a380-level i - ata 27 flight controls

A380 TECHNICAL TRAINING MANUAL

MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls

This document must be used for training purposes only

Under no circumstances should this document be used as a reference

It will not be updated.

All rights reservedNo part of this manual may be reproduced in any form,

by photostat, microfilm, retrieval system, or any other means,without the prior written permission of AIRBUS S.A.S.

LEVEL I - ATA 27 FLIGHT CONTROLSFlight Controls System Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 2"Fly by wire" Philosophy Presentation . . . . . . . . . . . . . . . . . . . . . . . 10Primary Flight Controls Presentation . . . . . . . . . . . . . . . . . . . . . . . . 24Secondary Flight Controls Presentation . . . . . . . . . . . . . . . . . . . . . . 50Flight Controls System Maintenance (1) . . . . . . . . . . . . . . . . . . . . . . 58


TABLE OF CONTENTS Mar 21, 2006Page 1

A380 TECHNICAL TRAINING MANUALL

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FLIGHT CONTROLS SYSTEM INTRODUCTION

General

The flight control system is used for the control of the aircraft during allthe flight phases.Firstly, the general architecture of the flight control system will bepresented.Then, the "fly by wire" philosophy,And finally, the subsystems of the flight control system including:- the PRIMARY flight controls,- and the SECONDARY flight controls.


FLIGHT CONTROLS SYSTEM INTRODUCTION Mar 15, 2006Page 2


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GENERAL




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General Architecture of The Flight Control System

This topic shows the main components of the flight control system.The flight control surfaces are able to control the aircraft on the threeaxes (roll, pitch, and yaw), and to provide other functions such as forexample, the speedbrake function and the "high lift" function.The CONTROL and INDICATING components, located in the cockpit,are in fact the interfaces between the pilots and the aircraft.

Flight Control SurfacesThe flight control surfaces can be divided into two categories.The first one is the PRIMARY flight control surfaces, which controlthe aircraft according to the three axes (roll, pitch, yaw) and do theauxiliary functions.The second one is the SECONDARY flight control surfaces, whichmake the "high lift" function.The PRIMARY flight control surfaces are:- 6 ailerons,- 16 spoilers,- 1 Trimmable Horizontal Stabilizer (THS),- 4 elevators,- and, 2 rudders.The SECONDARY flight control surfaces are:- 4 droop noses (new deployment system),- 12 slats,- and 6 flaps.




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GENERAL ARCHITECTURE OF THE FLIGHT CONTROL SYSTEM - FLIGHT CONTROL SURFACES




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General Architecture of The Flight Control System (continued)

Control and IndicatingThe CONTROL components of the flight control system are:- 2 side sticks,- 2 pairs of rudder pedals interconnected,- 1 rudder trim control panel,- 2 pitch trim control switches,- 1 speedbrake/ground spoiler lever,- 1 slat/flap control lever,- 6 FAULT/RESET pushbutton switches of the flight controlcomputers.One side stick is installed on the CAPT lateral console, the other oneis installed on the F/O lateral console.The 2 pairs of rudder pedals are installed in front of the CAPT andthe F/O seats.The 2 pitch trim control switches, the speedbrake/ground spoiler lever,and the slat/flap control lever are installed on the pedestal.The 6 FAULT/RESET pushbutton switches of the flight controlcomputers located on the left-hand side and the right-hand side of theoverhead panel.The INDICATING components are:- 2 PFDs,- 1 EWD and,- 1 SD.The 2 PFDs are installed on the pedestal, one in front of the CAPTseat and the other one, in front of the F/O seat.The EWD is installed on the main instrument panel.The SD is installed on the pedestal.




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GENERAL ARCHITECTURE OF THE FLIGHT CONTROL SYSTEM - CONTROL AND INDICATING




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"Fly By Wire" Philosophy

This topic shows the "fly by wire" philosophy.As on the previous Airbus aircraft programs, the flight control system ofthe A380 is based on a "fly by wire" technology.The orders from the pilots are sent to the PRIMARY flight controls.These computers convert the orders into an aircraft objective.The computers send surface deflection orders to the surfaces in order toachieve the aircraft objective.Then, the computers monitor the position feedback of the surfaces.The computers also receive an aircraft response and compare it to thedemand (coming from the orders).




