A320
Systems
Description
Contents
Contents
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2
Air Conditioning
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8
Air Conditioning Pack
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9
Ram Air
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9
Mixer Unit
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9
Hot Air Pressure Regulating Valves
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9
Trim Air Valves
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9
Temperature and Flow Regulation
...
9
Pack Controller
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9
Pack Flow Control
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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
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10
System operation Under Failure Condition
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10
Primary Channel Failure
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10
Primary and Secondary Channel Failure
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10
Pack Controllers
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10
Primary Channel Failure
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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.
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10
Pressurisation
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11
Automatic Operation
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11
Cabin Pressure Controllers
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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.
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11
Takeoff
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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
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12
Ventilation
...
13
Fans Two electric fans operate as long as electrical power available. Circulate air
around avionics.
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13
Skin Air Inlet And Extract Valves Admit air from outside aircraft, and evacuate
hot air from inside aircraft.
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13
Skin Exchange Inlet And Outlet Bypass Valves
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13
Air Conditioning Inlet ValvePermits air conditioning circuit to supply fresh air
to the avionics bay.
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13
Skin Exchange Isolation ValveThis valve connects or isolates the skin heat
exchanger.
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13
Normal Operation, Open Circuit Configuration
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13
Ground Operations
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13
Ground Operations
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13
Flight Operations
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13
Normal Operation, Intermediate Configuration
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13
Flight Operations
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13
Abnormal Operation
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13
Blower Fault or Extract Fault Warning
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13
Smoke Configuration
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13
Controller Failure
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14
Avionics Ground Cooling
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14
Battery Ventilation
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14
Lavatory And Galley
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14
Cargo Ventilation
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14
Aft Cargo Compartment Ventilation
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14
Aft Cargo Compartment Heating
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15
Auto Flight
...
15
Dual Mode
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15
Master FMGC Logic
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15
Independent Mode
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15
Single Mode
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15
Flight Management
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16
Position Computation
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16
Mix IRS Position
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16
GPS Position
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16
Radio Position
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16
Cost Index
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16
Engine Out Case
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16
Recommended Maximum Altitude
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16
Predictions for Alternates
...
16
Return to Trajectory Assumptions
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16
Energy Circle
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17
Interaction Between AP/FD and Authothrust Modes
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17
Soft Altitude
...
17
Land Mode
...
17
Flare Mode Once a/c reaches approximately 40’ radar altitude FLARE mode
engages.
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17
Align Sub Mode
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17
Roll Out Mode
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17
Speed Control
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17
Autoland Warning Light
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17
Thrust Lock Function
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17
Alpha Floor
...
18
Ground Speed Mini
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18
Vapp Computation
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18
Flight Augmentation
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18
Yaw Damping
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18
Rudder Trim
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18
Rudder Travel Limitation
...
18
PFD Speed Scale Management
...
18
Low Energy Warning
...
19
Windshear Detection Function
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19
Electrical
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19
Main Generators
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19
External Power
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19
Emergency Generator
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20
Static Inverter
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20
DC Generation
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20
Transformer Rectifiers
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20
Batteries
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20
Circuit Breakers
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20
Normal Configuration
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20
In Flight
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20
Abnormal Configurations
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20
Failure Of One Engine Generator
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20
Failure of AC Bus 1
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20
Failure Of One TR
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20
Failure of TR 1+2
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20
Emergency Generation After Loss of all Main Generators
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21
Smoke Configuration
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21
Pushing the Engine 1 or 2 Fire push button will :-
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21
Pushing the APU Fire push button will :-
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21
Avionics Bay
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21
Lavatory
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22
Cargo Compartment Smoke Detection
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22
Flight Controls
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22
Basic Principles
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22
Electrical Control
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23
Electric Control
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23
Speedbrakes and Ground Spoilers
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23
Speedbrake Control
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23
Speedbrake extension is inhibited if :-
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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
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24
Full Extension
...
