Airbus A320 Systems A4 Format

A320 Systems Description Uncontrolled Document

Geoff Klouth 4 Dec 07

Contents Contents.........................................................................................................................2 Air Conditioning ...........................................................................................................8 Air Conditioning Pack...................................................................................................9 Ram Air..........................................................................................................................9 Mixer Unit......................................................................................................................9 Hot Air Pressure Regulating Valves..............................................................................9 Trim Air Valves.............................................................................................................9 Temperature and Flow Regulation.................................................................................9 Pack Controller..............................................................................................................9 Pack Flow Control.......................................................................................................10 Engine Pressure Demand.............................................................................................10 APU Flow Demand With APU bleed valve open, the zone controller signals the APU’s Electronic Control Box to increase the APU flow output when any zone temperature demand can’t be satisfied.........................................................................10 Temperature Regulation...............................................................................................10 Basic Temperature Regulation.....................................................................................10 Optimised Temperature Regulation.............................................................................10 System operation Under Failure Condition.................................................................10 Primary Channel Failure..............................................................................................10 Primary and Secondary Channel Failure.....................................................................10 Pack Controllers...........................................................................................................10 Primary Channel Failure..............................................................................................10 Secondary Channel Failure Has no effect on pack regulation. Backup mode lost. ECAM signals related to the corresponding pack are lost. Primary and Secondary Channel Failure As a backup, corresponding pack outlet temperature is controlled by the anti ice valve and is stabilised between 5 – 30° C in a max of six minutes. ECAM signals, related to the corresponding pack are lost.......................................................10 Air Cycle Machine Failure...........................................................................................10 Hot Air Pressure Regulating Valve failure..................................................................10 Trim Air Valve Failure Optimised temperature regulation of the corresponding zone is lost............................................................................................................................10 Pressurisation...............................................................................................................11 Automatic Operation............................................................................................11 Cabin Pressure Controllers...........................................................................................11 Outflow Valve On right hand side of aircraft, behind aft cargo compartment below flotation line.The actuator controls the inward and outward opening flaps, and is powered by three motors.Two motors for automatic mode, and one motor for manual mode. Safety ValvesTwo independent pneumatic safety valves prevent cabin pressure from exceeding 8.6 psi or going below 0.25 psi.Located on rear pressure bulkhead, above flotation line...................................................11 Automatic Pressure Control Mode...............................................................................11 Ground.................................................................................................................12 2

Takeoff.................................................................................................................12 Climb....................................................................................................................12 Cruise...................................................................................................................12 Descent Controller maintains cabin rate of descent so cabin pressure equals landing field elevation just before touchdown. The maximum rate is 750 fpm.. 12 Abort This mode prevents cabin from climbing if aircraft does not climb after takeoff. Pressure is set back to takeoff altitude plus 0.1 psi................................12 Manual Pressure Control Mode...........................................................................12 Ventilation....................................................................................................................13 Fans Two electric fans operate as long as electrical power available. Circulate air around avionics....................................................................................................13 Skin Air Inlet And Extract Valves Admit air from outside aircraft, and evacuate hot air from inside aircraft...................................................................................13 Skin Exchange Inlet And Outlet Bypass Valves..................................................13 Air Conditioning Inlet ValvePermits air conditioning circuit to supply fresh air to the avionics bay................................................................................................13 Skin Exchange Isolation ValveThis valve connects or isolates the skin heat exchanger.............................................................................................................13 Normal Operation, Open Circuit Configuration..........................................................13 Ground Operations ...............................................................................................13 Ground Operations ...............................................................................................13 Flight Operations..................................................................................................13 Normal Operation, Intermediate Configuration...........................................................13 Flight Operations..................................................................................................13 Abnormal Operation....................................................................................................13 Blower Fault or Extract Fault Warning................................................................13 Smoke Configuration...........................................................................................13 Controller Failure.................................................................................................14 Avionics Ground Cooling............................................................................................14 Battery Ventilation.......................................................................................................14 Lavatory And Galley....................................................................................................14 Cargo Ventilation.........................................................................................................14 Aft Cargo Compartment Ventilation....................................................................14 Aft Cargo Compartment Heating.........................................................................15 Auto Flight...................................................................................................................15 Dual Mode............................................................................................................15 Master FMGC Logic............................................................................................15 Independent Mode................................................................................................15 Single Mode.........................................................................................................15 Flight Management......................................................................................................16 Position Computation...................................................................................................16 Mix IRS Position..................................................................................................16 GPS Position........................................................................................................16 Radio Position......................................................................................................16 FM Position..........................................................................................................16 Bias.......................................................................................................................16 3

