Air System Flashcards
How many temperature zones
7
1 Flight deck
6 Passenger A-D (Zones A and B contain sub-zones A1 and B1 that are not depicted on the air synoptic)
AOM 2.20.1
How many cabin air compressors (CAC)
4
AOM 2.20.1
When do deflector doors deploy in front of CAC inlets
During normal ground operations and landing phases of flight.
Doors may retract on the ground when ambient temperature is below 2 degrees C or above 35 degrees C
AOM 2.20.1
How many dedicated inlets supply the CAC’s
2
located in the wing to body fairings
AOM 2.20.1
How many air conditioning packs
2 identical packs
AOM 2.20.1
For ground operation how many CAC’s run when using APU as power source
Normally, to maximize system efficiency, only 1 CAC on each side runs.
During cold weather operations both CAC’s are commanded on.
AOM 2.20.2
What happens to the CAC’s during engine start
For normal engine start, all CAC’s are commanded off during initial start sequence.
Packs do not restart until at least 2 minutes after the engine start sequence is initiated and the engine is running.
If both engines are started together, and the 2 minute limit is met, packs restart immediately after the second engine is running.
AOM 2.20.2
How can you attempt to restore pack operation after an automatic shutdown
pressing the Air Conditioning Reset switch
AOM 2.20.2
What happens to the CAC’s during an in-flight starter assisted engine start
1 CAC runs to maintain pack operation and maximize power available for the engine cross start.
AOM 2.20.2
During a go-around with 1 engine inop, when could both packs load shed
If slat autogap is needed.
AOM 2.20.2
Is switching to standby cooling mode automatic
Yes
For certain internal malfunctions.
AOM 2.20.2
What happens when 1 pack is in standby cooling and the other is operating normally.
The pack in standby cooling mode shuts down at lower altitudes and higher outside air temperatures when ambient conditions do not permit standby cooling.
AOM 2.20.2/3
What do recirculation fans do
assist the packs to maintain a constant ventilation rate through the cabin.
AOM 2.20.3
What air does the flight deck receive.
100% conditioned outside air.
Some recirculated air is supplied to the flight deck if 1 pack is off and it’s associated lower recirculation fan is on.
AOM 2.20.3
What does turning the recirculation fans off do
does not increase the amount of fresh air to pax cabin, but results in a decreased airflow instead.
AOM 2.20.3
Where is trim air added
trim air from each pack is added to the pack conditioned air to control the temperature in each zone.
AOM 2.20.4
How many zone ducts does trim air supply
Each trim air system supplies 2 cabin zone ducts and 1 flight deck zone duct.
AOM 2.20.4
How are Cabin zone temperatures regulated
by controlling pack outlet temperature and adding hot trim air
AOM 2.20.4
What is the Cabin Temp selector reference temperature
between 18 and 29 deg C
AOM 2.20.4
Can the target temperatures of each cabin zone be modified
Yes
+/- 6 degC within the range of 18-29 using the cabin management system
AOM 2.20.5
What happens if the left or right trim air system is off
cabin temperature controllers attempt to maintain all zones at the average target temperature.
Flight deck temperature is maintained between 18-29 degC
AOM 2.20.5
When does the Humidification System operate
20 minutes into cruise above 25000’, when the HUMID switch is on and is automatically switched off approximately 1-1.5 hours prior to touch down.
AOM 2.20.5
Are cargo compartments temperature controlled
The forward and bulk cargo compartments have independent temperature control systems.
The aft cargo compartment is heated but the temperature is uncontrolled.
AOM 2.20.6
What is the difference between “Forward Cargo Heat” and “Forward Cargo Compartment Air Conditioning Systems” that may be installed on different aircraft
F.C.C.A.S can also carry perishable or other temperature sensitive cargo.
it’s temperature range is 4-27 degC while Forward Cargo Heat systems target temperature is 21 degC
AOM 2.20.6
When does the fwd Equipment Cooling automatically switch to override
- FWD EQUIP COOLING switch is selected to OVRD or
- in flight, both supply fans fail or
- both flow sensors fail, or
- in flight, low airflow is detected or
- in flight, excessive temperature is detected in the fwd equipment cooling system or
- smoke is detected in the fwd equipment cooling system or the fwd cargo area or
- the fwd Cargo Fire Arm switch is Armed
AOM 2.20.12
What happens when the Fwd Equip Cooling is in override
- fwd cargo heat and overboard vent valves are closed
- vent fan and both supply fans are commanded off
- fwd equipment cooling override valve is commanded to the override position
Cabin differential pressure draws air through the flight deck panels and the fwd E/E equipment racks to create reverse flow of air across the equipment, then exits through the override valve to an outboard venturi
AOM 2.20.12
What is PECS
Power Electronics Cooling System
it is a liquid cooling system for the large motor power distribution system located in the aft E/E equipment compartment. It also provides cooling to the supplemental cooling units and associated motor controllers of the integrated cooling system
AOM 2.20.14
How many loops does PECS have
2 independent liquid cooling loops
AOM 2.20.14
What temperature does PECS control the loop to
27 degC
AOM 2.20.14
How many modes does the pressurization system have
2
automatic and manual
AOM 2.30.1
What is the normal cruise cabin altitude
at or below 6000’
AOM 20.30.2
What does bleed air supply
Bleed air is only used for the engine core and inlet cowl anti-ice operations.
AOM 2.40.1