24
Partial Extension
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24
Retraction
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24
Yaw Control
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24
Electrical Rudder Control
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24
Mechanical Rudder Control
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24
Rudder Actuation
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24
Rudder Travel Limit
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24
Rudder Trim
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24
Normal Law
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24
Protections
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25
Pitch Attitude Protection
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25
High Angle of Attack Protection
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25
High Speed Protection
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26
Normal Law
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26
Bank Angle Protection
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26
Sideslip Target
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27
Reconfiguration Control Laws
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27
Alternate Law
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28
Ground Mode
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30
Flight Mode
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30
Lateral Control
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30
Yaw Alternate Law
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30
Load Factor Limitation
...
30
Pitch Attitude Protection
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30
Low Speed Stability
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30
Bank Angle Protection
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30
Lateral Control
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31
Roll Direct Law
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31
Yaw Mechanical Control
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31
Abnormal Attitude Laws
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31
Mechanical Backup
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31
Pitch Control
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31
Lateral Control
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31
Flaps and Slats
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31
Fuel System
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32
Outer Tank Inner Tank Centre Tank Inner Tank Outer Tank
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32
Tank Pumps
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32
Transfer Valves
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32
Cross Feed Valve
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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.
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32
Engine LP Valves
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32
Suction Valves
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32
Fuel Feed Sequence
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33
Centre Tank Pumps Control Logic
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33
Fuel Transfer From Outer To Inner Tanks
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33
Fuel Recirculation System
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33
Refuelling / Defuelling
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34
Hydraulics
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34
Green System Pump
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34
Blue System Pumps
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34
Yellow System Pumps
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34
Power Transfer Unit
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34
Ram Air Turbine
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34
System Accumulators
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34
Priority Valves
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34
Fire Shutoff Valves
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34
Reservoir Pressurisation
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34
Wing Anti Ice
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35
Wipers
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36
Rain Repellent
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36
Visual Ice Indicator
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36
Electronic Instrument System
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37
Display Unit
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37
Display Management Computer (DMC)
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37
System Data Acquisition Concentrator
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37
Flight Warning Computers
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37
Landing Gear
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38
Main Gear
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38
Nose Gear
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38
Nose Wheel Steering
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39
Brakes and Anti Skid
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39
Anti Skid System
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39
Auto Brake
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40
Normal Braking
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40
Alternate Braking With Anti Skid
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40
Alternate Braking Without Anti Skid
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40
Parking Brake
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40
Air Data and Inertial Reference System (ADIRS)
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41
Windshear Prediction Function
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42
Traffic alert and Collision Avoidance System (TCAS)
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42
Pneumatic System
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43
Engine Bleed System
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43
Air Bleed Selection
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43
Pressure Regulation And Limitation
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43
Temperature Regulation And Limitation
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43
APU Bleed Air Supply
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43
Crossbleed
...
44
Leak Detection
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44
Auxiliary Power Unit (APU)
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44
APU Engine
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44
Electronic Control Box
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44
Air Intake System The air intake and an electrically operated flap allow external
air to reach the compressor.
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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.
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45
Fuel System The left fuel feed line supplies the APU. The required pressure is
normally available from the tank pumps.
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45
Oil System The APU has an integral independent lubrication system (for
lubrication and cooling).
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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.
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45
Power Plant
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45
Low Pressure (LP) compressor / turbine
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45
High Pressure (HP) compressor / turbine
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45
Combustion Chamber
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45
Accessory Gearbox
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45
Full Authority Digital Engine Control (FADEC)
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45
EPR Mode
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46
N1 Modes
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46
Rated N1 Mode
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46
Unrated N1 Mode
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46
EPR Recovery Logic
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46
Ignition and Starting
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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.
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46
Engine Starting System (automatic)
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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.
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
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.
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
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.
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.
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 <22° C, or the ventilation air reaches upper limit of 62° C.
Battery Ventilation
A venturi in the skin draws air from around batteries, and vents overboard. Lavatory And Galley
An extraction fan draws ambient cabin air through the lavatories and galleys and exhausts it near the outflow valve. Extraction fan runs continually with electric power available.
