Cowl flaps are shutter‑like devices arranged around certain air‑cooled engine cowlings that may be opened or closed to regulate the flow of air around the engine. Which term describes these devices?

• A. Intake ducts
• B. Exhaust shrouds
• C. Cooling fins
• D. Cowl flaps

Answer: (D)

In air-cooled engines, controlling how much cooling air flows around the cylinders is essential for keeping temperatures in the safe range. Cowl flaps are adjustable, shutter-like openings around the engine cowling that you can open or close to regulate that airflow. When more cooling is needed—hot days, high power, or a climb—you open them to let in more air; during cruise or when the engine is already at a good temperature, you close them to reduce drag while still maintaining adequate cooling. This concept is distinct from intake ducts (which feed air to the engine’s intake), exhaust shrouds (around the exhaust), or cooling fins (static heat-dissipating surfaces). The term that describes these devices is cowl flaps.