"O. Sami Saydjari" wrote in
:

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?

Some folks do replace them on a regular basis... The idea being to
replace them before wear causes them to fail at a more inconvenient
time. Does it help? I don't think anyone knows. Probably, when you
consider the incidence of infant mortality that these devices see,
probably not. While they all will EVENTUALLY wear out (whether that
means 5 years or 50 years), more probably fail in the first couple of
months after installation than anything else.

Some things CAN cause premature wear and failu

o Smoking in the aircraft
o High-G maneuvers
o Long idle periods (and this includes sitting on the shelf in some
avionics shop).

Fortunately, they usually (but not always) give some warning days or
even months before they fail:

o Wind down quicker than usual
o More noise (after engine shutdown) than normal
o Slow to erect, or tends not to return to neutral when the plane does

Most of us, I think, wait and repair them when they *start* showing
signs of needing it. And BTW, in my opinion, a quality overhaul should
be just as good as a factory new in terms of reliability. A quality
overhaul replaces all the wear items.

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James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
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