Flashcards in Air Conditioning COPY Deck (28)
What is the purpose of emergency ram air?
An emergency ram air inlet ventilates the cockpit and cabin as part of the smoke removal procedure, or when both packs fail.
What is the function of the mixer unit?
Conditioned air is taken from both packs and mixed with recirculated cabin air in the mixing unit. From here it is then distributed to the three aircraft zones (cockpit, forward cabin, aft cabin)
What is the function of the trim air valves?
The three trim air valves add hot air to the air from the mixing unit just before it is pumped into the three zones.
What is the function of the APU flow demand?
When the APU bleed valve is open the air conditioning system controller signals the APUs Electronic Control Box (ECB) to increase the APU flow output when any zone temperature demand cannot satisfied.
For which zones is an independent temperature control possible?
Cockpit, forward cabin and aft cabin.
Is a temperature control from the cabin possible?
Yes - during cruise the cabin crew can modify each cabin zone temperature which is selected from the cockpit with a limited authority of +/- 2 5°C.
What is the function of the pack flow control valve?
This valve regulates the air flow through the pack dependant on cockpit selection of off/low/normal/high
What is the temperature selection range?
18°C to 30°C
Under which condition should the pack flow controller be set to LO?
With a low passenger load to reduce bleed air demand and improve fuel efficiency.
A319 - 138
A320 - 141
A321 - 168
Under which circumstances would the air conditioning system deliver high flow regardless of cockpit selection?
In single pack operation or when the APU is supplying bleed air.
Under which condition should the pack flow controller be set to HI?
With a high passenger load in hot conditions in order to help reduce the cabin temperature.
What happens to the pack flow control valves during engine start?
They automatically close.
Under which circumstances does the pack flow control valve close automatically?
Fire PB pressed (relevant side)
Ditching PB pressed
What is the purpose of the hot-air pressure-regulating valve?
Draws hot air upstream of the packs and adds it into the air conditioning zones via the trim air valves
How can you operate the emergency ram air inlet valve?
Guarded pushbutton on the air conditioning panel. This pushbutton opens the ram air valve provided that ditching is not selected.
What happens if the Air Cycle Machine (ACM) fails?
Affected pack with continue to run in heat exchanger cooling mode (degraded performance)
Where are temperature sensors located?
In the cockpit for the cockpit zone, in the lavatory extraction circuit and galley ventilation system for the cabin.
When does the hot-air pressure-regulating valve close automatically?
This valve closes automatically if the duct overheats, the cockpit trim air valve fails, or both cabin trim air valves fail.
What is the function of the HOT AIR pushbutton?
Normally left in "on" position, but can be selected manually off by flight crew, which closes the hot air regulator valve and trim air valves.
What does an amber "FAULT" light on the HOT AIR pushbutton indicate?
Duct overheat - the hot air and trim air valves close automatically
How is the pack flow control valve controlled and operated?
The valve is electrically controlled and pneumatically operated.
What would cause an amber "FAULT" light to illuminate in the PACK 1/2 pushbutton?
Overheat - pack outlet. Overheat - compressor outlet. Discontinuity - switch position disagreement with pack flow control valve
Describe how the Air Conditioning System Controllers regulate temperature?
BASIC temperature regulation: Both packs produce the required outlet temperature determined by the lowest demanded zone temperature. OPTIMISED temperature regulation: Hot air is added to the individual zones by the trim air valves to maintain the desired zone temperatures
When is conditioned air introduced into the avionics compartment?
Abnormal operation and SMOKE configuration
On aircraft with ACSCs, how many Air Conditioning System Controllers are there?
2. Each Air Conditioning Controller has 2 lanes: Active/Standby
The PACK FLOW selector has LO, NORM, and HI positions. What does this allow us to do?
Select pack flow rates representing LO 80%, NORM 100%, and HI 120% of norm
What occurs when an active lane of an Air Conditioning System Controller fails?
The second lane takes over