Cost Index............................................................................................................16 Engine Out Case...................................................................................................16 Recommended Maximum Altitude......................................................................16 Predictions for Alternates.....................................................................................16 Return to Trajectory Assumptions.......................................................................16 Energy Circle.......................................................................................................17 Interaction Between AP/FD and Authothrust Modes..........................................17 Soft Altitude.........................................................................................................17 Land Mode...........................................................................................................17 Flare Mode Once a/c reaches approximately 40’ radar altitude FLARE mode engages.................................................................................................................17 Align Sub Mode...................................................................................................17 Roll Out Mode.....................................................................................................17 Speed Control.......................................................................................................17 Autoland Warning Light......................................................................................17 Thrust Lock Function...........................................................................................17 Alpha Floor..........................................................................................................18 Ground Speed Mini..............................................................................................18 Vapp Computation...............................................................................................18 Flight Augmentation....................................................................................................18 Yaw Damping......................................................................................................18 Rudder Trim.........................................................................................................18 Rudder Travel Limitation.....................................................................................18 PFD Speed Scale Management............................................................................18 Low Energy Warning...........................................................................................19 Windshear Detection Function.............................................................................19 Electrical......................................................................................................................19 Main Generators...................................................................................................19 External Power.....................................................................................................19 Emergency Generator..........................................................................................20 Static Inverter.......................................................................................................20 DC Generation.............................................................................................................20 Transformer Rectifiers.........................................................................................20 Batteries ..............................................................................................................20 Circuit Breakers...................................................................................................20 Normal Configuration..................................................................................................20 In Flight................................................................................................................20 Abnormal Configurations............................................................................................20 Failure Of One Engine Generator........................................................................20 Failure of AC Bus 1.............................................................................................20 Failure Of One TR...............................................................................................20 Failure of TR 1+2.................................................................................................20 Emergency Generation After Loss of all Main Generators .................................21 Smoke Configuration...........................................................................................21 Fire Protection..............................................................................................................21 Fire Warning and Loop Cautions.........................................................................21 4

Pushing the Engine 1 or 2 Fire push button will :-......................................................21 Pushing the APU Fire push button will :-....................................................................21 Avionics Bay........................................................................................................21 Lavatory...............................................................................................................22 Cargo Compartment Smoke Detection................................................................22 Flight Controls.............................................................................................................22 Basic Principles............................................................................................................22 Electrical Control.................................................................................................23 Electric Control....................................................................................................23 Speedbrakes and Ground Spoilers...............................................................................23 Speedbrake Control..............................................................................................23 Speedbrake extension is inhibited if :-.........................................................................23 The maximum speedbrake deflection in manual flight is :- 40° for spoilers 3&4 and 20° for spoiler 2............................................................................................................24 The maximum speedbrake deflection with autopilot engaged is :- 25° for spoilers 3&4 and 12.5° for spoilers 2.................................................................................................24 Ground Spoilers...................................................................................................24 Full Extension......................................................................................................24 Partial Extension..................................................................................................24 Retraction.............................................................................................................24 Yaw Control.................................................................................................................24 Electrical Rudder Control....................................................................................24 Mechanical Rudder Control.................................................................................24 Rudder Actuation.................................................................................................24 Rudder Travel Limit.............................................................................................24 Rudder Trim.........................................................................................................24 Normal Law.................................................................................................................24 Protections....................................................................................................................25 Pitch Attitude Protection......................................................................................25 High Angle of Attack Protection.........................................................................25 High Speed Protection.........................................................................................26 Normal Law.........................................................................................................26 Bank Angle Protection.........................................................................................26 Sideslip Target.....................................................................................................27 Reconfiguration Control Laws.....................................................................................27 Alternate Law..............................................................................................................28 Ground Mode.......................................................................................................30 Flight Mode..........................................................................................................30 Lateral Control.....................................................................................................30 Yaw Alternate Law..............................................................................................30 Load Factor Limitation........................................................................................30 Pitch Attitude Protection......................................................................................30 Low Speed Stability.............................................................................................30 Bank Angle Protection.........................................................................................30 Direct Law...................................................................................................................30 Pitch Control ........................................................................................................30 5

