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.

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A380 TECHNICAL TRAINING MANUAL

LEVEL I - ATA 27 FLIGHT CONTROLS

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Flight Controls System Introduction (1) . . . . . . . . . . . . . . . . . . . . . . . 2 "Fly by wire" Philosophy Presentation (1) . . . . . . . . . . . . . . . . . . . . . 10 Primary Flight Controls Presentation (1) . . . . . . . . . . . . . . . . . . . . . . 24 Secondary Flight Controls Presentation (1) . . . . . . . . . . . . . . . . . . . . 50 Flight Controls System Maintenance (1) . . . . . . . . . . . . . . . . . . . . . . 58

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

TABLE OF CONTENTS

Apr 21, 2006 Page 1


FLIGHT CONTROLS SYSTEM INTRODUCTION (1) General

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The flight control system is used for the control of the aircraft during all the flight phases. Firstly, the general architecture of the flight control system will be presented. 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 (1)

Apr 18, 2006 Page 2

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


Apr 18, 2006 Page 3


FLIGHT CONTROLS SYSTEM INTRODUCTION (1) 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 three axes (roll, pitch, and yaw), and to provide other functions such as for example, 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.

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Flight Control Surfaces The flight control surfaces can be divided into two categories. The first one is the PRIMARY flight control surfaces, which control the aircraft according to the three axes (roll, pitch, yaw) and do the auxiliary functions. The second one is the SECONDARY flight control surfaces, which make 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.



Apr 18, 2006 Page 4

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GENERAL ARCHITECTURE OF THE FLIGHT CONTROL SYSTEM - FLIGHT CONTROL SURFACES MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 5


FLIGHT CONTROLS SYSTEM INTRODUCTION (1) General Architecture of The Flight Control System (continued)

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Control and Indicating The 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 control computers. One side stick is installed on the CAPT lateral console, the other one is installed on the F/O lateral console. The 2 pairs of rudder pedals are installed in front of the CAPT and the 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 control computers located on the left-hand side and the right-hand side of the overhead 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 CAPT seat 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.



Apr 18, 2006 Page 6

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GENERAL ARCHITECTURE OF THE FLIGHT CONTROL SYSTEM - CONTROL AND INDICATING MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 7


FLIGHT CONTROLS SYSTEM INTRODUCTION (1) "Fly By Wire" Philosophy

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This topic shows the "fly by wire" philosophy. As on the previous Airbus aircraft programs, the flight control system of the 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 to achieve the aircraft objective. Then, the computers monitor the position feedback of the surfaces. The computers also receive an aircraft response and compare it to the demand (coming from the orders).



Apr 18, 2006 Page 8

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"FLY BY WIRE" PHILOSOPHY MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 9


"FLY BY WIRE" PHILOSOPHY PRESENTATION (1) General

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


"FLY BY WIRE" PHILOSOPHY PRESENTATION (1)

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"FLY BY WIRE" PHILOSOPHY PRESENTATION (1) Computation Philosophy This topic shows the flight control laws and the functions done inside the flight control computers to compute the surface deflection orders.

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

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Computer Master/Slave Configuration Only one PRIM at a time is the "MASTER". The COMPUTATION function of the "MASTER" receives the orders from the pilot in manual mode or, from the Flight Guidance (FG) in autopilot mode. The "MASTER" PRIM generates the surface deflection orders and sends them to the two other PRIMary systems and to the three SEcondary Computers. Each PRIM, and each SEC signal their associated surfaces and do the "inner" control loop in their EXECUTION function. Each PRIM and each SEC have control over a particular flight control servo, for example: - PRIM2 commands the green system actuator on the left hand outboard 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.



Apr 18, 2006 Page 12

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COMPUTATION PHILOSOPHY - COMPUTER FUNCTIONS & COMPUTER MASTER/SLAVE CONFIGURATION MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 13


"FLY BY WIRE" PHILOSOPHY PRESENTATION (1) Flight Control Laws The flight control computers according flight control laws process surface deflection 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.

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Law Reconfiguration + Law Implementation Depending on the status of the PRIMARY flight control computers (PRIMs and SECs), and depending on the status of the other systems and sensors, the flight control computers can engage three different levels 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 NORMAL to ALTERNATE and then to DIRECT according to the nature and the number of failures. The NORMAL, the ALTERNATE, and the DIRECT flight control laws are implemented in the three PRIMary systems, while only the DIRECT flight control law is implemented in the three SEcondary Computers.



Apr 18, 2006 Page 14

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FLIGHT CONTROL LAWS - LAW RECONFIGURATION + LAW IMPLEMENTATION MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 15


"FLY BY WIRE" PHILOSOPHY PRESENTATION (1) 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 Order This rule is as follows: The priority order number one is the NORMAL law, the number two is the ALTERNATE law, and finally, the priority number three is the DIRECT law.

Rule 2: System Engagement Priority Order

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


Apr 18, 2006 Page 17


"FLY BY WIRE" PHILOSOPHY PRESENTATION (1) System and Law Engagement Logic (continued) Rule 1 + Rule 2: Normal + Alternate Modes

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According to these two rules, the PRIM that can engage the highest level of law, and becomes the "MASTER".



