Air Systems Flashcards
CACs?
Cabin Air Compressors
Air conditioning packs logic?
Controlled by two identical pack control systems. If one fails, the other system takes over automatically.
How many CAC inlets?
How many CACs?
How many packs?
How many pack controllers?
2 inlets
2x2 (4) CACs
2 packs
2x2 (4) pack controllers
How many temperature zones are there?
Seven temperature zones:
Flight Deck
6 passenger zones: A A1 (not depicted on synoptic) B B1 (not depicted on synoptic) C D
Range of cabin temperature selector?
65 to 85 degrees F
Using Cabin Management System, how much can the cabin temperature zones be modified?
Plus or minus 10 degrees, within the 65 to 85 degree range.
If FLT DECK or CABIN TEMP selector is unavailable, what is the pack outlet temperature regulated to?
It will achieve either:
The last temperature set
OR
average cabin temperature of 75 degrees F
How is pack outlet temperature determined?
By the zone requiring the coolest temperature. The trim air valves will modulate to adjust this temp for the rest of the zones.
TRIM AIR FAULT light?
The trim air valve is failed closed OR The trim air valve commanded closed because of zone supply duct overheat OR The trim air switch is selected OFF.
Pushing AIR COND RESET switch?
Resets any air conditioning faults, attempts to restart normal operation
Resets any trim air valves held closed due to overheat, control failure or valve failure
Attempts to reset a failed recirculating fan
Resets fault protection
What does selecting number of cabin occupants on the cabin attendant panel do?
Flight attendant can reduce the outside airflow based on the number of occupants. The reduction is limited to ensure that a minimum airflow is always supplied to the cabin.
Pilot shoulder heat?
Only available in flight.
Provided by electric elements in the side window air diffusers.
Pilot foot heat?
Heating element in floor panel.
Available on the ground and in flight when pack and recirculating fans are on.
How does HUMID switch work?
Normally left in ON position. The humidify action system will automatically switched off 1 to 1.5 hours prior to touchdown.
Which cargo compartments are heated?
All, but only the forward and the bulk compartments have temperature controls. The aft compartment is heated, but uncontrolled.
How is the forward cargo compartment heated?
From the forward E/E cooling exhaust fan, then routed through an electric heater.
FWD CARGO TEMP switch in AUTO?
Forward cargo heater will operate to maintain a target temperature of 70 degrees F
FWD CARGO TEMP switch OFF illuminated?
Forward E/E system in override
Forward E/E exhaust fan inoperative
Forward cargo fire is detected
How is the bulk cargo compartment heated?
Cabin air through a supply fan and an inline electric heater. Also some residual heating from the aft E/E cooling exhaust entering from below compartment floor.
BULK CARGO TEMP switch in AUTO?
Ventilation fan will operated allowing for live animal transport
System will target temperature of 70 degrees F
Does the BULK CARGO TEMP have automatic overheat protection?
Yes. If an overheat condition occurs, a shutdown will occur, and cannot be restored while in flight
BULK CARGO TEMP OFF light?
787-9:
BULK cargo switch OFF
OR
There is a bulk cargo overheat
787-8:
supply ventilation fan is inop
supply ventilation valve is closed
aft cargo fire is detected
Is aft cargo compartment heated?
Yes, although it is unregulated.
Ventilation and heat are provided by exhaust air from the AFT E/E exhaust under the floor, also residual heat from the BULK cargo area.
How many fans are used for the forward cooking and ventilation system?
2 supply fans
1 exhaust fan
If primary supply fan fails, backup operates automatically
EQUIP COOLING FWD switch in AUTO?
In OFF (AUTO not visible)?
