blaplante
Well Known Member
I have a Lightspeed II installed on an o-320-h2ad, and the second ignition is a conventional Bendix mag. Engine & mag have 240 hours. Yesterday in flight I had the engine start making snap / pop / bang noises. At first a few random ones and then quickly frequent. This was at 7500', quick check in the air didn't seem to isolate to one mag or the other. Reduced power, fuel pump on, it continued. Anyhow, long story short, I diverted, landed, and with help from A&P diagnosed this as fouled plugs... on the Bendix Mag. One plug had a couple large lead deposits in it. All of the Bendix plugs needed cleaning. Cleaned plugs, reinstalled, and problem solved. Flew 2 hours and was fine.
So I'm puzzled... #1 I'd expect the LSE to fire the cylinder successfully no matter how bad the plug on the magneto is fouled up. #2 On a misfire I don't expect to be hearing pop / snap / and bang. I'd expect quiet for a moment.
The only thoughts I have are that this could be somehow firing in the exhaust pipe (Vetterman crossover) perhaps aggravated by the way wasted spark works? Or maybe the big lead deposit was causing a hot spot?
Any insight is much appreciated as it will help me diagnose any sort of odd noises in the future!
So I'm puzzled... #1 I'd expect the LSE to fire the cylinder successfully no matter how bad the plug on the magneto is fouled up. #2 On a misfire I don't expect to be hearing pop / snap / and bang. I'd expect quiet for a moment.
The only thoughts I have are that this could be somehow firing in the exhaust pipe (Vetterman crossover) perhaps aggravated by the way wasted spark works? Or maybe the big lead deposit was causing a hot spot?
Any insight is much appreciated as it will help me diagnose any sort of odd noises in the future!