PRESSURIZATION Flashcards
When does the delta P indication become amber?
When delta P below 0.4 psi or over over 8.5 psi
What is the function of the ditching pb?
Closes the outflow valve
Closes emergency ram air inlet door
Closes avionics ventilation inlet and extract valves
Closes Pack Flow Control Valves
How many motors are available to operate the outflow valve?
Two automatic AC motors and one manual DC motor
Describe the different stages of pressurization during a normal flight?
- 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
What is the maximum cabin rate of descent in the descent?
750 ft/min
What systems feed information to the CPC (Cabin Pressurization Controller)?
- FMGC: Field ldg elevation, QNH
- ADIRS: Static pressure, baro correction
- LGCIU: Landing Gear Control Interface Unit
- EIU: Thrust lever angle for pre-press
Where is the outflow valve located?
Right aft fuselage
In what 3 modes can pressurization system operate in?
- 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
What are the main components of the pressurization system?
- Two CPC:s
- One residual pressure controller (RPCU)
- One outflow valve
- One cabin control panel
- Two safety valve
How do you manually switch between CPC:s?
Switching the MODE SEL pb to MAN for at least 10 seconds, then returning it to AUTO will select the other system
When does the cabin V/S indication on the ECAM CRUISE page start flashing?
When V/S is greater than 1750 ft/min and stops flashing when returning below 1650 ft/min
What is the purpose of the RPCU (Residual Pressure Control Unit)?
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
What is the function of the pressurization “Abort Mode” and what triggers it?
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
When does the delta P indication turn amber?
Goes Amber less than 0.4 psi and more than 8.5 psi
What does it mean if the delta P digital display is pulsating on final approach?
You are below 800ft with a delta P of more than 1.5 psi
What does it mean if the digital display for the cabin V/S is pulsating?
V/S is more than 1750 ft/min
When does the cabin altitude change to red?
At 9550 ft cabin altitude
What does it mean if the cabin altitude readout is flashing?
Cabin altitude is over 8800 ft
Flashing stops when the cabin returns to below 8600 ft cabin alt
When does the positive safety valve open?
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
When will the mask doors open when in AUTO mode?
At 14000 ft
From what system does the pressurization system obtain landing elevation?
FMGC database
What happens with the CPC:s after every landing?
They swap primary role between each other
Will the DITCHING pb always close the outflow valve?
Not if the valve is under manual control
If PACK FLOW switch is set to HI, will it automatically shift to lower flow?
No, only the opposite is true
What happens at a cabin altitude of 11300 ft?
All cabin signs illuminate
If the Lav/Galley Extract Fan fails, what happens with regards to cabin temperature control?
Cabin temperature defaults to a set value
Approximately what rate of cabin change does one “click” of the MAN V/S CTL switch produce?
50 fpm
How do you know which CPC is the active one?
SYS 1 or SYS 2 will be displayed on the AIR page
What does a FAULT light in the Cabin Press Mode Selector pb switch indicate?
That both CPC:s have failed
When do you have to manually set the landing elevation for the pressurization system?
Destination is not in data base or both FMGC:s fail
In MAN mode, what is the target cabin V/S?
500 ft/min
If the MAN V/S CTL is moved UP, what happens to Press Diff, Cabin V/S, Cabin Alt and Outflow Valve?
Outflow valve opens
Press diff decreases
Cabin V/S increases
Cabin Alt increases
What is the purpose of the two safety valves in the pressurization system?
To act as positive and negative pressure relief valves at +8.9 psi and -1.0 psi respectively
Where are the safety valves located?
In the rear pressure bulk head wall
In what situation is the negative pressure safety valve likely to operate?
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
Why would cabin alt increase slightly when a toilet is flushed?
Because over 16000ft the toilets uses differential pressure to flush. It’s like opening up a second outflow valve
At what cabin altitude will the outflow valve close automatically?
15 000 ft cabin altitude
