Air Conditioning

Question 1

What components make up the air conditioning system?

Answer 1

• 2 air conditioning packs
• Trim air system
• 2 upper and 2 lower recirculation fans

Question 2

What are the sources of hot bleed air for the air conditioning packs?

Answer 2

• Engines
• APU
• ground air sources

Question 3

FLT DECK TEMP:
What is the flight deck temperature range in AUTO?

Answer 3

65F - 85F (18C - 29C)

Question 4

Which air conditioning pack supplies air to the flight deck?

Answer 4

Left pack only

Question 5

Why is the air supplied to the flight deck at a slightly higher pressure than the passenger cabin?

Answer 5

Prevents smoke and objectionable odors from entering the flight deck

Question 6

What is the temperature range of the cabin temperature control?

Answer 6

The cabin temperature control sets the master temperature for the main cabin at a range of 65F - 85F (18C - 29C).

The control at mid position set the temperature at approximately 75F (24C)

Question 7

What controls the zone temperatures?

Answer 7

Cabin Air Conditioning and Temperature Control System (CACTCS)

Question 8

How does the CACTCS achieve the target temperature of the air conditioned in each zone?

Answer 8

By modulating the zone trim air valves

Question 9

How does the EQUIP COOLING supply cooling air to the flight deck panels and equipment racks?

Answer 9

• A supply fans pulls air from the cabin
• Air from the cabin enter ducts and passes by low flow sensors and smoke/override valve
• Cooling air enters the flight deck panels, displays, and equipment racks
• A vent fan then draws the air into the exhaust ducts and into the forward cargo compartment

Question 10

How does the forward cargo heating system operate differently in flight than on the ground?

Answer 10

In flight: Exhaust air always flows into the forward cargo compartment.

On the ground: A controller decides whether to vent the exhaust air into the forward cargo compartment or overboard through the forward outflow valve

Question 11

What brings on the EICAS advisory message: TRIM AIR L, R?

Answer 11

• TRIM AIR switch(es) could be off
• A trim air valve could have failed closed
• There could be a zone duct overheat

Question 12

What brings on the EICAS advisory message PACK L, R?

Answer 12

• The PACK switch(es) could be OFF
• The pack’s flow control valve could have failed closed
• Bleed air may have been shut off to the pack
• The pack could have overheated

Question 13

What brings on the EICAS advisory message EQUIP COOLING?

Answer 13

• Low airflow
• High air supply temperature

Note: The ground crew warning horn in the wheel well will sound to alert ground personnel

Question 14

What brings on the EICAS advisory message EQUIP COOLING OVRD?

Answer 14

• The EQUIP COOLING OVRD switch is set to OVRD
• Low airflow
• System fault occurs
• The FWD CARGO FIRE ARM switch is armed
• Both equipment cooling supply fans are inoperative