Shutting off a mag while the engine is running will not cause damage to the magneto. What do you think you are doing when yo do a mag check? Also some checklist for engines that have an idle cut off style mixture include momentarily shutting off the mags to check the ignition switch. There is even an AD for some switches that require this. Shutting down engines like this has been common practice since the 1930's, and probably longer, until the idle cut off type mixtures came along.
A slight rise in RPM right before the engine dies either with the fuel shut off or an idle cut off mixture indicates a proper adjustment of the idle mixture. The procedure is included in many aircraft maintenance manuals for adjusting the carburetor. To big of a rise indicates an overly rich idle mixture.
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If you have a stromberg you’re not going to starve the engine for fuel. The mechanic should research this vs telling you something is wrong. We have two ways to shut the engine off. One is to turn off the mags and the other to shut off the fuel and let the engine run out. My understanding is that if you get a slight RPM increase just before it dies you have a tight induction system.Leave a comment:
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proper way to shut down engine
When we did the mags, on my plane, I was told that turning off the mags at idle was bad for the mags, on all other aircraft I've flown you pulled the mixture knob to lean and starved the engine till it quit.
this didn't work on mine, and according to the carb shop it never will.
another A&P says the carb should be set to kill the engine when pulled to idle or pulled fully back, which doesn't make sense, I personally like the stop and the engine just purrs on at 400 rpms. I would be concerned to pull the throttle too far back and end up with a deadstick landing
So what is it, I would like to know I'm on the final repairs and should be soloed by christmas.
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