FAA Sport Pilot Airplane (SPA)Aircraft Performance and SystemsMedium
A pilot is climbing a light sport airplane equipped with adjustable cowl flaps at a high pitch attitude and reduced airspeed, causing decreased airflow through the engine cowling. To help prevent excessively high cylinder head temperatures under these conditions, the pilot should
- Areduce the mixture to full lean
- Bopen the cowl flaps to increase cooling airflow
- Capply carburetor heat to cool the cylinders
- Dclose the cowl flaps to reduce drag
Show answer & explanationAnswer & explanation
Correct answer: B. open the cowl flaps to increase cooling airflow
Opening the cowl flaps increases the amount of cooling air flowing across the engine cylinders, which helps lower cylinder head temperatures. This is especially important during climbs, where airspeed and airflow through the cowling are reduced, increasing the risk of engine overheating.
Why the other options are wrong
- A. Leaning the mixture at climb power can increase cylinder head temperature rather than reduce it.
- C. Carburetor heat is used to prevent or remove carburetor ice; it does not cool the cylinders and can reduce power.
- D. Closing cowl flaps reduces airflow and would worsen the overheating problem.
Cowl Flaps and Engine Cooling
Adjustable cowl flaps regulate airflow through the engine compartment to control cylinder head temperature.
- Opening cowl flaps increases cooling airflow, lowering CHT
- Closing cowl flaps reduces drag but decreases cooling
- Most critical during climbs when airflow is reduced
- Overheating can lead to detonation and engine damage
Memory trick: Open the flaps, let the engine breathe and cool