On Sun, 08 Feb 2004 17:43:43 -0600, "O. Sami Saydjari"
wrote:

As I reading through my aircraft logs, I noticed several replacements of
the Directional Gyro and Turn Coordinator. The plane is a 1978 Piper
Turbo Arrow 3. Is is normal to need to replace these things every 4-5
years?

Does anyone keep statistics or even projections for the mean time
between failures on airplane parts? It sure would be useful to know.
One would think the manufacturers would publish such information.

At some point, the gyros will fail, so the question is whether the
plane is being used for IFR or not.

If so, it makes sense to periodically replace/overhaul the gyro
instruments, and to replace the vaccuum pump.

If it is used only for VFR, who cares. Let the instruments fail, then
replace them.

Gyro life varies widely. Gyros may last years, or only months
depending on a number of factors:
-Manufacturing/overhaul quality
-Time on shelf before install (it is bad for gyros to sit idle)
-Temperature extremes. I've heard cold starts are hard on gyros.

-Nathan