Hydraulic & Pneumatic Power Systems Flashcards
(114 cards)
Which of the following lists only desirable properties of a good hydraulic fluid that has chemical stability?
low viscosity, high flash point, high fire point.
The main system pressure relief valve in a simple hydraulic system equipped with a power control valve should be adjusted
With the power control valve held in the CLOSED position.
Seals used with a mineral base hydraulic fluid are identified by which color code?
Blue dot or stripe
(Refer to Figure 12.) Which illustration (s) show(s) the correct spiral for teflon backup rings?
1 and 3
Relief valves are used in pneumatic systems
As damage-preventing units
Select the valves 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
Selector
Which is a characteristic of synthetic base hydraulic fluid?
High flash point
How many of these seals are used with petroleum base hydraulic fluids?
Neoprene, Buna-N
Components containing phosphate ester-base hydraulic fluid may be cleaned with
Stoddard solvent
An emergency supply of fluid is often retained in the main hydraulic system reservoir by the use of a standpipe. The supply line is connected to the
Inlet of the main hydraulic system.
Where can information be obtained about the compatibility of fire-resistant hydraulic fluid with aircraft materials?
Fluid manufacturer’s technical bulletins.
Which statement about fluids is correct?
All fluids readily transmit pressure.
After installation of a rebuilt hydraulic hand pump, it is found that the handle cannot be moved in the pumping direction (pressure stroke.) The most likely cause is an incorrectly installed
Hand pump outport check valve.
Characteristics of MIL-H-5606 Hydraulic fluid are
Red color, petroleum base, will burn, uses synthetic rubber seals.
If an aircraft’s constant pressure hydraulic system cycles more frequently than usual and no fluid leakage can be detected, the most probable cause is
Low accumulator air preload.
Extrusion of an O-ring seal is prevented in a high-pressure system by the use of a
Backup ring on the side of the 0-ring away from the pressure.
Excluding lines, which components are required to make up a simple hydraulic system?
Pump, reservoir, selector valve, and actuator.
Before removing the filler cap of a pressurized hydraulic reservoir, in order to service the system, you must
Relieve the air pressure.
The installation of a new metal hydraulic line should be made with
Enough bends to allow the tube to expand and contract with temperature changes and to absorb vibration.
If fluid is added to a reservoir in a constant pressure hydraulic system while the system is pressurized, what will result?
The fluid level will increase when system pressure is reduced.
The removal of air from an aircraft hydraulic system is generally accomplished
By operating the various hydraulic components through several cycles.
What is commonly used to connect an emergency source of power, and at the same time disconnect the normal hydraulic source from artificial parts of a landing gear or wheel braking system for operation (usually when the normal source system fails)?
Shuttle valve
Two types of hydraulic fluids currently being used in civil aircraft are
Mineral base, and phosphate ester base.
Hydraulic system thermal relief valves are set to open at a
Higher pressure than the system relief valve.