Peter Clark wrote:
On Sat, 03 Nov 2007 00:05:02 GMT, wrote:

JGalban via AviationKB.com u32749@uwe wrote:
wrote:

begin speculation

Now it could be that after some serial number Cessna changed something
and the later models don't do that, and that would be OK as long as
I have something at least quasi offical to tell me that.

end speculation


Do you have something quasi official that tells you the VSI must wiggle
when alt static is checked on the ground? If so, then your question would
appear to be answered.

Every CFI I had while a student said to do it and every 172 I've ever
flown does it.

Specifically, at the beginning of the preflight walk around, after
ensuring the master is off, pull the alternate static control out, then
shove it in to make sure it is off; the VSI should wiggle.

That's while standing in the open door.

Same for every 172 and 182 I've flown. Isn't the action of actuating
the flaper in the selector box (or t or whatever it is that it's
moving) creating a little pressure wave which is what makes the
needles move?

That's what I was told and that if the systems working, the needle
bounces one way when opened and the other when closed.

--
Jim Pennino

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