Cargo Ventilation
Aft Cargo Compartment Ventilation
Air from cabin goes via the inlet isolation valve to aft cargo compartment, driven by extraction fan. Air is controlled by outlet isolation valve and goes overboard via the outflow valve. The cargo ventilation controller controls inlet/outlet isolation valves and extraction fan. When isolation valves are fully open, the extraction valve operates continuously when aircraft is on ground and in flight.The controller closes the isolation valves and stops extraction fan when aft isolation valve push button is off or the aft cargo smoke detection unit detects smoke.
Aft Cargo Compartment Heating
Uses hot engine bleed air upstream of the packs, and mixes with ambient cabin air flowing through cargo compartment. The cargo regulating valve regulates the pressure of the hot air supply, and the trim air valve, which is modulated electrically by the controller, controls the flow. The regulating valve is pneumatically operated and electrically controlled from the Hot Air push button on the cargo heat panel. The hot air is mixed with cabin air and supplied to cargo compartment via the ventilation inlet isolation valve. If inlet temp exceeds 70° C, the controller closes trim air valve. If inlet temp exceeds 88° C, controller interprets as a duct overheat and closes pressure regulating valve. Valve remains closed until flight crew resets system by pressing hot air push button, which it can’t do until temp is <70° C.
Auto Flight
The Flight Management Guidance System (FMGS) contains two Flight Management Guidance Computers (FMGC), two Multipurpose Control And Display Units (MCDU), one Flight Control Unit (FCU) and two Flight Augmentation Computers (FAC).
Flight Management Guidance Computer (FMGC)
Flight management part controls navigation and navaids, flight planning, prediction and optimisation of performance, and management of displays.Flight guidance part controls autopilot command, flight director command and auto thrust command.
Multipurpose Control and Display Unit (MCDU)
The MCDU allows flight crew to interface with the FMGC with selection of a flight plan, etc.Flight Control Unit Located on glareshield. It is the short term interface between the crew and the FMGC. Is used to select
or modify the parameters selected in the MCDU. Flight Augmentation Computer (FAC)
Controls rudder, rudder trim and yaw damper inputs. It computes data for the flight envelope and speed functions. Also provides warning for low energy and windshear detection.
FMGS Modes Of Operation
Has 3 modes of operation. Dual mode (normal), independent mode (each FMGC controlled by its associated MCDU), and single mode (using one FMGC only).
Dual Mode
Normal mode. Both FMGC’s synchronised, and exchange data by cross talk bus. One is master, and one is slave. All info transferred to both MCDU’s.
Master FMGC Logic
If both autopilots engaged, then FMGC 1 is master. If one autopilot is engaged, the associated FMGC is master.
If no autopilot engaged, and flight director 1 is on, then FMGC 1 is master.
If no autopilot engaged, and flight director 2 is on, then FMGC 2 is master.
If no autopilot and no flight director engaged, then auto thrust is controlled by FMGC 1. Independent Mode
System selects this degraded mode automatically if there is a major mismatch.Both FMGC’s work independently, and are linked only to peripherals on own side.There is no cross talk between the FMGC’s.Independent Operation appears on MCDU scratch pad.
Single Mode
System selects this degraded mode automatically if one FMGC fails. The remaining FMGC drives all peripherals. An entry on either MCDU will be transferred to both MCDU’s, but only goes to the operating FMGC. Opposite FMGC In Progress is displayed on the MCDU on the side of the failed FMGC. The Nav Display on the side of the failed FMGC has to be set to the same range and mode as the other nav Display, otherwise Select Offside Range/Mode is displayed in amber.
Flight Management
Position Computation
Each FMGC computes its own aircraft position called the FM position, from a mix IRS position, and a computed radio position or GPS position. The FMGS selects most accurate position considering integrity of each, etc.
GPS/Inertial is the basic nav mode provided GPS data is valid and successfully tested, otherwise navaids plus inertial or inertial only are used.
Mix IRS Position
Each FMGC receives a position from each of the 3 IRS’s, and computes an average position called the Mix IRS position. If one IRS drifts abnormally, it uses an algorithm to decrease influence of drifting IRS with Mix IRS position. f one IRS fails, each FMGC uses only one IRS, which is continuously tested. If test fails, IRS is rejected. hen the mix IRS position differs from radio position by more than 12nm, check a/c position is displayed on MCDU’s.
