Air conditioning systemThe main purpose of the air conditioning system (ACS) is to create conditions for human life in flight on: maintaining a constant predetermined pressure, temperature and air humidity level, purification of air from harmful impurities and cooling of airborne avionics.
In aircraft cockpits, air conditioning is called automatic maintenance of air parameters (temperature, pressure, relative humidity, purity and speed) at a certain level in order to create comfortable conditions for the crew and passengers in flight and on the ground, and provide the necessary modes of cooled airborne avionics.
The main requirements of the airworthiness of aircraft for the work of the ACS and its subsystems are as follows:
- The ACS should provide predetermined values of pressure, humidity and gas composition of cabin air in all modes of flight and on the ground independently of external climatic conditions. The functioning of the ACS in the cabin should not depend on the work of other systems that use shared sources of compressed air.
- Cabin pressurization should be carried out by two or more sources of compressed air. This ACS should consist of at least two independent sub-systems that support flight normal temperature conditions in cabins in the event of failure of one of them.
The air temperature in the cabin and in the compartments must be set and controlled independently.
The ability to heat and cool cabins on the ground should be provided without starting the engine with the help of on-board and ground-based devices.
In aircrafts with a flight-duration over two hours, it is necessary to provide a humidification system to maintain relative humidity in the cabin of not less than 25%.