What component changes the power flow coming from the main transmission to the tail rotor gearbox?

• A. Intermediate gearbox
• B. Tail rotor drive shaft
• C. Primary gearbox
• D. Tail rotor

Answer: (A)

The intermediate gearbox is the component that changes the power flow from the main transmission to the tail rotor gearbox. It sits between the main (primary) gearbox and the tail rotor drive system, using gears to alter the speed and direction of rotation so the tail rotor gearbox receives torque at the correct RPM and orientation. The tail rotor drive shaft simply passes power along; it doesn’t change the speed or direction. The primary gearbox handles the main rotor, not the tail path, and the tail rotor is the final driven element, not a shaper of the power flow.