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2A353 Volume 2 CH 3
Air Force Tactical Aircraft Maintenance CDC Questions 2016
| Question | Answer |
|---|---|
| Define Matter | Any substance that occupies space and has weight |
| Since Liquids and gases have many properties in common, how are they frequently classified? | AS fluids |
| All matter is made up of what? | Molecules |
| Which matter has the property of resisting changes in shape when a force is applied? | Solid |
| When sufficient force to a solid causes distortion, the solid is said to have exceeded what? | Its elastic limit |
| Which factors affect the amount of expansion and contraction of a solid? | The amount of temperature change and the expansion characteristics of the solid |
| what are the most outstanding characteristics of a liquid? | Its ability to conform to the shape of its containing vessel and that it has a free surface |
| for a liquid to transmit a pushing force, what condition must exist first? | It must be completely enclosed in a container |
| what would cause a cylinder of air to increase in pressure when placed in the sun? | The air expands as its temperature increases, and since it is confined by the cylinder, its pressure will increase |
| what is one of the main differences in the characteristics of gases when compared to liquids? | Gases are compressible while liquids are not |
| State the basic principles of Pascal's Law | When a fluid is confined and force is applied, this force is transmitted equally to all points in the system |
| Under what conditions does Pascal's Law not apply to fluids? | Pascals law does not apply to fluids in motion |
| State the basic principle of Boyle's Law | If the pressure on a confined gas varies, its volume will vary inversely in the same proportion as long as the temperature does not change |
| Using Charles' Law, explain the effect of heating a gas in a cylinder that has a movable piston | Heating a confined gas will cause expansion in direct proportion to its temperature change, thus causing the piston to move |
| What is another name for the Boyle's-Charles' Law? | General Gas Law |
| What is the mechanical advantage ratio if a 60 pound force is used to raise a 240 pound weight? | 4:1 |
| What is the mechanical advantage if a 3 pound force is used to raise 99 pounds? | 33:1 |
| What characteristic of a fluid determines its resistance to flow? | Viscosity |
| What effect does an orifice have on fluid-flow when compare to a venturi? | An orifice will cause more turbulence and thus more energy loss than a venture because it is not streamlined |
| How can resistance to flow be reduced? | By streamlining the flow |
| What pressure difference can be observed during fluid-flow through a venture? | There is a pressure drop at the narrow opening of a venture as the rate of flow of the liquid increases at this point. The pressure will increase again after passing through the throat. |
| How much fluid should a reservoir hold? | Enough fluid to supply the normal operating needs of the system, along with an additional amount to replace fluid lost through minor leakage |
| Why do nonpressurized reservoirs have space above the fluid? | To allow the fluid to purge itself of air bubbles that are picked up from the system |
| What prevents foreign material from entering the reservoir during servicing? | a wire screen |
| What are the two main reasons for pressurizing a reservoir? | First, it stops the fluid from foaming at high altitudes, second, it ensures a positive supply of fluid to the pumps |
| How do you service a pressurized hydraulic reservoir with fluid? | Use a portable servicing cart |
| What unit in the pressurized hydraulic reservoir pressurizes the hydraulic fluid to 5 psi? | A piston spring |
| To service or perform maintenance on an air-pressurized reservoir, what is the first thing you must do:? | Depressurize the reservoir |
| Name 3 functions of the air pressurized reservoir pressure regulator? | It regulates the pressure to the reservoir, acts like a relief valve, and has a differential valve to allow equalization of pressures between outside air and air inside the reservoir |
| How are pumps classified? | By their displacement output |
| what two purposes does the hand pump serve? | It can be used as an emergency source of pressure or as an auxiliary source of pressure for ground checking the operation of the sytem units |
| When the hand pump handle is on the retraction stroke, which check valve is closed? | The inlet check valve |
| What indicates that either check valve inside the hand pump has malfunctioned? | The hand pump will become completely inoperative |
| If a third check valve is installed, what could be the problem if fluid is only sent into the system on the extension stroke? | The inlet check valve is malfunctioning |
| What is a drawback of a constant volume pump? | As long as the pump rotates, the fluid flow it produces will eventually build up more pressure high enough in the confines area to burst the lines and container |
| What is the thinned portion on the drive shaft of a gear-type pump called? | Shear section |
| On a Vane type pump, what keeps the vanes against the housing walls? | Springs |
| In the constant volume piston pump, what drives the cylinder block? | Universal Link |
| Why does a constant volume pump always have a constant intake and output of fluid? | There are always pistons somewhere between the upper and lower position |
| What does the suction boost pump do for engine driven pumps? | Ensures the engine pumps get an adequate supply of fluid |
| What regulates pressure in a variable volume pump? | An integral flow control valve |
| What is the main difference between a Vickers pump cylinder block and a yoke in when the system is at 0 psi? | The extreme angle position, full flow |
