AIRCRAFT CABIN ATMOSPHERE
SYSTEM -BLOCK VIII , PREPWARE
2025 UPDATED QUESTIONS WITH
ACTUAL ANSWERS VERIFIED BY
EXPERTS
Hot compressor bleed air operates the conditioned air system on some turbine aircraft, cold air
supplied by the - CORRECT ANSWER>>>>air cycle air conditioning.
For use in pressurized aircraft, which oxygen supply is generally the least complicated and
requires the least maintenance? - CORRECT ANSWER>>>>Chemical oxygen generator
systems.
What is the main cause of contamination in a gaseous oxygen system? - CORRECT
ANSWER>>>>Moisture.
Where does the last stage of cooling in an air-cycle air conditioning system occur? - CORRECT
ANSWER>>>>Expansion turbine.
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 - CORRECT ANSWER>>>>condenser.
The point at which freon flowing through a vapor-cycle cooling system absorbs heat and changes
from a liquid to a gas is the - CORRECT ANSWER>>>>evaporator.
How is the cabin pressure of a pressurized aircraft usually controlled? - CORRECT
ANSWER>>>>By an automatic outflow valve that dumps all the pressure in excess of the
amount for which it is set.
Which is considered a good practice concerning the inspection of heating and exhaust systems of
aircraft utilizing a jacket around the engine exhaust as a heat source? - CORRECT
ANSWER>>>>Supplement physical inspections with periodic operational carbon monoxide
detection tests.
On some cabin pressurization systems, pressurization on the ground is restricted by the -
CORRECT ANSWER>>>>main landing gear operated switch.
The cabin pressure control setting has a direct influence upon the - CORRECT
ANSWER>>>>outflow valve opening.
The function of the evaporator in a freon cooling system is to - CORRECT ANSWER>>>>lower
the temperature of the cabin air.
1
,What is the purpose of a mixing valve in a compressor bleed air air conditioning system? -
CORRECT ANSWER>>>>Control the supply of hot, cool, and cold air.
What component of a pressurization system prevents the cabin altitude from becoming higher
than airplane altitude? - CORRECT ANSWER>>>>Negative pressure relief valve.
If the liquid level gauge in a vapor-cycle cooling system indicates a low freon charge, the system
should - CORRECT ANSWER>>>>be operated for a period of time to reach a stable condition
and then the freon level rechecked
If the cabin rate of climb is too great, the control should be adjusted to cause the - CORRECT
ANSWER>>>>outflow valve to close faster.
The position of the thermostatic expansion valve in a vapor-cycle cooling system is determined
by temperature and pressure of the - CORRECT ANSWER>>>>freon in the outlet of the
evaporator
The function of the condenser in a freon cooling system is to - CORRECT
ANSWER>>>>transfer heat from the freon gas to ambient air.
The function of an expansion valve in a freon cooling system is to act as a metering device and
to - CORRECT ANSWER>>>>reduce the pressure of the liquid freon.
Which prevents a sudden loss of pressurization in the event that there is a loss of the
pressurization source? - CORRECT ANSWER>>>>Delivery air duct check valve.
When servicing an air conditioning system that has lost all of its freon, it is necessary to -
CORRECT ANSWER>>>>check oil and add as necessary, evacuate the system, and add freon.
Which section of a turbine engine provides high pressure bleed air to an air cycle machine for
pressurization and air conditioning? - CORRECT ANSWER>>>>Low or high pressure
compressor.
At which component in an air-cycle cooling system does air undergo a pressure and temperature
drop? - CORRECT ANSWER>>>>Expansion turbine.
In a freon vapor-cycle cooling system, where is cooling air obtained for the condenser? -
CORRECT ANSWER>>>>Ambient air.
What is ventilating air used for on a combustion heater? - CORRECT ANSWER>>>>Carries
heat to the places where needed.
Turbine engine air used for air conditioning and pressurization is generally called - CORRECT
ANSWER>>>>bleed air.
2
,In the combustion heater, combustion air system, what prevents too much air from entering the
heaters as air pressure increases? - CORRECT ANSWER>>>>Either a combustion air relief
valve or a differential pressure regulator.
How is the cabin pressure of an aircraft maintained in flight? - CORRECT ANSWER>>>>By
controlling the rate of the air flowing out of the cabin.
What controls the operation of the cabin pressure regulator? - CORRECT ANSWER>>>>Cabin
altitude.
The basic air-cycle cooling system consists of - CORRECT ANSWER>>>>a source of
compressed air, heat exchangers, and a turbine.
The purpose of the dump valve in a pressurized aircraft is to relieve - CORRECT
ANSWER>>>>all positive pressure from the cabin.
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 air temperature is
too low? - CORRECT ANSWER>>>>Compressor.
How can it be determined that a vapor-cycle cooling system is charged with the proper amount
of freon? - CORRECT ANSWER>>>>Air bubbles in the sight glass disappear.
When charging a vapor-cycle cooling system after evacuation, the low-pressure gauge fails to
come out of a vacuum. What is indicated? - CORRECT ANSWER>>>>Blockage in the system.
