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AIR CONDITIONING SYSTEM – INTRODUCTION

Air Conditioning Introduction (2)

The A320 Flight Deck and Cabin environment is controlled by the Air Conditioning System.

The main components of this system are: two air conditioning system controllers, two
air conditioning packs, trim air, ram air, cabin recirculation fans, and avionics
ventilation.

Three Zones (3)

The air conditioning operation is automatic.

In addition to supplying fresh air, the system maintains a constant selected temperature
that is independently controlled for each of the three zones.

The three zones are the Cockpit, Forward Cabin, and Aft Cabin.

Controls and Indicators (4)

The Air Conditioning system control panel is located on the Overhead Panel.

Indicating lights on the control panel and various ECAM pages provide status
information to the crew.

A temperature control panel is also provided on the Forward Attendant Panel.

Other ECAM Pages (5)

ECAM CRUISE page is the normal ECAM display during flight and shows the Air
Conditioning parameters on the lower portion.

Pneumatic Diagram Review (6)

The packs receive high pressure air through the pneumatic system from the engine
bleed, APU bleed, or a ground source of compressed air.

Coldest Zone Selection (7)

The two packs operate in conjunction with the trim air system to provide independent
temperature control for the three zones.

The packs provide air temperatures to satisfy the coldest zone selection, while hot trim air is
added to the specific zones that require a warmer air temperature.

This example shows the cockpit temperature selected cooler than the other zones.

The cockpit is receiving cold air from the packs and also a small amount of trim air.

The FWD and AFT zones are receiving pack air and hot trim air, so they are receiving more
warm air than the cockpit.

Pack Flow Control Valves (8)

The high pressure air flows through the two pack flow control valves to the two packs.
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From the packs, the conditioned air flows to the mixing unit.

This example shows the cockpit selected to full COLD.

The cockpit is receiving only cold air from the packs.

The FWD and AFT zones are receiving pack air and hot trim air, so they are receiving more
warm air than the cockpit.

Mixing Unit (9)

The mixing unit mixes the conditioned air from the packs with recirculated air from the cabin
that is pulled by the Cabin Fans.

The mixing unit then distributes the air mixture to the three zones.

Cabin Fans – Recirculation (10)

The Cabin Fans are electrically powered, and are installed to recirculate cabin air.

By recirculating the cabin air, the cabin airflow is increased and bleed air demand
from the engines is reduced, therefore increasing fuel efficiency.

CAB FANS pb (11)

The fans are controlled by the CAB FANS pushbutton on the Ventilation panel.

The normal position of this switch is ON, however the switch can be used to select the
fans to OFF during abnormal conditions as required by an ECAM procedure.

Temperature Selection (12)

Temperature selection for the three aircraft zones is set with the selectors on the air
conditioning panel.

Air Conditioning System Controllers (13)

To regulate the cooling air flow, temperature selections are sent to 2 Air Conditioning
System Controllers. Each controller has two channels, or lanes. One lane operates while
the other is on standby. The two controllers operate the entire air conditioning system.

Air Conditioning System Controller 1 (14)

The Air Conditioning System Controller 1, controls the #1 pack flow control valve, the
operation of the #1 pack, the hot air pressure regulating valve and the cockpit trim air
valve.

Air Conditioning System Controller 2 (15)

The Air Conditioning System Controller 2, controls the #2 pack flow control valve,
controls the operation of the #2 pack, and the forward and aft cabin trim air valves.

Flight Attendant (F/A) Temp Panel (16)

When the aircraft is in cruise, the cabin crew can modify each cabin zone temperature
with a limited authority of plus or minus 2.5 degrees Celsius (4.5 degrees Fahrenheit).
This is done at the Forward Attendant panel.
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Lane Failure (17)

If a single lane of an air conditioning system controller fails, the other lane automatically
supports the system and takes over. With one failed lane, there is no loss of
functionality. If both lanes of a controller fail, its associated pack shuts down and its
associated trim air valves close.

