The King Air and 1900's don't use vacuum pump, the weak link
in most GA airplanes. They use P3 air to power a venturi to
get both pressure and vacuum.




"Beavis" wrote in message
...
| In article ,
| Scott Skylane wrote:
|
| Here's a cockpit shot of one of the 1900s he flew:
| http://www.airliners.net/open.file/0585758/L/
|
| On a completely unrelated note, I see there is a vacuum
suction gage on
| the instrument panel. What is this for? Apparently all
of the "gyro"
| instruments are electronic.
|
| Correct. There are four remote gyroscopes (two attitude
gyros, two
| heading gyros), all powered by 115-Volt AC power. The
really nice thing
| about that kind of system is that if one gyro dies, you
can route the
| signal from the working gyro to both screens, so each
pilot still has a
| full set of instruments. Pretty neat.
|
| There's also a standby attitude indicator, which has its
own internal
| battery backup. You can see it above and to the left of
the GPS in the
| picture linked above.
|
| Is this strictly for the de-ice boots?
|
| Deice boots, and the operation of the pressurization's
outflow valve.
| (Suction pulls it open; springs push it closed.) That
works fairly well
| for a plane that size; larger planes, like the 737, have
an
| electrically-operated outflow valve.