AIR CONDITIONING - GENERAL
GENERAL
Applicable to: ALL
The air conditioning system is fully automatic.
It provides continuous air renewal and maintains a constant, selected temperature in the following
three zones :
- COCKPIT,
- FWD CABIN,
- AFT CABIN.
These three zones are independently controlled.
Air is supplied by the pneumatic system, via:
‐ Two pack flow control valves,
‐ Two packs,
‐ The mixing unit, which mixes the air that comes from the cabin and the packs.
Air is then distributed to the cockpit and the cabin.
Temperature regulation is optimized via the hot air pressure regulating valve, and the trim air valves
that add hot air, tapped upstream of the packs, to the mixing unit air.
In an emergency, a ram air inlet can provide ambient air to the mixing unit.
Temperature regulation is controlled by two Air Conditioning System Controllers.
Flight deck and cabin temperature can be selected from the cockpit’s AIR COND panel.
A control panel is provided on the Forward Attendant Panel. During cruise, the cabin crew can modify
each cabin zone temperature that is selected from the cockpit, with a limited authority of ± 2.5 °C. (±
4.5 °F).
Low-pressure air is supplied to the mixing unit by a ground connection.
ARCHITECTURE
Applicable to: PR-AVB, PR-AVC, PR-AVD, PR-AVP, PR-AVQ, PR-AVR
ARCHITECTURE
Applicable to: PR-AVH, PR-AVJ, PR-AVK, PR-AVL, PR-AVO
AIR CONDITIONING - MAIN COMPONENTS
AIR CONDITIONING PACK
Applicable to: ALL
The two packs operate automatically and independently of each other.
Pack operation is controlled by air conditioning system controller signals.
Warm pre-conditioned bleed air enters the cooling path via the pack flow control valve, and is ducted
to the primary heat exchanger.
Then, the cooled bleed air enters the compressor section of the air-cycle machine and is compressed
to a higher pressure and temperature.
It is cooled again in the main heat exchanger and enters the turbine section, where it expands and, in
expanding, generates power to drive the compressor and cooling air fan.
The removal of energy during this process reduces air temperature, resulting in very low air
temperature at turbine discharge.
A water separator system dries the air before it enters the turbine section.
PACK SCHEMATIC (SIMPLIFIED)
Applicable to: PR-AVB, PR-AVC, PR-AVD, PR-AVP, PR-AVQ, PR-AVR
PACK SCHEMATIC (SIMPLIFIED)
Applicable to: PR-AVH, PR-AVJ, PR-AVK, PR-AVL, PR-AVO
AIR CONDITIONING - MAIN COMPONENTS
PACK FLOW CONTROL VALVE
This valve is pneumatically-operated and electrically-controlled.
It regulates the air flow in accordance with signals received from the air conditioning system controllers.
In the absence of air pressure, a spring keeps the valve closed.
The valve closes automatically in case of pack overheating, engine starting, or operation of the fire or
ditching pushbutton.
The valve is controlled from the AIR COND panel.
RAM AIR
An emergency ram air inlet ventilates the cockpit and cabin to remove smoke, or if both packs fail.
The emergency ram air inlet valve is controlled by the RAM AIR pushbutton on the AIR COND panel.
This pushbutton opens the ram air valve, provided that ditching is not selected.
When the RAM AIR pushbutton is ON :
The outflow valve opens about 50 %, provided that it is
under automatic control and ▵P is less than 1 PSI.
The outflow valve does not automatically open if
it is under manual control, even if ▵P is less than 1 PSI.
If ▵P is greater than 1 PSI, the check valve
located downstream the ram air door will not open, even if the ram air door has been selected open.
No airflow will then be supplied.
MIXER UNIT
This unit mixes cold fresh air from the packs with the cabin air being recirculated through
recirculation fans. The mixer unit is also connected to the emergency ram air inlet and the low
pressure ground inlets.
