Plain English Meaning

A small door on the engine cover that the pilot can open or close to let more or less air flow over the engine. Open it when the engine needs more cooling, close it when it doesn't.

Full Definition

A movable, hinged panel on the engine cowling that the pilot opens or closes to control the volume of cooling air flowing across the engine cylinders. Opening the cowl flaps increases airflow and cooling at the cost of additional drag; closing them reduces airflow to keep the engine warm during low-power, high-airspeed, or cold-weather operations.

Context Anchor

You may see cowl flaps in engine temperature , abnormal engine , and for airplanes equipped with .