Air Conditioning Flashcards
When you select the APU BLD button:
1: The APU bleed opens
2: The crossbleed valve opens
3: The engine bleed valves close
If the APU bleed is left on during a climb, what altitude will the bleed automatically close? What altitude will the bleed automatically open during descent?
Close at 25,000ft
Re Open descending through 23,000
If the Crossbleed valve is in auto mode, will it be opened or closed during the following conditions:
Engines on
Apu Bleed off
Crossbleed valve is closed
When will the crossbleed valve automatically open or close? When will we manually move it?
It only automatically moves when the APU bleed valve opens or closes. (opens when APU bleed is on)
We manually move it when directed by the ECAM.
Two electronic motors control the valve. One for auto mode and the other for manual
X bleed closes automatically if a duct leak is detected (except during engine start)
What happens when the APU BLEED pushbutton is pressed?
The APU bleed valve opens (if N is > 95%)
The Crossbleed valve opens
The Engine bleed valves close
How many pack controllers? What happens if they fail?
1 pack controller per pack (works by adjusting the pack flow control valves)
If one fails, the pack outlet temp is regulated between 48 and 59 degrees F
How many Zone controllers?
What happens during failure?
There is one Zone controller with two channels. (regulates temps of the aircraft zones by adjusting the trim air valves)
If it fails, the temp is regulated to 68 degrees
What do the pack controllers do?
Regulate the temps of their associated pack, based on the demands of the zone controller.
Also, the pack controllers close the ram air inlets to avoid FOD ingestion. Closed during takeoff when thrust is above CL and closes again on landing with WOW
How does the Pack Flow selector work? (original system vs revised)
Original system: only installed on two aircraft:
Low / Norm/ High options
-LOW: for light loads (80% Flow)
60% of economy seats filled
No more than 200 pax total
-Norm : 100% flow - normal conditions
-High: 125% flow
(for hot or humid conditions)
Revised system (all other aircraft)
LOW and high are the same
Norm is replaced with AUTO
Based on pax count entered in MCDU, the AUTO mode adjusts flow based on entered load.
Both versions automatically go into high mode when APU bleed is on or during single pack operations
What are the trim air valves?
Hot air is tapped up stream of the packs and used to regulate the cockpit, cabin and FWD cargo temps via the trim air valves. Trim air valves are regulated by the zone controller.
What are the hot and cold air sources for the FWD cargo bay?
Hot air 1 and Pack 2
Cockpit heat source?
Hot air 1 via a restrictor valve
How are the valves of the A/C system controlled and operated?
Electronically controlled and pneumatically operated
How is the cabin temperature controlled
Centered in the flight deck. Adjustable via the flight attendant CIDS panel with a range of 5.4 degrees.
What is pack in bypass mode?
This is when the compressor turbine within the pack is is not working. The air is cooled with the main heat exchanger only, bypassing the pack compressor.
How does the emergency ram air work?
An emergency ram air inlet ventilates the cockpit and cabin, if both packs fail.
The emergency ram air inlet valve is controlled by the RAM AIR PB on the AIR COND panel.
Used for QRH Smoke/Fumes removal checklist.
This pushbutton opens the ram air valve, provided that ditching PB is NOT selected.
The outflow valves open about 50 %, provided that they are under automatic control and ΔP is less
than 1 PSI. They do not automatically open if they are under manual control, even if the ΔP is less
than 1 PSI. If ΔP is greater than 1 PSI, Ram air system will not open.
How does the pack controller work?
Regulates pack temp to meet signal demands of the zone controller. (lowest demanded zone temp is sent from the zone controller to the pack controller)
Pack controller adjusts the pack flow control valve, which supplies the pack with warm bleed air. The pack controller also adjusts Ram inlet and outlet valves which supply air for the heat exchanger within the pack.
What is the function of the mixer unit? Air sources?
Mixes air from the packs with recirculated air from the cabin.
Possible sources of air:
Packs
LP ground inlets
Emergency Ram air inlet
Where is the ram air scoop?
Lower left side of fuselage.
What channels control the zone controller?
The Zone controller is a dual channel controllers. Channel 1 is primary, channel 2 is a backup.
How can the Zone controller work to increase pack flow?
The zone controller can adjust the APU outlet or engine idle to increase pack flow demand.
