Which component is responsible for disconnecting the rotor from the engine when the engine stops?

Which component is responsible for disconnecting the rotor from the engine when the engine stops?

• A. Free Turbine
• B. Freewheeling Unit
• C. Clutch
• D. Gearbox

Answer: (B)

When the engine stops, the rotor must be able to run freely without being driven or loading the engine. The device that does this automatic decoupling is the freewheeling unit. It sits between the engine and the rotor transmission and acts like a one-way clutch: while the engine is turning and delivering torque, the unit engages and drives the rotor. If the engine stops, the sprags inside the freewheeling unit disengage, disconnecting the rotor from the engine so the rotor can coast. The free turbine is part of the engine’s own design and does not serve this decoupling function, while a clutch or gearbox alone does not provide automatic separation of the rotor from the engine in the event of an engine failure.

When the engine stops, the rotor must be able to run freely without being driven or loading the engine. The device that does this automatic decoupling is the freewheeling unit. It sits between the engine and the rotor transmission and acts like a one-way clutch: while the engine is turning and delivering torque, the unit engages and drives the rotor. If the engine stops, the sprags inside the freewheeling unit disengage, disconnecting the rotor from the engine so the rotor can coast. The free turbine is part of the engine’s own design and does not serve this decoupling function, while a clutch or gearbox alone does not provide automatic separation of the rotor from the engine in the event of an engine failure.