GPS Position
Each IRS computes hybrid position that is a mixed IRS/GPS position called GPIRS. Of the 3 GPIRS positions calculated, one is selected based on merit and priority. If GPIRS data does not comply with integrity criteria, the GPS mode is rejected, and radio position updating is used. GPS Primary Lost is displayed on ND and MCDU. During non ILS approach, a triple click is heard with loss of the GPS primary function. All navigation requirements are met if GPS Primary is in use.
Radio Position
Each FMGC uses onside navaids to compute its radio position. It uses LOC to update lateral position during an ILS approach. f one or more navaids fail, each FMGC can use offside navaids to compute the VOR/DME or the DME/DME radio position.
FM Position
Each FMGC displays an FM position that is a mixed IRS/GPS position (GPIRS). At takeoff, the FM position is updated to runway threshold. In flight, the FM position approaches the radio position, or GPS position, at a rate that depends on a/c altitude. The update of FM at takeoff is inhibited at takeoff if GPS Primary is active. Bias
Each FMGC computes a vector from its mix IRS position to the radio or GPIRS position. The vector is called the bias. Each FMGC continually updates its bias, if a radio or GPIRS position is available.If an FMGC loses its radio/GPIRS position, it memorises the bias and uses it to compute the FM position, which equals the mix IRS position plus the bias.
Crew can manually update the FM position. This also updates the bias. Cost Index
Is the ratio of flight time cost to fuel cost. (CT/CF) CI = KG/MIN
CI = 0 Corresponds to minimum fuel consumption (max range). CI = 999 Corresponds to minimum time.
Engine Out Case
The FMGS computes an engine out target speed for each flight phase. It also computes an engine out maximum altitude at LRC speed and displays on Progress page. Target speed becomes green dot in climb and EO cruise speed in cruise.System computes flight plan predictions to the primary destination. If a/c above EO max altitude, predicts immediate drift down to be performed to EO max altitude.
Recommended Maximum Altitude
The recommended max is lowest of that which the a/c can reach with a 0.3g buffet margin, can fly in level flight at max cruise rating, can maintain a v/s of 300 fpm at max climb thrust or can fly at a speed higher than green dot and lower than VMO/MMO for which it is certified. A maximum altitude using a 0.2g buffet margin is also computed, but not displayed to crew.
Predictions for Alternates
Based on default cruise of F220, if distance <200nm, otherwise F310.Simplified wind/temp, based on crew entries. Airway distance or direct distance as provided by the database.Cost Index 0 (minimum fuel)Initial a/c weight equal to landing weight at primary destination.
Return to Trajectory Assumptions
If a/c not on lateral flight plan, assumes an immediate return to active leg with a 45° intercept angle, or it will fly direct to the TO waypoint if required intercept is > than 45°.
Energy Circle
Is a green arc, centred on aircraft’s position and orientated towards the current track line. It represents the required distance to land from the aircraft’s position down to the airport elevation at VAPP speed, considering all speed constraints on the vertical profile.
Interaction Between AP/FD and Authothrust Modes
The AP/FD modes can control a target SPD/MACH or a vertical trajectory, and the A/THR mode can control a fixed thrust or a target SPD/MACH. They cannot control both simultaneously.If the AP/FD pitch mode controls pitch, the A/THR controls the SPD/MACH. If the AP/FD pitch mode controls SPD/MACH, the A/THR controls the thrust. If no AP/FD pitch mode is engaged, the A/THR reverts to controlling the SPD/MACH mode. In other word, the selection of an AP/FD pitch mode, determines which mode the A/THR controls.
Soft Altitude
Two minutes after ALT CRZ engages, if mach mode is operative, SOFT ALT mode engages. This allows a/c to deviate +/- 50 feet from the target altitude, reducing thrust variations and fuel consumption.