What component in a vapor-cycle cooling system would most likely be at fault if a system would
not take a freon charge? - CORRECT ANSWER>>>>Expansion valve.
Frost or ice buildup on a vapor-cycle cooling system evaporator would most likely be caused by
- CORRECT ANSWER>>>>inadequate airflow through the evaporator.
What test is used to determine the serviceability of an oxygen cylinder? - CORRECT
ANSWER>>>>Pressure test with water.
How often should standard weight high-pressure oxygen cylinders be hydrostatically tested? -
CORRECT ANSWER>>>>Every 5 years.
To be eligible for recharging, a DOT 3HT oxygen cylinder must have been hydrostatically tested
every three years and be retired from service after - CORRECT ANSWER>>>>24 years or
4,380 filling cycles.
Which oxygen system employs a regulator that operates only when the user inhales? -
CORRECT ANSWER>>>>Continuous-flow system.
3
, The component that determines the pressure level in the cabin is the cabin air pressure -
CORRECT ANSWER>>>>outflow valve.
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 - CORRECT ANSWER>>>>normal system power pump.
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 - CORRECT ANSWER>>>>inlet of the main
hydraulic system.
To check the air charge in a hydraulic accumulator, - CORRECT ANSWER>>>>reduce all
hydraulic pressure, then observe the reading on the accumulator air gauge.
How would the air pressure charge in the accumulator be determined if the engine is inoperative,
but the system still has hydraulic pressure? - CORRECT ANSWER>>>>Operate a hydraulic
unit slowly and note the pressure at which a rapid pressure drop begins as it goes toward zero.
How many of these seals are used with petroleum-base hydraulic fluids? - CORRECT
ANSWER>>>>Neoprene, Buna-N.
Hydraulic system thermal relief valves are set to open at a - CORRECT ANSWER>>>>higher
pressure than the system relief valve.
Chatter in a hydraulic system is caused by - CORRECT ANSWER>>>>air in the system.
If hydraulic fluid is released when the air valve core of the accumulator is depressed, it is
evidence of - CORRECT ANSWER>>>>a ruptured diaphragm or leaking seals.
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? - CORRECT
ANSWER>>>>20 percent.
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 - CORRECT ANSWER>>>>no air
pressure in the accumulator.
The purpose of restrictors in hydraulic systems is to - CORRECT ANSWER>>>>control the rate
of movement of hydraulically operated mechanisms.
A common cause of slow actuation of hydraulic components is - CORRECT
ANSWER>>>>internal leakage in the actuating unit.
A loud hammering noise in a hydraulic system that has an accumulator usually indicates -
CORRECT ANSWER>>>>too low or no preload in the accumulator.
4
SYSTEM -BLOCK VIII , PREPWARE
2025 UPDATED QUESTIONS WITH
ACTUAL ANSWERS VERIFIED BY
EXPERTS
Hot compressor bleed air operates the conditioned air system on some turbine aircraft, cold air
supplied by the - CORRECT ANSWER>>>>air cycle air conditioning.
For use in pressurized aircraft, which oxygen supply is generally the least complicated and
requires the least maintenance? - CORRECT ANSWER>>>>Chemical oxygen generator
systems.
What is the main cause of contamination in a gaseous oxygen system? - CORRECT
ANSWER>>>>Moisture.
Where does the last stage of cooling in an air-cycle air conditioning system occur? - CORRECT
ANSWER>>>>Expansion turbine.
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 - CORRECT ANSWER>>>>condenser.
The point at which freon flowing through a vapor-cycle cooling system absorbs heat and changes
from a liquid to a gas is the - CORRECT ANSWER>>>>evaporator.
How is the cabin pressure of a pressurized aircraft usually controlled? - CORRECT
ANSWER>>>>By an automatic outflow valve that dumps all the pressure in excess of the
amount for which it is set.
Which is considered a good practice concerning the inspection of heating and exhaust systems of
aircraft utilizing a jacket around the engine exhaust as a heat source? - CORRECT
ANSWER>>>>Supplement physical inspections with periodic operational carbon monoxide
detection tests.
On some cabin pressurization systems, pressurization on the ground is restricted by the -
CORRECT ANSWER>>>>main landing gear operated switch.
The cabin pressure control setting has a direct influence upon the - CORRECT
ANSWER>>>>outflow valve opening.
The function of the evaporator in a freon cooling system is to - CORRECT ANSWER>>>>lower
the temperature of the cabin air.
1
,What is the purpose of a mixing valve in a compressor bleed air air conditioning system? -
CORRECT ANSWER>>>>Control the supply of hot, cool, and cold air.
What component of a pressurization system prevents the cabin altitude from becoming higher
than airplane altitude? - CORRECT ANSWER>>>>Negative pressure relief valve.
If the liquid level gauge in a vapor-cycle cooling system indicates a low freon charge, the system
should - CORRECT ANSWER>>>>be operated for a period of time to reach a stable condition
and then the freon level rechecked
If the cabin rate of climb is too great, the control should be adjusted to cause the - CORRECT
ANSWER>>>>outflow valve to close faster.
