Which component reduces the engine output speed and transmits power from the engines to the main and tail rotor systems?

• A. Tail rotor gearbox
• B. Engine
• C. Main transmission
• D. Fuel pump

Answer: (C)

Power from the engine is slowed and made usable for the rotors by the main transmission. This gear train takes the high-speed, low-torque output of the engine and reduces its RPM while boosting torque so it can drive the main rotor. It also provides the drive path to the tail rotor system through the appropriate gear interfaces. The tail rotor gearbox handles the tail rotor speed once power is already coming from the main transmission, but it doesn’t directly reduce engine speed or source the drive from the engine to both rotor systems. The engine supplies the power, and the fuel pump merely delivers fuel—neither of these directly reduces speed to drive the rotors. Therefore, the main transmission is the component that reduces engine output speed and transmits power to both rotor systems.