B777 Aircon

Question 1

What two types of air are provided to the cabin?

Answer 1

Conditioned bleed air

Recirculated cabin air

Question 2

How many aircraft zones are there?

Answer 2

7 (FLT deck + 6 PAX Zones)

Question 3

How is pack control achieved after a failure of the pack controller?

Answer 3

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)

Question 4

When will pack output be automatically decreased?

Answer 4

During high bleed air demand periods (e.g. Landing gear rotation)
During certain phases of flight to reduce fuel consumption

Question 5

On the ground, which is noisier - 1 pack or 2 packs?

Answer 5

1 pack

Question 6

What is the difference between EICAS messages PACK L and PACK MODE L?

Answer 6

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)

Question 7

How is cooling achieved during standby cooling mode?

Answer 7

Ram air heat exchangers

Question 8

What would cause a single pack in standby cooling mode to shut down?

Answer 8

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

Question 9

Where does the flight deck receive fresh air from?

Answer 9

From L pack

Question 10

Why is fuel consumption affected by the re-circulation switches being off?

Answer 10

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%

Question 11

How many trim air systems are there?

Answer 11

2 - Left and Right engine

Question 12

What is the MASTER temperature selector range?

Answer 12

18-29 degrees C (65-85 F)

Question 13

When will the target temperature be automatically increases?

Answer 13

Target temperatures increase 1 degree per hour for first 2 hours of flight

Question 14

How many degrees can the flight attendant modify individual zone temperatures

Answer 14

+/- 6 W/in range of 18-29 degrees C

Question 15

How can the flight deck temperature be controlled manually?

Answer 15

By selecting the FLIGHT DECK TEMP selector to MAN

Question 16

What controls the pack outlet temperature?

Answer 16

Zone requiring coolest temperature controls pack outlet temperature

Question 17

What is the default temperature if control is lost?

Answer 17

24 degrees C (75 F)

Question 18

After a failure of both cabin temperature controllers, how is the pack flow control achieved?

Answer 18

ASCPCs - Air supply cabin pressure controllers control pack flow valves

Question 19

When are the shoulder and foot warmers available

Answer 19

In flight only

Question 20

How many lavatory and galley ventilation fans are there?

Answer 20

2 - 1 primary and 1 backup

Question 21

Which two cargo compartments are heated with bleed air?

Answer 21

• Aft cargo compartment. • Bulk cargo compartment.

Question 22

How is air drawn across the cargo temperature sensors?

Answer 22

Lavatory and Galley fans draw air across temperature sensors in each compartment.

Question 23

How is aft and bulk cargo heating affected by a failure of both vent fans?

Answer 23

Cargo heat shutoff valve closes and cargo heat not provided.

Question 24

What occurs when the BULK selector is positioned to HIGH?

Answer 24

Bulk ventilation fan operates.

Question 25

How is the forward cargo hold heated?

Answer 25

By warm air FM FWD equipment ventilation system.

Question 26

How many equipment cooling fans normally run?

Answer 26

1 (backup fan runs if primary fan fails).

Question 27

What will cause the automatic override mode?

Answer 27

• 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.

Question 28

How is the avionics equipment cooled during override mode?

Answer 28

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.

Question 29

What are the indications of a forward equipment cooling failure on the ground?

Answer 29

GND crew call horn sounds and EICAS EQUIP COOLING message displayed.