Pitot/Static/Transponder Problem

On Sun, 05 Aug 2007 10:27:25 -0700, quietguy wrote:

Building to the plans doesn't guarantee accurate static pressure
readings; the system is quite sensitive to tiny plane-to-plane
variations. And the official calibration check with the airplane
stationary wouldn't catch an in-flight static-pressure error.

Yes, but: If the encoder and the altimeter are using the same static source,
both should be in error the same amount. Kyle's problem is a split indication;
the encoder is sensing a different altitude than the altimeter.

This tends to argue that the problem is a leak related to the altimeter itself,
not in the static system. Perhaps the altimeter has a leak that only manifests
itself when it's being vibrated (i.e., the engine running).

My Microair transponder gives me a readout of the altitude that's being sent to
ATC. I can set the A/C altimeter to 29.92 and compare. That's how I discovered
my encoder had gone south two months back; the altitude readout wasn't matching
the altimeter.

Ron Wanttaja