Lateral Control.....................................................................................................31 Roll Direct Law....................................................................................................31 Yaw Mechanical Control.....................................................................................31 Abnormal Attitude Laws.............................................................................................31 Mechanical Backup......................................................................................................31 Pitch Control ........................................................................................................31 Lateral Control.....................................................................................................31 Flaps and Slats.............................................................................................................31 Fuel System..................................................................................................................32 Outer Tank Inner Tank Centre Tank Inner Tank Outer Tank......................................32 Tank Pumps..........................................................................................................32 Transfer Valves....................................................................................................32 Cross Feed Valve.................................................................................................32 Is controlled by a double motor, which allows both engines to be fed from one side or one engine to be fed from both sides........................................................32 Engine LP Valves.................................................................................................32 Suction Valves.....................................................................................................32 Fuel Feed Sequence.....................................................................................................33 Centre Tank Pumps Control Logic......................................................................33 Fuel Transfer From Outer To Inner Tanks...........................................................33 Fuel Recirculation System...................................................................................33 Refuelling / Defuelling........................................................................................34 Hydraulics....................................................................................................................34 Green System Pump.............................................................................................34 Blue System Pumps.............................................................................................34 Yellow System Pumps.........................................................................................34 Power Transfer Unit.............................................................................................34 Ram Air Turbine..................................................................................................34 System Accumulators ..........................................................................................34 Priority Valves.....................................................................................................34 Fire Shutoff Valves..............................................................................................34 Reservoir Pressurisation.......................................................................................34 Wing Anti Ice...............................................................................................................35 Wipers..................................................................................................................36 Rain Repellent......................................................................................................36 Visual Ice Indicator..............................................................................................36 Electronic Instrument System......................................................................................37 Display Unit.........................................................................................................37 Display Management Computer (DMC)..............................................................37 System Data Acquisition Concentrator................................................................37 Flight Warning Computers...................................................................................37 Landing Gear................................................................................................................38 Main Gear............................................................................................................38 Nose Gear.............................................................................................................38 Normal Operation........................................................................................................38 Emergency Extension..........................................................................................39 6

Nose Wheel Steering...................................................................................................39 Brakes and Anti Skid...................................................................................................39 Anti Skid System.................................................................................................39 Auto Brake...........................................................................................................40 Normal Braking....................................................................................................40 Alternate Braking With Anti Skid.......................................................................40 Alternate Braking Without Anti Skid..................................................................40 Parking Brake.......................................................................................................40 Air Data and Inertial Reference System (ADIRS).......................................................41 Windshear Prediction Function...................................................................................42 Traffic alert and Collision Avoidance System (TCAS)...............................................42 Pneumatic System........................................................................................................43 Engine Bleed System...........................................................................................43 Air Bleed Selection..............................................................................................43 Pressure Regulation And Limitation....................................................................43 Temperature Regulation And Limitation.............................................................43 APU Bleed Air Supply.........................................................................................43 Crossbleed............................................................................................................44 Leak Detection.....................................................................................................44 Auxiliary Power Unit (APU).......................................................................................44 APU Engine.................................................................................................................44 Electronic Control Box........................................................................................44 Air Intake System The air intake and an electrically operated flap allow external air to reach the compressor..................................................................................45 Starter The ECB controls the electric starter. The starter engages if the air intake is fully open and the MAST SW and the START push buttons are ON..............45 Fuel System The left fuel feed line supplies the APU. The required pressure is normally available from the tank pumps..............................................................45 Oil System The APU has an integral independent lubrication system (for lubrication and cooling).......................................................................................45 Inlet Guide Vanes The IGVs control bleed air flow, and a fuel pressure powered actuator position the IGVs. The ECB controls the actuator in response to aircraft demand.................................................................................................................45 Air Bleed System Is fully automatic. The APU speed is always 100% except for air conditioning, when the APU speed is 99% if the ambient temperature is above -18°, or if ambient temperature is below 35° C..........................................45 Ground Operation Safety Devices The APU may run without crew supervision when the aircraft is on the ground........................................................................45 Power Plant..................................................................................................................45 Low Pressure (LP) compressor / turbine..............................................................45 High Pressure (HP) compressor / turbine............................................................45 Combustion Chamber..........................................................................................45 Accessory Gearbox..............................................................................................45 Full Authority Digital Engine Control (FADEC)........................................................45 Power Supply.......................................................................................................45 Thrust Control System.........................................................................................46 7

