PRESSURIZATION

Question 1

When does the delta P indication become amber?

Answer 1

When delta P below 0.4 psi or over over 8.5 psi

Question 2

What is the function of the ditching pb?

Answer 2

Closes the outflow valve
Closes emergency ram air inlet door
Closes avionics ventilation inlet and extract valves
Closes Pack Flow Control Valves

Question 3

How many motors are available to operate the outflow valve?

Answer 3

Two automatic AC motors and one manual DC motor

Question 4

Describe the different stages of pressurization during a normal flight?

Answer 4

• Ground mode: Fully open outflow valve
• Pre-press: With TO thrust set cabin pressurizes to 0.1 psi at 400
  ft/ min
• Climb/cruise/descent: Normal pressurization at max 8.06 psi.
• Depress: Weight on wheels signals to release pressure to 0.1
  psi at 500 ft/min
  Ground mode: 55 seconds after weight on wheels outflow valve
  is fully open again

Question 5

What is the maximum cabin rate of descent in the descent?

Answer 5

750 ft/min

Question 6

What systems feed information to the CPC (Cabin Pressurization Controller)?

Answer 6

• FMGC: Field ldg elevation, QNH
• ADIRS: Static pressure, baro correction
• LGCIU: Landing Gear Control Interface Unit
• EIU: Thrust lever angle for pre-press

Question 7

Where is the outflow valve located?

Answer 7

Right aft fuselage

Question 8

In what 3 modes can pressurization system operate in?

Answer 8

• Automatic: Pressurization is controlled by the CPC:s
• Semi-automatic: Landing elevation data from the FMGC is
  missing and elevation has to be set manually
• Manual: Manual control of the MAN motor

Question 9

What are the main components of the pressurization system?

Answer 9

• Two CPC:s
• One residual pressure controller (RPCU)
• One outflow valve
• One cabin control panel
• Two safety valve

Question 10

How do you manually switch between CPC:s?

Answer 10

Switching the MODE SEL pb to MAN for at least 10 seconds, then returning it to AUTO will select the other system

Question 11

When does the cabin V/S indication on the ECAM CRUISE page start flashing?

Answer 11

When V/S is greater than 1750 ft/min and stops flashing when returning below 1650 ft/min

Question 12

What is the purpose of the RPCU (Residual Pressure Control Unit)?

Answer 12

To depressurize the aircraft in case of abnormal residual pressure on the ground.

It opens the outflow valve when:
- Outflow valves are not fully open
- Both CPCs are failed

Question 13

What is the function of the pressurization “Abort Mode” and what triggers it?

Answer 13

If the aircraft climb is less than normal below 8000 ft after take-off or descent is more then 200 fpm for 30 sec the Cabin pressure is set back to take-off pressure of 0.1 psi

Question 14

When does the delta P indication turn amber?

Answer 14

Goes Amber less than 0.4 psi and more than 8.5 psi

Question 15

What does it mean if the delta P digital display is pulsating on final approach?

Answer 15

You are below 800ft with a delta P of more than 1.5 psi

Question 16

What does it mean if the digital display for the cabin V/S is pulsating?

Answer 16

V/S is more than 1750 ft/min

Question 17

When does the cabin altitude change to red?

Answer 17

At 9550 ft cabin altitude

Question 18

What does it mean if the cabin altitude readout is flashing?

Answer 18

Cabin altitude is over 8800 ft
Flashing stops when the cabin returns to below 8600 ft cabin alt

Question 19

When does the positive safety valve open?

Answer 19

Opens when the cabin delta P is between 8.9 and 9.7 psi
The range is due to the reduced accuracy of the delta P measurements (in MAN mode) combined with the decrease in cabin differential pressure that occurs immediately after the safety valves open

Question 20

When will the mask doors open when in AUTO mode?

Answer 20

At 14000 ft cabin altitude

Question 21

From what system does the pressurization system obtain landing elevation?

Answer 21

FMGC database

Question 22

What happens with the CPC:s after every landing?

Answer 22

They swap primary role between each other

Question 23

Will the DITCHING pb always close the outflow valve?

Answer 23

Not if the valve is under manual control

Question 24

If PACK FLOW switch is set to HI, will it automatically shift to lower flow?

Answer 24

No, only the opposite is true

Question 25

What happens at a cabin altitude of 11300 ft?

Answer 25

All cabin signs illuminate

Question 26

If the Lav/Galley Extract Fan fails, what happens with regards to cabin temperature control?

Answer 26

Cabin temperature defaults to a set value

Question 27

Approximately what rate of cabin change does one "click" of the MAN V/S CTL switch produce?

Answer 27

50 fpm

Question 28

How do you know which CPC is the active one?

Answer 28

SYS 1 or SYS 2 will be displayed on the AIR page

Question 29

What does a FAULT light in the Cabin Press Mode Selector pb switch indicate?

Answer 29

That both CPC:s have failed

Question 30

When do you have to manually set the landing elevation for the pressurization system?

Answer 30

Destination is not in data base or both FMGC:s fail

Question 31

In MAN mode, what is the target cabin V/S?

Answer 31

500 ft/min

Question 32

If the MAN V/S CTL is moved UP, what happens to Press Diff, Cabin V/S, Cabin Alt and Outflow Valve?

Answer 32

Outflow valve opens Press diff decreases Cabin V/S increases Cabin Alt increases

Question 33

What is the purpose of the two safety valves in the pressurization system?

Answer 33

To act as positive and negative pressure relief valves at +8.9 psi and -1.0 psi respectively

Question 34

Where are the safety valves located?

Answer 34

In the rear pressure bulk head wall

Question 35

In what situation is the negative pressure safety valve likely to operate?

Answer 35

During descent if the Cabin altitude stays at 8000 ft and the aircraft descends below that. If that happens, the negative safety valve opens inwards to allow ambient air to come in and equalize the pressure

Question 36

Why would cabin alt increase slightly when a toilet is flushed?

Answer 36

Because over 16000ft the toilets uses differential pressure to flush. It's like opening up a second outflow valve

Question 37

At what cabin altitude will the outflow valve close automatically?

Answer 37

15 000 ft cabin altitude