HOT-AIR PRESSURE-REGULATING VALVE
Applicable to: ALL
In the absence of air, a spring keeps the valve closed. This pneumatically-operated and
electrically-controlled valve regulates hot air pressure, which is tapped upstream of the packs. The
air conditioning system controller 1 regulates this valve. This valve closes upon pressing the HOT
AIR pushbutton on the AIR COND panel, or when both lanes of one air conditioning system controller
fail.
The valve closes automatically, if:
‐ The duct overheats, or
‐ The cockpit trim air valve fails, or
‐ Both cabin trim air valves fail.
The hot-air pressure-regulating valve remains operative, even if either the forward or aft cabin trim air
valve fails.
TRIM AIR VALVES
These valves are electrically-controlled by the air conditioning system controllers.
The cockpit trim air valve, controlled by the air conditioning system controller 1,
and the cabin trim air valves, controlled by the air conditioning system controller 2,
adjust the temperature by adding hot air.
AIR CONDITIONING - TEMPERATURE AND FLOW REGULATION
Temperature regulation is automatic and controlled by the air conditioning system controllers.
PACK CONTROLLER
Each pack controller regulates the temperature of its associated pack, in accordance with a demand
signal from the zone controller, by modulating the bypass valve and the ram air inlet flaps.
The ram air inlet flaps close during takeoff and landing to avoid ingestion of foreign matter.
Note: During takeoff, the ram air inlet flaps close when TO power is set and the main landing gear
struts are compressed.
During landing they close as soon as the main landing gear struts are compressed, as long
as speed is at or above 70 kt.
They open 20 s after the speed drops below 70 kt.
The pack controllers also regulate flow by modulating the associated pack flow control valve.
TEMPERATURE REGULATION
The air conditioning system controller 2 regulates the temperature of the two cabin zones, and the air
conditioning system controller 1 regulates, the cockpit temperature.
BASIC TEMPERATURE REGULATION
The flight crew uses the temperature selectors on the cockpit’s air conditioning panel to select
the reference temperatures which are fine tuned through the Forward Attendant Panel (FAP) for
the cabin zones.
The air conditioning system controllers compute a temperature demand from the
selected temperature and the actual temperature.
The actual temperature is measured by sensors:
‐ In the cockpit, for the cockpit zone;
‐ In the lavatory extraction circuit and galley ventilation system, for the cabin.
A signal corresponding to the lowest demanded zone temperature goes to the air conditioning
system controllers, which then make both packs produce the required outlet temperature.
OPTIMIZED TEMPERATURE REGULATION
The air conditioning system controllers optimize temperature by acting on the trim air valves.
The temperature selection range is from 18 °C (64 °F) to 30 °C (86 °F).
AIR CONDITIONING SYSTEM CONTROLLERS
(PR-AVB, PR-AVC, PR-AVD, PR-AVP, PR-AVQ, PR-AVR)
Each air conditioning system controller regulates the temperature of its associated pack, by
modulating the bypass valve and the ram air inlet flap.
The ram air inlet flap closes during takeoff and landing to avoid the ingestion of foreign matter.
Note: During takeoff, the ram air inlet flap closes when takeoff power is set, and the main landing
gear struts are compressed.
During landing, it closes as soon as the main landing gear struts are compressed, as long
as speed is at or above 70 kt.
It opens 20 s after the speed drops below 70 kt.
The air conditioning system controllers also regulate flow by modulating the associated pack flow
control valve.
PACK FLOW CONTROL
The crew can use the PACK FLOW selector to adjust the pack flow for the number of passengers
and for external conditions.
Whatever the crew selects, the system delivers higher flow for any of the following circumstances:
‐ In single-pack operation,
‐ When the APU is supplying bleed air.
The system delivers normal flow if the crew selects LO flow and the temperature demand cannot
be satisfied.
ENGINE PRESSURE DEMAND
When the cooling demand in one zone cannot be satisfied, if the bleed pressure is too low, the
air conditioning system controller sends a pressure demand signal to both Engine Interface
Units (EIU) to increase the minimum idle and to raise the bleed pressure.
