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hydrualic and pneuma
Hydraulic and pneumatic power systems
| Question | Answer |
|---|---|
| a unit which transforms hydraulic pressure into linear motion is called | an actuating cylinder |
| characteristics of MIL-H-8446 hydraulic fluid are | Light purple color, phosphate ester base, fire resistant, butyl rubber seals. |
| components containing phosphate ester-base hydraulic fluid may be cleaned with | stoddard solvent |
| which is a characteristic of synthetic-base hydraulic fluid? | high flash point. |
| what is commonly used to connect an emergency source of power, and at the same time disconnect the normal hydraulic source from critical parts of a landing gear or wheel braking system for operation( usually when the normal source of system fails)? | shuttle valve |
| what is the purpose of using backup rings with O-rings in hydraulic systems above 1,500 PSI | prevent high pressure from extruding the seal between the moving stationary part. |
| pneumatic systems utilize | relief valves |
| which seals are use with pretoleum-base hydraulic fluids? | buna-N |
| which of the following is adversely affected by atmospheric humidity if left unprotected? | skydrol hydraulic fluid |
| which is true regarding the ground check of a flap operating mechanism which has just been installed? | if the time required to operated the mechanis, decreases with succesive operations, it indicates the air is being worked out of the system. |
| a worn hydraulic pump shaft seal can normally be detected by | hydraulic fluid flowing from the pump drain line |
| 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 | restriction in the pump outlet |
| 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 | hand pump outport check valve |
| phosphate ester-base hydraulic fluid is very susceptible to contamination from | water in the atmosphere |
| the hydraulic system accumulators serve which of the following functions? | supplement the system pump when demand is beyond the pump's capacity and store power for limited operation of components if the pump is not operating |
| 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 the other direction? | orifice check valve |
| 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 diameter? | 20 percent |
| characteristics of MIL-H-5606 hydraulic fluids are | red in color, petroleum base, will burn, uses synthetic rubber seals |
| which seal/material is used with phosphate este-base hydraulic fluids? | butyl rubber |
| the primary purpose of a hydraulic actuating unit is to transform | fluid pressure into work |
| severe kickback of the emergency hydraulic hand pump handle during the normal intake stroke will indicate which of the following | the hand pump outlet check valve is sticking open |
| when hydraulic system pressure control and relief units fail to function properly, how are most systems protected against overpressure? | a shear section on the main hydraulic pump drive shaft |
| which must be done before adjusting the relief valve of a main hydraulic system incorporating a pressure regulator? | eliminate the actin of the unloading valve. |
| the component in the hydraulic system that is used to direct the flow of fluid is the | selector valvea hydraulic motor converts fluid pressure to |
| a hydraulic motor converts fluid pressure to | rotary motion |
| a typical high-pressure pneumatic system, if the moisture seperator does not vent accumulated water when the compressor shuts down, a likely cause is a | malfunctioning solenoid dump valve |
| what function does the absolute pressure regulator perform in the pneumatic system? | regulates the compressor inlet air to provide a stabilized source of air for the compressor. |
| which of the following lists only desirable properties of a good hydraulic fluid that has chemical stability? | low viscocity, high flash point, high fire point |
| when servicing aircraft hydraulic systems, use the type fluid specified in the | aircraft manufacturer's maintenance manual or instruction plate affixed to the unit. |
| the purpose of restrictors in hydraulic systems is to | control the rate of movement of hydraulically operated mechanisms |
| a loud hammering noise in a hydraulic system that has an accumulator usually indicates | too low or no preload in the accumulator |
| materials which are skydrol compatible or resistant include | common aircraft metals, polyurethane, and epoxy paints. |
| one of the main advantages of slydrol is its | wide operating temperature |
| the unit on a hydraulic system that requires a certain action to be accomplished before another action can begin is called a | sequence valve |
| how can the proper hydraulic fluid to be used in an airplane be determined? | by consulting the aircraft manufacturer's service manual |
| 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 towrds zero. |
| the main system pressure relief valve in a sumple hydraulic system equipped with a power control valve should be adjusted | with the power control valve held in the CLOSED position |
