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1
A loud hammering noise in a hydraulic system having an accumulator usually indicates
To low or no preload in the accumulator.
2
(1) Relief valves are used in pneumatic system as damage- preventing units. (2) Check valves are used in both hydraulic and pneumatic systems. Regarding the above statements
both no.1 and no.2 are true.
3
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.
4
Hydraulic accumulator is charge with an air preload of 1000 PSI. when a hydraulic system pressure of 3000 PSI is developed, the pressure on the air side of the accumulator will be
3000psi
5
Which seals are with petroleum base hydraulic fluids?
Buna-N
6
What is one advantage of piston type hydraulic motors over electric motors?
There is no fire hazard if the motor s is stalled.
7
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 the main hydraulic system.
8
In a hydraulic system that has a reservoir pressurized with turbine-engine compressor bleed air, which unit reduces the air pressure between the engine and reservoir.
air pressure regulator
9
Quick – disconnect couplings in hydraulic systems provide a means of
Quickly connecting and disconnecting hydraulic lines without loss of fluid or entrance of air into the system.
10
Components containing phosphate ester-base hydraulic fluid may be cleaned with
stoddard solvent
11
Characteristic of MIL-H-5606 hydraulic fluid are
Red color, petroleum base will burn uses synthetic rubber seals
12
Some hydraulic system 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
hydraulic fuse
13
A worn hydraulic pump shaft seal can normally be detected by
Hydraulic fluid flowing from the pump drain line
14
(1) When servicing aircraft hydraulic system, use the type fluid specified in the aircraft manufacturer’s maintenance manual or on the instructions plate affixed to the reservoir or unit. (2)Hydraulic fluids for aircraft are dyed as specific color for each type of fluid regarding the statement
both No.1 and 2 are true
15
If two actuating cylinder which have the same cross- sectional area but different lengths of stroke connected to the same source of hydraulic pressure they will exert
Equal amounts of force and will move at the same rate of speed.
16
The internal resistance of fluid which tend to prevent it from flowing is called
viscosity
17
When hydraulic system pressure control and relief units fail to function properly. How are most systems protected against over pressure
A shear section on the main hydraulic pump drive shaft
18
One of the distinguishing characteristic of an open-center selector valve use in a hydraulic system is that.
Fluid flow through the valve in the OFF position
19
Heat exchanger cooling units are required in some aircraft hydraulic system because of
High pressure and high rates of fluid flow
20
Using a hand pump, pressure of 100 psi has been built up in a hydraulic system .the hand pump piston is 1 inch in diameter . A ½-inch line connects the hand pump to an actuating cylinder 2 inches in diameter. What is the pressure in the line between the hand pump and the actuator?
100psi
21
The air that is expended and no longer needed when an actuating unit is operated in a pneumatic system is
Exhausted or dumped, usually overboard.
22
Pressure is a term used to indicate the force per unit area. Pressure is usually expressed in
Pounds per square inch.
23
What function does the absolute pressure regulator perform in the pneumatic power system?
Regulates the compressor inlet air to provide a stabilized source of air for the compressor.
24
Teflon hose that has developed a permanent set from being exposed to high pressure or temperature should
Not be straightened or bent further.
25
An aircraft pneumatic system which incorporates an engine-driven multistage reciprocating compressor, also requires
a moisture separator
26
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
27
Before removing the filler cap of a pressurized hydraulic reservoir , in order to service the system, you must
Relieve the air pressure.
28
If hydraulic fluid is released when the air valve core of the accumulator is depressed , it is evidence
A ruptured diaphragm or leaking seals.
29
What is the purpose of using backup rings with O-rings in hydraulic systems above 1500 psi?
Prevent high pressure from extruding the seal between the moving and stationary part.
30
Although dents in the heel of a bend are not permissible, they are acceptable in the remainder of a hydraulic tube providing they are less than what percent of the tube damenter
20
31
What types of selector valve is one f he most commonly used in hydraulic system to providing for simultaneous flow of fluid into and out of a connected actuating unit?
Four-port, closed-center valve
32
What is the main purpose of a pressurized reservoir in a hydraulic system?
Prevent hydraulic pump cavitation