APU FLOW DEMAND
When the APU bleed valve is open, the air conditioning system controller signals the APU's
Electronic Control Box (ECB) to increase the APU flow output when any zone temperature
demand cannot be satisfied.
AIR CONDITIONING SYSTEM CONTROLLERS
(PR-AVH, PR-AVJ, PR-AVK, PR-AVL, PR-AVO)
Each air conditioning system controller regulates the temperature of its associated pack, by
modulating the bypass valve and the ram air inlet flap.
The ram air inlet flap closes during takeoff and landing to avoid the ingestion of foreign matter.
Note: During takeoff, the ram air inlet flap closes when takeoff power is set, and the main landing
gear struts are compressed.
During landing, it closes as soon as the main landing gear struts are compressed, as long
as speed is at or above 70 kt.
It opens 20 s after the speed drops below 70 kt.
The air conditioning system controllers also regulate flow by modulating the associated pack flow
control valve.
HI FLOW CONTROL
The crew can use the HI FLOW pushbutton to increase the pack flow in case of abnormal hot and
humid conditions.
Whatever the crew selects, the system delivers higher flow (144 % of the normal flow) for any of
the following circumstances:
‐ In single-pack operation,
‐ When the APU is supplying bleed air.
ENGINE PRESSURE DEMAND
When the cooling demand in one zone cannot be satisfied, if the bleed pressure is too low, the
air conditioning system controller sends a pressure demand signal to both Engine Interface
Units (EIU) to increase the minimum idle and to raise the bleed pressure.
APU FLOW DEMAND
When the APU bleed valve is open, the air conditioning system controller signals the APU's
Electronic Control Box (ECB) to increase the APU flow output when any zone temperature
demand cannot be satisfied.
AIR CONDITIONING - SYSTEM OPERATION UNDER FAILURE CONDITION
Each controller is comprised of two lanes.
One lane controls the system, the other takes over full
control, in case of an active lane failure.
AIR CONDITIONING SYSTEM CONTROLLER
ONE LANE FAILURE
No effect, as the second lane takes over.
BOTH LANES FAILURE
The related pack is lost, and the hot air pressure-regulating valve and associated trim air valves
close.
AIR CYCLE MACHINE FAILURE
If the Air Cycle Machine (ACM) fails (compressor/turbine seizure), the affected pack may be operated
in heat exchanger cooling mode.
Warm pre-conditioned bleed air enters the cooling path via the pack valve and goes to the primary
heat exchanger.
Then, the main part of the cooled air goes directly downstream of ACM turbine
through the bypass valve, and the rest goes through the failed ACM.
The ACM seizure reduces the pack flow.
As for normal pack operation :
‐ The air conditioning system controller regulates temperature by modulating the bypass valve and
the ram air inlet flap.
‐ The air conditioning system controller regulates the hot air flow through the trim air valves to
optimize cockpit/cabin temperature regulation.
Hot air flow is lower than in normal pack operation, because pack flow is reduced.
HOT AIR PRESSURE REGULATING VALVE FAILURE
Failed open : No effect.
Failed closed : Optimized regulation is lost.
Trim air valves are driven to the fully closed position.
Pack 1 controls the cockpit temperature to the selected value and pack 2
controls the cabin temperature (FWD and AFT) to the mean value of the selected
temperatures.
TRIM AIR VALVE FAILURE
Optimized temperature regulation of the corresponding zone is lost.
CONTROLS ON OVERHEAD PANEL
PR-AVB, PR-AVC, PR-AVD, PR-AVP, PR-AVQ, PR-AVR
(1) Zone temperature rotary selector
‐ 12 o'clock position: 24 °C (76 °F).
‐ COLD position: 18 °C (64 °F).
‐ HOT position: 30 °C (86 °F).
(2) HOT AIR pushbutton
ON : The valve regulates hot air pressure.