| a hydraulic system operational check during ground runup of an aircraft indicates that the wing flaps cannot be lowered using the main hydraulic system, but can be lowered by using the emergency hand pump. which is teh most likely cause? | the fluid level in the reservoir is low. |
| 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 viscocity of hydraulic fluid? | the internal resistance of a fluid which tends to prevent it from flowing |
| which characteristics apply to aircraft hydraulic systems? | minimum maintenance requirements, lightweight, and simple to inspect |
| what safety device is usually located between the driven unit and the hydraulic pump drive shaft? | pump drive coupling shear section |
| generally, the first step in removing an accumulator from an aircraft is to | relieve system pressure |
| a crossflwo valve which is designed to bypass fluid from one side of an actuating cylinder to the other side, under certain conditions, may be found in some aircraft installed in the | landing gear system |
| that purpose of a hydraulic pressure regulator is to | relieve the pump of its load when no actuating units are being operated |
| 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 |
| seals used with a mineral-base hydraulic fluid are indentify by which color code | blue dot or stripe |
| a flexible sealing elemenet subject to motion is | packing |
| (refer to figure 11) an AN flared tube fitting is referred to in which picture? | 1 |
| the internal resistance of a fluid which tends to prevent it from flowing is called | viscocity |
| in a gear-type hydraulic pump, a mechanical safety device incorporated to protect the pu,p from overload is the | shear pin |
| if an aircraft hydraulic system requires mineral-base hydraulic fluid, but phosphate ester-base hydraulic fluid is use, what will be the effect on the system? | system will be contaminated, fluids will not belnd, and the seals will fail. |
| the removal of air from an aircraft hydrauliz system is generally accomplished | by operating the various hydraulic components through several cycles |
| a hydraulic accumulator is charged with an air preload of 1,000 psi. when a hydraulic system pressure of 3,000 psi is developed, the pressure on the air side of the accumulator will be | 3,000 psi |
| before removing the filler cap of a pressurized hydraulic reservoir, in order to service the system, you must | relieve the air pressure |
| hydraulic system thermal relief valves are set to open at a | higher pressure than the system relief valve |
| pressure is a term used to indicate the force per unit area. pressure is usually expressed in | punds per square inch |
| if two actuating cylinders which have the same cross-sectional area but different lenghts of stroke are connected to the same source of hydraulic pressure, they will exert | equal amounts of force and will move at the same rate of speed. |
| which valve installed in a hydraulic system will have the highest pressure setting? | thermal relief valve |
| if an aircraft's constant-pressure hydraulic system cycles more frequently than usual and no fluid leakage can be detected, the most probable cause is | low accumulator air preload |
| relief valves are used in pneumatic systems | as damage-preventing units |
| if hydraulic fluid is released when the air valve core of the accumulator is depressed, it is evidence of | a ruptured diaphram or leaking seals |
| the air that is expended and no longer needed when an actuating unit is operated in a pneumatic system us | exhausted or dumped, usually overboard |
| what type of packing should be used in hydraulic components to be installed in a system containing skydrol? | packing materials made for ester-base fluids |
| teflon hose that has developed a permanent set from being exposed to high pressure or temperature should | not be straightnened or bent further |
| the isntallation of a new metal hydraulic line should be made with | enough bends to allow the tube to expand and contract with themperature changes and absorb vibrations. |
| an aircraft pneumatic system, which incorporates an engine-driven multistage reciprocating compressor, also requires | a moisture seperator |
| 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 |
| what is used to flush a system normally services with MIL-H-5606 hydraulic fluid? | naptha or varsol |
| the primary function of the flap overload valve is to | prevent the flaps from being lowered at a airspeed which would impose excessive structural loads. |
| which of the following safeguards ensures proper system operation and mitigates damage to non-metallic components of the hydraulic system? | when adding fluid to a system, use the type specified in the aircraft manufacturer's maintenance manuel or on the instruction plate affixed to the reservoir or unit being serviced |
| how is the air in a hydraulic accumulator prevented from entering the fluid system? | by physically seperating the air chamber from the oil chamber with a flexible movable seperator. |
| a hydraulic pump is a constant-displacement type if it | delivers a uniform rate of fluid flow |
| which of the following allows fluid to flow unimpeded in one direction but prevents fluid flow in the other direction? | check valve |