Pack Control (18)

The Air Conditioning System Controllers control the output flow and temperature of
air from each pack, to maintain the temperature of the coldest zone temperature
setting(s) on the COCKPIT, FWD CABIN, and AFT CABIN Zone Temperature Selectors on
the AIR COND panel.

Zone Temperature Control (19)

Trim Air is then added and modulated as necessary by the Air Conditioning System
Controllers to add hot air from the respective Trim Air Valves to the air from the
mixing unit to maintain the temperature demanded by the respective warmer Zone
Temperature Selector settings for the affected Zone(s).

HOT AIR pb (20)

The hot airflow to all Trim Air Valves is controlled by the Hot Air Pressure Regulator
Valve, that is normally on but can be selected OFF by the crew or when commanded to
close automatically for abnormal conditions.

External Conditioned Air (21)

When the aircraft is parked and the packs are not operating, low pressure conditioned
air may be supplied directly to the mixing unit by a ground connection.

In this situation, the mixing unit and ductwork are simply used to deliver the conditioned
ground air while the temperature is controlled by the ground conditioned air source.

Ram Air Introduction (22)

During flight below 10,000’, the Ram Air Valve can provide an emergency supply of
cabin ventilation during de-pressurized flight.

Ram Air Diagram (23)

Ram Air is controlled by a guarded pb.

When the RAM AIR pb is ON, and the Ditching switch is not selected, outside air can
flow through the Ram Air Inlet, through the mixing unit, and on to the cockpit and cabin.

If the differential pressure exceeds 1 psi., the check valve will not open to supply ram
air flow.

Outflow Valve (24)

When Ram Air is selected on and the Outflow Valve is operating under automatic
control, the Outflow Valve will open about 50% as long as the differential pressure is
less than 1 psi.
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Ram Air Memo (25)

When the RAM AIR pb is selected ON, a memo of RAM AIR ON displays in green.

In addition to providing an emergency supply of cabin air after a dual pack failure, the Ram
Air can also be used to ventilate the cabin in the event of cabin smoke.

Avionics Ventilation (26)

An automatic ventilation system provides cooling for the electronic and electrical
components in the flight deck and the avionics compartment.

This system is controlled by the Avionic Equipment Ventilation Computer (AEVC).

Blower / Extract pb's (27)

Avionics Ventilation uses external air, conditioned air, or skin heat exchanger air
cooling to provide cooling airflow, according to a specific configuration.

The Avionics Ventilation configuration is set by valves, a Blower Fan, and an Extract
Fan.

Avionics Smoke is detected by the FWS (Flight Warning System).

Battery Ventilation (28)

A Venturi in the skin of the aircraft draws air from the space around the batteries and vents
it overboard.

This provides ventilation for the batteries.

No control or indication of this system operation is provided to the flight crew.

Lav and Galley Vent (29)

An extraction fan draws ambient cabin air through the lavatories and galleys and exhausts it
near the outflow valve. The extraction fan operates whenever the aircraft has normal
electrical power. No control or indication of this system operation is provided to the flight
crew.
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AIR CONDITIONING SYSTEM – PACKS & OPERATION

Pack Introduction (2)

The two Air Conditioning packs operate automatically and independently of each other.
Let's follow the flow of bleed air as it enters and flows through a single pack.

Pack Flow Control Valve (3)

First, when the Pack is on, the warm pre-conditioned bleed air enters the cooling path via
the Pack Flow Control Valve and is ducted to the primary heat exchanger which provides
the initial cooling of the air.

Pack Flow Control Valve 2 (4)

Each Pack Flow Control Valve is pneumatically-operated and electrically-controlled.

The Pack Flow Control Valve regulates the flow of compressed air to the pack in
accordance with signals received from the Air Conditioning System Controller. It is turned
on when the Pack pushbutton is selected ON, and turned off when the pb is selected OFF.
If there is insufficient air pressure, a spring keeps the valve closed regardless of the
switch position.

