Answer:
Check valve
Explanation:
Check valve is used in the hydraulic system of an aircraft which permits the flow of fluid only in one direction and restricts the flow of fluid in the other direction.
The check valve may or may not be the integral part of the hydraulic system. A typical check valve consists of a spring loaded ball and seating groove inside the housing case of the valve. The spring gets compressed in one direction only according to its design and hence is a one way flow valve.
