3° every 15 minutes is what I remember from training. That's what some may
consider ultimately manageable in the cockpit under IFR/IMC workload
conditions (YMMV), and is an 'human factors' limitation.
This is not to say that this is the acceptable tolerance for an instrument
out of the factory. They should be much, much better than that. The
avionics shop can tell from the gyro overhaul manual.

HTH

javier

"Jay Moreland" wrote in message
...
I need to find out if there is an official maximum amount of precession
for a Directional Gyro. My aircraft precesses 10 degrees in 10 minutes
during mostly straight and level flight with only a few shallow banks.

One avionics tech told me that it depends on the gyro manufacturer as to
what is acceptable. He also told me that an out of the box unit tested
on the table should not precess more than ONE degree in four minutes.

Jay Moreland