Gearbox

The gearbox system transmits shaft power from the segments of the tail rotor driveshaft to the tail rotor and reduces the rotational drive speed. It also contains lubrication oil for the gears and bearings of the tail rotor gearbox. The gearbox system includes the tail rotor gearbox.

Tail rotor gearbox

The tail rotor gearbox is installed on a fitting support at the rear end of the tailboom. The casing of the tail rotor gearbox is made from a magnesium alloy and is closed with a cap assembly at the output shaft. The case assembly has provisions for attachment and alignment of the tail rotor gearbox to the fitting support on the tailboom, for attachment of the pitch change mechanism, and for installation of components of the tail rotor drive indicating system. The tail rotor gearbox includes the primary parts that follow:

• Case assembly

• Cap assembly

• Input quill

• Output shaft

Operation

The tail rotor gearbox is a single-stage reduction, single-input drive gearbox and transmits continuous power from the driveshaft segments of the tail rotor driveshaft to the tail rotor hub assembly through its input quill and output shaft. It also reduces the rotational speed to 2472 RPM (104% N2) at the output for the tail rotor hub assembly.

A filler cap is installed on the right side of the case assembly for the servicing of the tail rotor gearbox. The filler cap is of a breather-type to prevent pressurization of the tail rotor gearbox when the outside air temperature and pressure change. A sight gauge is also installed on the rear side of the case assembly to give an approximate oil level indication to the crew and personnel on ground.