USAir 427 Crash

From:         garwald@athena.mit.edu (Gary L Waldman)
Organization: Massachusetts Institute of Technology
Date:         19 Sep 94 01:28:38 
Followups:    1
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I am a little confused with all the speculation centering around the
in-flight deployment of the right engine thrust reverser as the cause
of the crash.  It was my impression that in a cascade reverser, the
hydraulic actuators move the nacelle sleeve to the rear, and that
during this movement blocker doors linked to the sleeve drop into the
bypass flow.  If this is the case, how is it possible that the sleeve
would have moved at all if only some of the actuators had extended?
Unless the force of the opening actuators (i've read any where from
1/3 out of 4/6) was sufficient to damage the "closed" ones, it seems
like the reverser should have remained stowed.

Another confusing thing is the simulated reenactments of the accident
being showed on the networks.  The graphics show a target reverser
similar to that found on the CFM56 on an A340.  It seems possible that
activation of some of the actuators could cause a partial thrust
reverser deployment.  However, this is not the thrust reversing system
on the 737 to my knowledge.