| What are the two major component groups of the Kellogg pump? | The rotating group and the pressure compensating group |
| What determines the length of the Kellogg pumps piston stroke? | The angle setting of the cam plate |
| What is the purpose of the creep plates in a Stratopower pump? | cooler operation |
| Describe the pistons of a stratopower pump | The pistons have fairly large hollow centers connected with cross dilled holes |
| Which way would you turn the adjusting screw on the stratopower pump to increase pressure? | Clockwise |
| What is the purpose of a hydraulic motor? | To convert hydraulic pressure into rotary mechanical motion |
| What can be used to control the speed of a hydraulic motor? | Flow control valve |
| Explain the principle of a jackscrew | The screw remains stationary and the nut turns |
| What is the purpose of an accumulator in a hydraulic system? | To store a volume of fluid under pressure, provide space for the thermal expansion, and act as a cushion against pressure surges |
| What is the most common type of accumulator used? | Cylindrical type |
| Where is the air servicing valve located on the piston accumulator? | Piston |
| What is the piston accumulator serviced with? | Dry air or nitrogen |
| Which accumulator has four separate chambers? | Self displacing accumulator |
| What is the only moving part of a self-displacing accumulator? | The piston |
| In the self-displacing accumulator system, where is the relief valve located? | Between the pressure line and return line |
| What are the three basic parts of a filter assembly? | head, element, and bowl |
| Which part of the filter assembly is mounted to the aircraft? | head |
| What does micron rating mean? | the amount of dirt or contaminates that can be filtered out |
| What are the 2 ways fluids can usually flow through a filter assembly? | Normal flow and bypass flow |
| How are the hydraulic manifolds designed? | To conserve space in the aircraft and permit ease of removing and replacing components |
| Why is it physically impossible to install the wrong valve in a manifold? | Alignment pins make it impossible |
| What is the purpose of an actuating cylinder? | To transform fluid pressure into mechanical force |
| What does Tandem mean? | One behind the other |
| How many pistons are in a tandem actuator? | Two |
| What is the purpose of the internal snubber actuator? | To reduce damage to mechanisms by preventing the actuator from slamming into its end of travel with great force |
| Where is the main system relief valve normally installed in a hydraulic system? | Between the pressure line and return line |
| What is the purpose of a selector valve? | To control and direct the flow of hydraulic fluid |
| What is the advantage of a slide selector valve over the poppet type? | Its ability to meter fluid |
| What is the purpose of a check valve? | To allow free flow in one direction and no flow in the other direction |
| What are the different types of automatic check valves? | Ball, Cone, and flapper |
| Which type of check valve is used primarily in low-pressure systems, such as the air pressurized reservoir system? | Flapper check valve |
| What order of events do sequence valves set? | Branches of hydraulic circuit |
| What is the purpose of the pressure regulator besides maintaining pressure within a predetermined range? | Permit the pump to turn without resistance |
| What component is used in systems to limit the speed of movement of such items as wing flaps and landing gear? | restrictors |
| Where is a restrictor check valve usually installed? | In the alternating line that carries fuild from the cylinder |
| What names are commonly used for the manually operated shutoff valves? | Globe and Needle |
| What are the parts of a motor-operated shutoff valve? | An electric motor, a slide, valve body, limit switches, and an indicator |
| What is installed in the hydraulic system to prevent total fluid loss? | A hydraulic fuse |
| How is internal leakage of a shuttle valve usually repaired? | By removing the unit and flushing it with clean hydraulic fluid |
| What is another name for the supply section of a basic hydraulic system? | Suction manifold |
| Which section of a basic hydraulic system contains all the lines and units starting with the pump to the selector valve? | Pressure manifold |
| What are the four units of a hand pump system? | Reservoir, hand pump, actuator, and manual shutoff valve |
| How much pressure is required to lift 2300 pounds using an actuator with 2 square inches of working area? | 1150 psi |
| What would happen to a constant volume pump hydraulic system if there were no relief valves? | The pressure would build up to the point where the tubing would rupture or damage units |
| In order to properly design a hydraulic system, what must be considered? | The pressure needed to operate the system |
| What is the disadvantage of a constant volume pump hydraulic system, which has a relief valve but does not have any components to relieve the pumps workload? | After a few hours of constant load, the pump would fail |
| What pressure does the pressure regulator and pressure switch maintain? | The pressure between the two designed pressure limits |
| Where does the fluid-flow go when a regulator is kicked out? | Returns to the reservoir through the regulator bypass |
| What does the term operating range mean? | The difference between two design limits |
| What is the main purpose of the accumulator in the regulator or pressure switch controlled system? | Prevent rapid loss of pressure due to fluid leaks in the return lines, which would cause continuous kick in and kick out. |
Created by:
wcarrel11
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