Which of the following is NOT a component of an aircraft hydraulic system?

The correct answer is that engines are not a component of an aircraft hydraulic system. An aircraft hydraulic system typically includes components designed specifically for the purpose of controlling and transmitting hydraulic fluid under pressure.

Pumps are critical in a hydraulic system as they move the hydraulic fluid through the system, creating the necessary pressure for operation. Reservoirs store the hydraulic fluid, ensuring the system has a sufficient supply to operate effectively. Valves control the flow and direction of the hydraulic fluid, allowing for the actuation of various systems, such as landing gear, flight control surfaces, and brakes.

Engines, while essential for generating thrust and providing power to an aircraft, do not constitute a part of the hydraulic system. Instead, they may utilize hydraulic power generated by the hydraulic system for their own operations but are not classified as a hydraulic system component. This distinction highlights the specific roles of different systems within an aircraft, particularly how they interact while serving separate functions.