AF213 FAA Practice Quiz #3

Question 1

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

Answer 1

a moisture separator.

Question 2

A hydraulic motor converts fluid pressure to

Answer 2

rotary motion.

Question 3

What is the main purpose of a pressurized reservoir in a hydraulic system?

Answer 3

Prevent hydraulic pump cavitation.

Question 4

If fluid is added to a reservoir in a constant pressure hydraulic system while the system is pressurized, what will result?

Answer 4

The fluid level will increase when system pressure is reduced.

Question 5

If an engine-driven hydraulic pump of the correct capacity fails to maintain normal system pressure during the operation of a cowl flap actuating unit, the probable cause is

Answer 5

restriction in the pump outlet.

Question 6

Extrusion of an O-ring seal is prevented in a high-pressure system by the use of a

Answer 6

backup ring on the side of the O-ring away from the pressure.

Question 7

Where can information be obtained about the compatibility of fire-resistant hydraulic fluid with aircraft materials?

Answer 7

Fluid manufacturer’s technical bulletins.

Question 8

How many of these seals are used with petroleum base hydraulic fluids?

Answer 8

Neoprene, Buna-N.

Question 9

If an aircraft hydraulic system requires mineral base hydraulic fluid, but phosphate ester base hydraulic fluid is used, what will be the effect on the system?

Answer 9

System will be contaminated, fluids will not blend, and the seals will fail.

Question 10

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

Answer 10

Inlet of the main hydraulic system.

Question 11

Characteristics of MIL-H-8446 (Skydrol 500 A & B) hydraulic fluid are

Answer 11

light purple color, phosphate ester base, fire resistant, butyl rubber seals.

Question 12

Which of the following lists only desirable properties of a good hydraulic fluid that has chemical stability?

Answer 12

Low viscosity, high flash point, high fire point.

Question 13

How would the air pressure charge in the accumulator be determined if the engine is inoperative, but the system still has hydraulic pressure?

Answer 13

Operate a hydraulic unit slowly and note the pressure at which a rapid pressure drop begins as it goes toward zero.

Question 14

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

Answer 14

hand pump outport check valve.

Question 15

If hydraulic fluid is released when the air valve core of the accumulator is depressed, it is evidence of

Answer 15

a ruptured diaphragm or leaking seals.

Question 16

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

Answer 16

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

Question 17

The component in the hydraulic system that is used to direct the flow of fluid is the

Answer 17

selector valve.

Question 18

Which seals are used with petroleum base hydraulic fluids?

Answer 18

Buna-N.

Question 19

What is the purpose of using backup rings with O-rings in hydraulic systems above 1,500 PSI?

Answer 19

Prevent high pressure from extruding the seal between the moving and stationary part.

Question 20

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

Answer 20

hydraulic fuse.

Question 21

What safety device is usually located between the driving unit and hydraulic pump drive shaft?

Answer 21

Pump drive coupling shear section.

Question 22

In a typical high-pressure pneumatic system, if the moisture separator does not vent accumulated water when the compressor shuts down, a likely cause is a

Answer 22

malfunctioning solenoid dump valve.

Question 23

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

Answer 23

hand pump outport check valve.

Question 24

The internal resistance of a fluid which tends to prevent it from flowing is called

Answer 24

viscosity.

Question 25

If an engine-driven hydraulic pump of the correct capacity fails to maintain normal system pressure during the operation of a cowl flap actuating unit, the probable cause is

Answer 25

restriction in the pump outlet.

Question 26

A hydraulic pump is a constant-displacement type if it

Answer 26

delivers a uniform rate of fluid flow.

Question 27

Chattering of the hydraulic pump during operation is an indication

Answer 27

that air is entering the pump.

Question 28

The installation of a new metal hydraulic line should be made with

Answer 28

enough bends to allow the tube to expand and contract with temperature changes and to absorb vibration.

Question 29

How can the proper hydraulic fluid to be used in an airplane be determined?

Answer 29

By consulting the aircraft manufacturer’s service manual.

Question 30

A pilot reports that when the hydraulic pump is running, the pressure is normal. However, when the pump is stopped, no hydraulic pressure is available. This is an indication of a

Answer 30

l leaking accumulator air valve.

Question 31

Heat exchanger cooling units are required in some aircraft hydraulic systems because of

Answer 31

high pressures and high rates of fluid flow.

Question 32

A loud hammering noise in a hydraulic system having an accumulator usually indicates

Answer 32

too low or no preload in the accumulator.