First Time in IMC and vacuum problem

Jose wrote:
[big snip]
Thanks for the full explanation. I had forgotten how the instrument
was engineered (the 30 degree cant) and don't think I ever realized
how important the damping was. How do you propose to check it on
preflight (and to what tolerance?) I make gentle turns during taxi to
see how it responds, but I obviously can't give it a roll hit very easily.

Watching the TC as you make taxi turns is a pretty good preflight
check. It confirms that the gyro has power, is spinning, bearings
haven't siezed, etc. It's hard to imagine any failure which would
cause it to react properly to yaw inputs (i.e. taxi turns) but not to
roll.