AUTO: forward equipment cooling mode controlled automatically
OFF: Both supply fans off, Flight deck supply and vent fans off, Both smoke/override valve and flight deck isolation valve open FWD cargo heat inop OVRD illuminates
EQUIP COOLING OVRD light illuminated
Will be illuminated if SMOKE/OVRD mode is operating because:
OFF is manually selected
Both equipment cooling supply fans fail
Smoke/Override mode automatically selected by smoke detection system
AFT equipment cooling system provides:
Cooling and ventilation for aft E/E bay
Heating and ventilation for aft cargo compartment
AFT EQUIP COOLING switch OFF (AUTO not visible)
Both aft equipment cooling supply fans and vent fan commanded off
Override valve commanded open
Aft cargo heat inop
OVRD illuminates
AFT EQUIP COOLING OVRD light illuminated
SMOKE/OVRD mode operating because:
Off is manually selected
Both supply fans fail
SMOKE/OVRD mode is automatically selected by the smoke detection system
PECS?
Power Electronics Cooling System
A liquid cooling system for the large motor power distribution system located in the aft E/E equipment bay.
Components of PECS
Two independent liquid cooling loops
Each loop has single pump package containing two fully redundant pumps
The PECS controls the liquid coolant supply temperature to what value?
85 degrees F
Liquid Cooling QTY display?
OF (in white)?
RF (in white)?
LO (amber)?
Why would single liquid cooling loop be displayed?
L and R reservoir quantities expressed as percentage of normal level, 1.00 being normal
Over-full
Re-fill recommended
Reservoir low, requires servicing
Only one forward external power source connected and selected ON
ICS?
Integrated Cooling System
is a centralized refrigeration system providing cooling for galley carts and supplements recirc air. Integrated with air conditioning system and liquid cooling system. No flight deck control.
MIscellaneous equipment cooling system
Fully automatic
Powered on when aircraft powered.
Can be turned off by IFE switch on overhead panel.
Number and location of outflow valves
Two outflow valves
One located forward left side
One located aft right side
Number and location of positive and negative pressure relief valves
Two positive pressure relief valves located mid-forward on left side
Four negative pressure relief valves, split between mid-forward left and mid-forward right sides
PRESSURIZATION OUTFLOW valves in AUTO
No inputs required beyond normal FMC setup.
PRESSURIZATION OUTFLOW switches in MAN (amber)?
Outflow valve is controlled manually
Automatic outflow valve and cabin altitude limiter is bypassed
AUTO is extinguished
How is LDG ALT controlled?
Landing altitude can be manually selected by pulling knob (slowly turning = 100 ft increments, fast = 500 ft)
Amber MAN on EICAS
If landing selector knob is pushed, the landing altitude is referenced to that in FMS, and white AUTO displayed on EICAS
Pressurization system indication displayed automatically when:
LDG ALT in MAN Either OUTFLOW VALVE in MAN Cabin altitude above normal range Cabin diff press excessive AIR synoptic selected on any MFD Other pressurization problem shown on EICAS
Cabin altitude displayed in white?
In amber?
In red?
(White) System in normal range
(Amber) System above normal range
(Red) System indicating “excessive” cabin altitude
Differential pressure in white?
Amber?
Red?
White = normal range
Amber = above normal range
Red = “excessive” differential pressure
Display of outflow valves on EICAS?
Position of outflow valves is indicated.
If in MAN, the gauge will be amber and an amber “M” is alongside the gauges
In AUTO, the gauge is in white, and the space next to it is blank
LANDING ALTITUDE message on EICAS?
FMC does not supply an landing altitude
OR
The landing altitude selector is pulled
At what ambient temperature do the CAC deflector doors close on the ground?
Below 35 degrees F or above 95 degrees F
How many CACs per pack?
How many CACs required to operate its associated pack?
Two
One, in all modes of operation
How many CACs operate when powered by the APU?
One per side, but both CACs commanded on during cold weather ops.
CAC operation during engine starts?
All four CACs commanded off
(PACK L and PACK R messages inhibited)
Packs will not restart until 2 minutes after engine has started
Cockpit/Cabin Air Sources?
100% fresh air to flight deck
Passenger cabin receives mix of outside air and recirculated air.
Flight deck may receive some recirculated air if one pack is off and associated lower recirc fan is on.
