During a magneto check before takeoff, what does it indicate if the right magneto runs extremely rough?

When the right magneto runs extremely rough during a magneto check before takeoff, it indicates a potential failure of one or more cylinders. This rough operation can be caused by various issues, such as a faulty spark plug, an ignition lead problem, or a malfunctioning ignition coil associated with the right magneto. It signifies that the engine is not firing correctly on that side, which could lead to decreased performance, increased fuel consumption, and potential engine failure if not addressed.

The rough operation of the engine during the right magneto check serves as a warning that further inspection and troubleshooting are necessary to identify and rectify the underlying issue, ensuring the engine can operate smoothly and efficiently. Proper functioning of both magnetos is crucial for engine reliability and safety during flight operations.