Peter Duniho wrote:

"G.R. Patterson III" wrote in message
...
If the engine won't stop with the mixture cut off, it won't stop with
the
mags grounded.

Not necessarily true.

What makes you say that? What motivating force are the magnetos providing
that keep the engine windmilling with just the mixture cut off, and which is
absent when you ground the mags?

No motivating force, however the mag switch in most planes works by grounding
(short circuiting) the magnetos, not opening a circuit. A grounded magneto has
a much greater load than a magneto happily humming around producing a spark.