AIRCONDITIONING

Question 1

What types of air is provided to the cabin?

Answer 1

Fresh conditioned air and recirculated cabin air

Question 2

How many zones are there in the pax compartment and in total?

Answer 2

6 in pax compartment labeled A - F
2 cargo (AFT and BULK)
F/D (Flight deck)

Question 3

What sources can provide bleed air?

Answer 3

1. Engines
2. APU
3. Ground source
   Conditioned air can also be connected on the ground directly to the conditioned air manifold

Question 4

What is the puropose of the recirculation fans?

Answer 4

To recirculate cabin air. This allows the packs to operate at a reduced capacity which saves fuel

Question 5

How is each pack controlled?

Answer 5

Each pack is controlled by two redundant channels in one of two controllers. If one channel fail in a controller, control of the repective pack is continued automatically by the redundant channel in that controller

Question 6

What would cause pack output to automatically decrease?

Answer 6

When demand for bleed air is high like during gear retraction and during certain phases of flight to reduce fuel consumption

Question 7

On the ground, which is noiser, one or two packs?

Answer 7

One pack

Question 8

What is the difference between the EICAS message PACK L/R and PACK MODE L/R?

Answer 8

PACK L/R: Means that the pack is inoperative

PACK MODE L/R: Means that the pack is in stand-by cooling mode

Question 9

How is cooling achived in stand-by cooling mode?

Answer 9

Bleed air is passed through the ram air heat exchanger only and bypassing the ACM in that pack.

Question 10

When does a pack in stand-by cooling mode shut down?

Answer 10

At lower altitudes and with high OAT when ambient conditions do not permit cooling. Pack restarts automatically when altitude and temperature permits

Question 11

From where does the F/D receive fresh conditioned air?

Answer 11

Frome the left pack

Question 12

What is the consequence of a RECIRC FAN being switched off?

Answer 12

The packs operates at full capacity which means more air is needed from the Engines and fuel consumption increases 0,7% for each fan that is OFF

Question 13

How many trim air systems are there?

Answer 13

Two (Left and Right)

Question 14

What provides the left and right trim air system?

Answer 14

Air from the respective Engine. Air is tapped off Before the heat exchanger and mixed into the conditioned air manifold to mix with cool conditioned air

Question 15

What is the max and min Master temp selector range?

Answer 15

18 - 29 deg C

Question 16

What is the flight attendants range for cabin temp control?

Answer 16

+- 6 deg C

Question 17

When will the Master target temp be automatically increased?

Answer 17

During the early part of the Cruise flight. This temp increase is to compensate for a presumed decrease in passenger activity and humidity

Question 18

How can the flight deck temp be manually controlled?

Answer 18

By using the FLT DECK TEMP selector in the MAN setting

Question 19

Which zone controls the pack output temperature?

Answer 19

The zone that is requireing the coolest temp

Question 20

What is the default temp if control is lost?

Answer 20

24 deg C

Question 21

After a failiure of both cabin temp controllers, how is pack flow achieved?

Answer 21

By the ASCPC controllers

Pack flow is modulated to achieve a pack outlet temp of between 5 - 43 deg C

Question 22

Are the flight deck shoulder and foot warmers available on the ground?

Answer 22

No, only in flight

Question 23

Where are the Upper and Lower RECIRC fans drawing air from and where are they recirculating it to?

Answer 23

Upper: Draws air from the area above the pax compartment and recirculates it back to the zone ducts after the conditioned air manifold

Lower: Draws air from under the floor area and recirculates the air into the conditioned air manifold

Question 24

Describe the Equipment cooling normal operation

Answer 24

A supply fan draws air from the FWD cargo bay over temp and smoke sensors. Those sensors also detects fan failiures if no air is coming over them.
Air flows into the flight deck panels and Equipment racks from below.
Air is then drawn into the exhaust duct via a vent fan and back into the FWD cargo compartment.
There is another smoke detector after the vent fan to detect smoke from the avionics bay.

Question 25

How is temp controlled in the FWD cargo compartment?

Answer 25

By valves that opens and close to direct more air into the compartment for heating or to send the air overboard before it reaches the compartment

Question 26

How are the AFT and BULK cargo compartments heated?

Answer 26

With bleed air from the normal bleed air system

Question 27

What system draws air across the cargo temperature sensors?

Answer 27

The lavatory/galley vent fans

Question 28

How is the AFT and the BULK cargo heating affected by failiure of both the lavatory and galley vent fans?

Answer 28

The cargo heat shut-off valve closes and cargo heat is not provided

Question 29

What are the two temp settings for the AFT and BULK cargo compartments?

Answer 29

Low: 4 - 10 deg C
High: 18 - 24 deg C

Question 30

When does the BULK cargo ventilation fan operate?

Answer 30

When tempcontroller is set to high (18-24 deg C)

Question 31

What air heats the FWD cargo compartment?

Answer 31

Air from the Equipment cooling system

Question 32

How many supply cooling fans are there and why?

Answer 32

There are two. One is for back up

Question 33

What does the EICAS message EQUIP COOLING mean?

Answer 33

Means supply fan failiure, low air flow, hot temperatures

Question 34

What does the EICAS message EQUIP COOLING OVRD mean?

Answer 34

Means smoke in the ducts, low airflow, system faults or arming FWD cargo fire arm switch

Question 35

What happens in the system when EQUIP COOLING OVRD message comes up?

Answer 35

Supply and vent fans stop
The override valves opens
FWD cargo heat valve closes
Air now flows into the Equipment area through differential pressure from the cabin and then over board via the override valve