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"FLY BY WIRE" PHILOSOPHY




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"FLY BY WIRE" PHILOSOPHY PRESENTATION

General

This module shows the "fly by wire" philosophy.The PRIMARY flight control computers can be divided into twofunctions, COMPUTATION and EXECUTION.Orders (from the pilots, or the autopilot) are sent to the COMPUTATIONfunction.The computation function converts the orders into an aircraft objectiveand surface deflection orders required to reach the objective. TheCOMPUTATION compares the aircraft response with the aircraftobjective, this loop is called an "outer" loop.The EXECUTION function fulfils the surfaces servoing.The EXECUTION function commands the flight control servos andmonitors the position of the surfaces to make sure that they reach thecommanded position. These loops are called "inner loops".Thus, each relevant surface (spoilers, ailerons, elevators, TrimmableHorizontal Stabilizer (THS), and rudders) receives a surface deflectionorder.


"FLY BY WIRE" PHILOSOPHY PRESENTATION Mar 15, 2006Page 10


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GENERAL




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Computation Philosophy

This topic shows the flight control laws and the functions done insidethe flight control computers to compute the surface deflection orders.

Computer FunctionsThe PRIMARY flight controls have three PRIMary systems calledPRIMs and three SEcondary Computers called SECs.Each of them fulfills two functions:- the COMPUTATION function, which computes the aircraftobjective, and the surface deflection orders.- the EXECUTION function, which commands the control surfaces.

Computer Master/Slave ConfigurationOnly one PRIM at a time is the "MASTER".The COMPUTATION function of the "MASTER" receives the ordersfrom the pilot in manual mode or, from the Flight Guidance (FG) inautopilot mode.The "MASTER" PRIM generates the surface deflection orders andsends them to the two other PRIMary systems and to the threeSEcondary Computers.Each PRIM, and each SEC signal their associated surfaces and do the"inner" control loop in their EXECUTION function. Each PRIM andeach SEC have control over a particular flight control servo, forexample:- PRIM2 commands the green system actuator on the left handoutboard aileron,- SEC3 commands the number8 spoiler on the left wing.In its COMPUTATION function, the "MASTER" does the "outer"control loop to compare aircraft response with the aircraft objective.




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COMPUTATION PHILOSOPHY - COMPUTER FUNCTIONS & COMPUTER MASTER/SLAVE CONFIGURATION




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Flight Control Laws

The flight control computers according flight control laws process surfacedeflection orders.The aircraft is controlled in the three axes through:- the lateral control laws (including the roll and the yaw axes),- and the pitch control law.

Law Reconfiguration + Law ImplementationDepending on the status of the PRIMARY flight control computers(PRIMs and SECs), and depending on the status of the other systemsand sensors, the flight control computers can engage three differentlevels of law:- the NORMAL law, all the protections are available,- the ALTERNATE law, some protections are reduced or lost,- the DIRECT law, no protection available.The flight control laws are automatically switched from NORMALto ALTERNATE and then to DIRECT according to the nature andthe number of failures.The NORMAL, the ALTERNATE, and the DIRECT flight controllaws are implemented in the three PRIMary systems, while only theDIRECT flight control law is implemented in the three SEcondaryComputers.




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FLIGHT CONTROL LAWS - LAW RECONFIGURATION + LAW IMPLEMENTATION




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System and Law Engagement Logic

The flight control laws engagement follows two rules:- the first rule is the engagement priority order of the laws,- and, the second rule is the engagement priority order of the systems.

Rule 1: Law Engagement Priority OrderThis rule is as follows: The priority order number one is the NORMALlaw, the number two is the ALTERNATE law, and finally, the prioritynumber three is the DIRECT law.

Rule 2: System Engagement Priority OrderThe engagement priority order of the systems is as follows:- PRIM 1,- PRIM 2,- PRIM 3.




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SYSTEM AND LAW ENGAGEMENT LOGIC - RULE 1: LAW ENGAGEMENT PRIORITY ORDER & RULE 2: SYSTEM ENGAGEMENTPRIORITY ORDER




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System and Law Engagement Logic (continued)

Rule 1 + Rule 2: Normal + Alternate ModesAccording to these two rules, the PRIM that can engage the highestlevel of law, and becomes the "MASTER".