EPR Mode............................................................................................................46 N1 Modes.............................................................................................................46 Rated N1 Mode....................................................................................................46 Unrated N1 Mode.................................................................................................46 EPR Recovery Logic............................................................................................46 Ignition and Starting....................................................................................................46 Ignition System IS used to start the engines on the ground and in flight. It consists of two identical independent circuits for each engine, normally controlled by FADEC channel A, with channel B on standby. Each FADEC channel can control both igniters. On the ground, automatic start only fires one igniter. The FADEC automatically alternates igniters used on successive starts. The ignition comes on automatically after the dry crank sequence, and cuts off automatically when N2 reaches 43%.On the ground with a manual start, both igniters start firing when the Master switch is switched on.Both stop firing when N2 reaches 43%. In flight, both igniters start firing when the Master switch is switched on .Continuous ignition may be selected either manually or automatically to maintain engine combustion.....................................................46 Engine Starting System (automatic)....................................................................46

Air Conditioning The air conditioning system operation is fully automatic.It maintains a constant selected temperature in the three zones. Cockpit, fwd cabin, aft cabin.Air is supplied by the pneumatic system via two pack flow control valves, two packs, and the mixing unit, which mixes the air coming in from the cabin and from the packs. Is then distributed to the cockpit and cabin.Temperature regulation is optimised through the hot air pressure regulating valve and the trim air valves which 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 a zone controller and two pack controllers. Flight deck and cabin temperature can be selected from the air conditioning panel in the cockpit.Low pressure air is supplied to the mixing unit by a ground connection.

8

Air Conditioning Pack Two packs operate automatically and independently of each other. Pack operation is controlled by pack controller signals. Warm pre conditioned bleed air enters the cooling path via the pack 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. Is then 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 the temperature of the air, resulting in very low air temperature at turbine discharge.A water separator system dries the air before it enters the turbine section. Pack Flow Control Valve Valve is pneumatically operated and electrically controlled. Regulates the airflow in accordance with signals received from the pack controller.With a loss of air pressure, a spring keeps valve closed.The valve closes automatically in case of pack overheating, engine starting, or operation of the fire or ditching push button.`Valve is controlled from the air conditioning panel. Ram Air An emergency ram air inlet ventilates the cockpit and cabin to remove smoke, or if both packs fail. Is controlled by the ram air push button on the air conditioning panel. This opens the ram air valve, provided that ditching is not selected. When ram air is on, the outflow valve opens about 50%, provided it is under automatic control, and pressure is less than one psi. Outflow valve does not automatically open if under manual control, even with pressure less than one psi. If pressure is greater than one psi, a check valve located downstream of the ram air door will not open, even if selected open. No air then supplied. Mixer 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 Valves Regulates the pressure of hot air, tapped upstream of the packs.Is pneumatically operated and electrically controlled from the hot air push button.With no air, a spring keeps the valve closed. The valve closes automatically if the duct overheats, or the cockpit trim air valve fails, or both cabin trim air valves fail. The valve remains operative even if either the forward or aft cabin trim air valve fails. Trim Air Valves Are electrically controlled by the zone controller.A trim air valve, associated with each zone, adjusts the temperature by adding hot air. Temperature and Flow Regulation Temperature regulation is automatic and controlled by one zone controller and two pack 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. During takeoff, the ram air inlet flaps close when takeoff power is set, and main landing gear struts are compressed. During landing they close as

