What is the maximum RPM drop allowed for each magneto during a check?

The maximum RPM drop allowed for each magneto during a check is 125 RPM. Performing a magneto check is crucial to ensure proper engine operation and functionality of the ignition system. During this check, the pilot turns off one magneto at a time to observe the engine's RPM drop.

The 125 RPM threshold is based on standard guidelines for many general aviation aircraft and considers the maximum allowable drop that ensures reliability and proper functioning of the ignition system. If the drop exceeds this value, it may indicate potential issues such as a defective magneto, faulty spark plugs, or wiring problems.

This procedure is important for safety as it helps detect problems before takeoff, ensuring that both ignition systems are functioning properly to mitigate the risk of engine failure in flight. Thus, the choice of 125 RPM effectively balances reliability with operational standards.