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SYSTEM AND LAW ENGAGEMENT LOGIC - RULE 1 + RULE 2: NORMAL + ALTERNATE MODES




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System and Law Engagement Logic (continued)

Direct ModeIf the three PRIMs are lost or not able to compute their laws, eachSEC computes its own control law called DIRECT law, and none isthe "MASTER".Consequently, each SEC executes its own orders on its own relatedservocontrols. This is the DIRECT law.




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SYSTEM AND LAW ENGAGEMENT LOGIC - DIRECT MODE




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New Flight Control Servocontrols

The A380 has three kinds of servocontrols. These servocontrols are:- the conventional servocontrols,- the Electro-Hydrostatic Actuators (EHAs),- and, the Electrical Backup Hydraulic Actuators (EBHAs).

Conventional ServocontrolThe conventional servocontrols can also be called electro-hydraulicservocontrols.They are composed of:- a hydraulic block connected to one hydraulic system of the aircraft,- an actuator, composed of a fixed body attached to the aircraftstructure, and a rod attached to the surface,- a servovalve receiving orders from the flight control computers,which ports hydraulic pressure to translate the rod.

Electro Hydrostatic Actuator (EHA)Electro-hydrostatic actuators (EHAs) are actuators which producetheir own hydraulic pressure and can be used when the normal aircrafthydraulic pressure is lost.The Electro-hydrostatic actuators (EHAs) are composed of:- a hydraulic block,- an actuator, same as a conventional servocontrol,- an electro-hydraulic generation system.The electro-hydraulic generation system receives orders from theflight control computers.The direction of rotation of the electro-hydraulic generation systemdetermines the direction of translation of the actuator rod. The speedof the system determines speed of translation of the actuator rod.

Electrical Backup Hydraulic Actuator (EBHA)Electrical Backup Hydraulic Actuators (EBHAs) are composed of aconventional servocontrol part and an EHA part controlling a commonactuator.During the normal mode of operation the EBHA operation is the sameas a conventional servocontrol using aircraft hydraulic pressure tomove the actuator, rod this mode is called the HYDRAULIC ACTIVEMODE.If there is a loss of aircraft hydraulic pressure the EBHA acts the sameway as an EHA, producing its own hydraulic pressure to move itsactuator rod; this mode is called the ELECTRICAL ACTIVE MODE.




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NEW FLIGHT CONTROL SERVOCONTROLS - CONVENTIONAL SERVOCONTROL ... ELECTRICAL BACKUP HYDRAULIC ACTUATOR(EBHA)




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PRIMARY FLIGHT CONTROLS PRESENTATION

General

This module shows the general architecture of the PRIMARY flightcontrols, and the functions done inside the flight control computers.It shows the links between the CONTROL block, the COMPUTATIONblock, the ACTUATION block, and the INDICATING block.The CONTROL block is mainly composed of pilot inputs located in thecockpit (side sticks, rudder pedals...).The COMPUTATION block is composed of:- three PRIMary systems (PRIMs),- three SEcondary Computers (SECs),- one electrical backup system with its computer: the backup controlmodule and,- one Flight Control Data Concentrator (FCDC) hosted into eachCPIOM-C1 and CPIOM-C2.Each PRIM and each SEC communicate with the two FCDCs.The ACTUATION block is mainly composed of flight control surfacesand their servocontrols.The INDICATING block is mainly composed of the two Primary FlightDisplays (PFDs), the Secondary Display (SD) and the Engine WarningDisplay (EWD).


PRIMARY FLIGHT CONTROLS PRESENTATION Mar 15, 2006Page 24


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GENERAL




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Architecture

This topic gives the basic architecture of the flight control computers,their links with:- the inputs,- the flight control surfaces and,- the other systems (interfaces).

Normal Operating ModeThe main computers of the flight control system are the three PRIMarysystems (PRIMs), and the three SECondary Computers (SECs).A PRIMary system (PRIM) is composed of two Flight Control andGuidance Units (FCGUs).For example: the PRIM 1 is composed of the FCGU 1A and the FCGU1B.A FCGU includes a flight control and a Flight Guidance (FG), whichis a part of the Automatic Flight System (AFS).The PRIMs and the SECs receive pilot orders from various transducerslocated inside:- the side sticks, used for the lateral (roll plus yaw) and pitch in manualmode,- the rudder pedals, used for the control of rudders,- the pitch trim control switches, used to control the TrimmableHorizontal Stabilizer (THS) in manual mode.The speedbrake/ground spoiler lever is only linked to the PRIMs. Thislever is used for the speedbrake function and the ground spoilerfunction.The rudder trim control panel is only linked to the SECs. The pilotsmanually used this panel to trim the rudders.- the rudders.

