ECS Flashcards
What must be controlled to maintain various aspects of the cabin environment? (5)
Temperature
Humidity
Ventilation
Purity
Pressure
Atmospheric pressure …… with increasing altitude
decreases
Temperature of air decreases by approximately how many degrees per 1000 ft and until what ft does the temperature remain at -56.5 degrees?
2 degrees
36000 ft
What are the dry volumetric proportions of the gases in the atmosphere?
78% Nitrogen
21% Oxygen
1% other gases
At 26,000ft what is the temperature?
-36 degrees
Sea level Temperature, Pressure and density?
Temperature - 15 degrees C
Pressure - 1.0132 bar or 14.7 PSI
Density - 1.225 kg/m3
Other pneumatic sources include? (6)
Ram air
Fan
Compressors
APU
Air bottles
Ground Supply
Cabin conditioning used to? (4)
Provide heating, ventilation and humidity control
Provide emergency ventilation
Automatic control of cabin pressures at different altitudes
Provide ancillary services
Air conditioning provides? (2)
Aircrew comfort - improves safety and efficiency
Radar and equipment cooling
Cabin Pressurisation defined as?
Controlled pressure created within an aircraft cabin in excess of ambient atmosphere, to stimulate lower altitude
Why are military aircraft limited to cabin differential air pressure? (2)
Heavier structure
Explosive decompression
Hot air is tapped from where and goes to?
Engine compressor and goes to the pressure reducing and shut off valve
What happens when the pressure reducing and shut off valve is open?
airflow flows to the heat exchanger and cold air unit, and also to the temperature control valve
What controls the temperature of the air that is fed to cabin conditioning and how is the air fed into the cabin?
Temperature control valve
fed into cabin via a water extractor
What controls the leakage in and out of the cabin to provide for ventilation and pressurisation?
Pressure controller and discharge valve
What does the pressure reducing and shut off valve do?
Automatically governs the mass air flow into the system by varying the outlet according to the compressor output pressure, ensuring a constant flow rate
What 2 compartments does a heat exchanger have?
primary (pre cooler)
secondary (inter cooler)
What does the oil pack of a cold air unit consist of?
Absorbent material impregnated with oil
Felt Wicks lead from the absorbent material to the bearings
Depression caused by the rotation of the scroll pumps draw oil up the felt wicks and pumps deposit oil to the bearings
What is the function of the water extractor?
Removes most of the water from the airflow before it passes from the conditioning supply system
What happens if the coalescer becomes blocked in the water extractor?
relief valves opens due to increased pressure adnd allows air to pass through the swirl plates and collector tubes
Up to what ft is the cabin pressure the same at atmospheric pressure?
8,000 ft
At 25, 000ft what is the maximum pressure that is achieved and maintained to the aircraft cieling?
4psi
What is the purpose of the pressure control and discharge valve?
To control the pressure of the air within the aircraft cabin by control the flow of air out the cabin
