FAA Powerplant Written Practice Test

From which component does oil pick up the most heat in a turbine engine?

1. Compressor bearing

2. Fuel system

3. Exhaust turbine bearing

4. Oil pump

The correct answer is: Exhaust turbine bearing

In a turbine engine, the exhaust turbine bearing is the component from which oil picks up the most heat. This is primarily due to its location in the engine, where it is subjected to high temperatures resulting from combustion processes. As the engine operates, the exhaust gases passing through the turbine rotor impart a substantial amount of thermal energy to nearby components, including the exhaust turbine bearing. As the oil circulates through the engine to lubricate various bearings and components, it absorbs heat primarily from the exhaust turbine bearing. This characteristic is crucial for maintaining the engine's efficiency and reliability, as the oil helps to transfer the heat away from hot components, preventing overheating and ensuring smooth operation. The other components listed, while they also experience heat, do not reach the same temperature levels as the exhaust turbine bearing. For instance, while compressor bearings do transfer some heat from the compressor section, they operate at lower temperatures compared to the turbine section where exhaust turbines are located. The fuel system generally operates at temperatures influenced by fuel rather than directly by engine components, and the oil pump primarily circulates oil, contributing little to heat absorption directly from hot engine surfaces.