Pressurisation

Question 1

Describe components of the pressurisation system

Answer 1

2 CPCs- controlling pressurisation schedule sending/receiving signals to the other components

1 outflow valve- to release air from the cabin to maintain a certain cabin pressure

2 safety valves- protect against under or over pressure

Cockpit control panel- to control the system in manual mode

Question 2

When do the CPCs change over?

Answer 2

70s after touchdown

Question 3

How many pressurisation modes are there?

Answer 3

4
Pre pressurisation
Pressurisation
Depressurisation
Ground mode

Question 4

What happens in pre pressurisation mode?

Answer 4

During Take off roll, outflow valves motors towards closed so that the pressure in the cabin increases to 0.1psi to avoid cabin surge at rotation

Question 5

How does pressurisation function during climb, cruise and descent?

Answer 5

CLB: activates at lift off and pressurised on schedule based on rate of climb
Cruise: maintained at cabin altitude at level off or LDG elevation whatever is higher
DES: calculates a descent schedule based on landing elevation so that landing cabin altitude is 0.1psi above ambient

Question 6

Max cabin rate of descent?

Answer 6

750fpm

Question 7

When do depressurisation and ground modes activate?

Answer 7

Depressurisation starts at touchdown, releasing any cabin over pressure
Ground mode 5s after touchdown, outflow valves motors to full open to release all pressure

Question 8

Max cabin altitude in auto mode?

Answer 8

8000ft

Question 9

What does pressurisation system use as reference for LDG elev?

Answer 9

QNH from perf APPR page and airport elevation from FMGC

Question 10

How does manual pressurisation work?

Answer 10

Use man mode button on overhead panel. Power switches to 3rd motor for outflow valve.
Control using dedicated part of CPC1 which is still available if CPC1+2 fail.

Cabin alt controlled using toggle switch which adjusts the outflow valve

Question 11

What QRH procedures are there for pressurisation?

Answer 11

Cabin overpressure

Switching off the packs and opening the blower and extract to vent pressure

Question 12

QRH advisories for pressurisation?

Answer 12

Cabin Vertical Speed >1800fpm
Switch CPCs

Cabin Altitude >8800ft
Revert to manual pressurisation

Cabin differential pressure
Adjust landing elev or go manual

Question 13

Max differential pressure before safety valves open?

Answer 13

8.6psi