On Wed, 27 Oct 2004 09:46:07 -0400, Dave Butler
wrote:

"I discussed mag drop problem with the IA: he complied with the mag AD during
the annual stating that he also timed the mag and set the points and would
expect very minimal RPM drop. He also tested the P lead and found it normal. The
only confirmation is turning the key off and the engine should stop, I guess
that was done. Looks like a non issue."

"Minimal" drop is different than "tachometer needle doesn't move at
all".

There are other failure modes that can cause this problem.

If the mags are properly timed, and if the ignition switch is shorting the
P lead, RPM should drop. You can have a faulty switch that is failing to
short the P lead(s).

Do you have an EGT gauge for each cylinder? If you do, then in single mag
operation, all EGT's should rise.

Don't hand turn the prop until this is corrected.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)