02. Air Conditioning Flashcards
What is the air source for the packs?
Outside air
How many Cabin Air Compressors (CACs) are there?
Four
What is the purpose of the CACs?
Pressurize and regulate the flow of outside air to the packs.
How many CACs are required to provide sufficient air to a single pack in all modes?
One
How many pack control systems are there?
Two
Following a pack shut down, how can the pack be reset?
Pressing the AIR CONDITIONING RESET switch
In Standby Cooling mode, which messages are displayed on: -
a. EICAS?
b. Air synoptic?
a. PACK MODE (L/R) – EICAS Advisory b. STBY COOLING (amber)
What is the source of flight deck air?
The flight deck receives 100% conditioned outside air
Why is the conditioned air in the flight deck maintained at a higher pressure than the cabin?
To prevent smoke from entering the flight deck
What is the purpose of the Recirculation Fans?
They assist the packs to maintain a constant ventilation rate through the cabin
What is the result of switching the Recirculation Fans to OFF?
Decreased air flow in the cabin
What is the purpose of the Alternate Ventilation System (AVS)?
To ventilate the cabin and flight deck when both packs are inoperative
Where is the selected Cabin Master temperature indicated?
The AIR synoptic
What is the source of trim air?
From each pack
Are all zones supplied with trim air?
Yes
What determines the pack outlet temperature?
The temperature zone requiring the coolest temperature
Over what temperature range can cabin crew adjust the cabin zones target temperature?
Plus or minus 6o C, within the range of 18o to 29o C.
What temperature is maintained in all zones if a trim air supply is lost?
The cabin temperature controllers attempt to maintain all zones at the average target temperature
What happens if either the flight deck or cabin temperature selection is unavailable to the pack temperature controller?
The pack outlet temperature is regulated to achieve either the last temperature set or an average cabin temperature of 24o C
What type of heater is used for: -
a. Shoulder heaters? b. Footheaters?
a. Electric elements in the side window air diffusers
b. Electric heating elements
Is shoulder and foot heat available on the ground?
No
Where are the controls for the Forward Cargo and Bulk heat?
Overhead panel
What is the source of air for the Forward Cargo heating system?
Forward E/E exhaust ventilation air
How is the temperature controlled in the Forward Cargo?
Automatically using forward E/E exhaust air, a dedicated refrigeration unit, an in-line electric heater and a forward cargo exhaust fan

What does selecting the FWD Cargo Flow switch to HIGH attempt to achieve?
To prevent or remove cargo odors from the passenger cabin
What is the source of air for the Bulk Cargo heating?
Cabin air passing through a supply fan, an in-line electric heater and residual heat from the aft E/E cooling exhaust
With AUTO selected for the Bulk Cargo temperature, how is airflow increased
The bulk ventilation fan operates

Should live animals be carried in the Aft Cargo compartment? If not, why not
No, the aft compartment is not temperature controlled
2.AIR

What is the source of air for the Aft Cargo heat?
Aft E/E cooling exhaust air
Which areas does the Forward Equipment Cooling system provide cooling airflow?
Flight deck and forward E/E equipment compartment
Which areas does the Aft Equipment Cooling system provide cooling airflow?
The Aft E/E equipment compartment
With the Forward or Aft Equipment cooling system in AUTO: -
Where is the cooling air drawn from? Whatmovesthecoolingairthroughthesystem? Where is the air exhausted?
a. Cabin air
b. One of two supply fans
c. A dedicated overboard vent valve or to the appropriate cargo
compartment, if it requires additional heat
With the Forward or Aft Equipment cooling system in OVRD: -
How is air drawn through the system? Whereisthisairexhausted?
a. Cabin differential pressure draws air to create a reverse flow of air across the equipment
b. Through the override valve to an overboard venturi
What is achieved with the: -
a. Forward Equipment Cooling switch in OVRD? b. AftEquipmentCoolingswitchinOVRD?
a. Aids smoke evacuation from the flight deck
b. Aids smoke evacuation from the passenger cabin
Where is the Power Electronics Cooling System (PECS) located?
Aft E/E equipment compartment
What does PECS supply liquid cooling for?
The Large Motor Power distribution system and the supplemental cooling units & associated motor controllers of the Integrated Cooling System (ICS)
What colours are used for Cabin Differential Pressure (∆P) operating ranges displayed on EICAS and what do they indicate?
- White: normal operating range
- Amber: above normal range
- Red: excessive differential pressure
What is the indication on the EICAS display that an outflow valve is under manual control?
The letter M (amber) is displayed next to the Outflow Valve Position indicators
How many outflow valves are there?
Two, one forward and one aft
What protects the fuselage against excessive pressure differentials?
Positive and negative pressure relief valves
When in the automatic pressurisation mode, list the data inputs used to calculate pressurisation schedule?
Ambient pressure and flight plan data from the FMC
In climb mode, at what rate will the cabin climb?
On a schedule related to the aircraft climb rate and flight plan cruise altitude
In cruise mode, what is the maximum cabin altitude?
6,000ft
From where is the landing altitude barometric pressure correction obtained?
Captain’s altimeter setting
What will the cabin altitude be just before touchdown?
Cabin altitude decrease to slightly below FMC planned landing altitude
What happens to the outflow valves at touchdown?
Both valves open to depressurise the cabin
How is cabin altitude controlled for: -
a. Takeoffs from airports above 8000ft? b. Landings at airports above 8000ft?
a. The cabin descends to the target altitude during climb
b. The cabin climbs to 6,000ft and before arrival climbs to destination
elevation
If a depressurisation occurs, what will the outflow valves do initially?
They close to preserve cabin pressure
During a descent after a depressurisation, when will the outflow valves automatically drive to fully open
When the airplane reaches 15,000ft or descends below the cabin altitude
How long does it take for an outflow valve to travel from fully closed to fully open when controlled manually?
30 seconds
What supplies bleed air?
The engines.
What is bleed air used for?
Engine core and inlet cowl anti–ice operations.
