"Ron Natalie" wrote in message ...
"John Galban" wrote in message om...

Lack of a mag drop would indicate that the P-lead to the mag switch
is not grounding properly.

Or that the magnetos are mistimed..

I've never heard of that one. The P-lead problem seems a lot more
common.

What sort of timing configuration would result in no mag drop when
going from "both" to one mag? I'd always assumed (perhaps
incorrectly) that running on 1 set of plugs would always result in
less than optimum combustion, with a coincidental drop in rpm during
run up.

This means the mag is always hot. I would
not only park the plane, but I'd attach a note to the prop, warning
others that the prop could be hot.

The prop could be hot even if both mags have a mag drop. Switches
have been known to stay hot in OFF when they worked normally in
L & R.

Also true. There's an AD for many planes dealing with that problem.
Of course, the point of my post was that the lack of a mag drop could
be an indicator of a potentially dangerous situation.

John Galban=====N4BQ (PA28-180)