How many Cabin Air Compressors (CAC) are there?
There are 4 CAC. Through two dedicated inlets located in the wing to body fairings
How many CAC’s run when on ground using the APU as a power source?
1 CAC for each pack only runs when on ground with the APU, during cold weather operations 2 CACs run in each pack
When will the deflector door retract automatically?
During normal ground operations and landing phases of flight, deflector doors deploy in front of the CAC inlets to prevent debris from entering the CACs.
These deflector doors may retract on ground when ambient air temperarure is below 2 C or above 35 C.
During engine starts, what happens to the packs?
For normal engine starts, all CACs are commanded off during initial start sequence with corresponding PACK L, R messages inhibited.
If both engines have been started together, when should the packs restart?
If both engines are started together, and the two minute limit is met, packs restart immediately after the second engineis running.
Which area receives 100% conditioned outside air under normal operation and what does the other areas are supplied with? Under what circunstances is this not the case for the 100% conditioned outside air supply?
- The flight deck receives 100% conditioned outside air and the passengers cabin receives a mix of outsisde air and recirculated ai.
- If 1 pack is OFF and its associated lower recirculation is ON
Why is the air pressure supplied to the flight deck higher than that supplied to the cabin?
To allow smoke to be extracted from the flight deck do the cabin.
If the EICAS advisory message PACK (L or R) appears, how might the system be restored?
By pressing the AIR COND RESET switch
For certain malfunctions, the packs have a built-in redundancy which automatically provides continuous service. How does this redundancy operate and in what mode? How will the airplane, inform the crew what is taking place? The system is “inteligent”. In this degraded mode, how does it adapt to high ambient temperarures and low altitudes?
The system uses the Standby cooling mode, it will display PACK MODE L, R message on EICAS.
The stand-by cooling mode will shut down at high ambient temperatures and low altitudes.
How can you draw fresh unpressurized air into the cabin?
By selecting the Alternate Ventilation System switch to ALTN
This positions the FWD and AFT outflow valves in the ten and one o’clock positions.
How many Trim air systems are there? Are there any manual controls? How do they supply the flight deck and cabin?
There are 2 Trim air systems. Each one supply the flight deck and 2 cabin zone ducts. They are controlled automatically or manually by the master reference temperature.
How do the Trim valves function as cabin zone temperature regulators and which temperature zone controls the pack outlet temperature?
They add hot trim air to the pack outlet air to meet the zone target temperature and is protected against overheat by automatic shutdown.
The temperature zone requiring the coolest temperature controls the pack outlet temperature.
Where does the trim air source come from? (Air synoptic display)
It comes from the Hot cabin air compressor (CAC) discharge air
How many recirc fans are there?
3 recirc fans
2 lower and 1 upper
What happens to the air after it goes to the lower deck recirculation system?
Air from the recirculation fans is mixed with air from the packs, then distributed to the cabin.
Describe the function of the HUMID switch.
The humidification system operates automatically 20 minutes into cruise above 25,000 ft when the HUMID switch is on and is automatically switched off approximately 1 - 1.5 hours prior to touch down.
How is the Forward Cargo compartment temperature controlled?
The foward cargo is temperature controlled thrught foward E/E cooling exhaust, a dedicated refrigeration unit, in-line eletric heaters, and a foward cargo exhaust fan.
How is the AFT Cargo compartment heated?
Aft cargo compartment ventilation and heat are provideded from aft E/E cooling exhaust entering from below the compartment floor and there is some residual heat due to air leakeage through the insulated curtain from the buld cargo compartment.
What system provides cooling and ventilation for the electrical and electronic equipment on the flight deck and in the foward eletrical and compartment eletronic (E/E) equipament racks?
The forward equipment cooling and ventilation systems
When does the forward equipment cooling system goes into OVERRIDE mode?
- The FWD EQUIP COOLING switch is selected to OVRD or,
- In flight, when both supply fans fail or,
- In flight, when low airflow is detected or,
- Both flow sensors fail,
- In flight when excessive temperature is detected in the foward equipament cooling system or,
- Smoke is detected in the foward equipament cooling system or the foward cargo aread or,
- The FWD CARGO FIRE ARM switch is ARMED
The cargo vent valve closes, and the system commands off the 2 supply fans and vent fan.
What is the function of the Integrated Cooling System (ICS)? Is its operation automatic? Can it be disabled by the crew?
It is a refrigeration unit that provides cooling to the galleys and assists cooling recirculated cabin air.
Its operation is automatic and it can not be disabled. by the crew
How is the Cabin Pressure Control System (CPCS) gets its information for the pressurization schedule for its various modes? What are those 3 modes? How is the cabin pressurization controlled?
- It gets information from ambient pressure and the FMC.
- It operates in Climb, Cruise and descent modes.
- Cabin pressurization is controlled by regulating the discharge of conditioned cabin air through the 2 outflow valves
What is the maximum cabin altitude normally in the cruise? Where does the system obtain its barometric reference for any correction?
- 6000’.
- The system gets the landing elevation from the FMC and the barometric reference from the Captain’s altimiter setting.
The system obtains its barometric reference from the captain’s altimeter setting.
If the landing altitude information is not available, in the normal way, is there any other method of setting it?
The eicas shows ** LANDING ALTITUDE**. If this is ignored and no action is taken, what cabin altitude will the controler default to?
- Landing altitude can be manually selected
- If the system is ignored the system will default to 2000’ as the landing altitude.
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Limitations18
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Memory Items and Checklist Legend27
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Systems - Airplane General, Emergency Equipaments, Doors, Windows23
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System - Air Systems34
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Systems - Anti-Ice, Rain14
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Systems - Automatic Flight31
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Systems - Communication6
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Systems - Eletrical37
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Systems - Engines, APU59
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Systems - Fire Protection27
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Systems - Flight Control58
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Systems - Flight Instruments and Display64
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Systems - Flight Management, Navigation14
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Systems - Fuel22
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Systems - Hydraulics8
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Systems - Landing Gear10
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Systems - Warning Systems20