Speed Reference System (SRS)
SRS mode controls pitch to steer a/c along a path in the vertical plane at a speed defined by the SRS guidance law. SRS automatically engages when thrust levers are set at TOGA or MCT/FLX if V2 inserted in MCDU PERF TO page, slats are extended and a/c been on ground for at least 30 seconds. It disengages automatically when a/c reaches acceleration altitude, or manually when another vertical mode engages. The pitch reference is V2+10 in normal engine configuration, or the current speed or V2, whichever is greater, if the FMGS detects an engine failure. Provides attitude protection to reduce a/c nose up on takeoff (18-22.5° in windshear). Provides FPA protection that ensures a minimum v/s of 120 fpm. Provides speed protection limiting the target speed to V2+15 knots.
Land Mode
Automatically engages when the LOC and G/S are engaged, and a/c is below 400’.
FMA displays LAND, indicating that LOC and G/S are locked, and no action on the FCU will disengage LAND mode. LAND mode disengages upon engagement of go-around mode, if the pilot presses the APPR button when a/c on ground for at least 10 seconds with AP disconnected, or when both AP/FD’s are disengaged.
Flare Mode Once a/c reaches approximately 40’ radar altitude FLARE mode engages.
The FMA dsplays FLARE in green.At 30’ RA, the a/c flares on the pitch axis. Thrust reduces if authothrust is active. When both AP/FD’s are disengaged, FLARE mode disengages. After main gear touch down, autopilot if engaged sends a nose down order.
Align Sub Mode
Is sub mode of LAND, also referred to as decrab. It lines a/c axis with ILS course at approximately 30’. Is not displayed to the crew.
Roll Out Mode
At touch down, ROLL OUT mode engages and guides a/c along runway centreline. FMA displays ROLL OUT in green, and PFD displays yaw bar with no FD bars.
Speed Control
Autothrust memorises the approach speed at 700’ RA, so that it can continue to fly a stable approach even if the FMGS fails.
Autoland Warning Light
The following, when occurring below 200’ RA, with a/c in LAND mode, will trigger the flashing AUTOLAND red warning and triple click aural warning
:-Both A/P’s off below 200’ RA
Excessive deviation in LOC (1/4 dot >15’RA) Excessive deviation in GLIDE (1 dot.100’ RA)
Loss of LOC signal above 15’, or loss of GLIDE above 100’ The difference between both radio altimeters is greater than 15’. Thrust Lock Function
Is activated when thrust levers in CL detent, or MCT detent on one engine, and the pilot pushes the A/THR push button or the A/THR disconnects due to a failure. The thrust is locked at its level prior to disconnection. Moving the levers out of CL or MCT suppresses the thrust lock, and gives the pilot manual control of the thrust levers. All warnings will then cease.
Alpha Floor
Is a protection that commands TOGA thrust, regardless of thrust lever position when aircraft reaches a very high angle of attack. The FAC generates the signal that triggers alpha-floor mode. This protection is available from lift off to 100’ RA on approach.
A FLOOR in green, surrounded by flashing amber box on FMA, and in amber on the EWD is displayed as long as alpha floor conditions are met.
TOGA LK in green, surrounded by flashing amber box on FMA is displayed when the a/c leaves the alpha floor conditions. TOGA thrust is frozen.
To cancel ALPHA FLOOR or TOGA LK thrust, the pilot must disconnect the auto thrust.
Ground Speed Mini
Purpose of the ground speed mini function is to take advantage of a/c inertia, when wind conditions vary during the approach. Provides crew with an adequate indicated speed target. When the a/c flies this indicated airspeed, the energy of the a/c is maintained above a minimum level, ensuring standard aerodynamic margins above the stall. If authothrust is active in SPEED mode, it will automatically follow the IAS target, ensuring efficient thrust management during the approach. The minimum energy level is the energy level the a/c will have at touch down, if it lands at Vapp speed with the tower reported wind entered in the PERF APPR page. This minimum energy level is represented by the ground speed the a/c will have at touch down. This ground speed is called Ground Speed Mini. During approach, the FMGS continuously computes speed target using actual winds experienced by a/c, in order to keep ground speed at or above ground speed mini. The lowest speed is limited to Vapp, and highest speed is Vfe of next configuration in CONF 1,2 or 3, and Vfe-5 in CONF full. Wind is a key factor in the ground speed mini function.
Vapp Computation
VAPP = VLS + 1/3 of the headwind component or VAPP = VLS + 5 knots, whichever is the highest.
