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

And since I've never seen a 172 where the VSI didn't wiggle when I
turned the alternate on and off, I would want to know why it didn't
before I flew it.


On the ground, there doesn't always have to be a significant difference
between cabin air pressure and outside pressure. I'd recommend trying the
check in flight. If you don't see any difference there, then you've got a
leak in the static system.

Correct me if I'm wrong here, but isn't a preflight supposed to be done
before you take off?

And one more time...

Since I've never seen a 172 where the VSI didn't wiggle when I turned
the alternate on and off on the ground, I would want to know why it didn't
before I flew it.

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

--
Jim Pennino

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