Chapter 12

Question 1

Does viscosity increase or decrease if temperature decreases?

Answer 1

Increases

Question 2

what does psi stand for?

Answer 2

Pounds per square inch

Question 3

liquids in hydraulic fluids may break down if exposed to

Answer 3

Air, water, salt or other impurities

Question 4

what are disirable properties for hydraulic fluids?

Answer 4

Viscosity, chemical stability, flash point, high fire point

Question 5

what is used to measure viscosity

Answer 5

Viscometer

Question 6

what is chemical stability

Answer 6

Liquid’s ability to resist oxidation and deterioration

Question 7

what are the three categories of hydraulic fluids

Answer 7

Minerals, polyalphaolefins, phosphate esters

Question 8

what are the two types of accumulators?

Answer 8

Spherical and cylindrical

Question 9

where are the heat exchangers located?

Answer 9

In the fuel tanks of the aircraft

Question 10

what is the range of psi in a high pressure system pneumatic?

Answer 10

1,000 - 3,000 psi

Question 11

a basic hydraulic system consists of what?

Answer 11

Pump, reservoir, directional valve, check valve, pressure relief valve, selector valve actuator, filter

Question 12

Do closed-center hydraulic systems have their selector/directional valves arranged in series or parallel?

Answer 12

Parallel

Question 13

Are pressurized reservoirs used in aircraft for high or low altitude flights?

Answer 13

High altitude

Question 14

What are baffles and fins in a reservoir used for?

Answer 14

prevent vortexing and surging of hydraulic fluid

Question 15

Do axial piston pumps contain an even or odd number of pistons?

Answer 15

odd

Question 16

The saybolt viscometer measure viscosity in what type of seconds?

Answer 16

universal seconds

Question 17

What is flash point?

Answer 17

the temperature at which a fluid ignites momentarily

Question 18

micron type filters are made of what?

Answer 18

Treated paper

Question 19

MIL-H-5606 is what type of fluid?

Answer 19

Mineral based fluid

Question 20

MIL-H-83282 is what type of fluid?

Answer 20

Polyalphaolefin based fluid

Question 21

phosphate ester fluid was commonly used on what type of aircraft?

Answer 21

Commercial aircraft

Question 22

Are open center selector valves arranged in series or parallel?

Answer 22

series

Question 23

Where is a finger strainer located?

Answer 23

reservoir filler neck

Question 24

What is the internal resistance to flow called?

Answer 24

viscosity

Question 25

What are the two types of contaminants?

Answer 25

abrasives and nonabrasives

Question 26

What type of fluid is typically red in color?

Answer 26

MIL-H-5606

Question 27

What is the function of an actuator in a hydraulic system?

Answer 27

convert hydraulic pressure into mechanical work

Question 28

What is the role of a hydraulic fuse?

Answer 28

to isolate a leak and prevent total system failure

Question 29

What does MSDS stand for

Answer 29

material safety data sheet

Question 30

where are non-pressurized reservoirs vented to?

Answer 30

the atmosphere or cabin

Question 31

What do you call a one direction flow control valve?

Answer 31

Check valve

Question 32

What do filters do?

Answer 32

cleans the hydraulic fluid and prevents foreign particles and contaminatng substances from staying in the system

Question 33

What do constant-displacement pumps do?

Answer 33

deliver a fixed quantity of fluid per revolution regardless of pressure demands

Question 34

What are the two classification of pumps?

Answer 34

Constant displacement and variable displacement pumps

Question 35

What does the shear section of the drive coupling do?

Answer 35

Prevents damage to the pump if pump becomes jammed or hard to turn

Question 36

What do flow control valves do?

Answer 36

control the speed and/or direction of fluid flow in the hydraulic system.

Question 37

What do selector valves do?

Answer 37

controls the direction of movement of a hydraulic actuating cylinder

Question 38

What is the purpose of a check valve?

Answer 38

allows fluid to flow unimpeded in one directions but prevents fluid flow in the opposite direction.

Question 39

What is the purpose of a hydraulic fuse?

Answer 39

if it detects any sudden increase in flow, it shuts off fluid flow.

Question 40

What is the purpose of a relief valve

Answer 40

limits the amount of pressure being exerted on a confined liquid

Question 41

What should you do before disassembling any accumulator?

Answer 41

Ensure that all preload air or nitrogen pressure has been discharged

Question 42

What color code is used for O-rings compatible with MIL-H-5606?

Answer 42

blue

Question 43

What color code is used for O-rings compatible with phosphate ester-based fluids?

Answer 43

green stripe

Question 44

What color is skydrol?

Answer 44

purple

Question 45

What is the purpose of a Desiccant/ moisture separator in a pneumatic system?

Answer 45

remove any moisture caused by the compressor

Question 46

What is pneudraulics?

Answer 46

when pressurized nitrogen helps to move hydraulic fluid to the actuator if main systems fail.

Question 47

What color is synthetic hydraulic oil?

Answer 47

amber

Question 48

What is the type of control valve used in pneumatic systems?

Answer 48

Restrictors

Question 49

What is the color code used on O-rings that are compatible with hydrocarbon fluid?

Answer 49

red

Question 50

When does the filter bypass valve open?

Answer 50

When filter becomes clogged

Question 51

Is a piston pump a constant displacement or variable displacement pump?

Answer 51

Can be both

Question 52

Is a gear type power pump a constant or variable displacement pump?

Answer 52

constant displacement pump

Question 53

Is a vane pump a constant or variable displacement pump?

Answer 53

constant displacement pump