Monitoring ModeDuring the NORMAL OPERATING MODE, the two Flight ControlData Concentrators (FCDCs) receive data from each PRIM, and eachSEC.The FCDCs fulfill the following functions:- data concentration for display (they send data to the Control andDisplay System (CDS): mainly to the PFDs, EWD and, SD for theF/CTL page construction),- flight control warnings via the Flight Warning System (FWS),- flight control maintenance via the Centralized Maintenance System(CMS).




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ARCHITECTURE - NORMAL OPERATING MODE & MONITORING MODE




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Architecture (continued)

Electrical Backup Operating ModeIn case of loss of the three PRIMary and the three SEcondaryComputers, the electrical backup system becomes active.The backup control module controls and monitors:- the Trimmable Horizontal Stabilizer (THS),- the inboard ailerons,- the inboard elevators- both ruddersThe electrical backup system is composed of three components:- two backup power supply units,- and one backup control module.Each backup power supply unit is an electrical power generatorsupplied by one hydraulic system to power the backup control module.One backup power supply unit uses the green hydraulic circuit pressurewhile the other one uses the yellow hydraulic circuit pressure.The backup control module is an analogical flight controller; it receivespilot orders, computes the control laws, and sends deflection ordersto the flight control surfaces.The backup control module uses dedicated rate gyros installed insidethe module to fulfill aircraft response monitoring (outer loop). Themodule also monitors flights control surface response (inner loop).The backup control module receives pilot orders from dedicatedtransducers installed inside:- the side sticks,- the pedal feel and trim unit,- and, the pitch trim control switches.The electrical backup system is activated.The backup control module does not communicate with the FlightControl Data Concentrators (FCDCs) which are used for the displayof the flight controls in the cockpit.




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ARCHITECTURE - ELECTRICAL BACKUP OPERATING MODE




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Type, Location And Operation Of The Servocontrols

This topic shows on which surfaces are installed the servocontrols, theirnumbers per surface, and the nature of their power supplies.So, each aileron (inboard, middle, and outboard), each rudder (upper,and lower), and each elevator (inboard, and outboard) are driven by twoservocontrols.Each spoiler is only driven by one servocontrol.A specific actuator called Trimmable Horizontal Stabilizer Actuator(THSA) drives the THS.The flight control computers control the conventional servocontrols, theElectro-Hydrostatic Actuators (EHAs), the Electrical Backup HydraulicActuators (EBHAs), and the THSA.The power supplies used by the servocontrols and the THSA are the twohydraulic circuits (the green and the yellow), and three different electricalcircuits.

AileronsThe ailerons control the aircraft about the roll axis. They are used forthe roll function plus the auxiliary functions.Three ailerons are attached onto each wing; the outboard ailerons aredriven by two conventional servocontrols.One conventional servocontrol and one Electro Hydrostatic Actuator(EHA) drive the inboard and middle ailerons.During normal operation, the outer conventional servocontrol of eachaileron operates in ACTIVE MODE, the other servocontrol operatesin DAMPING MODE.After a failure occurs, the conventional servocontrol becomes inDAMPING MODE, and so, the other one becomes in ACTIVEMODE.

RuddersTwo rudders (upper and lower) control the aircraft about the yaw axis.The two rudders are used for the yaw function, and roll/yawcoordination during turns and auxiliary functions.Two Electrical Backup Hydraulic Actuators (EBHAs) drive eachrudder (one upper and one lower).During normal operation, the upper EBHAs of upper and lower ruddersoperate in HYDRAULIC ACTIVE MODE, the lower actuators ofeach rudder operate in DAMPING MODE.Nevertheless, both EBHAs of each rudder can be activatedsimultaneously, in case of high rates or large deflection demands.After a failure of the active EBHA, the EBHA switches to DAMPINGMODE, and, the adjacent EBHA switches to HYDRAULIC ACTIVEMODE.The only time when the EBHA operates in the ELECTRICALACTIVE MODE is when the HYDRAULIC ACTIVE MODE cannotbe engaged.

