Re: DC-10-30 (and -10's ??) #2 Thrust rever

From:         tturton@samson.TX.HAC.COM (Tom Turton)
Organization: Hughes Training Incorporated, WCO
Date:         10 Feb 96 15:12:16 
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In article 170@ohare.Chicago.COM, peter neville gurnell <pgurnell@direct.ca> () writes:
>
> According to the DC-10-30 F.C.O.M. Vol.III p.17-10-03 (This should be
> in my instantly retrivable data file, but it isn't) to quote para. 3
> of the description of the T/R system, "An in-flight reverse thrust interlock
> prevents deployment of the thrust reversers unless the landing gear is
> down.  After landing gear is down, initial reverser lever movement un-
> locks the respective system, starts reverser deployment which is indicated
> by the REVERSER UNLOCK (easily visible) and REVERSER VALVE OPEN lights
> (situated where no-one is looking) coming on.  The reverser system, when fully
> deployed, will release the reverser lever interlocks for engine 1 and
> 3. (Here is the important part) For engine 2 reverser lever interlock
> release, full reverser deployment and ***NOSE GEAR*** ground shift
> (gear squat switch) mechanism actuation is required.
>
> ie:  You can pull 1 & 3 into reverse as soon as the mains are on but
> you have to wait for the nosewheel to touch to get #2 out.

 Any idea if this nose gear weight on wheel switch is something new or if
it has always been on DC-10's?  I'm curious because back around the very
early 1980's, I was working at Douglas in the aero stability and control
section as a relatively new engineer.  We had a question at that time from
an airline customer who wanted to know the best technique for landing with
different landing gear failures (i.e. nose gear up/mains down , one main
up/other main and nose down).

 I was tasked with doing the analysis work, but at that time was unaware
of any lockout, and was not told of any by my supervisor.  Therefore, I
took into account the thrust reverser effect of #2 in trying to hold the
nose up(with nose gear failed) as long as reasonable  (have to let it down
before airspeed drops too low and you lose elevator effectiveness resulting
in the nose coming down less than gracefully).  If this switch WAS in
existance at that time, it points out one danger of compartmentalizing
groups in large companies (right hand doesn't know what left hand is
doing!).  Usually, our data books included notes of under what conditions
something like a thrust reverser would not be available.

 --Tom T.