Air Conditioning

Question 1

How many Air Conditioning Zones are there?

Answer 1

3 independent zones:

1. Cockpit
2. FWD Cabin
3. Aft Cabin

Question 2

Basic Summary of how air conditioning system works

Answer 2

1. Pneumatic hot air sent to Pack 1 and Pack 2 (Via Pack Control Valve)
2. The hot pneumatic air entered the primary heat exchanger
3. The heat exchanger cools the air by the external air from the ram air inlet
4. The cooled air from heat exchanger enters the Air Cycle Machine where it is compressed (higher pressure and temperature)
5. The hot/high pressure air is then sent to the Main Heat Exchanger where it is cooled again (by external RAM air)
6. Air then passed through a reheater and condenser (converting air moisture into water droplets)
7. Water droplets collected and sprayed into ram air inlet (increasing cooling)
8. Air then sent to Turbine section of the ACM where it expands (creating cooling), powering the compressor and cooling fan
9. Cool air ducted to mixer unit for distribution to the cabin

Question 3

How is the air temperature controlled?

Answer 3

The conditioned air from the mixer unit has hot air added to it from the hot pneumatic air (tapped upstream of the packs)

Question 4

How many Air Conditioning Controllers are there and what do they do?

Answer 4

2 of them for temp control:

No. 1 used for cockpit

No.2 used for both the Fwd and Aft cabins

Question 5

Where are the Packs located?

Answer 5

In the belly area just forward of the main landing gear

Question 6

What are the components of a Pack?

Answer 6

Each pack is comprised of:

1. Air Cycle Machine
2. Primary Heat Exchanger
3. Main Heat Exchanger
4. Components for water removal

[heat exchangers use RAM air to cool the hot pneumatic air - then ram air is exhausted overboard]

Question 7

What does the Turbine Bypass Valve do?

Answer 7

Modulates the pack outlet temperature

Question 8

How is are the Pack Flow Control Valves controlled?

Answer 8

1. Electronically controlled and pneumatically operated
2. Via PACK 1 and PACK 2 pbs

Question 9

What does the Mixer Unit do?

Answer 9

1. Mixes conditioned air with cabin air
2. It is able to accept ground conditioned air or ram air

Question 10

What does the RAM AIR pb do?

Answer 10

1. Opens the RAM AIR INLET VALVE (if opened in auto mode - will open 50%)
2. Emergency supply of external air to cabin
3. Used if both packs fail or for cabin smoke removal

Question 11

What does the HOT AIR pb do?

Answer 11

1. When on (normal lights out position), supplies the trim air valves with hot pneumatic air
2. Valve will close automatically if duct overheat senses

Question 12

What do the three turn knobs do for cockpit, fwd cabin and aft cabin do (hot to cold)?

Answer 12

Temperature setting.

They are electronically adjust the trim air valves which add hot pneumatic air to the conditioned air of the mixer unit

Question 13

Amber “FAULT” light on PACK 1 pb. What does this indicate?

Answer 13

Overheat; and/or

Pack control valve not in the position commanded

Question 14

What is the range of the 3 temp controllers

Answer 14

1. Max cold - 18 degrees
2. 12 o’clock position - 24 degrees
3. Max hot - 30 degrees

Question 15

What does the PACK FLOW selector positions do? (Lo, Norm and Hi)

Answer 15

Controls the pack flow valve

1. LOW - 80% flow
2. NORM - 100% flow
3. HI - 120% flow

Note: if operating on one pack or APU bleed supply - Hi is automatically provided (regardless of pack flow selector)

Question 16

AIR PACK 1 and 2 AMBER FAULT

Answer 16

Update if covered in class

Question 17

A cabin altitude above ???? will cause the EXCESS CAB ALT warning to be displayed?

Answer 17

9,550 feet

Question 18

Components of the pressurisation system

Answer 18

1. 2 x Cabin Pressure Controllers
2. 1 x Residual Pressure Control Unit
3. 1 x Outflow Valve
4. 3 x Electric Motors
5. CABIN PRESS panel
6. 2 x Safety Valves

Question 19

What does the DITCHING pb do on the Cabin Press Panel?

