Aircraft air conditioning and cabin pressurisation 

in the Airbus A310

Aircraft air conditioning systems serve four independently controlled zones in the aircraft: the flightdeck and three passenger cabins, with the forward and rear areas including galleys and toilets.

Airflow routing also provides ventilation of the avionics compartment and the lower cargo holds.

In the Airbus A310, air is supplied to the aircraft toilets and aircraft galleys from individual ventilation systems, with cabin pressure differential providing extraction during the flight, while a fan is used when the aircraft is on the ground.

Hot air is tapped downstream of the bleed air control valves and supplied via a pneumatics distribution manifold to two air conditioning packs, located under the central wing box and accessed via the main landing gear well.

Each pack incorporates a three-wheel `bootstrap' air cycle machine with air-to-air heat exchangers, where the air is cooled and routed, via a common manifold, to the four zones.

Temperature control is achieved automatically or manually by varying the pack outlet temperature and adding trim (hot) air. As environmental control systems go, simple in its design.

The air supply can also be taken from the APU, and conditioned air can be supplied directly to the cabin air distribution systems by two low-pressure ground connections.

A ram air inlet is provided for fresh air ventilation in flight when the packs are not operating. The proportion of fresh air to recirculated air in normal mode is between 60 percent and 40 percent.

Cabin pressure control systems. 

Pressurised areas in the A310 are the flightdeck, passenger cabin, avionics compartment and cargo holds.

Control is provided by two electric outflow valves, one situated forward of the air conditioning bay, the other aft of the bulk cargo compartment, operated by two independent automatic cabin pressure systems, one active and the other stand-by. Switch-over from one to the other is automatic after each flight, and in the case of failure of the active system.

Manual control of the outflow valves is possible by switches in the overhead panel. Ground depressurisation is achieved automatically by electrically opening the outflow valves.

Automatic pre-pressurisation of the cabin before take-off is provided to prevent a noticeable pressure fluctuation in the cabin during rotation on take-off.