Air Systems Flashcards
Air Systems
In how many temperature zones is the 787 divided ?
7
Flight deck + 6 passenger cabin zones.
Only 5 are depicted on the synoptic.
Nitpicking: zones A and B contain sub-zones A1 and B1, not depicted on the air synoptic.
Air Systems
How many Packs are there ?
2
Air Systems
How many electric Cabin Air Compressors per Pack ?
2
A single CAC provides enough air to operate its Pack in all operating modes.
Air Systems
How is air supplied to the 4 CACs (Cabin Air Compressors) ?
Through 2 dedicated air inlets located in the Wing/Body fairings.
Air Systems
How are the CACs (Cabin Air Compressors) air inlets protected ?
During normal ground ops and the landing phase, deflector doors deploy in front of the CAC inlets to prevent debris from entering the CACs. These deflectors may retract on the ground when ambient temp is below 2°C or above 35°C.
Air Systems
What do the CACs (Cabin Air Compressors) do ?
They pressurize and flow-regulate the incoming air before supplying it to their dedicated Pack.
Air Systems
How are Packs controlled ?
By 2 identical pack control units (PCUs).
If one system fails, pack control automatically switches to the other system.
Air Systems
Ground operations :
When running on APU, how many CACs (Cabin Air Compressors) are running ?
2 in normal operations as only one CAC on each side will run.
4 during cold weather as both CACs are commanded ON.
Air Systems
Can Air Conditioning be used during ENG start ?
NO.
All CACs are commanded OFF during normal start.
Air Systems
When do PACKS restart after ENG start ?
2 minutes limit from start of sequence.
If both engines are started together, immediately after the second engine is started and the 2 minutes limit is met.
Air Systems
How do pilots manage the Standby cooling mode of a Pack ?
They don’t !
The entire process is automatic.
The EICAS displays a PACK MODE (L,R) message and STBY COOLING is displayed in amber on the AIR synoptic.
Air Systems
What does an EICAS message PACK MODE (L,R) mean ? What action(s) can be done ?
A significant fault or overheat was detected and the pack was shut down automatically.
An attempt to restore pack operation may be made by pressing the AIR CONDITIONING RESET switch.
Air Systems
What do recirculation fans do ?
They assist the Packs to maintain a constant ventilation rate through the cabin.
Air Systems
How do recirculation fans work ?
They draw cabin air through filters, then reintroduce the air into the condition air distribution system.
Air Systems
What type of air does the flight deck receive ?
The flight deck receives 100% conditioned outside air.
Some recirculated air is supplied to the flight deck if one pack is off and its associated lower recirculation fan is on.
Air Systems
What type of air does the passenger cabin receive ?
The passenger cabin receives a mix of outside air and recirculated air.
Air Systems
Can cabin attendants reduce outside air to the cabin based on the number of occupants?
Yes, but this reduction is limited to ensure a minimum airflow to the cabin.
Air Systems
Which temperature range can be selected for cabin and flight deck ?
18°C to 29°C
Air Systems
Can flight attendants change the temperature in the cabin ?
YES
± 6°C from the cockpit-selected temperature.
Air Systems
In normal pack operating mode, when is ECONOMY mode triggered ?
Economy cooling mode is a normal mode of operation that occurs regularly above FL290.
The Economy Cooling Valve is opened, bypassing the condenser and 1st stage turbine of the Pack.
Air Systems
How are Pack temperatures controlled ?
1- By modulation of the pack control valves.
2- By opening or closing ram doors of the ram air heat exchanger.
Air Systems
What prevents smoke from entering the flight deck ?
The flight deck is kept at a slightly higher pressure than the cabin.
Air Systems
What is the purpose of the Alternate Ventilation System (AVS) ?
To provide an alternate means of ventilation to the flight deck and cabin if both packs become inoperative.
Air Systems
Which zone controls the pack temperature ?
The zone supplied by that pack that is set to the lowest temperature (white on synoptic).
Air Systems
Can Air Conditioning be used on the ground without APU running ?
Only if all 3 GND power supplies are used.
Air Systems
What conditions will cause the Equipment Cooling System to automatically reconfigure to OVRD mode?
- The FWD/AFT EQUIP COOLING switch is selected to OVRD
- SMOKE is detected
- The FWD/AFT CARGO FIRE ARM switch is ARMED
- Both supply fans fail in flight
- Low airflow is detected in flight
- Excessive Temperature in flight
- Both Flow sensors fail.
Air Systems
How is temperature regulated with the TRIM AIR system OFF?
- The flight deck temperature is maintained between 18-29 °C
- The cabin temperature controllers attempt to maintain all zones at the average target temperature.
Air Systems
If a pack is in Standby Cooling mode and the other operates normally, will it stay on throughout the flight?
No, the pack in Standby Cooling mode will shutdown at lower altitudes and higher outside air temperatures.
Air Systems
What provides additional cooling in the lower recirculation ducts ?
Liquid-to-Air heat exchangers.
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 diffusersb. 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 controlled2.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 airb. One of two supply fansc. A dedicated overboard vent valve or to the appropriate cargocompartment, 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 equipmentb. 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 deckb. 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 climbb. The cabin climbs to 6,000ft and before arrival climbs to destinationelevation
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 is Engine bleed air used for?
Engine core and inlet cowl anti–ice operations.
