From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
Date:         08 Oct 96 13:00:06 
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>All ETOPS airplanes and some others have RATs.

In the "some others" category, the A340 is one example.  I assume the
rationalle is to power the FBW system in the event of fuel starvation
(a la the Gimli Glider) or some other cause of a total engine failure.
While it probably was easy to include (carried over from the A330), it
adds weight.

I'm not sure I agree with the "all ETOPS ... have RATs" comment,
however.  I thought there only needed to be some additional source of
power that could be started in-flight.  Boeing elected to implement
this using a RAT on the 757 and 767 (probably the 777, too, though I
don't know for sure), but on the A300 and A310, Airbus did it be
certifying the APU for in-flight start, at altitude and after a long
cold soak.  I thought that having that capability obviated the need
for a RAT on those aircraft, though the next message says that the
A300 does indeed have a RAT.  Can anyone here clarify what exactly
the requirement is?

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