21 Air Conditioning

Single Aisle TECHNICAL TRAINING MANUAL

RAMP & TRANSIT COURSE - M03 (IAE V2500) (Level 2&3) AIR CONDITIONING

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AIR CONDITIONING

GENERAL

Air Conditioning System Line Maintenance (2) . . . . . . . . . . . . . . . . . 2

ZONE TEMPERATURE CONTROL

System Presentation (2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Pack Presentation (2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

GENERAL VENTILATION

System Design Presentation (2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

RAMP & TRANSIT COURSE - M03 (IAE V2500) (Level 2&3) 21 - AIR CONDITIONING

TABLE OF CONTENTS Nov 19, 2009Page 1

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AIR CONDITIONING SYSTEM LINE MAINTENANCE (2)

SYSTEM OVERVIEW

The air conditioning system main function is to keep the air in thepressurized fuselage compartments at the correct pressure andtemperature. In details, this system provides the following functions:- cabin temperature control,- pressurization control,- avionics ventilation,- cargo compartment ventilation & heating (optional).


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SYSTEM OVERVIEW




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SYSTEM OVERVIEW (continued)

CABIN TEMPERATURE CONTROLThe Single Aisle family is equipped with two air conditioning packslocated in the wing root area forward of the landing gear bay. Thepacks supply dry air to the cabin for air conditioning, ventilation andpressurization. The main component of each pack assembly is the aircycle machine.Hot air from the pneumatic system is supplied to the pack through thepack Flow Control Valve (FCV). The FCV adjusts the flow ratethrough the pack and is the pack shut-off valve. During normaloperation, the Air Conditioning System Controller (ACSC) calculatesthe flow mass demand and set the flow control valve in the necessaryreference position.The pack temperature control system controls the pack outlettemperature and sets its maximum and minimum limits. The systemincludes two ACSCs. Each ACSC controls one pack. To control thepack outlet temperature, the ACSC modulates the BYPASS VALVEand the RAM-AIR INLET doors.The packs supply the mixer unit. Three separate aircraft zones aresupplied from the mixer unit:- cockpit,- forward cabin,- aft cabin.Two cabin recirculation fans are installed to reduce the bleed airdemand and therefore save fuel. These fans establish a recirculationflow of air from the cabin zones to the mixer unit. In normal operation,there are no ECAM indications associated with the cabin fans.The ACSC controls and monitors the temperature regulation systemfor the cabin zones. On the overhead AIR COND panel, the flightcrew selects the desired individual compartment temperature.The hot air system for cabin temperature control has a trim air PressureRegulating Valve (PRV) and trim air valves controlled by the ACSC.

For the zones, which require warmer temperature, the ACSC signalsto the related TRIM AIR VALVE to open. Hot air mixes with thepack discharge air and the temperature increases.




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SYSTEM OVERVIEW - CABIN TEMPERATURE CONTROL




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PRESSURIZATION CONTROLThe pressurization system on the Single Aisle family normally operatesautomatically to adjust the cabin altitude and rate of climb to ensuremaximum passenger comfort and safety. The pressurized areas are:- the cockpit,- the avionics bay,- the cabin,- the cargo compartments.The concept of the system is simple. Air is supplied from the airconditioning packs to the pressurized areas. An outflow valve is usedto regulate the amount of air allowed to escape from the pressurizedareas.Automatic control of the outflow valve is provided by two CabinPressure Controllers (CPCs). Each CPC controls one electric motoron the outflow valve assembly. The CPCs interface with other aircraftcomputers to optimize the pressurization / depressurization schedule.There are two automatic pressurization systems. Each CPC and itselectric motor make up one system. Only one system operates at atime with the other system acting as backup in case of a failure. Thesystem in command will alternate each flight.A third motor is installed for manual operation of the outflow valvein case both automatic systems fail.To protect the fuselage against excessive cabin differential pressure,safety valves are installed on the rear pressure bulkhead. The safetyvalves also protect against negative differential pressure.The Residual Pressure Control Unit ( RPCU ) controls the residualpressure in the cabin and takes over the control of the outflow valveautomatically by providing power directly to the manual motor of theoutflow valve.