The position of the thermostatic expansion valve in a vapor-cycle cooling system is determined
by temperature and pressure of the - CORRECT ANSWER>>>>freon in the outlet of the
evaporator
The function of the condenser in a freon cooling system is to - CORRECT
ANSWER>>>>transfer heat from the freon gas to ambient air.
The function of an expansion valve in a freon cooling system is to act as a metering device and
to - CORRECT ANSWER>>>>reduce the pressure of the liquid freon.
Which prevents a sudden loss of pressurization in the event that there is a loss of the
pressurization source? - CORRECT ANSWER>>>>Delivery air duct check valve.
When servicing an air conditioning system that has lost all of its freon, it is necessary to -
CORRECT ANSWER>>>>check oil and add as necessary, evacuate the system, and add freon.
Which section of a turbine engine provides high pressure bleed air to an air cycle machine for
pressurization and air conditioning? - CORRECT ANSWER>>>>Low or high pressure
compressor.
At which component in an air-cycle cooling system does air undergo a pressure and temperature
drop? - CORRECT ANSWER>>>>Expansion turbine.
In a freon vapor-cycle cooling system, where is cooling air obtained for the condenser? -
CORRECT ANSWER>>>>Ambient air.
What is ventilating air used for on a combustion heater? - CORRECT ANSWER>>>>Carries
heat to the places where needed.
Turbine engine air used for air conditioning and pressurization is generally called - CORRECT
ANSWER>>>>bleed air.
2
,In the combustion heater, combustion air system, what prevents too much air from entering the
heaters as air pressure increases? - CORRECT ANSWER>>>>Either a combustion air relief
valve or a differential pressure regulator.
How is the cabin pressure of an aircraft maintained in flight? - CORRECT ANSWER>>>>By
controlling the rate of the air flowing out of the cabin.
What controls the operation of the cabin pressure regulator? - CORRECT ANSWER>>>>Cabin
altitude.
The basic air-cycle cooling system consists of - CORRECT ANSWER>>>>a source of
compressed air, heat exchangers, and a turbine.
The purpose of the dump valve in a pressurized aircraft is to relieve - CORRECT
ANSWER>>>>all positive pressure from the cabin.
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 air temperature is
too low? - CORRECT ANSWER>>>>Compressor.
How can it be determined that a vapor-cycle cooling system is charged with the proper amount
of freon? - CORRECT ANSWER>>>>Air bubbles in the sight glass disappear.
When charging a vapor-cycle cooling system after evacuation, the low-pressure gauge fails to
come out of a vacuum. What is indicated? - CORRECT ANSWER>>>>Blockage in the system.
What component in a vapor-cycle cooling system would most likely be at fault if a system would
not take a freon charge? - CORRECT ANSWER>>>>Expansion valve.
Frost or ice buildup on a vapor-cycle cooling system evaporator would most likely be caused by
- CORRECT ANSWER>>>>inadequate airflow through the evaporator.
What test is used to determine the serviceability of an oxygen cylinder? - CORRECT
ANSWER>>>>Pressure test with water.
How often should standard weight high-pressure oxygen cylinders be hydrostatically tested? -
CORRECT ANSWER>>>>Every 5 years.
To be eligible for recharging, a DOT 3HT oxygen cylinder must have been hydrostatically tested
every three years and be retired from service after - CORRECT ANSWER>>>>24 years or
4,380 filling cycles.
Which oxygen system employs a regulator that operates only when the user inhales? -
CORRECT ANSWER>>>>Continuous-flow system.
3
, The component that determines the pressure level in the cabin is the cabin air pressure -
CORRECT ANSWER>>>>outflow valve.
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 - CORRECT ANSWER>>>>normal system power pump.
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 - CORRECT ANSWER>>>>inlet of the main
hydraulic system.
To check the air charge in a hydraulic accumulator, - CORRECT ANSWER>>>>reduce all
hydraulic pressure, then observe the reading on the accumulator air gauge.
How would the air pressure charge in the accumulator be determined if the engine is inoperative,
but the system still has hydraulic pressure? - CORRECT ANSWER>>>>Operate a hydraulic
unit slowly and note the pressure at which a rapid pressure drop begins as it goes toward zero.
How many of these seals are used with petroleum-base hydraulic fluids? - CORRECT
ANSWER>>>>Neoprene, Buna-N.
Hydraulic system thermal relief valves are set to open at a - CORRECT ANSWER>>>>higher
pressure than the system relief valve.
Chatter in a hydraulic system is caused by - CORRECT ANSWER>>>>air in the system.
If hydraulic fluid is released when the air valve core of the accumulator is depressed, it is
evidence of - CORRECT ANSWER>>>>a ruptured diaphragm or leaking seals.
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? - CORRECT
ANSWER>>>>20 percent.
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 - CORRECT ANSWER>>>>no air
pressure in the accumulator.
The purpose of restrictors in hydraulic systems is to - CORRECT ANSWER>>>>control the rate
of movement of hydraulically operated mechanisms.
A common cause of slow actuation of hydraulic components is - CORRECT
ANSWER>>>>internal leakage in the actuating unit.
A loud hammering noise in a hydraulic system that has an accumulator usually indicates -
CORRECT ANSWER>>>>too low or no preload in the accumulator.
4
