Re: Stand-by instruments (was external inspection)

Date:         01 Feb 99 02:37:03 
From:         Seth Dillon <>
Organization: MindSpring Enterprises
References:   1 2 3 4
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Phil. G. Felton wrote:
> In article <airliners.1998.1894@ohare.Chicago.COM>,
> "" <> wrote:
> > >You may not be aware that the flight instruments in newer transports are
> > >electrically driven instruments; that is to say breaking the VSI or
> > >other pressure gauge might work in a light plane but will not recover
> > >the pitot-static system ...
> Well it wouldn't work in a pressurized plane anyway.  I'd be surprized
> if all the instruments on the modern planes were all electric.  Even on
> a light plane like a Cessna there are vacuum driven gyros and elect
> driven gyros to prevent total system dropout in case of a power failure.

They are usually powered off the emergency or hot battery bus.  The
battery must be capable of providing power to them for a min of 30