Pressurization Flashcards
How many cabin altitude controllers are there?
Two - A and B
How many controllers work with each outflow valve.
Each controller can control both outflow valves
What are 3 modes controlled by cabin altitude controllers?
Climb, cruise, and descent
What do cabin altitude controllers use to calculate schedule?
Ambient pressure and flight plan from FMC
What does controller do during an intermediate level off during climb?
Cabin altitude continues to increase during the level segment.
Max cabin altitude in cruise mode?
8000’
When do cabin altitude controllers enter descent mode?
- TOD
- Initial descent of 1000’
Describe pressurization upon touchdown?
Small positive pressure
When does cabin rate limiter close both outflow valves?
When cabin altitude exceeds 11,000’
What altitude is assumed if no auto or manual landing field elevation is selected/available?
2000’
What happens if primary controller fails?
Auto switch to secondary controller
What action would allow manual operation of pressurization system?
Turn both Outflow Manual switches to ON
What protection is lost when both outflow valves are operated manually?
Cabin Altitude Limiter
Which Cabin Altitude Controller is used for a flight segment?
Alternates between controllers for each flight.
What happens is excessive cabin pressurization occurs?
Positive pressure relief valves OPEN and PACK 2 shuts down until pressure is relieved.
During climb, the cabin altitude gradually increases so that when cruise is reached a target differential pressure of ____ is achieved?
8.9 PSI
When does the cabin altitude controller enter cruise mode?
When within 200’ of cruise altitude or when the aircraft vertical climb falls below 100FPM for more than one minute.
When does CABIN ALT AUTO message appear on EICAS?
- Both cabin altitude controllers FAILED
- Both manual switches are on
When does EICAS Warning CABIN ALTITUDE and aural warning message sound?
10000’ cabin altitude
When do outflow valves close?
11000’ cabin altitude in AUTO mode
When do O2 masky automatically deploy in flight?
14000’ cabin altitude
When can pax oxygen system be reset?
Once cabin altitude has dropped to below 12000’
When do cabin warning messages rearm after being triggered?
Below 9500’ cabin altitude. EICAS message CAB ALT returns to amber
If you forget to enter a CRZ altitude into FMC, what will controllers assume cruise altitude to be?
FL390
What is the cabin altitude sequence of events?
8500’ - Cabin Altitude Indicator turns amber
10000’ - Warning, Aural
11000’ - Outflow Valves Close
14000’ - Masks Drop
12000’ - Passenger O2 system can be reset
9500’ - Cabin Warning Messages Rearm
How many positive pressure relief valves? Location?
- 2 total
- In EE Compartment + FWD Left Fuselage
Where are negative pressure relief valves located?
- Side cargo door
- FWD + AFT Cargo Doors
