Originally Posted by
Big Pistons Forever
Would you fly the airplane if only one magneto was working ?
Probably not, because the failure of the remaining ignition circuit would certainly result in an immediate loss of engine power.
On a related note however there are quite many simple aircraft in low-cost category (ultralights, trikes), which fly with non-certified engines, or even with automotive engines having a single ignition circuit. Naturally, as a mitigation, they have to fly overterrain with emergency landing options avaiable at all times, this is part of the POH, placarded etc.