What is the purpose of the freewheeling unit in the TH-73 engine?

• A. To increase rotor speed
• B. To allow independent rotation during autorotation
• C. To stabilize engine power
• D. To decrease fuel consumption

Answer: (B)

The purpose of the freewheeling unit in the TH-73 engine is to allow independent rotation during autorotation. When the helicopter is in an autorotation condition, the rotor needs to continue spinning even if the engine has lost power. The freewheeling unit enables this by disconnecting the rotor from the engine, allowing the rotor to maintain its rotational speed driven by aerodynamic forces, even when the engine is not providing power. This capability is crucial for safely descending and landing the aircraft during an engine failure. The design ensures that the rotor system can still function effectively, providing necessary control and lift until the helicopter reaches the ground safely.