Pack Overheat - Pack Flow Valve (5)

Even with the Pack pb selected ON, the Air Conditioning System Controller will close the
Pack Flow Control Valve if the pack overheats, if the Fire pushbutton of the
associated engine is pressed, or if the Ditching switch is selected ON.

PACK pb (6)

The Pack pushbutton normally remains in the ON position. During engine start, the Pack
Flow Control Valves will automatically close as soon as the ENG MODE SEL is set to
Ignition or Crank for start. During engine start, the Pack Flow Control Valves remain
closed when the ENG MASTER switch is set to On, or the Manual Start pushbutton is set to
On, the start valve is open and N2 RPM is less than 50%.

After Start (7)

After engine start, the Pack Flow Control Valves automatically open; however on the
ground, reopening of the valves is delayed for 30 seconds after the first engine start.

This delay avoids cycling of the valves before the second engine start.

If the second engine is not started within 30 seconds, the Pack Flow Control Valves will
open until the second ENG MASTER switch is set to ON.

Pack FCV on Bleed Page (8)

The operation of the Pack Valve is displayed as a symbol on the ECAM BLEED page.

The amount of flow that is provided by the Pack Valve is also displayed.

When the Pack Valve is closed, the flow line indicates on the LO side and is amber.

At other times, the flow line displays in green and to the right of the LO position.
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Heat Exchanger Cooling (9)

The cooling air over the pack heat exchangers is provided by a pack driven cooling fan, and
in flight, cooling air is provided by ram air.

Compressor Section (10)

The cooled bleed air enters the compressor section of the air-cycle machine and is
compressed to a higher pressure and temperature. The temperature of the air that exits the
compressor section is displayed above the Pack Flow. It normally displays green, but
displays amber for temperatures above 260 degrees C.

Main Heat Exchanger (11)

After passing through the compressor, the air flows through the main heat exchanger where
it is cooled again.

Water Separator (12)

A water separator system dries the air before it enters the turbine section.

Turbine (13)

After the main heat exchanger, the air flows through the turbine section, where it expands,
and heat is removed from the air. This expansion generates power to drive the compressor
and cooling air fan. The removal of heat energy during this process reduces the
temperature of the air, resulting in very low air temperature at turbine discharge.

Anti-Ice Valve (14)

The Air Conditioning Pack Anti-ice Valve automatically opens when icing conditions are
sensed at the output of the turbine section. The purpose of this valve is to allow warm air to
bypass the cooling process and stop the formation of ice. It can provide a backup method of
temperature control in abnormal conditions.

Bypass Valve (15)

A Bypass Valve is also installed. It is automatically modulated by the Air Conditioning

System Controller to provide control of the output temperature of the air from this pack.
Without the operation of the Bypass Valve, the pack would always provide the coldest
possible output. With the operation of the Bypass Valve, the output temperature of air from
each pack can be controlled.

Bypass Valve Position Display (16)

The position of the Bypass Valve is displayed on the BLEED page, and automatically
modulates between C (cold-valve closed) and H (hot-valve open).

Pack Output Temp. Display (17)

The temperature output from the pack is also displayed on the BLEED page. The display is
normally green, but becomes amber if the temperature exceeds 90C. Read the pop-up
information about this display.
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End of Pack Description (18)

Ok, we have described the operation and displays for the packs. Next, we'll describe the
operation of the temperature control for each zone.

Hot Air PRV (19)

The Hot-Air Pressure-Regulating Valve controls and regulates the pressure of hot air,
tapped upstream of the packs, that is delivered to the Trim Air Valves. The operation of the
Hot-Air Pressure-Regulating Valve is controlled by the Air Conditioning System Controllers
and is displayed on the ECAM Air Conditioning page.