1/3 of the headwind has 2 limits. 0 knots as the minimum value and +15 kts as maximum value.
Flight Augmentation
The aircraft has 2 flight augmentation computers (FACs) that perform 4 main functions. 1. Yaw function Yaw damping and turn coordination, rudder trim, and rudder travel limitation 2. Flight envelope function
PFD speed scale management, min/max speed computation, manoeuvring speed, Alpha-floor. 3. Low energy warning
4. Windshear detection function.
Each FAC interfaces with the elevator aileron computers (ELACs) when the AP’s are disengaged, or with the FMGS when one AP is engaged. Both FACs engage automatically at power up. Pilots can disengage or reset the FACs. If both FACs are valid, FAC1 controls the yaw damper, turn coordination, rudder trim, and rudder travel limit. FAC2 is in standby. If a failure is detected on any channel of FAC1, FAC2 takes over the corresponding channel.
Yaw Damping
Stabilises the aircraft in yaw and coordinates its turns.In auto flight during takeoff and go around, it assists with rudder application after an engine failure (short term yaw compensation). When AP is engaged, the FMGS sends orders to the FAC to give yaw damping during an approach and yaw control for runway alignment in ROLL OUT mode.
Rudder Trim
Executes trim orders the pilot enters with the manual trim knob.When AP is engaged, it executes the trim orders from the FMGS, and assists the system in recovering from engine failure in all flight guidance modes. If the pilot pushes the rudder more than 10 degrees out of trim, it disengages the autopilot.When AP is engaged, the rudder trim is inoperative; the master FMGC sends rudder trim orders to the FAC. Rudder Travel Limitation
This function limits rudder deflection as a function of speed in order to avoid high structural loads. If both FACs lose the rudder travel limitation function, the value of the rudder deflection limit is locked at the time of the second failure. When the slats are extended, the FACs automatically set the rudder deflection limit at the low speed setting (maximum authorised deflection).
PFD Speed Scale Management
The FAC computes VSW (stall warning), VLS, VFE, VLE, VMO/MMO, Green Dot Speed, S Speed and F Speed.
Low Energy Warning
Warns pilot that the aircraft’s energy level is going below a threshold under which he has to increase thrust, in order to regain a positive flight path angle through pitch control. “Speed speed speed” is repeated every 5 seconds. Is available in config 2,3 and full. The warning is inhibited when TOGA is selected, or below 100’ RA, or above 2000’ RA, or Alpha floor, or GPWS is triggered, or a/c is in alternate or direct law or both Radio Altimeters fail. During deceleration, the low energy warning is triggered before alpha floor. The amount of time between the two depends on the deceleration rate.
Windshear Detection Function
Whenever a FAC detects windshear conditions it triggers a warning. It is active at takeoff, from lift off to 1300’, and during approach from 1300’ to 50 feet. In both situations, aircraft must be in configuration 1,2,3 or full. In computing the energy level prediction, the FACs use data from different sources. The FACs express this energy level as an angle of attack, and compare it with an angle of attack threshold, above which windshear conditions are most likely, and pilot action is required.
In windshear conditions, flight guidance acts on specifically adapted FD pitch orders received from the speed reference system. Pilot must set go-around thrust immediately and follow pitch order to execute the optimum escape manoeuvre.
Electrical
The electrical system consists of a 3 phase 115/200 volt 400 hertz constant frequency AC system and a 28 volt DC system.Nor mally system produced AC, some of which it transforms to DC for certain applications.Each of the aircrafts 3 generators can supply the whole network. If all normal AC generation is lost, an emergency generator can supply AC power. If all AC generation is lost, the system can transform DC power from the batteries into AC power.
AC Generators
Main GeneratorsTwo 3 phase AC generators (GEN 1, GEN 2). Each driven by one main engine through an integrated drive. Each generator can supply up to 90 KVA at 115/200 volts and 400 Hertz. A third generator (APU), driven directly by the APU, and producing same power output as both main engine generators at any time. A generator control unit (GCU) controls output of each generator. The GCU controls the frequency and voltage of the generator output, and protects the network by controlling the associated generator line contactor (GLC).
