AF213 FAA Practice Quiz #4 Flashcards
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.
Selector.
What is the main purpose of a pressurized reservoir in a hydraulic system?
Prevent hydraulic pump cavitation.
The primary purpose of a hydraulic actuating unit is to transform
fluid pressure into useful work.
What type of selector valve is one of the most commonly used in hydraulic systems to provide for simultaneous flow of fluid into and out of a connected actuating unit?
Four-port, closed-center valve.
(1) When servicing aircraft hydraulic systems, use the type fluid specified in the aircraft manufacturer’s maintenance manual or on the instruction plate affixed to the reservoir or unit. (2) Hydraulic fluids for aircraft are dyed a specific color for each type of fluid. Regarding the above statements,
both No. 1 and No. 2 are true.
Petroleum base hydraulic fluid is which color?
MIL-H-5606 petroleum-base hydraulic fluid is dyed red.
Which of the following is adversely affected by atmospheric humidity if left unprotected? 1. MIL-H-5606 hydraulic fluid. 2. Skydrol hydraulic fluid. 3. None of the above.
2
(Refer to Figure 12.) Which illustration(s) show(s) the correct spiral for teflon backup rings?Y
1 and 3.
Seals used with a mineral base hydraulic fluid are identified by which color code?
Blue dot or stripe.
Which of the following is the most commonly used seal to prevent internal and external leakage in both directions of a hydraulic unit?
O-ring.
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.
What happens to the output of a constant-displacement hydraulic pump when the hydraulic system pressure regulator diverts the fluid from the system to the reservoir?
The output pressure reduces, but the volume remains the same.
Some hydraulic systems incorporate a device which is designed to remain open to allow a normal fluid flow in the line, but closed if the fluid flow increases above an established rate. This device is generally referred to as a
hydraulic fuse.
Hydraulic system accumulators serve which of the following functions? 1. Dampen pressure surges. 2. Supplement the system pump when demand is beyond the pump’s capacity. 3. Store power for limited operation of components if the pump is not operating. 4. Ensure a continuous supply of fluid to the pump.
1, 2, 3.
If the hydraulic system pressure is normal while the engine-driven pump is running, but there is no pressure after the engine has been shut off, it indicates
no air pressure in the accumulator.
