FAA Powerplant Written Practice Test

What position should the ignition switch be in when timing a magneto to the engine?

1. Left

2. Right

3. Both

4. Off

The correct answer is: Both

When timing a magneto to the engine, the ignition switch should be in the "Both" position. This is crucial because the magneto is a self-contained ignition system that generates its own electrical current. By placing the ignition switch in the "Both" position, both magnetos are activated. This ensures that the timing is set accurately for both systems simultaneously, which is essential for proper engine operation and performance. Timing the magneto involves ensuring that the spark occurs at the correct point in the engine's cycle for optimal ignition of the air-fuel mixture. If only one magneto were to be timed, it would not account for the firing of the other, leading to potential imbalances and inefficiencies in engine performance. Having the switch in "Both" guarantees that the timing is synchronized across both ignition systems, allowing for uniform firing and smoother engine operation.