FAA Powerplant Written Practice Test

Why is excess capacity in the main fuel pump important for turbine engines?

1. It allows for quick engine startups

2. It provides adequate capacity at all operating conditions

3. It reduces engine noise

4. It normalizes exhaust emissions

The correct answer is: It provides adequate capacity at all operating conditions

Excess capacity in the main fuel pump is crucial for turbine engines because it ensures that the engine receives an adequate supply of fuel under all operating conditions. Turbine engines often experience varying demand for fuel depending on factors like throttle position, altitude, and operating conditions. If the fuel pump does not have sufficient capacity, it could lead to fuel starvation, resulting in poor engine performance, potential stalling, or even engine failure during critical phases like takeoff or high-power maneuvers. Having excess capacity also means that the pump can handle sudden increases in fuel demand, such as during rapid acceleration or changes in flight attitude, without compromising the engine's operation. Consequently, this characteristic contributes to the reliability and safety of turbine engines, allowing them to function effectively across a wide range of operating scenarios.