[nomocom]

Back in March, when the left mag was 172 hours post 500 hour inspection, an odd thing was observed during the timing check with the standard buzz box. The left mag would show high resistance (the light and buzzer would weakly engage) as we were turning the prop well before the correct 20 before top dead center. Then, at some point close to 20 btdc we’d get the obvious and usual change- a strong light and buzzer. The loose hold downs perhaps not sustaining a bond? We added a ground jumper, no change. At the time, our mag shop reported that Tim Davis, who ran the continental Mag division, said that this is a known phenomenon, an interaction between the coil and the buzz box. Not to worry.

This last month, on the way back from Osh, the mag decreased in performance. Single mag operation had engine roughness and a 200 rpm drop. The airplane sits in Nebraska and both mags are back in Montana for service.

I can’t be the only one. thoughts?

Longtime donor (autopay bank checks apparently to much work to track)