It's not switching off the mags that's the problem, it's switching them off and then on again!
Apart from anything else, that's begging for a massive backfire (explosion in the exhaust) as the unburned fuel/air mixture is ignited by the next blast of hot exhaust gas as the engine re-lights. Try it in your car / on your motorbike some time. Switch off the ignition when driving / riding along, then on again. BANG! Damage to your exhaust baffles at best! (Probably won't work with modern electronic fuel injection as the injectors will shut off when the ignition is switched off. It's carburated and probably the simple non-electronic injection of aero engines where this will happen - Lycoming, Continental, Rotax, de Havilland etc).
And I ask again, WHY would you do it in any aeroplane anyway? What is the reasoning? Surely we don't have pilots doing daft things they haven't thought though?
Last edited by Shaggy Sheep Driver; 20th Nov 2014 at 18:10.