How are the two power turbines connected to drive the propeller?

• A. On separate shafts
• B. On the same shaft through a planetary gear reduction gearbox
• C. Through hydraulic coupling
• D. They do not drive the propeller

Answer: (B)

Power is put to the propeller through a planetary gear reduction gearbox that connects to a single drive shaft. The two turbine sections on the engine feed that same shaft, and the planetary gear set multiplies the torque while reducing the rotational speed to match the propeller’s required RPM. This compact gear arrangement transfers the high-speed, high-torque energy from the turbines into the lower-speed, higher-torque rotation the propeller needs, all on one shaft driven through the gearbox. Hydraulic coupling or separate shaft drives wouldn’t provide the same efficient, compact power transfer to the propeller.