At takeoff, how should cowl flaps be selected?

At takeoff, cowl flaps should be selected to be open. This positioning is important because open cowl flaps enable better airflow through the engine compartment, which helps in cooling the engine. During takeoff, the engine is under maximum power conditions, generating significant heat. By having the cowl flaps open, this excess heat is effectively dissipated, maintaining optimal operating temperatures and enhancing engine performance.

Selecting cowl flaps in any other configuration, such as fully closed, would restrict airflow and could lead to overheating of the engine. While partially closed might seem to balance drag and cooling, the primary focus during takeoff should be on effective cooling to prevent engine damage and ensure reliable operational performance. Therefore, keeping the cowl flaps fully open maximizes engine cooling safety during the critical phase of takeoff.