9

soon as main landing gear struts are compressed, as long as speed at or above 70 knots. They open 20 seconds after speed drops below 70 knots. Pack Flow Control Crew can use pack flow selector to adjust the pack flow for the number of passengers and for external conditions. Lo 80%, Norm 100%, Hi 120%.Regardless of what is selected, high flow is delivered in single pack operation or when the APU is supplying bleed air.System delivers normal flow if low flow selected and temperature demand can’t be met. Engine Pressure Demand When the cooling demand in one zone can’t be satisfied or if the bleed pressure is too low, the zone controller sends a pressure demand signal to both Engine Interface Units to increase minimum idle and to raise the bleed pressure. APU Flow Demand With APU bleed valve open, the zone controller signals the APU’s Electronic Control Box to increase the APU flow output when any zone temperature demand can’t be satisfied. Temperature Regulation The zone controller regulates the temperature of the two cabin zones and the cockpit. Basic Temperature Regulation Crew use temperature selectors to select reference temperatures.The zone controller computes a temperature demand from selected and actual temperatures.Actual temperature measured by sensors in the cockpit and in the lavatory extraction circuit and galley ventilation system for the cabin.A signal corresponding to the lowest demanded zone temperature goes to the pack controller, which then makes both packs produce the required outlet temperature. Optimised Temperature Regulation The zone controller optimises the temperature by action on the trim air valves.The temperature selection range is from 18 – 30° Celsius. System operation Under Failure Condition Each controller consists of a primary channel that is normally in control, and a secondary channel that acts as backup in case of primary failure. Primary Channel Failure The secondary channel operates as backup. Flow setting function and optimised temperature regulation not available. Hot air and trim air valves close.The zones controlled to 24° C. Pack 1 controls cockpit, Pack 2 controls cabin.Alternate mode appears on the ECAM. Secondary Channel FailureHas no effect on zone temperature regulation. Backup mode is lost. Primary and Secondary Channel Failure Optimised and backup regulation lost.Packs deliver a fixed temperature of 20° for pack 1, and 10° for Pack 2.This failure removes all info from ECAM COND page, which then displays Pack Reg. Pack Controllers Primary Channel Failure The secondary channel operates as backup. The regulation is not optimised. Pack flow is fixed at the previous setting. Secondary Channel Failure Has no effect on pack regulation. Backup mode lost. ECAM signals related to the corresponding pack are lost. Primary and Secondary Channel Failure As a backup, corresponding pack outlet temperature is controlled by the anti ice valve and is stabilised between 5 – 30° C in a max of six minutes. ECAM signals, related to the corresponding pack are lost. Air Cycle Machine Failure If it 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 primary heat exchanger. Then, the main part of the cooled air goes directly downstream of the 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 pack controller regulates temperature, in accordance with zone controller demand, by modulating the bypass valve and the ram air inlet flap.The zone controller regulates the hot air flow through the trim air valves to optimise temperature regulation. Hot air flow is lower than in normal pack operation, because pack flow is reduced. Hot Air Pressure Regulating Valve failure If it fails open there is no effect.If it fails closed, optimised regulation is lost. Trim air valves go to full closed position. Pack 1 controls cockpit temps to the selected value, and Pack 2 controls cabin temps to the mean value of the selected temperatures. Trim Air Valve Failure Optimised temperature regulation of the corresponding zone is lost.

