HYDRAULIC &PNEUMATIC POWER SYSTEM

100問 • 1年前

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

To low or no preload in the accumulator.

(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.

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.

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

Which seals are with petroleum base hydraulic fluids?

Buna-N

What is one advantage of piston type hydraulic motors over electric motors?

There is no fire hazard if the motor s is stalled.

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.

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.

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.

Components containing phosphate ester-base hydraulic fluid may be cleaned with

Stoddard solvent.

Characteristic of MIL-H-5606 hydraulic fluid are

Red color, petroleum base will burn uses synthetic rubber seals

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 a

Hydraulic fuse

A worn hydraulic pump shaft seal can normally be detected by

Hydraulic fluid flowing from the pump drain line

(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

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.

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

Viscosity

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

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

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

High pressure and high rates of fluid flow

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?

100 psi.

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.

Pressure is a term used to indicate the force per unit area. Pressure is usually expressed in

Pounds per square inch.

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.

Teflon hose that has developed a permanent set from being exposed to high pressure or temperature should

Not be straightened or bent further.

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

A moisture separator.

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

Before removing the filler cap of a pressurized hydraulic reservoir , in order to service the system, you must

Relieve the air pressure.

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

A ruptured diaphragm or leaking seals.

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.

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

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

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

Prevent hydraulic pump cavitation

A unit which transform hydraulic pressure which linear motions is called

An actuating cylinder

(1) materials which are skydrol compatible or resistant include most common aircraft metals and polyurethane and epoxy paints. (2) skydrol hydraulic fluid is compatible with nylon and natural fivers regarding the above statements

Both No.1 and No.2 are true

Characteristic of MIL-H-7644 hydraulic fluid are

Blue color, vegetable base, will burn, natural rubber seals

After installation of a rebuilt hydraulic hand pump. It is found that the handle cannot be moved in the pumping directions (pressure stroke). The most likely cause is an incorrectly installed

Hand pump outport check valve

Two types of hydraulic fluids currently being used in civil aircraft are

Mineral base, and phosphate ester base

Which seal/material is used with phosphate ester base hydraulic fluids?

Butyl rubber

How is the air in a hydraulic accumulator prevented from entering the fluid system?

By physically separating the air chamber from the oil chamber with a flexible movable separation

A hydraulic motor converts fluid pressure to

Rotary motion

One of the main advance of skydrol is its

Wide operation temptation

If an aircraft’s constant-pressure hydraulic system and no more frequently than detected the most probable cause is

Low accumulator airpreload

Hydraulic fluid filtering elements constructed of pours paper are normally.

Discarded at regular intervals and replaced with new filtering elements

Characteristic of MIL-H-8446 (skydrol 500 A & B hydraulic fluids are

Light purple color, phosphate ester base, fire resistant, butyl rubber seals

A hydraulic system operational check during ground runup the wing flaps cannot be allowed using the main hydraulic system, but can be lowered by using the emergency likely cause

The fluid level in the reservoir is low

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

Leaking accumulator air valve

If a rigid tube is too short for the flare to reach its seat before tightening, pulling it into place by tightening

May distort the flare.

Which of the following is adversely affected by atmospheric humidity if left unprotected? 1. MILH-H- 5606 hydraulic fluid. 2. Skydrol hydraulic fluid. 3. None of the above.

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

Neoprene, Buna-N.

Excluding lines, which components are required to make up a simple hydraulic system?

Pump, reservoir, selector valve, and actuator.

Petroleum base hydraulic fluid is which color?

Red

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

Pump drive coupling shear section.

A crossflow valve which is designed to bypass fluid from one side of an actuating cylinder to the side, under certain conditions, may be found in some aircraft installed in the

Landing gear system.

If a hydraulic brake system uses neoprene rubber packing materials, the correct hydraulic fluid to service the system is

Mineral base oil.

The primary purpose of a hydraulic actuating unit is to transform

Fluid pressure into useful work.