Emergency Generator
The blue hydraulic drives an emergency generator (ram air turbine RAT), that automatically supplies emergency AC power to the electrical system if all 3 main generators fail. This generates 5 KVA of 3 phase 115/200 volt 400 Hertz power.
A generator control unit (GCU) keeps emergency generator at a constant speed, controls the output, protects the network by controlling the GLC and controls the emergency generator start up.
Static Inverter
Transforms DC power from Battery 1 into 1 KVA of AC power, which is supplied to the AC essential bus. When a/c is above 50 knots, the inverter is automatically activated if only the batteries are supplying the power, regardless if BAT 1+2 push buttons are both on at auto.
DC Generation
Transformer RectifiersTwo main transformer rectifiers, TR 1 + TR 2 supply electrical system with up to 200 amperes of DC current. A third TR (ESS TR) can power the essential DC circuit from the emergency generator, if main generators all fail, or if TR 1+2 both fail. Each TR controls its contactor by internal logic.
Batteries
Two main batteries, each with a capacity of 23 ampere hours, are permanently connected to the two hot buses.Each battery has an associated Battery Charge Limiter (BCL). The BCL monitors battery charging and controls its battery contactor.
Circuit Breakers
There are two types of circuit breakers. Monitored (green) : When out for > 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 FlightEach 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 GeneratorThe 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
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 <100 knots, the RAT has nothing to drive it. Emergency generation transfers over to the batteries and static inverter, and system sheds the AC SHED BUS and DC SHED ESS buses.
When a/c is on the ground
:-<100 knots the DC BAT BUS is connected to the batteries. <50 knots the AC ESS BUS is shed, leading to the loss of all CRTs.
During RAT extension and emergency coupling (8 seconds), the batteries power the network. Smoke Configuration
Main bus bars are shed. The electrical distribution is the same for emergency configuration (loss of main generators), except that the fuel pumps are connected upstream of the GEN 1 connector. This sheds about 75% of electrical equipment. All equipment that remains powered is supplied through C/Bs on overhead panel, except for that which is supplied by hot buses).
Fire Protection
The engines and APU each have a fire and overheat detection system consisting of two identical gas detection loops (A+B) mounted in parallel. The gas detection loops consist of three sensing elements for each engine. One in the pylon nacelle, one in the engine core and one in the engine fan section. There is one sensing element in the APU compartment.
When subjected to heat they send a signal to the fire detection unit. As soon as Loops A+B detect temperature at a preset level, they trigger the fire warning system. A fault in one loop does not affect the warning system. The good loop still protects the aircraft. If an APU fire occurs on the ground, the system shuts down the APU automatically and discharges the extinguishing agent. (does not do so in the air).
Extinguishing
Each engine has two extinguisher bottles equipped with electrically operated squibs to discharge their contents. Each squib has a dual electric supply.
The APU has one fire extinguisher bottle with an electrically operated squib. Fire Warning and Loop Cautions
Fire detection units process all warnings and cautions. A fire warning occurs with a fire signal from both Loop A+B, or a signal from one loop when other is faulty, or breaks in loops occurring within 5 seconds of each other (flame effect), or a test performed on the control panel. The loop fault cautions appear if one loop is faulty, or both loops are faulty, or the fire detection unit fails.
Pushing the Engine 1 or 2 Fire push button will
:-Silences the aural fire warning and arms the fire extinguisher squibs. Closes the low pressure fuel valve.
Closes the hydraulic fire shut off valve. Closes the engine bleed valve. Closes the pack flow control valve. Cuts off the FADEC power supply. Deactivates the IDG.
Pushing the APU Fire push button will :-Shuts down the APU and silences the aural warning.
Arms the squib on the APU fire extinguisher.
Closes the low pressure fuel valve. Shuts off the APU fuel pump. Closes the APU bleed valve and cross bleed valve, and deactivates the APU generator.
