What is the function of a magneto in a piston aircraft engine?

What is the function of a magneto in a piston aircraft engine?

• A. To provide a reliable ignition spark to the spark plugs independent of the aircraft's electrical system
• B. It generates all the electric power for the aircraft
• C. It regulates fuel flow to the engine
• D. It controls engine timing via the alternator

Answer: (B)

A magneto is a self-contained ignition system that uses rotating magnets and windings to generate a high-voltage spark and deliver it to the spark plugs at the correct moment, all independent of the aircraft’s electrical system. Because it runs from the engine’s rotation, it provides a reliable spark even if the battery or alternator fails, which is crucial for engine starting and steady operation. It does not generate electrical power for the aircraft—that role belongs to the generator or alternator. It also doesn’t regulate fuel flow to the engine—that’s handled by the fuel metering system. And the ignition timing isn’t controlled by the alternator; timing is set by the magneto’s internal advance mechanism and its mechanical timing relative to the piston position.

A magneto is a self-contained ignition system that uses rotating magnets and windings to generate a high-voltage spark and deliver it to the spark plugs at the correct moment, all independent of the aircraft’s electrical system. Because it runs from the engine’s rotation, it provides a reliable spark even if the battery or alternator fails, which is crucial for engine starting and steady operation. It does not generate electrical power for the aircraft—that role belongs to the generator or alternator. It also doesn’t regulate fuel flow to the engine—that’s handled by the fuel metering system. And the ignition timing isn’t controlled by the alternator; timing is set by the magneto’s internal advance mechanism and its mechanical timing relative to the piston position.