21-20-10 pressurisation Flashcards
What are the four general functions?
Ground
Pressurisation
Pressurisation in flight
Depressurisation
What does the system consist of?
2 CPCs (cabin pressure controllers)
One outflow valve
One control panel
2 safety valves
Where does the air pressure in the cabin get the signals from?
FMGS
What happens if FMGS data is not available for auto pressurisation
Crew use the landing elevation knob
How many motors are there for the outflow valve?
3!
2 automatic motors
1 manual motor
What happens when the ram air pb is ON and delta P is less than 1PSI
The system drives the outflow valve to 50%
What are the settings of the safety valves?
+8.6PSI
-1PSI
When does transfer between CPCs occur?
70s after landing
If the other system fails
What are the 6 pressurisation modes?
6! Ground Takeoff Climb Cruise Descent Abort
Pressurisation: What is the ground mode?
Before takeoff and 55s after landing opens valve fully to make sure no residual pressure. Touch down -500ft/min
What is the takeoff mode?
Pre pressure of 400ft/min until 0.1PSI
What is the target limit for cabin altitude?
8000ft
What is the descent mode?
Maintains rate of descent so that pressure before landing is 0.1PSI. MAX RATE OF 750ft/min
What valves does the ditching pb close?
Outflow
Ram air
Avionics inlet and outflow valves
Pack flow control valves
What prevents the pressurisation from getting too high?
Two safety valves
+8.6 PSI
-1.0PSI
