Re: Squat interlock

Date:         25 Jun 99 01:32:52 
From: (PS2727)
Organization: AOL
References:   1
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Airplanes with retractable gear have squat switches to avoid retraction
when on the ground. If the handle is raised on the ground and the switch
is in the "ground" mode, the gear will not retract.

On larger planes the squat switch is used for many things. One example
that comes to mind is that window and pitot heaters (and water drain
masts) operate on low power when on the ground and switch to high power
inflight. Each design is different but some systems need to know when
the plane is on the ground.  When spoilers are armed for automatic
deployment they can be triggered by wheel spin-up or the squat switch,
or thrust reversal.