10

Pressurisation Has four general functions which are:• Fully opens the outflow valve on the ground • During takeoff, increases cabin pressure to avoid a surge in cabin pressure during rotation. • Adjusts cabin altitude, and rate of change to provide passengers with a comfortable flight. • After touchdown, gradually releases residual cabin overpressure before the ground function fully opens the outflow valve. System consists of two Cabin Pressure Controllers (CPC).One outflow valve, with an actuator that incorporates three motors (two for automatic operation and one for manual operation).One control panel.Two safety valves. Any one of three independent electric motors may power the outflow valve. Normally, one of the two CPC operates the outflow valve by its associated motor. In a ditching, an override switch allows 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. Normally system is fully automatic. Automatic Operation Flight crew monitor but do not control. System controls air pressure from signals from the FMGS.When FMGS data not available, the crew only need to select landing field elevation.The system then uses that elevation for internal schedules. Manual Operation The flight crew controls the cabin altitude via the manual motor of the outflow valves. Cabin Pressure Controllers Two identical, independent, digital controllers automatically control the system. They receive signals from ADIRS, the FMGC, the EIU, and the LGCIU. When system is auto or semi auto, one controller is active and other is standby. The controllers also generate signals for the ECAM. In manual mode, each controller has a backup section, which is powered by an independent power supply in the controller N1 position. The controllers communicate with each other via a cross channel link. Outflow Valve On right hand side of aircraft, behind aft cargo compartment below flotation line.The actuator controls the inward and outward opening flaps, and is powered by three motors.Two motors for automatic mode, and one motor for manual mode. Safety ValvesTwo independent pneumatic safety valves prevent cabin pressure from exceeding 8.6 psi or going below 0.25 psi.Located on rear pressure bulkhead, above flotation line. Automatic Pressure Control Mode Two identical, independent, automatic systems with its own motor and controller control cabin pressure. Either system can control the single outflow valve, but only one at a time. Automatic transfer occurs 70

11

seconds after each landing, and if operating system fails.The controller controls cabin pressure, limiting it to 8000 feet maximum. The controller uses landing elevation and QNH from the FMGC, and the pressure altitude from the ADIRS. If no FMGC data, controller uses Captain’s Baro Reference from the ADIRS and the LDG ELEV selection. Ground Outflow valve fully opens to ensure no residual pressure before takeoff, and 55 seconds after landing. Takeoff To avoid pressure surge at rotation, controller pre-pressurises cabin at 500 fpm until pressure reaches 0.1 psi. At lift off, controller initiates climb phase. Climb Cabin altitude varies according to a fixed pre-programmed law. Cruise In cruise, controller maintains cabin altitude at level off value, or landing field elevation, whichever is higher. Descent Controller maintains cabin rate of descent so cabin pressure equals landing field elevation just before touchdown. The maximum rate is 750 fpm. Abort This mode prevents cabin from climbing if aircraft does not climb after takeoff. Pressure is set back to takeoff altitude plus 0.1 psi. Manual Pressure Control Mode Used when both automatic systems fail. Flight crew use cabin pressure control panel to control cabin pressurisation. Press the Mode Selector push button to select Manual, and push the Man V/S control switch up or down to increase or decrease cabin altitude.The first of these actions cuts power to the auto motors, and enables the manual motor to control the outflow valve.There is a 5 second lag on ECAM of the outflow valve position in manual mode.When manually controlled the outflow valve does not open automatically at touch down.

Ditching Flight crew push ditching push button to close outflow valve, emergency ram air inlet, avionics ventilation inlet and extract valves, and the pack flow control valves.

12

Ventilation This system includes ventilation for the avionics, controlled by the avionics equipment ventilation controller (AEVC), the battery, the lavatories and the galleys. System is fully automatic. It cools the electric and electronic components in avionics compartment and on flight deck, including instrument panel and circuit breaker panels.It uses two electric fans to force circulation of cooling air.Regardless of configuration of system, a part of avionics ventilation air is sucked from flight deck through the different flight deck panels. Fans Two electric fans operate as long as electrical power available. Circulate air around avionics. Skin Air Inlet And Extract Valves Admit air from outside aircraft, and evacuate hot air from inside aircraft. Skin Exchange Inlet And Outlet Bypass Valves Permit air to circulate between avionics bay and the space under cargo compartment floor. Air Conditioning Inlet ValvePermits air conditioning circuit to supply fresh air to the avionics bay. Skin Exchange Isolation ValveThis valve connects or isolates the skin heat exchanger. Avionics Equipment Ventilation Computer (AEVC) Controls operation of all fans and valves in the avionics ventilation system. Normal Operation, Open Circuit Configuration Ground Operations Operates when skin temperature is above the on ground threshold, which is 12° C with temperature increasing, or 9° C with temperature decreasing.Normal Operation, Close Circuit Configuration

