Private Pilot Private Exam

On engines equipped with a constant-speed propeller, how is engine operation controlled?

1. Throttle controls both RPM and power output

2. Only the propeller control manages engine RPM

3. The throttle controls power output and the propeller control regulates engine RPM

4. The mixture setting has no effect on RPM

The correct answer is: The throttle controls power output and the propeller control regulates engine RPM

In engines equipped with a constant-speed propeller, engine operation is controlled through a combination of the throttle and the propeller control. The throttle primarily manages the power output to the engine, affecting how much fuel-air mixture is supplied for combustion. This directly influences the engine's power and performance. The propeller control, on the other hand, adjusts the blade pitch of the propeller, which is crucial for managing engine RPM. By regulating the pitch, the propeller is able to maintain an optimal RPM regardless of variations in power output from the engine. This allows pilots to achieve efficient performance throughout different phases of flight, such as climb, cruise, and descent. Thus, in this system, the throttle and the propeller control work in tandem: the throttle adjusts the engine's power output, while the propeller control ensures that the engine maintains the desired RPM. This dual control mechanism is essential for maximizing performance and fuel efficiency in flight.