Which component drives the main rotor mast as well as the tail rotor drive components?

• A. Main gearbox/Main Transmission
• B. Tail gearbox
• C. Free-wheeling unit
• D. Accessory Gearboxes/Drives

Answer: (A)

Power from the engine is routed through the main gearbox, which acts as the central drive for the helicopter. It provides the reduction and torque needed to turn the main rotor mast, and the same gearbox also supplies the drive path to the tail rotor through the tail-drive assembly. In other words, the main gearbox is the source that powers both the main rotor and the tail rotor drive components. The tail gearbox itself is the stage that reduces speed for the tail rotor and is driven by the main gearbox. The free-wheeling unit allows autorotation by disconnecting the rotor from the engine, and accessory gearboxes/drives power non-rotor systems.