Ground Operations Operates when skin temperature is beneath the on ground threshold, which is 12° C with temperature increasing, or 9° C with temperature decreasing. Flight Operations Operates when skin temperature is beneath the in flight threshold which is 35° C with temperature increasing, or 32° C with temperature decreasing. Normal Operation, Intermediate Configuration Flight Operations Operates when skin temperature is above the in flight threshold which is 35° C with temperature increasing, or 32° C with temperature decreasing. Abnormal Operation Blower Fault or Extract Fault Warning When blower or extract push button is set at override, the system is in closed circuit configuration, and adds air from air conditioning system to the ventilation air.When the blower switch is set to override, the blower fan stops and extract fans continues to run. When the extract switch is set to override, the extract fan is controlled directly from the push button. Both fans to continue to run. Smoke Configuration When smoke detector detects smoke in avionics ventilation air, the blower and extract fault lights illuminate. When blower and extract push buttons are set to override, the air conditioning system supplies cooling air, which is then exhausted overboard. The blower fan stops.

13

Controller Failure System goes to above configuration, except skin exchange isolation valve remains open.The inlet valve and skin exchange inlet bypass valve remain in position they were in before the failure occurred. The extract fan continues to run.

Avionics Ground Cooling System is fully automatic. It ensures cooling of the avionics air on the ground in cases of extreme outside hot air. The system is integrated into avionics ventilation system, but operates independently. Ambient outside air is drawn from outside by the ground cooling fan through the inlet valve. Air from cooling unit is discharged overboard via the outlet valve. All are controlled by the ground cooling controller. The ground cool valves open when aircraft is on ground, engines are stopped and ground cool push button is set at auto position. The cooling unit operates when above conditions are met and temperature of avionics ventilation air is >27° C. The ground cool unit stops when the engines start, or the ventilation air temp is one minute, the C/B TRIPPED displayed on ECAM. Non Monitored (black) The wing tip breaker C/Bs have red caps on them to prevent them from being reset.

Operations Gen 1+2 have priority over APU and external power. External power has priority over APU generator when EXT power push button is on. The APU or external power can supply entire network. One engine generator can supply the entire network. The generators cannot be connected in parallel.

Normal Configuration In Flight Each engine driven generator supplies its respective AC BUS 1+2 via its GLC 1+2. AC BUS 1 normally supplies the AC ESS BUS via a contactor. TR 1 normally supplies DC BUS 1, DC BAT BUS, and DC ESS BUS. TR 2 normally supplies DC BUS 2. The two batteries are connected to the DC BAT BUS if they need charging. When fully charged battery charge limiter disconnects them. On Ground Either the APU generator or external power may supply the complete system. On ground, when only ground services are required, external power can supply the AC and DC GND/FLT BUSES directly without supplying the entire a/c network. Personnel select this configuration with the MAINT BUS switch in the forward entrance area.

Abnormal Configurations Failure Of One Engine Generator The system automatically replaces failed generator with the APU Gen if available, or the other engine generator (shedding part of the galley load). Failure of AC Bus 1 AC BUS 2 can supply the AC ESS BUS and the ESS TR can supply the DC ESS BUS, both through the AC ESS FEED push button switch. The DC BUS 2 supplies the DC BUS 1 and DC BAT BUS automatically after 5 seconds. Failure Of One TR The contactor opens in case of overheat or minimum current. The other TR automatically replaces the faulty one. The ESS TR supplies the DC ESS BUS. Failure of TR 1+2 If both fail, DC BUS 1 and DC BAT BUS are lost. The DC ESS BUS is supplied by the ESS TR.

20

Emergency Generation After Loss of all Main Generators If both AC BUS 1+2 are lost, and a/c speed is above 100 knots, the Ram Air Turbine extends automatically. This powers the blue hydraulic system, which drives the emergency generator by means of a hydraulic motor. This generator supplies the AC ESS BUS and the DC ESS BUS via the ESS TR. If the RAT stalls or if a/c on the ground 125°. Angle of attack >30° or < -10° Speed >440 knots or 0.91 or