What is pre-ignition in an aircraft engine?

Pre-ignition is defined as the premature burning of the air/fuel mixture in an aircraft engine, which occurs before the spark plug has its intended ignition event. This can happen when a localized hot spot within the combustion chamber ignites the fuel mixture prior to the normal ignition timing. As a result, the mixture starts to burn at an incorrect phase in the engine cycle, which can lead to a series of negative effects such as loss of power, engine knocking, and potential engine damage.

In essence, pre-ignition disrupts the designed efficiency of the engine's operation, as it alters the timing of the combustion event. Understanding this concept is crucial for pilots, as it emphasizes the importance of engine management and maintenance to prevent conditions that could lead to such malfunctions.