. The pilots used asymmetric thrust in getting the plane down (at
>Detroit, if memory serves) without further damage. But I don't recall how
>severe the damage was, and whether there was in fact total loss of
>hydraulics. Anyone?

I don't have the full NTSB report, but from excerpts and some other
accounts, it appears that they still had full hydraulics.  The rudder
controls were jammed, however, and two of the four elevator control
cables were severed with the other two being partly jammed, allowing
only sluggish pitch control.  They still had full ailerons and flaps.
Roughly half left aileron was required to counteract the right rudder
and they used the engines both differentially for directional control
and together to assist the crippled elevator controls so as to maintain
a reasonable rate of descent.  The availability of the flaps allowed
them to fly the approach at a much more reasonable speed than UA 232
at Sioux City.

In summary, I'd say Windsor doesn't make a convincing argument for
control using only asymmetric engine thrust.

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Karl Swartz	|Home	kls@chicago.com
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