What is a critical characteristic of the free-wheeling unit during single engine failure?

During a single engine failure scenario, a critical characteristic of the free-wheeling unit is that it disengages the engines from the transmission. This is essential because it allows the rotor system to keep turning independently of the engine that has failed. By disengaging, the free-wheeling unit permits the other operational engine to continue powering the helicopter while minimizing stress on the failed engine and transmission system.

This disengagement is crucial for maintaining control and stability during flight, as it prevents the loss of rotor speed that could be catastrophic. The rotor can continue to operate, and the pilot can manage the descent and landing more effectively. Other options, such as generating additional power, enhancing blade rigidity, or stabilizing rotor speed, do not accurately describe the function of the free-wheeling unit. These functions are related to different aspects of helicopter design and operation, but they do not pertain to the specific role of the free-wheeling unit in the context of single engine failure.