On 2007-05-15 05:59:05 -0700, "Doug Palmer" said:

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?

An engine can be made to run backwards. Model airplane engines do it
all the time, usually as a result of mixture that is too rich. Granted,
real airplane engines are different and have more safety systems, but I
could not say that it is impossible, especially given the enormous
variety in types of engines, magnetos, starters, and fuel systems you
see on airplanes.

I have never heard of an accident involving an engine running backward.
I haven't found one, either. You can be the first! :-)
--
Waddling Eagle
World Famous Flight Instructor