Hmmm, the little red pins on the gauge that stuck out when stopped, and
retracted when we started, said "Vacuum Source". We didn't have vacuum pumps
on the Lear, but did on the C-340.

Al G.

"karl gruber" wrote in message
...
All the pressurized airplanes I've flown have "pressure" not vacuum
systems.

Karl
ATP, CFI, ETC
"Curator" N185KG


"Al" wrote in message
news
Hi Group.

I had a trip Friday in a 1977 C-337G(pressurized). On the taxi out I
noticed the suction gauge was pegged high. The AI erected ok, but the DG
required many updates on the way to the run-up area. Pulling on to the
runway, we corrected the DG again, by 30 degrees.
We flew VFR to Boise, and checked out the new Garmin 530 just
installed. Once we got on the ground, the avionics guy, we had along,
pulled the access panel in front of the left windshield. On the back of
the panel there is a component that looks like the back of an altimeter,
only about half as deep. It has a tube labeled "Air IN" and this one had
no hose attached. Nearby was a loose hose, which we reconnected. The
system worked fine, and we had no more problems.
Can anyone explain to me how opening a fault anywhere in vacuum system
can deliver a high vacuum? The gauge worked normally, low before start,
rising when the engine lit off. Two source indicators both showed a
working pump on each engine. I assume the component I was looking at was
a regulator, but I fail to see how the fault we found, could give us the
indication we saw.

Al G (There is another Al on the goup now )