OFF : The valve closes, and the trim air valves close.
The FAULT circuit is reset.
FAULT : The FAULT light comes on amber, along with an associated ECAM caution, when
duct overheat is detected. The fault circuit detects an overheat when the duct
temperature reaches 88 °C (190 °F) once.
The valve and trim air valves close automatically.
The FAULT light goes off when the temperature drops below 70 °C (158 °F), and
the flight crew selects OFF.
(3) PACK pb-sw
ON : The pack flow control valve is automatically-controlled.
It opens, except in the following cases:
‐ Upstream pressure below minimum.
‐ Compressor outlet overheat.
‐ Engine start sequence:
1. If the crossbleed valve is closed, the valve located on the starting engine
side immediately closes, when the MODE selector is set to IGN (or CRK).
2. It remains closed on the starting engine side (provided the crossbleed valve
is closed) when:
‐ the MASTER switch is set to ON (or MAN START pushbutton is set to
ON) and,
‐ the start valve is open and,
‐ N2 < 50 %. Note: If the crossbleed valve is open at engine start, both pack flow control valves close. 3. On ground, reopening of the valves is delayed for 30 s to avoid a supplementary pack closure cycle during second engine start. ‐ Fire pushbutton, of the engine on the related side, is pressed, ‐ Ditching is selected. OFF : The pack flow control valve closes.
FAULT lt : Comes on amber, and a caution appears on the ECAM, if the pack flow control
valve position disagrees with the selected position, or in the case of compressor
outlet overheat or pack outlet overheat.
(4) PACK FLOW sel
‐ Permits the selection of pack valve flow, according to the number of passengers and
ambient conditions (smoke removal, hot or wet conditions).
LO (80 %) – NORM (100 %) – HI (120 %).
‐ Manual selection is irrelevant in single pack operation, or with APU bleed supply. In these
cases, HI is automatically selected.
‐ If LO is selected, the pack flow can be automatically selected up to 100 % when the cooling
demand cannot be satisfied.
(5) RAM AIR pushbutton (guarded)
ON : The ON light comes on white.
If the DITCHING pushbutton, on the CABIN PRESS panel, is in normal position:
‐ The RAM air inlet opens.
‐ If Δp ≥ 1 PSI: The outflow valve control remains normal. No emergency RAM air
flows in.
‐ If Δp < 1 PSI: The outflow valve opens to about 50 % when under automatic control. It does not automatically open when it is under manual control. Emergency RAM airflow is directly supplied to the mixer unit. OFF: The RAM air inlet closes.
CONTROLS ON OVERHEAD PANEL
PR-AVH, PR-AVJ, PR-AVK, PR-AVL, PR-AVO
(1) Zone temperature selector
‐ 12 o'clock position: 24 °C (76 °F).
‐ COLD position: 18 °C (64 °F).
‐ HOT position: 30 °C (86 °F).
(2) HOT AIR pushbutton
ON : The valve regulates hot air pressure.
OFF : The valve closes, and the trim air valves close.
The FAULT circuit is reset.
FAULT : The FAULT light comes on amber, along with an associated ECAM caution, when
duct overheat is detected. The fault circuit detects an overheat when the duct
temperature reaches 88 °C (190 °F).
The valve and trim air valves close automatically.
The FAULT light goes off when the temperature drops below 70 °C (158 °F), and
the flight crew selects OFF.
(3) PACK pushbutton
ON : The pack flow control valve is automatically-controlled.
It opens, except in the following cases:
‐ Upstream pressure below minimum.
‐ Compressor outlet overheat.
‐ Engine start sequence:
1. If the crossbleed valve is closed, the valve located on the starting engine
side immediately closes, when the MODE selector is set to IGN (or CRK).