HOT AIR pb (20)

It is pneumatically-operated and electrically-controlled from the HOT AIR pushbutton on the

AIR COND panel. This pushbutton normally remains ON for automatic operation of Trim
Air. In the absence of air, a spring keeps the Hot-Air Pressure-Regulating Valve closed.

Optimize the Zones (21)

With the Hot-Air Pressure-Regulating Valve open, the individual Trim Air Valves can
optimize the temperature of each zone.

Abnormal - Hot Air PRV Closes (22)

In abnormal conditions, the Air Conditioning System Controller automatically closes the Hot
Air Pressure Regulating valve if the duct overheats, or the cockpit trim air valve fails, or
both cabin trim air valves fail.

Note: The hot-air pressure-regulating valve remains operative, even if either the forward or
aft cabin trim air valve fails, but not both.

Trim Air Valves Ops (23)

The Trim Air Valves are electrically-controlled by the Air Conditioning System controller.

One trim air valve, associated with a specific zone, adjusts the temperature by adding hot
air to the air from the mixing unit according to the selected temperature of the Zone
Temperature Selector.

Trim Air Valves Position Display (24)

The operation of the Trim Air Valves is displayed on the ECAM Air Conditioning page.

Air Conditioning System Controllers (25)

Automatic temperature and flow regulation is controlled by the number 1 and number 2 Air
Conditioning System Controllers.

Pack Controller (26)

Each Air Conditioning System Controller regulates the temperature produced by its
associated pack. This temperature, commanded by the Zone Temperature Selector, is
achieved by modulating the bypass valve and the ram air inlet flap. The Air Conditioning
System Controller also regulates air flow by modulating the associated pack flow control
valve.
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Ram Air Inlet Flaps (27)

Although you have learned that the Ram Air Inlet Flaps are normally modulated for
temperature control, they close during takeoff and landing to avoid ingestion of foreign
matter.

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 knots. They open 20 seconds after the
speed drops below 70 knots.

Zone Temp. Selectors (28)

The flight crew uses the Zone Temperature selectors on the air conditioning panel in the
cockpit to select the reference temperatures. With a Zone temperature selector at the 12
o'clock position, the approximate selection equals 24 degrees Celsius (or 75 degrees
Fahrenheit). The full COLD position represents an approximate setting of 18 degrees
Celsius (or 64 degrees Fahrenheit), while the full HOT position represents an approximate
setting of 30 degrees Celsius (or 86 degrees Fahrenheit).

Temperature Sensors (29)

The Air Conditioning System Controllers compute a temperature demand from the selected
temperature and the sensed actual temperature. The actual temperature is measured by
sensors located:

- in the cockpit, for the cockpit zone, or

- in the lavatory extraction circuit and galley ventilation system, for the cabin.

Zone Temp Displays (30)

The temperature of each zone is displayed in green on the ECAM Air Conditioning page.
The temperature of the air in the duct to the zone is also displayed. The duct temperature
normally displays in green, but displays amber at or above 80 degrees Celsius (or 176
degrees Fahrenheit).

Lowest Demanded Temperature (31)

A signal corresponding to the lowest demanded zone temperature goes to the Air
Conditioning System Controllers, which then makes both packs produce the required outlet
temperature. As you know, the Air Conditioning System Controllers optimize zone
temperatures by action of the trim air valves. The temperature selection range is from
temperatures 18 degrees Celsius (or 64 degrees Fahrenheit) to 30 degrees Celsius (or 86
degrees Fahrenheit).

Pack Flow Selector (32)

The crew can use the PACK FLOW selector to adjust the pack flow for the number of
passengers and for external conditions. There are 3 positions for this selector.

LO equals 80%, NORM equals 100%, and HI equals 120% of normal flow.
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LO Flow (33)

In the pack valve flow LO mode, the pack is set to 80 percent of the normal airflow
produced by the pack. If the cooling demand from the pack in the LO mode cannot be
satisfied, pack flow is automatically provided up to the NORM (100 percent) flow.

