Air Conditioning Flashcards
How many air conditioning packs are there?
2 air conditioning packs controlled by ACSC 1&2 respectively
How does the air cycle machine in the air conditioning packs function?
Air from the bleed system enters the pack flow control valve at approx 200 degrees. The air passes through the primary heat exchanger where it is cooled and then enters the compressor where it is compressed and heated. Then passes through the main heat exchanger where it is cooled and then finally it crossed the pack turbine (having been through the water seperator) where expansion of the air cools it further. It is then ducted to the mixer unit.
How is the aircraft temperature regulated by the air conditioning system?
Both pack outputs feed into the mixing unit. The pack outlet temperatures are dictated by the lowest selected a/c zone temperature so the air within the mixing unit is at the lowest selected temp. Hot air is then added via the trim air valves to optimise the cockpit and cabin zone temperatures. Pack outlet temperature is adjusted by the ACSCs input on the ram air inlet flap and turbine bypass valve.
Pack flow is controlled by the pack flow control valve
What do the trim air valves do?
Trim air valves add hot air to the cockpit, forward and aft air supplied via the mixing unit to optimise zone temperatures.
How many ACSCs are there and what do they do?
2 ACSCs
ACSC controlling pack 1 & cockpit temp
ACSC controlling pack 2 & FWD and AFT temp
The ACSCs input on ram air inlet flap & turbine bypass valve to control pack outlet temp & trim air valves to optimise zone temperatures
What is the purpose of the ram air inlet & when will it open the outflow valve if pressed?
Enables the cabin to be supplied with outside fresh air in the event of smoke or following loss of both packs.
Pressing the button will open ram air valve if ditching PB not pressed. The outflow valve will open to 50% provided:
- pressurisation is under auto control
-differential pressure less than 1psi
What are the minimum and maximum temperature selections for air conditioning?
18 & 30 degrees
What happens in the case of single or dual channel failure of an ACSC?
Single failure, other channel takes over
Dual failure, pack is lost
What happens if air cycle machine fails?
The pack operates in heat exchanger mode. Air passes through the primary heat exchanger and then majority of air passes through the bypass valve with some going through the failed air cycle machine. Pack outlet temp is adjusted by adjusting ram air inlet flap and bypass valve.
What happens if hot air valve fails?
Open - nothing
Closed - optimized zone temp control is lost and trim air valves close. Temp is adjusted through pack outlet temperature adjustments
What are the consequences or a trim air valve failure?
Optimised temperature control in the associated zone is lost
Draw the Air Conditioning Schematic
In FCOM
Draw the Air Cycle Machine
In notes
Name all components on the ECAM systems BLEED page
