Cabin Atmosphere Control Systems

Question 1

The function of an expansion valve in a freon cooling system is to act as a metering device and to

Answer 1

Reduce the pressure of the liquid freon.

Question 2

In an operating vapor-cycle cooling system, if the two lines connected to the expansion valve are essentially the same temperature, what does this indicate?

Answer 2

The expansion valve is not metering freon properly.

Question 3

When purging a freon air-conditioning system, it is important to release the charge at a slow rate. What is the reason for the slow-rate discharge?

Answer 3

Prevent excessive loss of refrigerant oil.

Question 4

When a vapor-cycle cooling system is not in operation, what is an indication that the system is leaking freon?

Answer 4

Oil seepage

Question 5

What component might possibly be damaged if liquid refrigerant is introduced into the low side of a vapor-cycle cooling system when the pressure is too high or the outside temperature is too low?

Answer 5

Compressor

Question 6

An aircraft oxygen bottle may be considered airworthy if it has been hydrostatically tested and identified

Answer 6

With the test date, DOT number and serial number stamped on the cylinder near the neck.

Question 7

What is the condition of the refrigerant as it leaves the condenser of a vapor-cycle cooling system?

Answer 7

High pressure liquid.

Question 8

In a gaseous oxygen system, which of the following are vented to blowout plugs in the fuselage skin?

Answer 8

Pressure relief valves

Question 9

What is ventilating air used for on a combustion heater?

Answer 9

Carries heat to the places where needed.

Question 10

one purpose of a jet pump in a pressurization and air-conditioning system is to

Answer 10

Provide for augmentation of airflow in some areas of the aircraft.

Question 11

Frost or ice buildup on a vapor cycle cooling system evaporator would most likely be caused by

Answer 11

Inadequate airflow through the evaporator.

Question 12

Which selection of a turbine engine provides high pressure bleed air to an air cycle machine for pressurization and air-conditioning?

Answer 12

Low or high pressure compressor.

Question 13

What controls the amount of oxygen delivered to a mask in a continuous-flow oxygen systems?

Answer 13

Calibrated orifice

Question 14

In what position should the bottle be placed when adding liquid freon to a vapor-cycle cooling system?

Answer 14

Vertical with the outlet at the bottom.

Question 15

At which component in an air-cycle cooling system does air undergo a pressure and temperature drop?

Answer 15

Expansion turbine

Question 16

For use in pressurized, which is generally the least complicated and requires the least maintenance?

Answer 16

Chemical oxygen generator systmes.

Question 17

Composite oxygen bottles that conform to DOT-E-8162 have a service life of

Answer 17

15 years or 10,000 filling cycles whichever occurs first.

Question 18

In a freon vapor-cycle cooling system, where is cool air obtained for the condenser?

Answer 18

Ambient air

Question 19

What does a steady stream of bubbles indicate when servicing a vapor cycle air conditioning system?

Answer 19

The system is under charged.

Question 20

What is used in some oxygen systems to change high cylinder pressure to low system pressure?

Answer 20

Pressure reducer valve

Question 21

The function of the evaporator in a freon cooling system is to

Answer 21

Lower the temperature of the cabin air.

Question 22

If a high-pressure oxygen cylinder is to be installed in an airplane, it must meet the specifications of the

Answer 22

Department of transportation

Question 23

What type of oxygen system uses the rebreather bag-type mask?

Answer 23

Continuous flow.

Question 24

The purpose of the airflow metering aneroid assembly found ing oxygen diluter demand regulators is to

Answer 24

Regulate airflow in relation to cabin altitude when in driver demand position.

Question 25

What is the main cause of contamination in a gaseous oxygen system?

Answer 25

Moisture

Question 26

If oxygen bottle pressure is allowed to drop below a specified minimum, it may cause

Answer 26

Moisture to collect in the bottle.

Question 27

The position of the thermostatic expansion valve in a vapor-cycle cooling system is determined by temperature and pressure of the

Answer 27

Freon in the outlet of the evaporator.

Question 28

Which is considered a good practice concerning the inspection of heating and exhaust systems of aircraft utilizing a jacket around in the engine exhaust as a heat source?

Answer 28

Supplement physical inspections with periodic operational carbon monoxide detection tests.

Question 29

Where does the last stage of cooling in an air-cycle air-conditioning system occur?

Answer 29

Expansion turbine

Question 30

On transport category aircraft what might be an indication of an over pressure event of the aircraft oxygen system?

Answer 30

The green thermal expansion disk missing.

