Final answer:
A constant speed feathering propeller is feathered by increasing the blade angle to align the blades with the airflow, thus minimizing drag and preventing the propeller from turning when the engine is not running. The correct answer is b) Increasing blade angle.
Step-by-step explanation:
To understand how a constant speed feathering propeller is feathered, it's important to know that feathering a propeller refers to the process of adjusting the angle of the propeller blades so that the blades are aligned with the airflow, minimizing drag and preventing the propeller from turning when the engine fails or is shut down.
This is particularly important for multi-engine aircraft, where a non-functioning propeller can create significant drag and cause control issues. To feather a propeller, the blade angle is increased until the blades are nearly parallel to the direction of flight, which is indicated by option b) Increasing blade angle.
In scenarios where aircraft propellers are involved, during normal operation, the propeller blades are angled to bite into the air and create thrust. When feathering occurs, a mechanism within the propeller hub changes the pitch of the blade. If a propeller is fixed-pitch, it cannot be feathered. However, variable-pitch propellers, including constant-speed propellers, may allow feathering.
For turbine engines and some larger piston aircraft with reversible propellers, feathering is controlled by moving the propeller control into the feather position, which redirects oil pressure within the propeller hub to rotate the blades toward the feathered position.