CEA Fundamentals Block 3 Practice Test

A free-wheeling unit lets the rotor keep turning even when the engine isn’t delivering power, by decoupling the engine from the rotor. When the engine speed falls below the rotor speed, the unit disengages the engine so the rotor can continue to spin driven by its own inertia and aerodynamic forces. This keeps the rotor running and enables autorotation, so the system can still operate even with a drop in engine RPM.

The other scenarios don’t trigger this decoupling: a tail rotor fault affects yaw control, not the drive connection between engine and rotor; low hydraulic pressure impacts control surfaces and systems relying on hydraulics; coolant temperature rising signals engine overheating, not the rotor–engine decoupling mechanism.