How many magnetos per engine are typically installed in light aircraft?

• A. One
• B. Three
• C. Two
• D. Four

Answer: (C)

Redundancy in the ignition system is the key idea here. In light aircraft, engines are typically equipped with two magnetos, each driven by the crankshaft. Each magneto supplies a spark to all cylinders, and in a dual-ignition setup there are two spark plugs per cylinder—one spark plug fed by each magneto—so you get two independent ignition events each cycle. This means the engine can continue running if one magneto fails, though with a bit less power and roughness. Having only one magneto would remove that backup capability, and having more than two is not common in standard light aircraft.