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SYSTEM OVERVIEW - PRESSURIZATION CONTROL




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AVIONICS VENTILATIONThe avionics ventilation system supplements the air conditioningsystem to supply cooling air to the avionics equipment. This equipmentincludes the avionics compartment, the flight deck instruments andthe circuit breaker panels.A blower fan and an extraction fan circulate the air through theavionics equipment.

NOTE: Note: These fans operate continuously as long as the aircraftelectrical system is supplied.

The Avionics Equipment Ventilation Computer (AEVC) controls thefans and the configuration of the skin valves in the avionics ventilationsystem based on flight / ground logic and fuselage skin temperature.There are 3 configurations for the skin air inlet and outlet valves:- open circuit: both valves open (on ground only),- closed circuit: both valves closed (flight or low temperature onground). The air is cooled in the SKIN HEAT EXCHANGER. Theskin heat exchanger is a chamber which allows the air to contact thefuselage skin in flight,- intermediate circuit: inlet closed, outlet partially open (smokeremoval in flight or low ventilation airflow condition).




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SYSTEM OVERVIEW - AVIONICS VENTILATION




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CARGO VENTILATION AND HEATINGAs an option on the Airbus single aisle family, the forward and aftcargo compartments can have a ventilation system. In addition, aheating system may be installed in either or both compartments. Notethat the heating system will only be installed along with a ventilationsystem.The operation for both compartments is similar so we will only lookat the forward cargo compartment. Air from the main cabin is drawndown into the cargo compartment by the extract fan or by differentialpressure in flight (FWD Cargo Compartment only). After circulatingthrough the compartment, the air is discharged overboard.The operation of the two isolation valves and the extract fan iscontrolled automatically by the cargo Ventilation Controller (VC).One VC is able to control either or both compartments.For the heating of the cargo compartment, the pilots select the desiredcompartment temp and hot bleed air is mixed with the air comingfrom the main cabin to increase the temperature if necessary. Thesupply of hot air is controlled by the Cargo Heating Controller. Eachheated compartment has a dedicated Cargo Heating Controller. Notethat there is NO direct air conditioning supply to the cargocompartments. The pilots cannot add "cold" air to the compartments.The isolation valves and extract fans of the forward cargo compartmentventilation system are located behind the compartment sidewall panels.The air inlets and outlets are protected by grills.




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SYSTEM OVERVIEW - CARGO VENTILATION AND HEATING




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SYSTEM OVERVIEW - CARGO VENTILATION AND HEATING




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MEL/DEACTIVATION

Per the Minimum Equipment List (MEL), the following deactivationprocedures may be performed to dispatch the aircraft with air conditioningand ventilation problems.

PACK FLOW CONTROL VALVEThe aircraft may be dispatched per MEL with the pack Flow ControlValve (FCV) failed. With the valve secured in the CLOSED position,single pack operations are limited to 31,500 / 35,400 / 37,000 ft.(depending on aircraft/engine combination).Deactivation procedure:- no pneumatic supply to the air conditioning system,- remove access panel on belly fairing,- set pack pushbutton switch OFF,- remove the blanking cap from the position (A),- make sure that the forked valve position indicator lever is at theCLOSED position,- install the blanking cap between the forks of the valve position leverand on screwed boss (B),- safety the blanking cap with corrosion-resistant steel lockwire 0.8mm.




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MEL/DEACTIVATION - PACK FLOW CONTROL VALVE




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MEL/DEACTIVATION (continued)

AVIONICS VENTILATION SKIN AIR OUTLET VALVEIn case of failure, the Skin Air Outlet Valve may be deactivated inthe PARTIAL-OPEN position for dispatch per the MEL. ThePARTIAL-OPEN position is when the main flap of the valve is closedand the auxiliary flap is OPEN. This will allow for smoke removal incase of avionics smoke in flight. The valve is equipped with a handlewhich is used to crank the valve open or closed. When the Skin AirOutlet Valve is deactivated PARTIALLY OPEN, the Skin ExchangerIsolation Valve must be deactivated into the OPEN position.The Skin Exchanger Isolation Valve is located in the avionicscompartment. The valve is equipped with a manual lever/positionindicator which may be used to put the valve in the OPEN position.Procedure:- push latch to release the handle from the valve,- pull the handle to engage the splines,- set the Deactivation switch to OFF,- turn the handle clockwise until the main flap is closed and theauxiliary flap is OPEN,- stow and latch the handle,- disconnect the electrical connector of the Skin Exchanger IsolationValve and move the manual override handle to the OPEN position,- perform AEVC BITE.