ElevatorsThe elevators (with the THS) control the aircraft in the pitch axis.They are used for short-term actions. There are two elevators attachedonto each side of the Trimmable Horizontal Stabilizer (THS).Each elevator is driven by one conventional servocontrol and oneEHA.During normal operation, the elevator operation is as an aileronoperation.During normal operation the conventional servocontrol operates inACTIVE MODE, and the EHA operates in DAMPING MODE.After a failure of the conventional servocontrol, this one switches toDAMPING MODE and the EHA switches to ACTIVE MODE.Nevertheless, in case of high rate or deflection demands, bothservocontrols of the same elevator can be activated simultaneously.




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Trimmable Horizontal Stabilizer (THS)The Trimmable Horizontal Stabilizer (THS) controls the aircraft aboutthe pitch axis. The THS is only used for long-term actions.Three motors, two hydraulics, and one electrical actuate the THSthrough a gearbox.In normal operation, the green hydraulic motor is active, the yellowhydraulic is in standby, and the electrical motor is not electricallysupplied.Both hydraulic motors can be simultaneously activated when a highrate is necessary.In case of failures of the hydraulic motors, the electrical motor isactivated but it can be only used in AUTOMATIC MODE.When the AUTOMATIC MODE is available, this mode has thepriority over the MANUAL MODE, and the pitch trim control switchesare inhibited.If the AUTOMATIC MODE is lost, the pilots can control the THSvia the pitch trim control switches, this mode is called MANUALMODE.

SpoilersThe spoilers (with the ailerons) control the aircraft in the roll axis.Spoilers 3 to 8 are mainly used for the roll function.All spoilers are used for the speedbrake function and some spoilersare used for other auxiliary functions.Each spoiler is driven by one servocontrol.Spoilers 1, 2, 3, 4, 7 and 8 are driven by a conventional servocontrol,whereas spoilers 5 and 6 are each driven by one EBHA.During normal operation, the conventional servocontrol is in theHYDRAULIC ACTIVE MODE.If a failure occurs, the spoiler operation is inhibited and the spoiler islost and retracted to its zero position.For spoilers driven by an EBHA, during normal operation, theservocontrol operates in the HYDRAULIC ACTIVE MODE. In caseof hydraulic failure, the EBHA switches to ELECTRICAL ACTIVE

MODE. In that case, the spoiler actuation is actuated with a reduceddeflection speed.On ground, for maintenance tasks, the conventional servocontrols andthe EBHAs of the spoilers have a manual mechanical device to let thespoiler be manually moved.




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TYPE, LOCATION AND OPERATION OF THE SERVOCONTROLS - AILERONS ... SPOILERS




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This Page Intentionally Left Blank




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Main Flight Control Functions

This topic shows the main functions done inside the computers inNORMAL OPERATING MODE, and in addition in the ELECTRICALBACKUP OPERATING MODE. This topic shows also the auxiliaryfunctions.

Lateral (Roll + Yaw) Function - Normal Operating ModeDuring the NORMAL OPERATING MODE, for the lateral functioncomputation, in manual mode, the PRIMary systems and theSEcondary Computers receive orders from:- the side sticks,- the rudder pedals and the pedal feel and trim unit.Only the SEcondary Computers receive data from the rudder trimcontrol panel, used for the yaw function only.Only the PRIMary systems, receive autopilot order from the FG.In addition, to fulfil the "outer" control loop, the PRIMs and the SECsreceive data from:- the Air Data and Inertial Reference System (ADIRS) and,- the accelerometers and rate gyrometer units.For the lateral function, the surfaces involved are:- all the ailerons (roll function),- spoilers 3 to 8 (roll function),- the upper and the lower rudders (yaw function).Related to the ailerons and the spoilers, the rudders automatically dothe roll/yaw coordination during turns. It also does the Dutch rolldamping function.




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MAIN FLIGHT CONTROL FUNCTIONS - LATERAL (ROLL + YAW) FUNCTION - NORMAL OPERATING MODE




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Main Flight Control Functions (continued)

Roll + Yaw Functions - Electrical Backup Operating ModeDuring the ELECTRICAL BACKUP OPERATING MODE, thePRIMary systems and the SEcondary Computers are inoperative.When the electrical backup system is activated, the two backup powersupply units energize the backup control module.For roll and yaw control the backup control module controls andmonitors:- the outer servocontrols of the inboard ailerons- the upper EBHA of both rudders-The backup control module receives orders from dedicated transducerslocated inside:- the side sticks for the roll function,- the pedal feel and trim unit (gives the rudder pedal positions) for theyaw function.The "outer" control loop is done by the yaw rate gyrometer installedinside the module. There is no dedicated roll rate gyrometer.Even if the backup control module controls few surfaces, it still doesthe Dutch roll damping function.




