Air Conditioning/Ventilation/Pressurisation Flashcards
How is temp regulated by the air con system?
Both air con pack outlets feed into the mixing unit. Air is ducted into the 3 zonal areas. Hot air is added via the trim air valves to optimise the zonal temperatures.
What do the trim air valves do?
Add hot air to the cool air ducted in to the cabin to optimise the cabin air temperature.
How many air conditioning controllers are there?
- Controller 1 controls pack 1 and vice versa. Controller 1 controls cockpit temp and controller 2 controls the cabin zones.
What is the purpose of the ram air inlet and when will it be opened if pressed?
It enables the cabin to be supplied with fresh air in the event of smoke or loss of both packs. It is activated by a guarded pb on the overhead panel. The valve will open automatically when pushed, however cabin differential pressure must be below 1 psi. Ram air pb shall not be selected til FL100 or below.
Where are the 3 zonal temperatures measured?
Cockpit - behind the FO seat. Cabin zones - lavatory extraction system and the galleys.
What occurs if an air conditioning controller suffers a single or dual channel failure?
The air conditioning controller will still function with a single lane failure. A dual lane failure will cause the loss of the controller.
What happens if a hot air valve fails?
If it fails in the open position, there is no effect. If it fails in the closed position, the trim air valves will not be supplied, so temp control of the cabin is lost.
What happens if a trim air valve closes?
Temperature control is lost in that cabin zone.
The ram air inlet flaps automatically close under two conditions, what are they?
Take-off - T/O power set and MLG struts compressed
Landing - MLG struts compressed, speed greater than 70 knots
What is the ACSC and what does it do?
Air Conditioning System Controller. Each ACSC regulates the temperature of its associated pack by modulating the bypass valve and ram air inlet flap. It has the following functions:
Pack operation control.
Controls pack flow control valve.
Controls hot air pressure regulating valve.
Controls trim air valve.
Regulates temperature and flow.
What is pre pressurisation mode?
Active during the take off roll, the outflow valve moves towards a closed position, the pressure in the cabin then increases to 0.1psi above ambient to avoid a cabin surge during rotation.
When do de pressurisation and ground modes activate and what happens in automatic mode?
De pressurisation mode occurs on touchdown which releases any cabin over pressure. Ground mode occurs 5 seconds after landing at which point the outflow valve fully opens.
What is the maximum cabin altitude in automatic mode?
8000ft
What does the pressurisation system use in automatic mode as a reference for landing elevation?
The destination QNH from the PERF APPR page and the airfield elevation from the FMGC.
How is manual pressurisation achieved and how does it work?
By using the manual override pb on the overhead panel. The third motor for manual mode is not energised. Manual control is achieved through a dedicated part of CPC1 which remains available even in dual CPC failure. Cabin altitude is controlled using the toggle switch which adjusts the position of the outflow valve. Pressurisation will now be displayed by ECAM.