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MEL/DEACTIVATION - AVIONICS VENTILATION SKIN AIR OUTLET VALVE




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MEL/DEACTIVATION (continued)

AVIONICS VENTILATION SKIN AIR INLET VALVEIn case of failure, the Skin Air Inlet Valve may be deactivated in theCLOSED position for dispatch per the MEL. The valve is equippedwith a handle which is used to crank the valve open or closed. Whenthe Skin Air Inlet Valve is deactivated CLOSED, the Conditioned AirInlet Valve must be deactivated to the OPEN position. This allowssupplemental cooling from the cockpit air conditioning supply for theavionics equipment when the normal supply is affected.The conditioned air inlet valve is located in the avionics compartment.The valve is equipped with a manual lever/position indicator whichmay be used to put the valve in the OPEN position.Deactivation procedure:- push latch to release the handle from the valve,- pull the handle to engage the splines,- set the Deactivation switch to OFF,- turn the handle counter-clockwise until the flap is closed,- stow and latch the handle,- remove the electrical connector from the Conditioned Air Inlet Valveand move the manual override handle to the OPEN position,- perform AEVC BITE.

AVIONICS VENTILATION CONDITIONED AIR INLETVALVEIn addition to the Skin Air Inlet Valve deactivation, other ventilationsystem deactivation tasks also include deactivation of the ConditionedAir Inlet Valve in the OPEN position. These affected components are:- the blower fan,- the extract fan,- the ventilation filter.




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MEL/DEACTIVATION - AVIONICS VENTILATION SKIN AIR INLET VALVE & AVIONICS VENTILATION CONDITIONED AIR INLETVALVE




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MAINTENANCE TIPS

When the aircraft is on the ground with the electrical systems powered,the avionics ventilation system is normally in the OPEN configuration.In this configuration, the ventilation BLOWER fan pulls air in from theopen Skin Air Inlet Valve on the LH side of the fuselage. The air iscirculated through the ventilation system and then the EXTRACTIONfan discharges the air overboard through the open Skin Air Outlet Valve.If maintenance is being performed on the aircraft in heavy rain conditionswith the ventilation system in the OPEN configuration, the blower fanmay draw water into the ventilation system and subsequently, into theaircraft computers. To prevent water ingestion, the ventilation systemshould be put in the CLOSED configuration by selecting the EXTRACTpushbutton to OverRriDe (OVRD) on the VENTILATION panel. Foradditional cooling in the CLOSED configuration, select the packs ON.If the Skin Air INLET or OUTLET valve fails on the ground and noreplacement part is available, either valve may be manually operated tothe OPEN position. This will allow cooling for the avionics equipmentif the aircraft is powered for maintenance operations. Before flight, thefailed valve must be deactivated in the proper configuration.




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MAINTENANCE TIPS




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SYSTEM PRESENTATION (2)

BASIC PRINCIPLE

The flow of hot air from the air bleed system is regulated before it entersthe packs in order to be temperature regulated. Hot air pressure ismaintained above the cabin pressure, which lets the hot airflow join thepack air supply when necessary. Part of the cabin air is recirculated todecrease air supply demand.

PACK UNITS

The airflow from the air bleed system is regulated by two pack FlowControl Valves (FCVs). Two independent packs then supply air with aregulated temperature to the mixer unit. Both packs supply air at the sametemperature.

MIXER UNIT

The mixer unit mixes air with a regulated temperature from the packswith part of the cabin air supplied by the recirculation fans. The mixerunit can also receive conditioned air from an LP ground connection orfresh outside air from the emergency ram air inlet. The emergency ramair inlet supplies outside fresh air for ventilation of the A/C in emergencyconditions when there is loss of both packs or smoke removal.

TRIM AIR PRV

Hot air tapped upstream of the packs supplies the trim air valves througha trim air Pressure Regulating Valve (PRV). This valve regulates thedownstream pressure 4 psi above the cabin pressure.

