Re: DC-9 Flight Control

From: (Robert Dorsett)
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Date:         27 May 96 13:35:36 
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In article <airliners.1996.790@ohare.Chicago.COM> Steve Lacker <> writes:
> (RD Rick) wrote:
>I believe that fact is pointed out on the L-1011 page. IF the DC-10 that
>crashed in Iowa had had a 4th hydraulic system, the result might have been
>different... but that is pure speculation.

Sure.  If Douglas bunched three hydraulic systems in a fragmentation
plane, they could have just as easily done four.

>I've never heard much about hydraulic failures in a 727... how many systems
>does it have? Are they particularly well located? Or have I just not *heard*
>about problems?

The 727 has a manual reversion mode.  If hydraulic power is lost, there
are cables leading to control tabs on the ailerons and elevators, thus
aerodynamically moving the surfaces.  The controls just get rather heavy,
but the airplane has a get-on-the-ground capability.

I do not believe there has ever been a crash of a 727 due to a failure
of the flight controls.  The DC-10, on the other hand, has had three, and
the 747, 1.  The jury's still out on the 737.

Robert Dorsett                         Moderator, sci.aeronautics.simulation