every time i preflight any aircraft i have the keys in my hand and know the master is OFF, especially when turning the prop to check the belt.
Well, that's a good thing, but remember a broken earth wire on anything with traditional mags means the mag will be live, keys or no keys. I have had an MS 893 180 hp engine start and run in -10 deg C with the mixture lean and the keys in my pocket when pulling through prior to startup. It didn't run for long, but it would have made a nasty mess of my hand if I didn't routinely treat all props as potentially live.