Question 31

A contaminated oxygen system is normally purged with

Answer 31

Oxygen

Question 32

The operation of an aircraft combustion heater is usually controlled by a thermostat circuit which

Answer 32

Alternatively turns the fuel on and off, a process known as cycling.

Question 33

What is the purpose of a mixing valve in a compressor bleed air air conditioning system?

Answer 33

Control the supply of hot, cool, cool and cold air

Question 34

What type of oil is suitable for use in vapor-cycle cooling systems?

Answer 34

Special high grade refrigeration oil.

Question 35

Which of the following are characteristic of a chemical or solid state oxygen system? 1) An adjustable oxygen release rate. 2) A volume storage capacity about three ties that of compressed oxygen. 3) The system generators are inert below 400 degrees F even under sever impact. 4) A distribution and regulating system similar to gaseous oxygen systems.

Answer 35

2&3

Question 36

The basic-air cycle cooling system consists of

Answer 36

A source of compressed air, heat exchangers, and a turbine.

Question 37

Which prevents a sudden loss of pressurization in the event that there is a loss of pressurization source?

Answer 37

Delivery air duct check valve.

Question 38

1) A small amount of water in a vapor-cycle cooling system can freeze in the receiver-dryer and stop the entire system operation. 2)Water in a vapor-cycle cooling system will react with refrigerant to form hydrochloric acid which is highly corrosive to the metal in the system. Regarding the above statements,

Answer 38

Only no.2 is true

Question 39

Before a high-pressure oxygen cylinder is serviced, it must be the correct type and have been

Answer 39

Hydrostatically tested within the proper time interval.

Question 40

The point at which freon flowing through a vapor-cycle cooling system gives up heat and changes from a gas to a liquid is the

Answer 40

Condenser

Question 41

What may be used as a lubricant on oxygen system tapered pipe thread connections?

Answer 41

Teflon tape

Question 42

The primary function of the cabin pressurization system airflow valve is to

Answer 42

Maintain the desired cabin pressure

Question 43

What component in a vapor-cycle cooling system would most likely be at fault if a system would not take a freon charge?

Answer 43

Expansion valve

Question 44

The purpose of the dump valve in a pressurized aircraft is to relieve

Answer 44

All positive pressure from the cabin.

Question 45

The cabin pressure control setting has a direct influence upon the

Answer 45

Outflow valve opening

Question 46

Turbine engine air used for air-conditioning and pressurization is generally called

Answer 46

Bleed air

Question 47

An aircraft pressurization cycle is normally considered to be

Answer 47

One complete series of events or operations that recur regularly

Question 48

How often should standard weight high-pressure oxygen cylinders be hydrostatically tested?

Answer 48

Every 5 years

Question 49

After cleaning or replacing the filtering element in a combustion heater fuel system, the system should be pressurized and

Answer 49

All connections checked for leaks

Question 50

The cabin pressurization modes of operation are

Answer 50

differential, unpressurized, and isobaric.

Question 51

What is the condition of the refrigerant as it leaves the evaporator of a vapor-cycle cooling system?

Answer 51

Low pressure vapor

Question 52

On some cabin pressurization systems, pressurization on the ground is restricted by the

Answer 52

Main landing gear operated switch.

Question 53

How is the cabin pressure of an aircraft maintained in flight?

Answer 53

By controlling the rate of the air flowing out of the cabin.

Question 54

The component that determines the pressure level in the cabin is the cabin air pressure

Answer 54

Outflow valve

Question 55

The point at which freon flowing through a vapor-cycle cooling system absorbs heat and changes from a liquid to a gas is the

Answer 55

Evaporator

Question 56

When servicing an air-conditioning system that has lost all of its freon, it is necessary to

Answer 56

Check oil and add as necessary, evacuate the system, and add freon.

Question 57

The purpose of pressurizing aircraft cabins is to 1) Create the proper environment for prevention of hypoxia. 2) Permit operation at high altitudes. Regarding the above statements,

Answer 57

Both no.1 and no.2 are true

Question 58

How is the cabin pressure of a pressurized aircraft usually controlled?

Answer 58

By an automatic outflow valve that dumps all the pressure in excess of the amount for which it is set.

Question 59

The air-cycle cooling system produces cold air by

Answer 59

Extracting heat energy across an expansion turbine.

Question 60

Oxygen systems in unpressurized aircraft are generally of the

Answer 60

Continuous-flow and pressure-demand types.

Question 61

In the diluter demand oxygen regulator, when does the demand valve operate?

Answer 61

When the user breathes.

Question 62

What component of a pressurization system prevents the cabin altitude from becoming higher than airplane altitude?