High Flow – Automatic (34)

Regardless of the selected flow rate, the system delivers high flow when:

- in single-pack operation, or

- when the APU is supplying bleed air.

Bleed Outputs Increased (35)

The Engine and APU bleed outputs can be automatically increased when the packs provide
insufficient cooling. When the APU bleed valve is not open and the cooling demand in one
zone cannot be satisfied because the engine bleed pressure is too low, the associated 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.

Increased APU Output (36)

When the APU bleed valve is open and any zone temperature demand cannot be satisfied,
the zone controller signals the APU's Electronic Control Box (ECB) to increase the APU
flow output.

Lane Failure (37)

Remember the A320 Air Conditioning System Controllers each have two lanes. One is
active and one is on standby. If one lane fails, the other lane takes over and the system
continues to operate normally.

Dual Lane Failure (38)

If both lanes of a single controller fail, the associated pack will shut down, the hot air
pressure regulating valve will close, and associated trim air valves will close. The remaining
pack flow rate will increase and its output temperature will control the temperature
throughout the aircraft.

Description of Switches / Lights (39)

PACK pb

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.)
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2. It remains closed on the starting engine side (provided the crossbleed valve is closed)
when :

- The MASTER switch is set to ON (or the 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 seconds to avoid a

supplementary pack closure cycle during second engine start.

- The fire pushbutton, of the engine on the related side, is pressed,

- Ditching is selected

OFF - The pack flow control valve closes

FAULT It - 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

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.

Zone temperature sel

- 12 o'clock position : 24 degrees C (76 degrees F)

- COLD position : 18 degrees C (64 degrees F)

- HOT position : 30 degrees C (86 degrees F)

HOT AIR pushbutton

ON - The valve regulates hot air pressure

OFF - The valve closes, and the trim air valves close

FAULT - The amber light, and associated ECAM caution come on when duct overheat is
detected. The fault circuit detects an overheat when the duct temperature reaches 88
degrees C (190 degrees F).

The valve and the trim air valves close automatically.

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The FAULT light goes off when the temperature drops below 70 degrees C (158 degrees
F), and the flight crew selects OFF.

RAM AIR pb (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 p>= 1 psi : The outflow valve control remains normal. No emergency RAM air flows in.

- If p< 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.

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AIR CONDITIONING SYSTEM – AVIONICS VENTILATION

Avionics Ventilation Intro. (2)

Avionics Ventilation is an automatic system that provides cooling to the electrical and
electronic components in the Avionics Compartment and on the flight deck. The items that
are cooled by this system include the instrument and circuit breaker panels.

Two Electric Fans (3)

Two electric cooling fans are used to provide the necessary airflow. A system of valves
operate to direct the airflow for various configurations. The configuration is normally
controlled automatically by the Avionics Equipment Ventilation Computer (AEVC), but may
be controlled manually by the BLOWER and EXTRACT pushbuttons on the VENTILATION
panel during abnormal operations.

FANS

Two electric fans continuously circulate air around the avionics equipment, when the aircraft
is electrically supplied.

SKIN AIR INLET AND OUTLET VALVES

These valves admit air from outside the aircraft and evacuate hot air from the avionics
equipment.

SKIN EXCHANGE INLET AND OUTLET BYPASS VALVES

These valves enable air to circulate between the avionics bay and the space under the
cargo compartment floor.

AIR CONDITIONING INLET VALVE

This valve opens to permit the air conditioning circuit to supply fresh air to the avionics bay.

SKIN EXCHANGE ISOLATION VALVE

This valve connects or isolates the skin heat exchanger.

AVIONICS EQUIPMENT VENTILATION CONTROLLER (AEVC)

The AEVC controls the operation of all fans and valves in the avionics ventilation system.

Blower and Extract Pushbuttons (4)

For normal operations, these BLOWER and EXTRACT pushbuttons are in the AUTO
position and all lights are out; for abnormal operations, one or both pushbuttons will be
selected to OVRD as directed by ECAM.

