First the AI, then the DG, then...?

Jay Honeck wrote:
Again, there is no logic to this -- but what else is new?
snip

Jay,

I joined this thread a bit late...after my local server flushed the
original message, but I believe your original question was "what could
cause premature gyro failure"?

In my experience, two things:

1) If it fails within a few hours of being new, that's typically because
of manufacturing, long-term storage, or shipping damage -- all of which
can cause the bearings to "flat spot". Apparently the bearings are
*that* soft.

2) If it fails after a few hundred (as opposed to a few thousand) hours,
improper mounting or excessive vibration is usually the culprit. The
problem is most severe in aircraft whose panels aren't shock mounted AND
when those same aircraft don't have their props properly (dynamically)
balanced.

Our gyros were so damn expensive that when we had our panel apart last
time I had the shop replace the mounts. Not only does the panel NOT sag
like it used to, but as we encounter various (normal) harmonics in our
particular engine/prop combination, the shock-mounted instruments simply
don't shake like some of the other fixed mounted units (fuel gauges, etc).

I forget if your airplane has a fixed or shock-mounted panel, but if
it's shock mounted, I'd recommend replacing the shock mounts and getting
the prop redressed / painted, then dynamically balanced for good measure.

HTH,

-Doug

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Doug Vetter, CFIMEIA

http://www.dvcfi.com
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