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MAIN FLIGHT CONTROL FUNCTIONS - ROLL + YAW FUNCTIONS - ELECTRICAL BACKUP OPERATING MODE




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Pitch Function - Normal Operating ModeDuring the NORMAL OPERATING MODE, for the pitch functioncomputation, in manual mode, the PRIMary systems and theSEcondary Computers receive orders from:- the side sticks,- the pitch trim control switches.The pitch trim control switches are only used by the pilots in theMANUAL MODE, when the AUTOTRIM function done by thecomputers is lost.Only the PRIMs receive autopilot order from the FG.To fulfil the "outer" control (aircraft response) loop, the PRIMs andthe SECs receive data from:- the Air Data and Inertial Reference System (ADIRS) and,- the accelerometers and rate gyrometer units.For the pitch function, the surfaces involved are:- the elevators for short term actions,- the Trimmable Horizontal Stabilizer (THS) for long term actions.




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MAIN FLIGHT CONTROL FUNCTIONS - PITCH FUNCTION - NORMAL OPERATING MODE




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Pitch Function - Electrical Backup Operating ModeThe electrical backup system is activated during the ELECTRICALBACKUP OPERATING MODE, as for the roll and yaw functions.This module controls and fulfills the "inner" control loops of:- the outer servocontrols of each inner elevator,- the motor 2 (yellow) of the THSA.The backup control module receives orders from dedicated transducerslocated inside:- the side sticks,- the pitch trim control switches.The "outer" control loop is done through the pitch rate gyrometerinstalled inside the module.




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MAIN FLIGHT CONTROL FUNCTIONS - PITCH FUNCTION - ELECTRICAL BACKUP OPERATING MODE




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Auxiliary Flight Control Functions

Auxiliary flight control functions are as follows;- speedbrake function, uses the spoilers to slow the aircraft in flight.- lift dumping function, uses the spoilers and ailerons to slow the aircraftand reduce the lift provided by the wings on aircraft touchdown.- aileron droop function, lowers the ailerons to increase the lift providedby the wings on aircraft approach.- Load Alleviation Function (LAF) uses the ailerons and some spoilersto reduce wing fatigue and bending moments.The auxiliary flight control functions are computed by the PRIMs only.

Speedbrake FunctionThe objective of the speedbrake function is to decrease the aircraftspeed with an acceptable buffet for the passenger comfort.The pilots control the deflection and retraction of the spoilers throughthe speedbrake/ground spoiler lever.The spoiler deflection depends on the lever position.Spoiler extension or retraction is automatically compensated in thepitch axis by the other laws.A roll order has priority over the speedbrake function.




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AUXILIARY FLIGHT CONTROL FUNCTIONS - SPEEDBRAKE FUNCTION




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Auxiliary Flight Control Functions (continued)

Lift DumpingAs soon as the aircraft touches down, the lift dumping function (alsocalled ground spoiler function):- slows the aircraft.,- reduces the lift caused by the wings to stick the aircraft to the ground,and reduces aircraft bounce risks.All of the ailerons and spoilers are usedThe PRIMary systems receive data from:- the speedbrake/ground spoiler lever,- the wing and body landing gears,- the Throttle Control Assembly (TCA),- the Radio Altimeters (RAs),The speedbrake/ground spoiler lever gives the "armed position" ofthe lever.The wing and body landing gears give the speed wheels and, theinformation "landing gears compressed".The TCA gives the position of the engine throttle levers.The RAs gives the aircraft height.When all the logic conditions are fulfilled, the PRIMary systemscompute the deployment orders of the surfaces.All the spoilers (1 to 8) and all ailerons are involved in the lift dumpingfunction.PHASED LIFT DUMPINGThe phased lift dumping function activates during uneven aircrafttouchdown.All of the spoilers and ailerons will partially deploy upon touchdownof one main landing gear to help the complete touchdown of theaircraft. Once all of the main gears have touched down full liftdumping will occur




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AUXILIARY FLIGHT CONTROL FUNCTIONS - LIFT DUMPING




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Aileron Droop FunctionThe objective of the aileron droop function is to help the "high lift"function done by the slats and flaps during the approach.The Slat Flap Control Computers (SFCCs) send "flaps out" signal tothe PRIMs to lower (droop) all of the ailerons.All the ailerons droop downwards to increase the curve of the wing.Note that the ailerons continue to do the roll function.




