What component does the primary hydraulic system's selector manifold contain?

The primary hydraulic system's selector manifold contains electrical selector valves. These valves play a crucial role in directing fluid flow within the hydraulic system, allowing for the actuation of different components, such as the landing gear, flaps, and brakes. The use of electrical selector valves enhances the reliability and responsiveness of the hydraulic system, as they can be controlled more precisely and integrate seamlessly with the aircraft's electrical systems.

Mechanical selectors involve physical movements that might not provide the same level of precision or speed as electrical systems. Pneumatic valves deal with air systems rather than hydraulics, making them irrelevant to the hydraulic manifold. Hydraulic actuators, while important in converting hydraulic pressure into mechanical movement, are not part of the selector manifold; rather, they are the components that are actuated by the fluid flow controlled by the valves within the manifold. Therefore, the presence of electrical selector valves in the primary hydraulic system's selector manifold is essential for efficient and effective hydraulic operation within the aircraft.