What component sits between the main transmission and the tail rotor gearbox?

• A. Intermediate gearbox
• B. Tail rotor
• C. Primary gearbox
• D. Nose gear

Answer: (A)

The main concept here is how the helicopter’s drivetrain uses a gearing stage to route power to the tail rotor. After the engine power goes into the main transmission, which reduces speed for the main rotor, a separate intermediate gearbox sits in the drive line to the tail rotor. This intermediate gearbox takes the output from the main transmission and provides the appropriate gear ratio and drive path to power the tail rotor gearbox. It also helps align and mount the tail-drive components and handles the load transfer between the two gear trains.

So, the component between the main transmission and the tail rotor gearbox is the intermediate gearbox. The tail rotor itself is the driven element at the end of the chain, the primary gearbox serves the main rotor, and the nose gear is unrelated to this power path.