Answer 19

Closes the outflow valve and all other valves below the floatation line

Question 20

Where is the outflow valve and how is it operated?

Answer 20

1. Location - rear right of fuselage
2. Operated by an actuator that is driven by three electric motors (2 motors for auto mode and 1 for manual mode)

Question 21

Where are the safety valves and what to do they do?

Answer 21

1. There are 2 safety valves in rear bulkhead.
2. They operate automatically to prevent cabin pressure from going too high (8.6 to minus 1 PSI)

Question 22

How does the pressurisation system work if the FMGC has failed?

Answer 22

1. It operates in Semi-Automatic Mode
2. Pilot selects the landing elevation on overhead panel
3. This causes the pressurisation system to adjust its internal schedules for timings on pressurisation

Question 23

What does the MAN V/S control toggle do?

Answer 23

1. Positions the manual motor to open or close the outflow valve to the desired position
2. It uses the CPC independent backup section (which uses own electrical power supply and pressure sensor to provide ECAM info)

Question 24

What is ground mode (pressurisation)

Answer 24

At the Gate

1. Outflow valve fully open
2. This prevents pressure differential in cabin
3. Allows cabin doors to be open

Question 25

Describe Pre Pressurisation Mode

Answer 25

Take Off

1. When thrust levers set for take off
2. Cabin differential pressure set to plus 0.1 PSI, using a rate of change of minus 400 ft/min
3. Purpose is to prevent a pressure surge at rotation

Question 26

Climb mode

Answer 26

From rotation

Pressurisation is done in accordance with a fixed schedule which depends on the aircraft rate of climb and altitude

Question 27

Cruise mode

Answer 27

1. Cabin differential pressure maintained at max 8.06 (this figure from CBT) or landing field elevation (whichever is higher)
2. Cabin altitude maintained at 8,000 ft

Question 28

Descent Mode

Answer 28

1. Controlled rate of descent of 750ft/min
2. Computer target is to be at cabin differential pressure of plus 0.1 PSI just prior to landing

Question 29

Landing mode

Answer 29

1. At touchdown - the final 0.1 PSI of pressure is released at 500ft/min

Question 30

Ground mode 2 (after landing)

Answer 30

1. After aircraft has landed and on ground for 55 seconds, the outflow valve fully opens - reducing the cabin differential pressure to 0 PSI

Question 31

What is Abort Mode

Answer 31

1. Resets cabin altitude to departure airport if:a) below 8,000 ft; OR
   b) change of altitude less than 5,075 since take off AND rate of descent greater than 200 ft per second for 30 seconds

Question 32

Ditching push button caution

Answer 32

Caution - with the ditching push button switch ON, the outflow valve will close only when the pressurisation is in the automatic mode

Question 33

When do the safety valves open?

Answer 33

When cabin differential pressure is between 8.2 and 8.9 PSI

Question 34

What are the three separate aircraft ventilation systems?

Answer 34

1. Avionics (blower / extract fans)
2. Battery (Venturi effect)
3. Cabin, Toilets and Galleys (Fans draw cabin air from toilets and galleys and exhaust overboard near the outflow valve)

Question 35

3 Avionics Ventilation Configuration

Answer 35

1. OPEN CIRCUITa) on ground before take off
   b) uses skin cooling (outside air drawn in through skin air inlet valve)
2. CLOSE CIRCUITa) on ground (when skin temp below threshold, when thrust levers set for take off or in flight)
   b) skin air inlet and extraction valves are closed
3. INTERMEDIATEa) in flight when skin temp above 35 degrees
   b) same as closed config save that sole of extracted air is discharged through a small flap in the skin air extract valve

Question 36

Smoke in avionics

Answer 36

1. Smoke detector detects smoke
2. BLOWER and EXTRACT pbs show an amber FAULT and are selected to OVRD
3. Blower fan stops
4. Extract fan continues to run
5. Air conditioning inlet valve opens
6. Skin air extract valve opens