Dave Butler wrote:
Matt Young wrote:

Ok, a curious question just popped in my mind. Say that one was
flying IFR in a piston single, maybe a 172 or 182. While enroute,
either in actual or above a cloud layer, the engine fails. Will the
windmilling prop keep the vacuum pump going enough to make the AI and
DG usuable during descent through the clouds, or will the gyros keep
spinning fast enough long enough to make the vacuum pump irrelevant?


No and no.

Personal experience, credible sources, or just a guess?


All the best,


David