FAA Powerplant Written Practice Test

Which type of heat exchanger is used to regulate fuel temperature?

1. Air-to-liquid for bleed air type and liquid-to-liquid for oil type

2. Liquid-to-gas type only

3. Air-to-air type only

4. Steam-to-liquid type

The correct answer is: Air-to-liquid for bleed air type and liquid-to-liquid for oil type

The choice identifying air-to-liquid and liquid-to-liquid configurations as types of heat exchangers used to regulate fuel temperature is accurate due to the specific functions these systems perform in aircraft engines. Air-to-liquid heat exchangers are commonly employed in systems where heated bleed air from the engine can be used to warm the fuel, preventing it from becoming too cold and potentially causing icing or engine performance issues. In contrast, liquid-to-liquid heat exchangers often handle oil systems, where engine oil can circulate to help maintain optimal fuel temperatures by transferring heat effectively within the system. Both of these configurations provide essential temperature management, ensuring that fuel remains within an ideal temperature range for efficient combustion and overall engine performance. The correct identification of these types highlights a fundamental understanding of aircraft engine thermodynamics and the care taken to manage fluid temperatures in various aircraft subsystems.