Pressurisation Flashcards
How the pressurisation system is controlled ?
It can be controlled automatically - semi automatically and manually
How many CPC ?
There are 2 independant Cabin Pressure Controllers
What kind of data do the CPC use ?
Multiple data : landing elevation, QNH from FMGS, position of the thrust levers, position of the landing gear, pressure altitude from the ADIRS to control the and optimize the cabin altitude
What is the maximum cabin altitude under normal conditions ?
8000ft
How many pressurisation modes does the system have ?
4 modes :
- Ground
- Pre-pressurisation
- Pressurisation in flight
- Depressurisation
What is the Ground mode ?
It fully opens the outflow valve on the ground
What is the Pre-pressurisation mode ?
During takeoff, it decreases the cabin pressure to avoid surge during rotation.
What is the Pressurisation in flight mode ?
It adjusts the cabin altitude and rate of change to provide passenger with a confortable flight.
What is the Depressurisation mode ?
After touchdown, it gradually releases cabin residual overpressure before the ground mode function fully opens the outflow valve.
When does a change of CPC occur ?
70 seconds after touchdown or by pressing the MODE SEL in the overhead panel for at least 10 seconds.
What is the outflow valve and how does it work ?
It consists of a rectangular body with two flaps, linked to an actuator (two automatic motor and one manual motor).
In automatic mode : the operating controller signals the position to the ECAM
In manual mode : the backup section of the CPC1 signals the position to the ECAM
What happens to the outflow valve when RAM air pb is ON, in automatic mode ?
When RAM air pb is ON and p < 1PSI, the system drives the outflow to 50% open.
What happens to the outflow valve when RAM air pb is ON, in manual mode ?
The outflow valve does not automatically open, even if p < 1 PSI
How many safety valve ?
There are 2, and located in the rear bulkhead, above the flotation line.
How do the safety valves work ?
They prevent cabin pressure from going too high (8.6PSI above ambient) or too low (1PSI below ambient)
What is the RPCU ?
Residual Pressure Control Unit, it automatically depressurises the aircraft in case of abnormal residual pressure on the ground.
When does the RPCU open the outflow valve ?
It opens automatically the outflow valve when :
- the outflow valve is not open, and
- both CPC are failed or manual mode selected, and
- the aircraft is on the ground, and
- all engine shutdown, or all ADIRS indicate speed below 100kt.
What are the pressurisation modes under automatic control ?
There are 6 modes :
- Ground mode
- Takeoff mode
- Climb mode
- Cruise mode
- Descent mode
- Abort mode
Whats is the GROUND mode under automatic control ?
Before takeoff and 55 secondes after landing, the outflow valve fully opens to ensure there is no residual pressure. Upon touchdown, the CPC controls the cabin descent rate to +500ft/min until the inside/outside pressures equalise.
Whats is the TAKEOFF mode under automatic control ?
When N2 reaches takeoff power, the CPC pressurises the aircraft at a rate of -400ft/min until it reaches +0.1PSI to avoid surge during rotation
Whats is the CLIMB mode under automatic control ?
When the main landing gear retract, the CPC controls the pressure based on the actual climb rate
Whats is the CRUISE mode under automatic control ?
The maximum altitude is maintained at a constant differential pressure with a maximum cabin altitude of 8000ft and a maximum differential pressure of 8.06 PSI
Whats is the DESCENT mode under automatic control ?
It is optimised so that the cabin altitude reaches the landing field pressure prior to landing at a maximum rate of 750ft/min. The aircraft is pre-pressurised, similar to takeoff at +0.1PSI in order to avoid surge
Whats is the ABORT mode under automatic control ?
It prevents cabin altitude from climbing, it the aircraft stops to climb before reaching 8000ft, or initiates a descent after takeoff.
The cabin pressure resets to the value before takeoff (takeoff altitude + 0.1PSI)
What is the semi-automatic mode ?
When the data from the FMGS is not available, the crew can manually select the landing elevation using the LDG ELEV knob.
What is the range of the LDG ELEV knob ?
From - 2000ft below sea level to +14 000ft above sea level
What is the manual mode ?
If both CPC fail, the crew must first push the MAN SEL pb, then control the outflow valve by using the MAN V/S CTL toggle to increase (UP) or decrease (DOWN) the cabin altitude.
How many seconds can it take to notice a change of the outflow valve in manual mode on the ECAM ?
Up to 5 seconds
Does the outflow valve open under manual control on the ground after landing ?
No
Whats happens if DITCHING pb is pressed ?
When pressed, it commands the closure of the :
- outflow valve
- the emergency RAM air
- avionic ventilation inlet / outlet valves
- pack flow control valves
- forward cargo isolation outlet if installed
Whats happens if DITCHING pb is pressed, with low ground cart connected and doors closed on the ground ?
It will pressurise the aircraft !
When does the cabin altitude rate flash on the ECAM ?
It flashes when reaching 1750ft/min and stops flashing when returning below 1650ft/min
When does the delta p flash on the ECAM ?
It flashes when delta p > 1.5PSI and stops flashing when returning at 1PSI during flight (phase 7)
When does the delta p become amber on the ECAM ?
When delta p is out of normal range (<0.4PSI or >8.5PSI)
When does the cabin altitude flash on the ECAM ?
It flashes when reaching 8800ft and stops flashing when returning to 8600ft
When does the cabin altitude become red on the ECAM ?
When at or above 9550ft
When does the safety valves open on the ECAM ?
When delta p is between 8.9PSI and 9.7PSI.
When does the outflow valve become amber on the ECAM ?
When open more than 95% in flight, under automatic mode
At what altitude the PAX SIGNS WARNING occurs ?
When cabin altitude goes above 11 300ft (all cabin signs illuminate)
At what altitude the CABIN OXYGEN MASKS drop ?
When cabin altitude goes above 14 000ft (the masks drop automatically)
At what altitude the OUTFLOW VALVE closes ?
When cabin altitude goes above 15 000ft (the actuator commands the outflow valve to the closed position)
