Which component transmits power from the engine to the reduction gear assembly?

• A. Extension shaft assembly
• B. Rear of the case used for mounting accessories
• C. Diffuser
• D. Fuel control unit

Answer: (A)

Transmitting engine power to the reduction gear is done by the extension shaft assembly. In a turbomachinery setup, the power from the engine’s core has to reach the reduction gearbox, and the extension shaft is the direct drive path that connects the power turbine to the reduction gear, carrying the torque and keeping alignment between components. The other items don’t form the power path: the rear of the case for mounting accessories houses mounting points for accessory gearboxes and supports, not the power transfer; the diffuser is a compressor component that slows and handles incoming air; and the fuel control unit meters fuel to control engine speed—none of these transmit mechanical power to the reduction gear.