Hydraulic and Pneumatic Power Systems

To protect packing rings or seals from damage when it is necessary to install them over or inside threaded sections, the

• threaded section should be coated with a heavy grease.

• packings should be stretched during installation to avoid contact with the threads.

• threaded section should be covered with a suitable sleeve.

To prevent external and internal leakage in aircraft hydraulic units, the most commonly used type of seal is the

• O-ring seal.

• gasket seal.

• chevron seal

Which allows free fluid flow in one direction and no fluid flow in the other direction?

• Check valve

• Metering piston.

• Shutoff valve.

Select the valve used in a hydraulic system that directs pressurized fluid to one end of an actuating cylinder and simultaneously directs return fluid to the reservoir from the other end.

• Sequence

• Shuttle

• Selector

What function does the absolute pressure regulator perform in the pneumatic power system?

• Regulates the compressor outlet air pressure to stabilize the system pressure.

• Regulates the pneumatic system pressure to protect the moisture separator from internal explosion.

• Regulates the compressor inlet air to provide a stabilized source of air for the compressor.

(1) Relief valves are used in pneumatic systems as damage-preventing units. (2) Check valves are used in both hydraulic and pneumatic systems.

• both No. 1 and No. 2 are true.

• neither No. 1 nor No. 2 is true.

• only No. 1 is true

One of the distinguishing characteristics of an open-center selector valve used in a hydraulic system is that

• fluid flows through the valve in the OFF position.

• fluid flows in three directions in the ON position.

• a limited amount of fluid flows in one direction and no fluid flows in the opposite direction

What type of packings should be used in hydraulic components to be installed in a system containing Skydrol?

• AN packings made of natural rubber.

• Packing materials made for ester base fluids.

• AN packings made of neoprene

Relief valves are used in pneumatic systems

• for one direction flow control.

• to reduce the rate of airflow.

• as damage-preventing units.

An aircraft pneumatic system, which incorporates an engine-driven multistage reciprocating compressor, also requires

• an oil separator.

• a surge chamber.

• a moisture separator.