Avionics Bay
One smoke detector in the air extraction duct of the avionics
the ECAM to display a warning in the cockpit when it detects smoke for longer than 5 seconds. A single chime sounds, the master caution lights up, ECAM displays caution on EWD, the smoke light on the EMER ELEC PWR panel lights up, and the BLOWER and EXTRACT FAULT on the ventilation panel light up. Lavatory
One smoke detector in each lavatory and a double channel Smoke Detection Control Unit (SDCU). When a detector senses smoke in a lavatory, it sends a signal to the SDCU. The SDCU transmits it to the flight warning computer (for warning in the cockpit) and to the CIDS (for warning in the cabin). Each lavatory waste bin has an automatic fire extinguishing system.
Cargo Compartment Smoke Detection
There are two detectors in the forward cargo compartment and 4 detectors in the aft compartment.
Each detector is linked to one of two detection loops (dual loop principle). The SDCU receives signals from the detectors and transmits them to the ECAM. The SDCU has two identical channels. If cargo ventilation is installed, and a cargo smoke warning is activated in either compartment, the associated isolation valves automatically close and the extraction fan stops.
Cargo Compartment Fire Extinguishing
One fire bottle supplies three nozzles (one in forward, and two in aft). The bottle has two discharge heads, one for each compartment. When flight crew press discharge button for either compartment, the action ignites the corresponding squib on the fire bottle, which then discharges extinguishing agent into that compartment.
Flight Controls
Basic Principles
The flight controls are all electrically controlled and hydraulically activated.The stabiliser and rudder can also be mechanically controlled. Computers interpret pilot input and move the flight control surfaces, as necessary, to follow their orders. However, in normal law, regardless of pilot input, the computers will prevent excessive manoeuvres and exceedance of the safe envelope in pitch and roll axis. The rudder has no such protection, as like conventional aircraft.
Computers
2 ELACS (Elevator Aileron Computer)
For Normal elevator, stabiliser control and aileron control. 3 SECS (Spoilers Elevator Computer)
or Spoilers control and Standby elevator and stabiliser control.
2 FACS (Flight
Augmentation Computer) For Electrical rudder control. 2 FCDC (Flight Control Data Concentrators) They acquire data from the ELACs and SECs and send to the electronic instrument system and the centralised fault display system.
Pitch Control Two elevators and trimmable horizontal stabilisers (THS) control the a/c in pitch. Maximum elevator deflection is 30° nose up and 15° nose down. Maximum THS deflection is 13.5° nose up and 4° nose down.
Electrical Control
In normal operations, ELAC 2 controls elevators and horizontal stabiliser, and the G&Y hydraulic jacks drive the L&R elevator surfaces respectively.The THS is driven by No1 of 3 electric motors.If ELAC 2, or associated hydraulic systems or jacks fail, pitch control shifts to ELAC 1.ELAC 1 then controls elevators via the blue hydraulics and controls the THS via No2 electric motor.If neither ELAC 1 or 2 is available, pitch control shifts to SEC1 or 2, and to THS electric motor 2 or 3.
Mechanical Control
Mechanical control of the THS is available from pitch trim wheel at any time if either green or yellow hydraulic systems are available. Mechanical control has priority over electrical control.
Roll Control
One aileron and four spoilers on each wing control the a/c about the roll axis.Maximum deflection of the ailerons is 25°. The ailerons extend down 5° when the flaps are extended (aileron droop). Maximum deflection of the spoilers is 35°.
Electric Control
ELAC 1 normally controls the ailerons.If ELAC 1 fails, aileron control shifts to ELAC 2. IF both ELACs fail, the ailerons revert to damping mode (jack follows surface movement). SEC 3 controls No2 spoilers, SEC 1 controls No 3&4 spoilers, and SEC 2 the No 5 spoilers. If a SEC fails, the spoilers it controls are automatically retracted.
If the system loses hydraulic pressure, the spoiler retains the deflection it had at the time of the loss, or a lesser deflection if aerodynamic forces push it down.When a spoiler on one wing fails, the symmetric one on opposite wing is inhibited.
Speedbrakes and Ground Spoilers
Speedbrake ControlPilot uses speed brake lever to control speedbrakes. Speed brakes are actually spoilers 2,3 and 4.
Speedbrake extension is inhibited if
:-• SEC 1&3 both have faults.
• An elevator has a fault (spoilers 3&4 are inhibited).
