Re: Airbus Safety

Date:         26 Oct 98 02:59:32 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
References:   1 2 3 4 5
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>> The vulnerability of the DC-10's hydraulic system
>> still hasn't been fully acknowledged, though the cutoff valve installed
>> in the DC-10 (and MD-11) after UA 232 crashed in Sioux City helps a bit.

>Could you develop a l'ill bit more. What circuits were isolated in which
>manner?

An electrically-actuated cutoff valve was added to one of the three
hydraulic systems in the aft cabin area.  This valve closes if a drop
in hydraulic pressure is detected, isolating the presumably damaged
portion of the system.  I don't have all my references here in the air
so I can't say which one of the systems it was, but I think the DC-10
has electric pumps so even if all three hydraulic systems were
compromised and the one with the cutoff was compromised on the same
side of the cutoff as the engine, it would still be possible to power
the remaining, isolated portion of that system, affording some degree
of control.

Obviously it would be better to have a design which did not route the
hydraulic lines such that a single failure in a critical area could
compromise all available systems.

>Has the 11 the same change as the 10, or are there any
>additional changes made?

The same patch was applied to the MD-11, which as far as I know has
essentiall the same hydraulic systems as the DC-10.  (There probably
are some differences in actuator sizes due to larger elevators and the
like, but nothing that would constitute a significant redesign.)

--
Karl Swartz	|Home	kls@chicago.com		http://www.chicago.com/~kls/
		|Work	kls@netapp.com		http://www.netapp.com/
"The average dog is a nicer person than the average person."
  - Andrew A. Rooney