2. It remains closed on the starting engine side (provided the crossbleed valve
is closed) when:
- the MASTER switch is set to ON (or MAN START pushbutton is set to ON) and,
- the start valve is open and,
- N2 < 50 %. Note: If the crossbleed valve is open at engine start, both pack flow control valves close. 3. On ground, reopening of the valves is delayed for 30 s to avoid a supplementary pack closure cycle during second engine start. ‐ Fire pushbutton, of the engine on the related side, is pressed, ‐ Ditching is selected. OFF : The pack flow control valve closes. FAULT lt : Comes on amber, and a caution appears on the ECAM, if the pack flow control valve position disagrees with the selected position, or in the case of compressor outlet overheat or pack outlet overheat. (4) HI FLOW pushbutton ‐ Permits the selection of normal or HI pack valve flow according to the number of passengers and ambient conditions (smoke removal, hot or wet conditions). ON: HI flow is selected. HI flow provides 20 % more than normal flow. OFF: F normal flow is selected. ‐ The manual selection is irrelevant in single pack operation or with APU bleed supply. In these cases, the system delivers 144 % of the normal flow. (5) RAM AIR pushbutton (guarded) ON : The ON light comes on white. If the DITCHING pushbutton, on the CABIN PRESS panel, is in normal position: ‐ The RAM air inlet opens. ‐ If Δp ≥ 1 PSI: The outflow valve control remains normal. No emergency RAM air flows in. ‐ If Δp < 1 PSI: The outflow valve opens to about 50 % when under automatic control. It does not automatically open when it is under manual control. Emergency RAM airflow is directly supplied to the mixer unit. OFF: The RAM air inlet closes.
(1) CAB FAN pb
ON : The two cabin fans are on.
OFF: The two cabin fans are off.
ECAM BLEED PAGE
(1) Pack outlet temperature
It appears in green. It becomes amber, if the temperature is higher than 90 °C.
(2) RAM AIR inlet
Crossline : The flap is normally closed.
– Green
In transit: The flap is partially open
– Amber
Inline : The flap is fully open on ground.
- Amber
Inline: The flap is fully open in flight.
– Green
(3) Pack bypass valve position
Indication is green.
C = Cold – Valve closed
H = Hot – Valve open.
(4) Pack compressor outlet temperature
It appears in green. It becomes amber, if the temperature is higher than 230 °C.
(5) Pack flow
It appears in green.
It becomes amber, if the pack flow control valve is closed.
Note: The pack flow indication can be up to 30 % below the actual flow rate.
(6) Pack flow control valve
Inline - Green : Open.
Inline - Amber : Open, and disagrees with the control position.
Crossline - Green : Fully closed.
Crossline - Amber : Fully closed, and disagrees with the control position.
(7) User Indication
It appears in green.
It becomes amber:
‐ On ground, when both pack flow control valves are closed, or
‐ In flight, when RAM AIR flap is not fully open, and both pack flow control valves are closed.
ECAM COND PAGE
(1) Cabin FAN fault indication
It appears in amber, if the recirculation fan is detected as faulty.
(2) Zone temperature
It is in green.
(3) Zone duct temperature
It appears in green, and becomes amber at 80 °C (176 °F).
(4) Zone trim air valve position
The arrow is green. It is replaced by amber crosses (“XX”) if the valve fails.
C = Cold valve fully closed.
H = Hot valve fully open.
(5) Hot air pressure regulating valve
In line - Green : Valve is normally open.
In line - Amber : Valve is abnormally open (disagrees with control position).
Crossline - Green : Valve is normally fully closed.
Crossline - Amber : Valve is closed and pushbutton OFF, or valve position disagrees with
control position.
(6) TEMP
Unit of measure (°C or °F) is indicated in cyan.
ECAM CAB PRESS PAGE
(1) PACK indication
Triangle normally green, PACK 1(2) indication normally white. Both become amber when pack
flow control valve is closed with associated engine running.
ECAM CRUISE PAGE
(1) Zone indication
This field also displays the temperature scale in use (°C or °F).
(2) Zone temperature
WARNINGS AND CAUTIONS
MEMO DISPLAY
RAM AIR ON appears in green if the ram air pushbutton switch is ON.
