What function does a hydraulic accumulator serve in a single acting propeller?

A hydraulic accumulator plays a crucial role in the operation of a single acting propeller, especially concerning the unfettering process. In this context, the term "unfettering" refers to moving the propeller blades from a feathered position back to a normal operating position. When the propeller blades are feathered, they are angled to reduce drag, typically during engine failure or when the aircraft is on the ground.

The hydraulic accumulator stores hydraulic fluid under pressure, and when the propeller needs to be unfettered, the pressurized fluid can be released to move the blades back to a high-pitch position for effective thrust. This mechanism ensures that the propeller can quickly and efficiently revert to its operational state, enhancing safety and performance for the aircraft.

Other options, while related to propeller operation, do not directly address the specific function of the hydraulic accumulator in the context of a single acting propeller. The function of maintaining constant speed or providing operation in the event of a CSU pump failure is more aligned with other systems or components in the propeller control mechanism, and feathering might involve more complex interactions beyond just the accumulator's function.