Air Con 13.11.2 Q’s Flashcards
HEPA filters are used in
A cabin air recirculating system
If pressurisation air supplies come from an engine compressor an internal oil leak will
Contaminate the air and be hazardous to the passengers and crew
International markings for air conditioning pipelines are
Dots
Ozone is removed from cabin charge air
At the inlet to the air conditioning system
When carrying out a ground pressure run you should use
The aircraft engines because you can test the whole system
HEPA stands for
High efficiency particulate arrestor
A cabin humidifier is operated at
High altitudes
A combustion heater overheats during flight
It will automatically reset but the pilot needs to relight
A high pressure water separator in a ACM consists of what heat exchangers
Reheater
Condensor
A skin heat exchanger may be used to cool
Electronic equipment
Air conditioning systems
Decrease the temperature of the air
An air to air heat exchanger in an air conditioning system is provided to
Reduce the air supply temp
An aircraft can is air conditioned and pressurised in order to
Maintain human performance and comfort during flights at high altitudes
Where is a low pressure water separator located in a ACM
After the turbine
How does a combustion heater vary its temp
Switches fuel and ignition on and off as required
In air conditioning system distribution the preferred dictons section for wase of manufacturing and fitting and for strength is
Circular
Maintenance tasks to be carried out on the air conditioning can be found in
AMM chapter 21
On a combustion heater fitted to a rotorcraft where the heat exchanger or the ventilation air temp exceed safe limits
There must be a automatic cut off for ignition and fuel supply at a point remote from the heater
Which of the following sometimes inhibits an air conditioning pack
Throttle switches
A variable expansion valve in a vapour cycle cooling system is responsive to
The temperature at the evaporator
After passing through the primary heat exchangers the supply air in an air cycle system flows to the
Fan
What unit in a vapour cycle cooling system serve as a reservoir for the refrigerant
Receiver dryer
Air exiting the turbine of an air cycle machine
Will have decreased pressure and temp
An advantage of using an air cycle system over the vapour cycle system in large aircraft is
Both air con and pressurisation are obtained
What is the condition of refrigerant when it enters the condenser of vapour cycle cooling
High pressure vapour
An air cycle machines turbine
Drives a compressor where the temp increases
Frost or ice build up on a vapour cycle cooling system evaporator would most likely be caused by
Inadequate airflow through the evaporator
An air cycle pack usually has protection temp sensors
At pack out let at the compressor outlet and at the turbine inlet
An air cycle system used for air cycle cooling will
Decrease pressure and temp of the charge air
Before filling a vapour cycle cooling system
Apply suction to remove air and moisture
Humidifiers are operated at
High altitude
In a three wheel air cycle machine air circulated from the cabin is directed to the
Efflux turbine / mixer unit
In a boot strap air conditioning system a low pressure water separator is located
Down stream of the turbine
In a vapour cycle cooling system water will condense from the air at the
Evaporator
In pressurised aircraft temperature conditioning is mainly achieved by
Extracting heat from the pressurised air
In the case of a vapour cycle cooling system heat is removed from the charge air by
Changing a liquid into a vapour
Name the components of a vapour cycle system in order
Compressor condenser expansion valve evaporator
One of the principles of cooling employed in an air cycle system is
Conversion of heat energy to mechanical energy in the air cycle machine
R134a is used in
A vapour cycle cooling system
Temperature control of cabin air is achieved by
Regulating the amount of air bypassing the cooling system
The compressor of a vapour cycle cooling system is found to be operating intermittently
This is normal
The effective temperature of a cabin is given by
Temperature and humidity
The expansion valve in a vapour cooling system is located
Before the evaporator
The heat exchanger in a air cycle system is cooled by
Ambient ram air
The humidity within a passenger cabin should be
Be between 30% & 70%
The purpose of the expansion valve in a vapour cycle cooling system is to
Reduce the pressure of the refrigerant
The receiver/dryer in a vapour cycle air cooling system
Removed moisture from the refrigerant fluid
The temperature at which an air cycle system outputs conditioned air is determined by
The selected temperature of the coldest cabin
The temperature within the cabin of the aircraft is normally selectable between
18-30 degrees centigrade
The thermostatic valve sensing bulb is located just before
The evaporator
When a new cabin temperature is selected temperature overshoot and hunting is protected by
An anticipator circuit and damping bridge circuit
When a vapour cycle cooling system is topped up with refrigerant the new refrigerant is put into the
Low pressure side only
When the refrigerant dissipates heat in a vapour cycle system
The vapour converts to a liquid
Where is the last stage of cooling in an air cycle system
Expansion tube or space
Which of the following can be used on the ground
Turbofan
Which refrigerant type is no longer allowed to be use
R12
Which vapour cycle air conditioning system component must have protection form ice formation
The evaporator
Which vapour cycle system component is located on the aircraft cabin
Evaporator
Which vapour cycle system component is required to be most strongly constructed
Condenser
Which zone normally has the greatest cooling demand
The flight deck
