21-20 Pressurisation Flashcards
What is the maximum positive differential pressure of the aircraft?
9.0psi
What is the maximum negative differential pressure of the aircraft?
-1.0psi
What is the safety relief valve setting?
8.6psi
Cabin altitude warning at?
9550ft
Maximum normal cabin altitude?
8000ft
What does CPC stand for? How many are there?
Cabin Pressure Controller (x2)
When does a transfer of CPC take place?
70 seconds after landing or when one fails
What information does the CPC use from the FMGC?
Landing elevation and landing QNH
What information does the CPC use from the ADIRS?
Pressure altitude
In automatic pressure control mode, how many phases of flight are there? What are they?
6
GROUND (GN): Outflow valve fully open
TAKEOFF (TO): Pre-pressurises to difference of +0.1 psi
CLIMB (CL): Uses aircraft climb rate
CRUISE (CR): Maximum 8000ft cabin altitude
DESCENT (DE): Maximum cabin rate of -750ft/m, and pressurises aircraft to landing field pressure + 0.1psi
ABORT (AB): No climb after takeoff? Cabin pressure set back to +0.1psi
FCOM 21-20-30
For how long must you leave the cabin pressure MODE SEL in MAN before returning it to AUTO to force a transfer to the other system?
At least 10 seconds
FCOM 21-20-40
Describe components of the pressurisation system
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
When do the CPCs change over?
70s after touchdown
How many pressurisation modes are there?
4
Pre pressurisation
Pressurisation
Depressurisation
Ground mode
What happens in pre pressurisation mode?
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
How does pressurisation function during climb, cruise and descent?
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
Max cabin rate of descent?
750fpm
When do depressurisation and ground modes activate?
Depressurisation starts at touchdown, releasing any cabin over pressure
Ground mode 5s after touchdown, outflow valves motors to full open to release all pressure
Max cabin altitude in auto mode?
8000ft
What does pressurisation system use as reference for LDG elev?
QNH from perf APPR page and airport elevation from FMGC
How does manual pressurisation work?
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
What QRH procedures are there for pressurisation?
Cabin overpressure
Switching off the packs and opening the blower and extract to vent pressure
QRH advisories for pressurisation?
Cabin Vertical Speed >1800fpm
Switch CPCs
Cabin Altitude >8800ft
Revert to manual pressurisation
Cabin differential pressure
Adjust landing elev or go manual
Max differential pressure before safety valves open?
8.6psi