Answer 62

Negative pressure relief valve.

Question 63

(Refer to figure 13.) Determine what unit is located immediately downstream of the expansion valve in a freon refrigeration sysem.

Answer 63

Evaporator coils

Question 64

1) Oxygen used in aircraft systems is at least 99.5% and is practically water free. 2) Oxygen used in aircraft systems is at least 99.5% and is hospital quality. Regarding the above statements,

Answer 64

only no.1 is true

Question 65

Hot compressor bleed air operates the conditioned air system on some turbine aircraft, cold air supplied by the

Answer 65

Air cycle air conditioning

Question 66

A pressurization controller uses

Answer 66

Barometric pressure, cabin altitude, and cabin rate of change.

Question 67

How should you determine the amount of oxygen in a portable, high-pressure cylinder?

Answer 67

Read the pressure gauge mounted on the cylinder.

Question 68

The function of the condenser in a freon cooling system is to

Answer 68

Transfer heat from the freon gas to ambient air.

Question 69

To be eligible for recharging, a DOT 3HT oxygen cylinder must have been hydrostatically tested every three years and be retired from service after

Answer 69

24 years or 4,380 filling cycles.

Question 70

If the cabin rate of climb is too great, the control should be adjusted to cause the

Answer 70

Outflow valve to close faster

Question 71

Which best describes cabin differential pressure?

Answer 71

Difference between the ambient and internal air pressure.

Question 72

When charging a vapor-cycle cooling system after evacuation, the low-pressure gauge fails to come out of a vacuum. What is indicated?

Answer 72

Blockage in the system.

Question 73

What test is used to determine the serviceability of an oxygen cylinder?

Answer 73

Pressure test with water.

Question 74

If the liquid level gauge in a vapor-cycle cooling system indicates a low freon charge, the system should

Answer 74

Be operated for a period of time to reach a stable condition and then the freon level rechecked.

Question 75

What is the condition of the refrigerant as it enters the condenser of a vapor-cycle cooling system?

Answer 75

High-pressure vapor

Question 76

1) Usually bleed air from a gas-turbine engine compressor can be safely used for cabin pressurization. 2) Independent cabin condition air machines (air cycle machine) can be powered by bleed air from an aircraft turbine engine compressor. Regarding the above statements,

Answer 76

Both no.1 and no.2 are true.

Question 77

What is the condition of the refrigerant as it enters the evaporator of a vapor-cycle cooling system?

Answer 77

Low-pressure liquid

Question 78

What unit in a vapor-cycle cooling system serves as a reservoir for the refrigerant?

Answer 78

Receiver-dryer

Question 79

(Refer to Figure 14.) one hour after an oxygen system was charged for a leakage check, the oxygen pressure gauge read 460 PSI at 63 degrees F; 6 hours later the temperature was 51 degrees F. (A 5 PSI change is the maximum allowable in a 6-hour period.) What pressure gauge readings would be acceptable to remain within the allowable limits?

Answer 79

445 to 450 PSI

Question 80

The evacuation of a vapor-cycle cooling system removes any water that may be present by

Answer 80

Lowering the boiling point of the water and drawing out the vapor.

Question 81

The purpose of a subcooler in a vapor-cycle cooling system is to

Answer 81

Cool the freon to prevent premature vaporization.

Question 82

When an aircraft's oxygen system has developed a leak, the lines and fittings should be

Answer 82

Bubble tested with a special soap solution manufactured specifically for this purpose.

Question 83

The primary difference between aviation breathing oxygen and other types of commercially available compressed oxygen is that

Answer 83

Aviation breathing oxygen has had all the water vapor removed.

Question 84

When refrigerant-12 is passed over an open flame, it

Answer 84

Changes to phosgene gas

Question 85

How can it be determined that a vapor-cycle cooling system is charged with the proper amount of freon?

Answer 85

Air bubbles in the sight glass disappear.

Question 86

In a high pressure oxygen system, if the pressure reducer fails, what prevents high-pressure oxygen from entering the system downstream?

Answer 86

Pressure relief valve

Question 87

High-pressure cylinders containing oxygen for aviation use can be identified by their

Answer 87

Green color and words 'Aviators Breathing Oxygen' stenciled in 1-inch white letters.

Question 88

In the combustion heater, combustion air system, what prevents too much air from entering the heaters as air pressure increases?

Answer 88

Either a combustion air relief valve or a differential pressure regulator.

Question 89

What controls the operation of the cabin pressure regulator?

Answer 89

Cabin altitude