Re: DC-9 Flight Control

From: (RD Rick)
Organization: Netcom
Date:         25 May 96 14:40:18 
References:   1 2
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In <airliners.1996.779@ohare.Chicago.COM> gsmoff@Mcs.Net (Gary S.
Moffitt) writes:

>...inputs actuate cables which actuate control tabs, the flight controls
>respond opposite to the tab movements.  The control tab flies the control
>surface.  This is one aircraft whose flight control forces do not change
>with loss of hydraulic power.  There are of couse exceptions.

>On the MD80s (I am not ssure about older DC9s)  there is hydraulic assist
>to the elevator in the nose down direction only to assist in stall
>recovery and...

That is actually a stick pusher that is triggered by a stall.  It is
required in the MD-80, not the DC-9.  The first flight test MD-80 went
into an uncontrollable mode something like a falling leaf maneuver when
they were doing deep stalls.  They had to deploy the drag chute to

The stick pusher slams the stick hard forward in a stall.

>...Neither of these hydraulic assists is necessary in normal flight.

I'll bet they can't dispatch with the stick pusher inop.