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AUXILIARY FLIGHT CONTROL FUNCTIONS - AILERON DROOP FUNCTION




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Load Alleviation Function (LAF)The objective of the Load Alleviation Function (LAF) is to reducethe structural fatigue and the static loads on the wing.This function is automatically activated in flight above specific speedmeasured by the ADIRS, and vertical acceleration thresholds measuredby the vertical accelerometer units to reduce the wing bending moment.The LAF is in addition to the NORMAL flight control laws.The spoilers 6 to 8 and all the ailerons are involved in the LoadAlleviation Function.




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AUXILIARY FLIGHT CONTROL FUNCTIONS - LOAD ALLEVIATION FUNCTION (LAF)




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SECONDARY FLIGHT CONTROLS PRESENTATION

General

The main functions of the SECONDARY flight controls give to theaircraft:- Sufficient "high lift" and low drag at take off,- minimum drag during the cruise phase,- Sufficient "high lift" and drag at landing.For that, the surfaces involved are:- 4 droop noses,- 12 slats,- 6 flaps,- and the ailerons for the increase of the high lift function (aileron droopfunction).The orders are sent to the SECONDARY FLIGHT CONTROLCOMPUTERS. The orders are converted into surface positions and sentto the surfaces for deflection.The computers monitor the position of the surfaces and check that thesurfaces have reached their correct positions.The aileron droop function helps the flaps and slats.


SECONDARY FLIGHT CONTROLS PRESENTATION Mar 15, 2006Page 50


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GENERAL




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Secondary Flight Control Laws And Operation

The computers controlling the slats and flaps are called Slat Flap ControlComputers (SFCC). There are two SFCCs installed on the aircraft.Each computer has two channels (a slat channel, and a flap channel).These two channels are in the same Line Replaceable Unit (LRU) butare functionally segregated operating on different power supplies. Thechannels can communicate each other.The SFCCs receive a pilot orders from the slat/flap control lever locatedon the center pedestal in the cockpit.The crew can select 5 positions ("0" position means surfaces fullyretracted, to "Full" position means surfaces fully extended).The positions of the slats and the flaps are displayed on the two PrimaryFlight Displays (PFDs).

LawsThere are two types of command:- manual command and,- automatic command.A manual command on the slat/flap control lever position correspondsto a position of the slats and flaps.But, the SFCCs can automatically modify the position of the slats andflaps for flight safety reasons.The five automatic command laws are:- the slat alpha lock protection function,- the slat baulk protection function,- the flap load relief protection function,- the flap auto command protection function and,- the slat/flap cruise baulk protection function,The slat alpha lock protection function prevents retraction of the slatsat high angle of attack of the aircraft.The slat baulk protection function prevents retraction at low aircraftairspeed.

The flap load relief protection function commands a flap retractionto the next lower position if the airspeed exceeds the maximum speednecessary for the currently selected configuration. When the airspeeddrops below this maximum speed, the flaps are automatically restoredto their initial positions.The flap auto command protection function hass two alternative flapsettings depending on the airspeed when the slat/flap control lever isin the position 1.The slat/flap cruise baulk protection function retains all the surfacesin their fully retracted position if the crew accidentally moves theslat/flap control lever to the 1 position during the cruise phase.




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SECONDARY FLIGHT CONTROL LAWS AND OPERATION - LAWS




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Architecture

This topic shows the architecture of the SECONDARY flight controlsmain components and their descriptions.The slat numbering is such as that slat 1 is made of the INBD and theOUTBD droop noses, and the other slats are numbered from 2 to 7.

Power Control Units (PCU)

There are two Power Control Units (PCUs) installed on the aircraft forthe drive of the slat and flap transmission systems.A PCU is composed of two drive units and a differential gearbox. Duringa normal operation, both drive units in each PCU are active. If one driveunit fails the PCU is able to move the surfaces by using only one driveunit with full torque but at half speed.For the control of drive units, each is linked to the two SFCCs.

