How is a constant speed feathering propeller feathered?

A constant speed feathering propeller is feathered by releasing oil pressure in the governor. In a feathered position, the blades of the propeller are turned edge-on to the airstream to reduce drag and maximize efficiency during engine failure situations. This is achieved by allowing the engine oil, which normally maintains the propeller's pitch, to drain out of the propeller hub.

When the oil pressure is released, usually via a feathering button or lever, the springs within the propeller mechanism push the blades into the feathered position. This is crucial for aircraft safety because it minimizes drag from the non-operating engine, allowing the pilot to maintain better control and reduce the aircraft's descent rate.

Increasing oil pressure in the governor would keep the blades in a flat pitch position, which is not desirable during an engine failure. Switching the propeller control off may not properly execute the feathering action since it does not directly control the oil dynamics required for feathering. Adjusting the throttle lever influences engine power but does not directly affect the propeller's feathering mechanism. Thus, releasing oil pressure is the key action that facilitates feathering.