B777 Aircon Flashcards
B777 Aircon
What two types of air are provided to the cabin?
Conditioned bleed air
Recirculated cabin air
How many aircraft zones are there?
7 (FLT deck + 6 PAX Zones)
How is pack control achieved after a failure of the pack controller?
Pack controlled through redundant channel in a controller (if one channel fails in a controller, the respective pack is continued automatically by the redundant channel in that controller)
When will pack output be automatically decreased?
During high bleed air demand periods (e.g. Landing gear rotation)
During certain phases of flight to reduce fuel consumption
On the ground, which is noisier - 1 pack or 2 packs?
1 pack
What is the difference between EICAS messages PACK L and PACK MODE L?
PACK L/R indicates L pack is shut down (the pack valve closed) due to overheat or fault
PACK MODE L/R indicates pack is operating in STBY cooling mode (for certain internal malfunctions)
How is cooling achieved during standby cooling mode?
Ram air heat exchangers
What would cause a single pack in standby cooling mode to shut down?
If one pack is in standby cooling and the other pack is operating normally, the pack in standby cooling shuts down at lower altitudes and higher outside air temperatures when ambient conditions do not permit standby cooling
Where does the flight deck receive fresh air from?
From L pack
Why is fuel consumption affected by the re-circulation switches being off?
Recirculation fans off increase demand for conditioned air –> Pack reverts to full flow to provide sufficient ventilation –> Increases bleed air demand –> Increases fuel flow by approx 0.7%
How many trim air systems are there?
2 - Left and Right engine
What is the MASTER temperature selector range?
18-29 degrees C (65-85 F)
When will the target temperature be automatically increases?
Target temperatures increase 1 degree per hour for first 2 hours of flight
How many degrees can the flight attendant modify individual zone temperatures
+/- 6 W/in range of 18-29 degrees C
How can the flight deck temperature be controlled manually?
By selecting the FLIGHT DECK TEMP selector to MAN
What controls the pack outlet temperature?
Zone requiring coolest temperature controls pack outlet temperature
What is the default temperature if control is lost?
24 degrees C (75 F)
After a failure of both cabin temperature controllers, how is the pack flow control achieved?
ASCPCs - Air supply cabin pressure controllers control pack flow valves
When are the shoulder and foot warmers available
In flight only
How many lavatory and galley ventilation fans are there?
2 - 1 primary and 1 backup
Which two cargo compartments are heated with bleed air?
• Aft cargo compartment. • Bulk cargo compartment.
How is air drawn across the cargo temperature sensors?
Lavatory and Galley fans draw air across temperature sensors in each compartment.
How is aft and bulk cargo heating affected by a failure of both vent fans?
Cargo heat shutoff valve closes and cargo heat not provided.
What occurs when the BULK selector is positioned to HIGH?
Bulk ventilation fan operates.
How is the forward cargo hold heated?
By warm air FM FWD equipment ventilation system.
How many equipment cooling fans normally run?
1 (backup fan runs if primary fan fails).
What will cause the automatic override mode?
- In FLT, both supply fans fail or low airflow detected. • Smoke detected in FWP equipment cooling system or FWD equipment ventilation system.
- FWD CARGO FIRE switch is armed.
How is the avionics equipment cooled during override mode?
Cabin differential pressure draws air through the FLT deck panels into the E & E equipment compartment to create reverse flow of air across equipment, then through the override valve to an overboard vent.
What are the indications of a forward equipment cooling failure on the ground?
GND crew call horn sounds and EICAS EQUIP COOLING message displayed.