AIR CONDITIONING - ELECTRICAL SUPPLY
BUS EQUIPMENT LIST
AIR CONDITIONING / PRESSURIZATION / VENTILATION
PRESSURIZATION - GENERAL
PR-AVH, PR-AVJ, PR-AVK, PR-AVL, PR-AVO
The cabin pressurization system has four general functions :
1‐ Ground function : Fully opens the outflow valve on ground.
2‐ Prepressurization : During takeoff, increases cabin pressure to avoid a surge in cabin pressure
during rotation.
3‐ Pressurization in flight : Adjusts cabin altitude, and rate of change to provide passengers with a
comfortable flight.
4‐ Depressurization : After touchdown, gradually releases residual cabin overpressure before the
ground function fully opens the outflow valve.
The system consists of :
‐ 02ea Cabin Pressure Controllers (CPC)
‐ 01ea outflow valve, with an actuator that incorporates three motors (02ea for automatic operation,
01ea for manual operation)
‐ 01ea control panel
‐ 02ea safety valves
Any one of the three independent electric motors may power the outflow valve.
Normally, one of the two cabin pressure controllers operates the outflow valve by means of its
associated automatic motor.
In case of ditching, an override switch on the control panel allows the pilots to close the outflow
valve and all valves below the flotation line.
The pilot can set the system to operate automatically, semi-automatically, or manually.
In normal operation, cabin pressurization is fully automatic.
GENERAL
PR-AVB, PR-AVC, PR-AVD, PR-AVP, PR-AVQ, PR-AVR
The cabin pressurization system has four general functions :
‐ Ground function : Fully opens the outflow valve on ground.
‐ Prepressurization : During takeoff, increases cabin pressure to avoid a surge in cabin pressure
during rotation.
‐ Pressurization in flight : Adjusts cabin altitude, and rate of change to provide passengers with a
comfortable flight.
‐ Depressurization : After touchdown, gradually releases residual cabin overpressure before the
ground function fully opens the outflow valve.
The system consists of :
‐ Two Cabin Pressure Controllers (CPC)
‐ One Residual Pressure Control Unit (RPCU)
‐ One outflow valve, with an actuator that incorporates three motors (two for automatic operation,
one for manual operation)
‐ One control panel
‐ Two safety valves
Any one of the three independent electric motors may power the outflow valve.
Normally, one of the two cabin pressure controllers operates the outflow valve by means of its
associated automatic motor.
In case of ditching, an override switch on the control panel allows the flight crew to close the outflow
valve and all valves below the flotation line.
The flight crew can set the system to operate automatically, semi-automatically, or manually.
In normal operation, cabin pressurization is fully automatic.
AUTOMATIC OPERATION
The pilots monitors the operation of the system, but does nothing to control it.
Air pressure in the cabin follows external schedules that the system receives
as signals from the Flight Management and Guidance System (FMGS).
When FMGS data is not available for automatic pressurization, the crew only needs to select the
landing field elevation.
The pressurization system then uses the manually-selected landing field elevation for internal
schedules.
MANUAL OPERATION
In manual mode, the flight crew controls the cabin altitude via the manual motor of the outflow valves,
by operating controls on the pressurization control panel.
PRESSURIZATION SCHEMATIC
PRESSURIZATION - MAIN COMPONENTS
CABIN PRESSURE CONTROLLERS
Two identical, independent, digital controllers automatically control the system, by maintaining the
proper cabin pressure.
They receive signals from the Air Data Inertial Reference System (ADIRS),
the Flight Management and Guidance Computer (FMGC), the Engine Interface Unit (EIU), and the
Landing Gear Control Interface Unit (LGCIU).
When the system is in automatic or semi-automatic mode, one controller is active, the other is on
standby.
The controllers also generate signals for the Electronic Centralized Aircraft Monitoring (ECAM).
For operation in manual mode, each controller has a backup section, which is powered by an
independent power supply in the controller N°1 position.