Hydraulic fluid reservoirs are sometimes designed with a standpipe in one of the outlet ports in order to assure emergency supply of fluid. The outlet port with the standpipe in it furnishes fluid to the

Normal system power pump.

Unloading valves are used with many engine-driven hydraulic pumps to

Relieve the pump pressure.

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

Fluid manufactures technical bulletins.

Phosphate ester base hydraulic fluid is very susceptible to contamination from

Water in the atmosphere.

A common cause of slow actuation of hydraulic components is

Internal leakage in the actuating unit.

Which allows free fluid flow in one direction and no fluid flow in the other direction?

Check valve.

What type of packings should be used in hydraulic components to be installed in a system containing skydrol?

Packing materials made for ester base fluids.

Hydraulic system accumulating 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 it is necessary to adjust several pressure regulating valves in a hydraulic system , what particular sequence , if any, should be followed ?

Units with the highest pressure settings and adjusted first.

Most variable displacement aircraft hydraulic pumps in use.

Contain a built- in means of system pressure regulation.

Which must be done before adjusting the relief valve of a main hydraulic system incorporating a pressure regulator?

Eliminate the action of the unloading valve.

In a gear-type hydraulic pump, a mechanical safety device incorporated to protect the pump from overload is the

Shear pin.

To prevent external and internal leakage in aircraft hydraulic units, the most commonly used type of seal is the

O-ring seal.

Generally the first step in removing an accumulator from an aircraft is to

Relieve system pressure.

Pneumatic systems utilize

Relief valves.

The primary function of the flap over load valve is to

Prevent the flaps from being lowered at airspeeds which would impose excessive structural loads.

The hydraulic component that automatically directs fluid from either the normal source or an emergency source to an actuating cylinder is called a

Shuttle valve.

Chattering of the hydraulic pump during operation is an indication

That air is entering the pump.

Which valve installed in a hydraulic system will have the highest pressure setting?

Thermal relief valve.

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.

The purpose of the pressure regular in a hydraulic system

Maintain system operating pressure within a pressure a predetermined range and to unload the pump

Which is true regarding the ground check of a flap operating mechanism which has just been installed?

If the time required tp operate the mechanism decrease with successive operations, itindicates the air is being worked out of the system

Relief valves are used in pneumatic system

As damage-preventing units.

What type of valve in an aircraft hydraulic system permits fluid to flow freely in one direction, but restricts the rate at which fluid is allowed to flow in the other direction?

Orifice check valve

If an engine-drive 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

Restriction in the pimp outlet.

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

What is used to flush a system normally serviced with MIL-H-5606 hydraulic fluid?

Naphtha or varsol

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

The purpose of a hydraulic pressure regulator is to

Relieve the pump of its load when no actuating units are being operated

Which is a characteristics of petroleum base hydraulic fluid?

Flammable under normal conditions

A flexible sealing element subject to motion is a

Packing

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

Low viscosity, high flash point, high fire point

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

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

What is the viscosity of hydraulic fluid?

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

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 O-ring away from the pressure

Many hydraulic reservoir contain a small quantity of fluid which is not available to the main system pump. This fluid is retained to

Supply fluid the auxiliary pump.

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

Selector valve.

The removal of air from an aircraft hydraulic system is generally accomplished

By operating the various hydraulic components through several cycles.

After a hydraulic accumulator has been installed and air chamber charged, the main system hydraulic pressure gauge will not show a hydraulic pressure reading until

The fluid side of the accumulator has been charged.

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?

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

Which statement about fluids is correct?

All fluids readily transmit pressure.

To check the air charge in a hydraulic accumulator,

Reduce all hydraulic pressure, then observe the reading on the accumulator air gauge.

Hydraulic system thermal relief valves are set to open at a

Higher pressure than the system relief valve.

Seals used with a mineral base hydraulic fluid are identified by which color code?

Blue dot or stripe.

100

Chatter in a hydraulic system is caused by

Air in the system.

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