What feature allows a variable pitch propeller to operate in the reverse mode?

The feature that allows a variable pitch propeller to operate in the reverse mode is primarily the hydraulic pressure from the system. This hydraulic pressure enables the adjustment of the propeller blades' pitch angle, allowing them to change direction effectively during operation.

In reverse mode, the propeller blades are set to a pitch angle that pushes the aircraft backward rather than forward. This manipulation is crucial for certain flight maneuvers, especially when landing on shorter runways or when taxiing in confined spaces. The hydraulic system precisely controls these adjustments, ensuring that the blades can swiftly transition between different pitch settings, including the reverse angle.

Other mechanisms, like the feathering latch and governor weight, serve different functions in the operation of a variable pitch propeller. While they are essential for managing blade angles and optimizing performance during flight, they do not directly facilitate the reverse mode operation as effectively as the hydraulic pressure does. The hydraulic system's ability to provide the necessary force to alter the blade pitch direction is what fundamentally enables the propeller to rotate in reverse.