Slat PCUThe slat PCU has one hydraulic drive unit and one electrical driveunit.The hydraulic unit is composed of a hydraulic motor and aPressure-Off Brake (POB). The green hydraulic pressure powers thehydraulic motor and the POB.The electrical unit has an electrical motor, an electronic motorcontroler, and a POB.The POBs are pressure-off type. When the motor is powered(hydraulically or electrically), the POB is actuated and unlocks thetransmission.Without supply, the POB is applied, and then, locks the transmission.

Flap PCUThe flap PCU has two hydraulic drive units.The green hydraulic pressure supplies one hydraulic unit and theyellow hydraulic pressure supplies the other one.

Position Pick-off Units (PPU)

Two Feedback Position pick-off units (FPPUs) are installed on the PCUs.One is installed on the slat PCU while the other one is installed on theflap PCU. Each FPPU is linked to the two SFCCs, they provide positionaldata for system control and monitoring.Four Asymmetry Position Pick-off Units (APPUs) are installed at eachend of the transmission systems:- two for the slat transmission system, and,- two for the flap transmission system.Each APPU is linked to the two SFCCs; the two SFCCs are used asmonitoring by sending data of the transmission system position.The positional data sent by the two APPUs and the FPPU (belonging tothe same system) are permanently compared in the SFCCs for failuredetection. For example, an asymmetry of one transmission system.

Flap Interconnection Struts

There are four flap interconnection struts. They are installed between theinboard and the middle flaps, and between the middle and the outboardflaps.Each flap interconnection strut has sensors. These sensors are connectedto the SFCCs, and give a warning against a flap misalignment.When the normal relative movement between the flaps is exceeded (amisalignment for example), the sensors send a signal to the SFCCsto shutdown the PCU flap.

Wing Tip Brakes (WTB)

There are four Wing Tip Brakes. Two are installed at each end of the slattransmission system, and two at the end of the flap transmission system.Each WTB is connected to the two SFCCs. They make sure that thesystems are locked in their current position in case of critical failures (an




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asymmetry detected by the slat APPUs for example due to a rupture ofone transmission system).The WTBs are of pressure-off type; the slat WTBs are electrically releasedand the flap WTBs are hydraulically released.




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FLIGHT CONTROLS SYSTEM MAINTENANCE (1)

Flight Control Safety Items

When you work on the flight control system, make sure that you obeyall the AMM safety precautions. This will prevent injury to persons and/ordamage to the aircraft. Here is an overview of main safety precautionsrelative to the flight control system.When you are working near or on the flight controls, you have to beaware that the flight control surfaces can move.Before any maintenance operations, make sure that all the safety devicesand all the warning notices are in position.Before any maintenance operations, due to the fact that either hydraulicor electrical power supplies the servocontrols , make sure that all thepower supplies related to the flight controls are off.Due to the A380 dimensions, all flight control surfaces are very high.For example, the top of the vertical tail plane is at around 24 meters highand, the Trimmable Horizontal Stabilizer (THS) is at around 9 metershigh.Thus, for safety reasons, any people who need to work on flight controlsurfaces must use a harness connected to the dedicated attachment points.Related also to the aircraft dimensions, the servocontrols are now biggerand heavier.For example, each rudder Electrical Backup Hydraulic Actuator (EBHA)weighs around 100 kg and the top EBHA of the upper rudder is at around20 meters high.By consequence, the servocontrol removal/installation tasks requirespecific tooling.


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FLIGHT CONTROLS SYSTEM MAINTENANCE (1)

Flight Control Ground Support Equipment

The flight control maintenance tasks need some Ground SupportEquipment (GSE).As an example, a GSE used for flight control maintenance is the EBHAremoval/installation tool.This tool is used to hold an EBHA during the removal and the installationtasks. A rudder EBHA weights approximately 100kg (220lbs)Refer to the Aircraft Maintenance Manual (AMM) for the tasks.Also, refer to the illustrated Tool and Equipment Manual (TEM) for thecomplete list of tools.




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a380-level i - ata 27 flight controls

Documents

flight controlsthis

allthe flight phases

retrieval system

indicatingthe control

training purposes onlyunder

controlthe aircraft

high lift function

speedbrake function