What should you do if you experience a bad RPM drop while checking the magnetos?

Experiencing a bad RPM drop while checking the magnetos indicates that one of the magnetos may not be functioning properly, which could affect engine performance. When faced with this situation, increasing the RPM before rechecking the magnetos can help to stabilize the engine. A higher RPM can generally provide a more accurate reading by allowing the engine to run more smoothly and potentially clear issues that could cause a momentary drop.

It's also important to conduct the magneto check as part of the pre-flight procedure, as it identifies issues that could affect engine reliability during flight. After increasing the RPM and rechecking, if a significant drop is still present, it would warrant further investigation or maintenance on the engine. This approach ensures that the pilot is not prematurely shutting down the engine when there might be a simple operational solution.