Doug Palmer wrote:
Several pilots found themselves in a debate at our field yesterday. The
issue is weather it is safer to move the propeller on a (parked) aircraft in
the direction of usual engine rotation, or opposite usual rotation. This is
assuming that the propeller needs to move for some reason.

The reasonings ranged from "you should not turn an engine backwards" to
"turning the engine backwards disarms the impulse coupling", to several
issues in between.

Any thoughts from the groups collective wisdom?

Never, ever turn a Rotax 912/914 backwards. It
will break the suction in the oil line. To regain
oil pressure you have to undo oil lines and refill
them.