Skin Temp. Thresholds (5)

During this module, we’ll refer to skin temperature thresholds for on-ground and in-flight
operation of the Avionics Ventilation. The two thresholds are shown here and are available
for reference throughout this module.

The on-ground threshold is:

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- +12° C (53° F), with temperature increasing, or

- +9° C (48° F), with temperature decreasing.

The in-flight threshold is:

- +35° C (95° F), with temperature increasing, or

- +32° C (90° F), with temperature decreasing.

Various Configurations (6)

Depending on the skin temperature, the cooling air is provided by outside air, circulated air
in the pressurized portion of the aircraft, or by the air conditioning system. The
configurations we’ll describe in this module are shown on this frame. We’ll begin with the
Normal Operations and will describe the Open-Circuit Configuration.

Open Circuit - Normal Ground (7)

The Open-Circuit Configuration is the NORMAL GROUND CONFIGURATION and operates

only if the thrust levers are not at Takeoff and the skin temperature is above the on-ground
threshold. We would expect to see this configuration during mildly cool, warm, or hot
ground operations and it is not available in flight. The AEVC will select the configuration to
the closed circuit configuration on the ground if the skin temperature is very cool or cold.

Open Circuit Diagram (8)

This Open-Circuit Configuration diagram shows that outside air is pulled through the open
Skin Air Inlet valve by the Blower Fan and then moves through the Avionics Equipment.
The extract fan pulls this air and conditioned air from the cockpit panels and blows it
overboard through the skin air outlet valve. All other valves are closed in the Open-Circuit
Configuration.

Closed Circuit - Ground – Cold (9)

The Closed-Circuit Configuration operates while the aircraft is on the ground, thrust levers
not at Takeoff, and the skin temperature below the on-ground threshold. This is the
operation that we would expect to see during very cool or cold ground operations.

Closed Circuit - Normal Inflight (10)

Also, the Closed-Circuit Configuration is the NORMAL IN-FLIGHT CONFIGURATION and

during flight, operates if the skin temperature is below the in-flight threshold. The AEVC will
select the configuration to the Intermediate Configuration if the skin temperature is above
this threshold (above average, hot in-flight temperature).

Closed Circuit Diagram (11)

The closed-circuit configuration diagram shows that air is circulated; with the skin air inlet,
skin air outlet, and air conditioning inlet valves closed. The air from the Avionics Bay is
pulled by the Blower Fan from the Skin Exch Outlet Bypass Valve through the Avionics
Equipment, and then the Extract Fan pulls this air (along with cockpit conditioned air) into
two areas.
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Skin Exchanger Valves (12)

Notice that the Skin Exchanger Inlet Bypass Valve and Skin Exchanger Isolation Valve are
both open in this configuration. The air from the Extract Fan is recirculated through the Skin
Heat Exchanger for improved cooling and some of the air from the Extract Fan is delivered
to the under floor cargo area for ventilation.

Intermediate Configuration (13)

The Intermediate Configuration provides ventilation when the aircraft is on the ground (with
takeoff power) or during in-flight, if the skin temperature is above the in-flight threshold. The
only difference between this and the closed-circuit configuration is that a smaller internal
door flap opens on the skin air outlet valve to allows some of the air to flow overboard. This
completes the normal configurations of the Avionics Ventilation system. Now we will
describe the two abnormal configurations for this system.

Blower FAULT (14)

An abnormal configuration that is very similar to the Closed-Circuit Configuration operates if

the Blower Fan or Extract Fan is shut down. This configuration will be set by the crew as a
result of an ECAM Procedure. With only the Blower pb in OVRD, the Blower Fan stops and
the Air Conditioning Inlet valve opens to supply cooling air.

Extract FAULT (15)

With only the Extract pb in OVRD, both fans continue to run and the Skin Exchanger Inlet
Bypass valve closes to force all recirculating air over the Skin Heat Exchanger.