HOT TRIM AIR

A trim air valve associated with each zone optimizes the temperature byadding hot air, if necessary, to the air from the mixer unit.

AIR DISTRIBUTION

The conditioned air is distributed to three main zones:- cockpit,- forward cabin,- aft cabin.Normally, the mixer unit lets the cockpit be supplied from pack 1 andFWD and aft cabins from pack 2.

LAV AND GALY VENTILATION

The LAVatory and GALleY ventilation system uses air from the cabinzones. A fan extracts this air through the outflow valve.

NOTE: Note: The LAV and GALY ventilation system is also used toventilate the cabin zone temperature sensors.

ACSC

The Air Conditioning System Controller (ACSC) does:- temperature regulation in accordance with demand,- flow control and monitoring in accordance with flow control demand.


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BASIC PRINCIPLE ... ACSC


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PACK PRESENTATION (2)

PACK FCV

Each pack Flow Control Valve (FCV) is pneumatically actuated andelectrically controlled. The flow regulation is done by a torque motorunder the control of the Air Conditioning System Controller (ACSC). Ifthe pack compressor outlet temperature is > 215°C (419°F), the FCVstarts to reduce the flow. A compressor outlet temperature > 260°C(500°F) results in a pack overheat warning.

NOTE: Note: Part of the hot air, downstream of the pack FCV, is sentto the trim air Pressure Regulating Valve (PRV).Each pack FCV is automatically closed during either a sameside engine start sequence or an opposite side engine startsequence, if the crossbleed valve is detected open. It reopens30 seconds after the end of any engine start sequence.

EXCHANGERS - COMPRESSOR

Bleed air is ducted to the primary heat exchanger, then to the compressor.The air is cooled in the main heat exchanger. It then goes through thereheater, the condenser and the water extractor in order to remove waterparticles from the air entering the turbine.

TURBINE

The air expands in the turbine section, which results in a very low turbinedischarge air temperature. The turbine drives the compressor and thecooling air fan.

RAM AIR INLET FLAP AND BYP VALVE

The BYPass valve and the ram air inlet flap are simultaneously controlledby the air conditioning system controller. The BYP valve is operated byan electro-mechanical actuator to modulate the pack discharge temperatureby adding hot air. The ram air inlet flap modulates the airflow through

the exchangers. To increase cooling, the ram air inlet flap opens moreand the BYP valve closes more. To increase heating, the ram air inletflap closes more and the BYP valve opens more. During take-off andlanding, the ram air inlet flap is closed to prevent ingestion of foreignobjects.


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PACK FCV ... RAM AIR INLET FLAP AND BYP VALVE


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SYSTEM DESIGN PRESENTATION (2)

AVIONICS

The avionics ventilation system ensures a proper ventilation of theelectrical equipment. Air is taken from different sources depending onthe A/C configuration and ambient conditions. Ventilation air is blownto the equipment by a blower fan and extracted by an extraction fan. Thecockpit temperature sensor for the temperature control system is connectedto the extraction part of the avionics ventilation.

LAVatories and galleys

The lavatory (LAV) and galleys (GALY) ventilation system is used toremove unpleasant odors before they enter the cabin. Ventilation air issupplied from cabin distribution ducts and discharged overboard via theoutflow valve by an extraction fan. The FWD and AFT cabin zonestemperature sensors are connected to the lavatory and galley extractionsystem.

CARGO

The FWD and aft cargo compartments are ventilated by cabin ambientair coming from the cabin zones through openings in the cabin floorbehind the sidewall panels. The FWD cargo compartment is ventilatedby means of an extraction fan or by differential pressure. The aft cargocompartment is ventilated by means of an extraction fan only.

NOTE: Note: The ventilation system is optional and independent foreach compartment.

CONTrollers

The Avionics Equipment Ventilation Computer (AEVC) ensures controland monitoring of the AVNCS ventilation system. The cargo ventilationcontroller (CONT) controls and monitors the isolation valves and theextraction fan of the cargo ventilation system.


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AVIONICS ... CONTROLLERS


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AIRBUS S.A.S.31707 BLAGNAC cedex, FRANCE

STMREFERENCE UAF09471

NOVEMBER 2009PRINTED IN FRANCEAIRBUS S.A.S. 2009

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21 Air Conditioning