What does the main driveshaft connect to the input of in the TH-73A system?

• A. Tail gearbox, engine
• B. No.1 hydraulic pump, main transmission oil system
• C. Engine reduction gearbox, main transmission accessory gearbox
• D. Auxiliary generator, main transmission

Answer: (C)

The main driveshaft in the TH-73A system connects to the input of the engine reduction gearbox as well as the main transmission accessory gearbox. This is critical as the engine reduction gearbox reduces the speed of the engine while increasing the torque, and the accessory gearbox provides power to various components and systems, including the main transmission. Therefore, the connection of the main driveshaft to these components ensures that the helicopter can effectively translate engine power into usable mechanical power for flight operations. This relationship is essential for the overall functioning and performance of the helicopter, making option C the right choice.