Smoke Detected in Avionics Air (16)

Another abnormal configuration is set when smoke is detected in the Avionics Ventilation
Air. The detection of smoke will cause both the Blower Fault and Extract Fault warning to
occur.

Smoke Configuration (17)

The Smoke configuration is set by the crew as a result of selecting both BLOWER and
EXTRACT pbs to OVRD. The Blower Fan stops, but the Extract Fan continues to operate.
All valves close except the air conditioning inlet valve and a smaller door flap opens on the
skin air outlet valve. This configuration purges smoke from the system by using conditioned
air to blow through the avionics equipment and then overboard through the smaller internal
door flap on the skin air outlet valve.

AEVC Failure (18)

Finally, a variation of the smoke configuration is set if the Avionics Equipment Ventilation
Computer fails.

However, the Skin Exchange Isolation valve remains open, the Inlet Valve and Skin
Exchange Inlet Bypass Valve remain in their last position, and the Extract Fan continues to
operate.
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AIR CONDITIONING SYSTEM – CARGO COMPARTMENT HEATING

Compartment Heating & Ventilation (2)

The Airbus A320 can be equipped with optional heating and ventilation in both the forward
and aft cargo compartments. Check your airlines FCOM to determine if your aircraft have
these systems.

Cargo Heat Panel (3)

Controls for the cargo compartment heating and ventilation systems are on the Cargo Heat
panel on the overhead panel. The Aft cargo compartment has a HOT AIR switch, an AFT
ISOL VALVE switch and a temperature selector. The Forward compartment has only a
FWD ISOL VALVE switch and a temperature selector. Some aircraft come with both
systems installed. With the HOT AIR and FWD/AFT ISOL VALVE switches selected to
Auto, and the cargo compartment doors closed and locked, system operation is automatic
and temperature is maintained at the selected value.

Cargo Heat (4)

Since both the forward and aft systems operate about the same, we'll look at just the aft
system. This is a cutaway of the aft cargo compartment showing the valves and ducting.
Shown first is the hot air pressure-regulating valve. Its switch is on and the valve is open.
Hot bleed air passes through this valve and the temperature selector regulates its flow. Hot
air is then blended with ambient cabin air to provide warm air for cargo compartment
heating. This warm air passes through the inlet isolation valve and goes on to the cargo
compartment. The warm air circulates through the cargo compartment and is then drawn
out by a ventilation extract fan and exhausts though the outlet isolation valve.

ECAM Conditioning Page (5)

The display on the Electronic Centralized Aircraft Monitoring (ECAM) Air Conditioning page
shows a display almost identical to the schematic. The hot air pressure-regulating valve, the
temperature selector position and the isolation valves are shown. The two temperatures
shown are the temperature of the air entering the cargo compartment and the actual
temperature inside the cargo compartment.

Duct Overheat (6)

If a duct overheat is sensed in the hot air system, the amber fault light in the Hot Air switch
will illuminate, and the hot air valve will close automatically. The ECAM Air Conditioning
page will show the Hot Air Valve cross-line amber. Selecting the switch to OFF will reset the
system once the ducting has cooled. The FAULT light will extinguish when the ducting
cools.

Cargo Smoke Detected (7)

With the AFT ISOL VALVE switch in Auto, if smoke is detected in the cargo compartment,
both isolation valves automatically close, displaying as cross-line amber on ECAM. At the
same time the extract fan stops, and the FAULT light illuminates in the AFT ISOL VALVE
switch. Selecting the AFT ISOL VALVE switch to OFF will cause the FAULT light to
extinguish and both isolation valves will display cross-line green.
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Cargo Door Open (8)

Whenever the cargo door is opened, such as upon arrival at the gate, the hot air valve
automatically closes, shutting off heat to the cargo compartment. The valve will also go
closed whenever the HOT AIR switch is placed to the OFF position. This concludes the
discussion of the Cargo Compartment heating and ventilation.