Today's Pop Quiz

[Jrskygod]

For all the experts out there -

Yesterday I went to go flying, pulled the plane out and had starting problems. I have a O320 D1A, 300 hours SFN, Slick mags. I use two toggle switches on the panel to turn off the mags. This engine always starts right up hot or cold.

So I go to start it - always start on left mag - and it cranked just fine but would not start. On the third try it finally caught and ran. Turned on right mag and all was well. Warmed it up did mag check - perfect!! I thought I might have flooded it or something so off I went.

Returned to the airport later, taxied in and did another mag check - perfect. Awhile later decided to go out again. Same routine - would not start on left mag - this time on the second attempt I flipped on the right mag switch after the engine was cranking and she started right up. Perfect mag check again even an idle mag check was good.

Ok now I'm thinking impulse coupler must be stuck or broken. So I pull the mag to have a look. Impulse coupler catches as it should and mag is hot - don't ask how I know it is hot - I grounded the mag and tried the coupler several more times and all works like it should.

Before I send this mag in for repair can anybody give me a clue whats going on here? One thought I had was maybe the skytec was spinning it up fast enough that the impulse was throwing out and not catching - but I never had that problem before.

[Mel]

Several years ago I had the same situation. This went on for almost a year until the left mag finally failed a LOE. Mags tend to give warnings but many times we don't listen.
BTW, switching on the non-impulse mag during the starting sequence can cause a kick-back, breaking the starter shaft and/or stripping the flywheel teeth.

I have since installed another impulse mag so now I can start on "both".