Flight deck maintains slightly higher pressure than the cabin to prevent smoke.
CAC during load shed conditions
Outside air flow will be reduced protecting the electrical distribution system.
Is there additional cabin cooling, aside from pack air?
Yes. Liquid-air heat exchangers in the lower recirculating ducts provide additional cooling. This is provided by the Integrated Cooling System (ICS). This reduces the power required by the CACs
If the RECIRC FANS switches are positioned off…
EICAS advisory messages
RECIRC FAN UPPER OFF
RECIRC FAN LWR OFF
Fresh air is reduced to the cabin
Recirc fans must be left ON during hot weather operations unless commanded OFF by non-normal checklist
Describe de-humidification system
Operates automatically with electric power
2 zonal dryers FWD and AFT to remove moist air from crown area. Fans circulate dry air to crown and moist air is exhausted below cabin floor
What will cause the FWD equipment cooling system to reconfigure to override mode?
FWD EQUIP COOLING switch to OVRD
Inflight, both supply fans fail
Both flow sensors fail
Inflight, if low airflow detected
Inflight, if excessive temp in FWD EQUIP COOLING SYS
Smoke detected in FWD EQUIP COOLING SYS or FWD CARGO area
FWD CARGO FIRE ARM switch ARMED
AFT EQUIP COOLING system reconfigures to override mode if:
AFT EQUIP COOLING switch to OVRD
Inflight, if both supply fans fail
Both flow sensors fail
Inflight, if low airflow detected
Inflight, if excessive temp in AFT EQUIP COOLING system
Smoke detected in AFT EQUIP COOLING system or aft equipment ventilation system
When AFT CARGO FIRE ARM switch ARMED
What will shut off lower recirc fans automatically?
If smoke detected in aft E/E compartment
Placing FWD EQUIP COOLING in OVRD aids in….
Smoke evacuation from flight deck
Placing AFT EQUIP COOLING in OVRD aids in….
Smoke evacuation from the cabin
What is standby cooling mode?
An automatic backup to the normal cooling mode in case of certain malfunctions
No pilot input required
In standby mode, PACK MODE L and
PACK MODE R will be displayed on the EICAS and an amber STBY COOLING displayed on the synoptic
Works better at altitude
What is the AVS?
Alternate Ventilation System
Provides an alternate method of ventilating the cabin and flight deck if both packs inop.
Turned on via VENTILATION switch on air conditioning panel
Used both FED and AFT outflow valves
Placing VENTILATION switch to ALTN when aircraft is unpressurized?
Drives FWD outflow valve to ten o’clock position
Drives AFT outflow valve to one o’clock position
Allowing fresh air to be drawn into distribution system
CPCS?
Cabin Pressure Control System
What is the climb logic in the CPCS?
During takeoff, system supplies small positive pressure
Cabin altitude increases on a schedule related to aircraft climb rate and scheduled cruise altitude. If level segment planned, cabin keeps climbing. If unscheduled level off, cabin altitude pauses.
If aircraft climb rate greater than planned and max differential is reached, cabin climb rate becomes function of aircraft climb rate.
Default cruise altitude is 43,000 feet
What is the maximum cabin altitude in cruise mode?
6,000 feet.
May reach 8,000 feet in degraded operations.
Descent logic for the CPCS?
Descent mode initiated at TOD.
Cabin altitude will decrease to slightly below landing altitude.
Both outflow valves open at touchdown.
Where does CPCS get its landing altitude pressure correction?
Captain’s altimeter setting.
How long does it take to move the outflow valve from full open or closed to the desired position?
30 seconds
How do you manually set landing altitude?
Pull LDG ALT selector knob,
-2,000 ft to 14,000 ft
Describe outflow valve function during rapid decompression
Outflow valves will initially close to preserve cabin pressure.
They will remain closed until aircraft reaches 15,000 feet or descends below cabin altitude
After descent and cabin and actual altitudes are approximately equal, out flow valves open to protect against negative pressure