This section also has a pressure sensor that generates the cabin altitude and
pressure signal for the ECAM, when MAN mode is selected.
The controllers communicate with each other via a cross-channel link.
OUTFLOW VALVE
The outflow valve is on the right-hand side of fuselage, behind the aft cargo compartment and below
the flotation line.
The outflow valve assembly consists of a flush, skin-mounted, rectangular frame, carrying inward and
outward opening flaps linked to the actuator.
The actuator contains the drives of the two automatic motors and the manual motor.
Either of two automatic motors operates the valve in automatic mode,
and the manual motor operates it in manual mode.
In automatic mode, the operating controller signals the position of the valve to the ECAM.
In manual mode, the backup section of the N° 1 controller signals the position of the valve to the
ECAM.
Note: When the RAM AIR pushbutton is ON, and ▵p is below 1 PSI, the system drives the outflow
valve about 50 % open if it is under automatic control. If the system is under manual
control, the outflow valve does not automatically open, even if ▵p is below 1 PSI.
SAFETY VALVES
Two independent pneumatic safety valves prevent cabin pressure from going too high (8.6 PSI
above ambient) or too low (1 PSI below ambient).
They are located on the rear pressure bulkhead, above the flotation line.
RESIDUAL PRESSURE CONTROL UNIT
: PR-AVB, PR-AVC, PR-AVD, PR-AVP, PR-AVQ, PR-AVR
The Residual Pressure Control Unit (RPCU) automatically depressurizes the aircraft in case of
abnormal residual pressure on ground.
It automatically opens the outflow valve, when:
‐ The outflow valve is not fully open, and
‐ Both CPCs are failed, or manual mode is selected, and
‐ The aircraft is on ground, and
‐ All engines are shutdown, or all ADIRS indicate an airspeed below 100 kt.
PRESSURIZATION - SYSTEM OPERATION
AUTOMATIC PRESSURE CONTROL MODE
GENERAL
‐ Two identical, independent, automatic systems (each consisting of a controller and its
associated motors) control cabin pressure.
Either system controls the single outflow valve.
Only one controller operates at a time.
An automatic transfer occurs:
• 70 s after each landing.
• If the operating system fails.
‐ The controller automatically controls the cabin pressure.
It limits the cabin pressure to 8 000 ft maximum and optimizes it during climb and descent phases.
‐ The controller normally uses the landing elevation and the QNH from the FMGC, and the
pressure altitude from ADIRS.
If FMGC data are not available, the controller uses the captain BARO Reference from the
ADIRS and the LDG ELEV selection.
‐ Pressurization is assumed through the following modes:
GROUND (GN)
Before takeoff, and 55 s after landing, the outflow valve fully opens to ensure that there is no
residual cabin pressure. At touchdown, any remaining cabin pressure is released at a cabin
vertical speed of 500 ft/min.
TAKEOFF (TO)
To avoid a pressure surge at rotation, the controller pre-pressurizes the aircraft at a rate of
400 ft/min, until the ▵P reaches 0.1 PSI. At liftoff, the controller initiates the climb phase.
CLIMB (CL)
During climb, the cabin altitude varies according to a fixed pre-programmed law that takes into
account the aircraft’s actual rate of climb.
CRUISE (CR)
During cruise, the controller maintains cabin altitude at the level-off value, or at the landing field
elevation, whichever is higher.
DESCENT (DE)
During descent, the controller maintains a cabin rate of descent, such that the cabin pressure is
equal to the landing field pressure +0.1 PSI, shortly before landing.
The maximum descent rate is 750 ft/min.
ABORT (AB)
If the aircraft does not climb after takeoff, the abort mode prevents the cabin altitude from
climbing.
Cabin pressure is set back to the takeoff altitude +0.1 PSI.
