In article , Nathan Young
writes:

Many (OK, some) ignition switches have an AD with a recurring inspection
requirement that requires testing the OFF position every 100 hours. AD
76-07-12

Yep, and you can tell when the mechanic is testing the Bendix switch
by the backfires outside his hangar.

Question. If you let the engine come to a stop and then restarted it, would
that be better? Would it possibly cause a manifold fire? It would prevent the
backfire.

Chuck