Which gearbox is located at the base of the tail pylon?

• A. Primary gearbox
• B. Intermediate gearbox
• C. Tail rotor gearbox
• D. Accessory gearbox

Answer: (B)

Power is transmitted from the engine to the tail rotor through a sequence of gearboxes, and the one mounted at the base of the tail pylon is the intermediate gearbox. This gearbox sits right along the tail pylon, receiving input from the main gearbox and providing the necessary reduction and a drive path toward the tail rotor. It harmonizes the direction and speed before the power reaches the tail rotor assembly.

The other gearboxes have different roles and locations: the tail rotor gearbox is located at the tail rotor itself and handles the final reduction for the rotor speed; the primary (or main) gearbox is in the main fuselage area where the engine drives it; and the accessory gearbox is mounted on the main gearbox to power items like generators and hydraulic pumps. So the insertion point at the base of the tail pylon specifically matches the intermediate gearbox.