PRESSURIZATION MODES SWITCHING
(1) Engine running
0 : Condition not valid
1 : Condition valid
1A : Only one A condition is necessary
EXAMPLE The cabin pressure controller switches from Climb mode (CL) to Abort mode (AB)
when:
‐ The aircraft is below 8 000 ft, or the aircraft has changed altitude less than
5075 ft since takeoff and,
‐ The aircraft rate of descent is greater than 200 ft/min for 30 s.
PRESSURIZATION FLIGHT PROFILE
MANUAL PRESSURE CONTROL MODE
If both automatic systems fail, the flight crew may use the CABIN PRESS control panel to take over
manual control of cabin pressurization.
• Release the MODE SEL pushbutton to select MAN, and
• Push the MAN V/S CTL switch UP or DN to increase or decrease cabin altitude.
The first of these actions cuts off power to the AUTO motors, and enables the MAN motor to control
the outflow valve.
Note:
1. Due to the slow operation of the outflow valves in manual mode, and the limited
resolution of the outflow valves' position on the ECAM, the visual ECAM indication of a
change in the outflow valves' position can take up to 5 s.
2. As the pressurization system is manually-controlled, the outflow valve does not open
automatically at touchdown.
DITCHING
to: PR-AVH, PR-AVJ, PR-AVK, PR-AVL, PR-AVO
To prepare for ditching, the pilot must press the DITCHING pushbutton on the CABIN PRESS
control panel to close:
1- the outflow valve,
2- the emergency ram air inlet,
3- the avionics ventilation inlet and
4- extract valves, and
5- the pack flow control valves.
DITCHING
to: PR-AVB, PR-AVC, PR-AVD, PR-AVP, PR-AVQ, PR-AVR
To prepare for ditching, the pilot must press the DITCHING pushbutton on the CABIN PRESS
control panel to close:
1-the outflow valve,
2-the emergency ram air inlet,
3-the avionics ventilation inlet and
4-extract valves,
5-the pack flow control valves, and
6-the forward cargo outlet isolation valve.
OVERHEAD PANEL
to: PR-AVH, PR-AVJ, PR-AVK, PR-AVL, PR-AVO
(1) LDG ELEV knob
AUTO : The pressurization system uses the FMGS data to construct an optimized
pressure schedule.
To exit the AUTO position, pull out and turn the selector.
Other positions : The pressurization schedule does not use the landing elevation from the
FMGS, but instead uses the landing elevation selected with this knob
(from -2 000 to +14 000 ft) as its reference.
Note: The LDG ELEV knob scale is only given as an indication; refer
to the ECAM information for accurate adjustment.
(2) MODE SEL pb
AUTO : Automatic mode is operating. One of the two systems controls the outflow
valve.
MAN : This legend appears in white, and FAULT does not come on. The flight crew
then uses the MAN V/S CTL selector to control the outflow valve.
Note: Switching the MODE SEL pb to MAN, for at least 10 s, then returning it to AUTO will
select the other system.
FAULT lt : This legend appears in amber and the ECAM caution light comes on only when
both automatic systems are faulty.
Note: The pilot may notice a variation in the CAB ALT indication on the
ECAM PRESS page, when the system switches from the cabin
pressure control AUTO mode to MAN mode, due to the reduced
resolution of the backup pressure sensor.
(3) MAN V/S CTL toggle switch
The switch, springloaded to neutral controls the outflow valve position through operation of the
MAN motor, when the MODE SEL pb is in the MAN position.
UP : The valve moves towards the open position.
DN : The valve moves towards the closed position.
Note: The outflow valve operates slowly, so the pilot must hold the toggle switch in the UP
or DN position until reaching the target V/S.
(4) DITCHING guarded pushbutton
Normal : The system functions normally.
ON : The operating system sends a “close” signal to the outflow valve, emergency
ram air inlet, avionics ventilation inlet and extract valves, pack flow control
valves.
Note: The outflow valve will not close automatically, if it is under manual
control.
CAUTION If the ditching pb is set to ON, with the low pressure ground
cart connected and all doors closed, a differential pressure will
build up.