| if the hydraulic system pressure is normal while engine-driven oumo us running, but there is no pressure after the engine has been shut off, it indicates | no air pressure in the accumulator |
| which statement about fluids is correct? | all fluids readily transmit pressure |
| excluding lines, which components are required to make up a si,ple hydraulic system? | pump, reservoir, selector valve, and actuator |
| after a hydraulic accumulator has been installed and air chamber charged, the main system hydraulic pressure gauge wll not show a hydraulic pressure reading until | the fluid side of the accumulator has been charged |
| what is one advantage of piston-type hydraulic motors over electric motors? | there is no fire hazard if the motor is stalled |
| 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 |
| a common cause of slow actuation of hydraulic components is | internal leakage in the actuating system |
| 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 setting are adjusted first. |
| 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 the reservoir? | air pressure regulator |
| hydraulic fluid filtering elemnts constructed of porous paper are normally | discarded at regular intervals and replaced with ned filtering elements |
| which is a characteristic of petroleum-base hydraulic fluid? | flammable under normal conditions(5606) |
| 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 of the main hydraulic system.` |
| to protect seals from damage when installed over a threaded section should be | covered with a suitable sleeve |
| how many of these seals are used with pertoleum-base hydraulic fluids? | neoprene, buna-N |
| many hydraulic reservoirs contain a small quantity of fluid which is not avalable to the main system pump. this fluid is retained to | supply fluid to the auxiliary pump |
| a pilot reports that when the hydraulic pump is running, the pressure is normal. however, when the pump us stopped, no hydraulic pressure is avalable this is an indication of | leaking accumulator air valve |
| using a hand pump, pressure of 100 psi has been built up un a hydraulic system. the hand pu,p puston is 1 inch in diameter. a 1-2 inch line connects the hand pump to an actuating cylinder 2 inches in diameter. what is the pressure in the line between th.. | 100 psi |
| to check the air charge in a hydraulic accumulator, | reduce all hydraulic pressure, then observe the reading on the accumulator air gauge. |
| characteristics of MIL-H-7644 hydraulic fluids are | blue color, vegetable base, will burn, natural rubber seals. |
| quick disconnect couplings im hydraulic systems provide a means of | quickly connecting and disconnecting hydraulic lines without loss of fluid or entrance of air into the system. |
| what is the main purpose of a pressurized reservoir in a hydraulic system? | prevent hydraulic pump cavitation. |
| if a rigid tube is too short for the flare to reach its seat before tighting, oulling it into place by tighting | may distort the flare |
| most variable displacement aircraft hydraulic pumps in use | contain a built-in means of a system pressure regulation |
| 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 |
| where can information be obtained about the compatibility of fire-resistant hydraulic fluid with aircraft materials? | fluid manufacturer's technical bulletins. |
| two types of hydraulic fluids currently being used in civil aircraft are | mineral base and phosphate ester base |
| if a hydraulic brake system uses neoprene rubber packing materials, the correct hydraulic fluid to service the system is | mineral-base oil |
| chattering of the hydrauilic pump during operation is an indication | that air is entering the pump |
| some hydraulic systems incoporate a device which is designed to remain open to allow a normal fluid of flow in the line, but closed if the fluid flow increases above an established rate. this device is generally reffered to as a | hydraulic fuse |
| petroleum-base hydraulic fluid is which color? | red |
| heat exchanger cooling units are required in some aircraft systems because of | high pressures and hugh rates of fluid flow |
| unloading valves are used with many engine-driven hydraulic pumps to | relieve the pump pressure |
| the purpose of the pressure regulator in a hydraulic system is to | maintain system operating pressure within a predetermined range and to unload the pump |
| (Refer to figure 12) which illustration(s) show(s) the correct spiral for teglon backup rings? | 1 and 3 |
| one of the distinguishing charactersitics of an open-center selector valve used in a hydrauli system is that | fluid flows through the valve in the OFF position |
| chatter in a hydraulic system is caysed by | air in the system |
| if fluid is added to a reservoir in a constant pressure hydraulic system while the system is pressurized, what will result? | the fluid level will increase when system pressure is reduced |
| 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 |
| what type of selector valve is one of the most commonlu used in a hydraulic system to provide for simultaneous flow of fluid into and out of a connected actuating unit? | fpur port, closed-center valve |
Created by:
cordon.gabriel
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