Apr 18, 2006 Page 18

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SYSTEM AND LAW ENGAGEMENT LOGIC - RULE 1 + RULE 2: NORMAL + ALTERNATE MODES MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 19


"FLY BY WIRE" PHILOSOPHY PRESENTATION (1) System and Law Engagement Logic (continued) Direct Mode

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



Apr 18, 2006 Page 20

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SYSTEM AND LAW ENGAGEMENT LOGIC - DIRECT MODE MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 21


"FLY BY WIRE" PHILOSOPHY PRESENTATION (1) 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 Servocontrol The conventional servocontrols can also be called electro-hydraulic servocontrols. 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 aircraft structure, and a rod attached to the surface, - a servovalve receiving orders from the flight control computers, which ports hydraulic pressure to translate the rod.

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

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Electro Hydrostatic Actuator (EHA) Electro-hydrostatic actuators (EHAs) are actuators which produce their own hydraulic pressure and can be used when the normal aircraft hydraulic 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 the flight control computers. The direction of rotation of the electro-hydraulic generation system determines the direction of translation of the actuator rod. The speed of the system determines speed of translation of the actuator rod.



Apr 18, 2006 Page 22

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NEW FLIGHT CONTROL SERVOCONTROLS - CONVENTIONAL SERVOCONTROL ... ELECTRICAL BACKUP HYDRAULIC ACTUATOR (EBHA) MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 23


PRIMARY FLIGHT CONTROLS PRESENTATION (1) General

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This module shows the general architecture of the PRIMARY flight controls, and the functions done inside the flight control computers. It shows the links between the CONTROL block, the COMPUTATION block, the ACTUATION block, and the INDICATING block. The CONTROL block is mainly composed of pilot inputs located in the cockpit (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 control module and, - one Flight Control Data Concentrator (FCDC) hosted into each CPIOM-C1 and CPIOM-C2. Each PRIM and each SEC communicate with the two FCDCs. The ACTUATION block is mainly composed of flight control surfaces and their servocontrols. The INDICATING block is mainly composed of the two Primary Flight Displays (PFDs), the Secondary Display (SD) and the Engine Warning Display (EWD).


PRIMARY FLIGHT CONTROLS PRESENTATION (1)

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PRIMARY FLIGHT CONTROLS PRESENTATION (1) 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).

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Normal Operating Mode The main computers of the flight control system are the three PRIMary systems (PRIMs), and the three SECondary Computers (SECs). A PRIMary system (PRIM) is composed of two Flight Control and Guidance Units (FCGUs). For example: the PRIM 1 is composed of the FCGU 1A and the FCGU 1B. A FCGU includes a flight control and a Flight Guidance (FG), which is a part of the Automatic Flight System (AFS). The PRIMs and the SECs receive pilot orders from various transducers located inside: - the side sticks, used for the lateral (roll plus yaw) and pitch in manual mode, - the rudder pedals, used for the control of rudders, - the pitch trim control switches, used to control the Trimmable Horizontal Stabilizer (THS) in manual mode. The speedbrake/ground spoiler lever is only linked to the PRIMs. This lever is used for the speedbrake function and the ground spoiler function. The rudder trim control panel is only linked to the SECs. The pilots manually used this panel to trim the rudders. - the rudders.


Monitoring Mode During the NORMAL OPERATING MODE, the two Flight Control Data Concentrators (FCDCs) receive data from each PRIM, and each SEC. The FCDCs fulfill the following functions: - data concentration for display (they send data to the Control and Display System (CDS): mainly to the PFDs, EWD and, SD for the F/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 MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 27


PRIMARY FLIGHT CONTROLS PRESENTATION (1) Architecture (continued)

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Electrical Backup Operating Mode In case of loss of the three PRIMary and the three SEcondary Computers, 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 rudders The 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 generator supplied by one hydraulic system to power the backup control module. One backup power supply unit uses the green hydraulic circuit pressure while the other one uses the yellow hydraulic circuit pressure. The backup control module is an analogical flight controller; it receives pilot orders, computes the control laws, and sends deflection orders to the flight control surfaces. The backup control module uses dedicated rate gyros installed inside the module to fulfill aircraft response monitoring (outer loop). The module also monitors flights control surface response (inner loop). The backup control module receives pilot orders from dedicated transducers 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 Flight Control Data Concentrators (FCDCs) which are used for the display of the flight controls in the cockpit. MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 28

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ARCHITECTURE - ELECTRICAL BACKUP OPERATING MODE MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 29


PRIMARY FLIGHT CONTROLS PRESENTATION (1) Type, Location And Operation Of The Servocontrols

Rudders

This topic shows on which surfaces are installed the servocontrols, their numbers 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 two servocontrols. 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, the Electro-Hydrostatic Actuators (EHAs), the Electrical Backup Hydraulic Actuators (EBHAs), and the THSA. The power supplies used by the servocontrols and the THSA are the two hydraulic circuits (the green and the yellow), and three different electrical circuits.

Two rudders (upper and lower) control the aircraft about the yaw axis. The two rudders are used for the yaw function, and roll/yaw coordination during turns and auxiliary functions. Two Electrical Backup Hydraulic Actuators (EBHAs) drive each rudder (one upper and one lower). During normal operation, the upper EBHAs of upper and lower rudders operate in HYDRAULIC ACTIVE MODE, the lower actuators of each rudder operate in DAMPING MODE. Nevertheless, both EBHAs of each rudder can be activated simultaneously, in case of high rates or large deflection demands. After a failure of the active EBHA, the EBHA switches to DAMPING MODE, and, the adjacent EBHA switches to HYDRAULIC ACTIVE MODE. The only time when the EBHA operates in the ELECTRICAL ACTIVE MODE is when the HYDRAULIC ACTIVE MODE cannot be engaged.

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Ailerons The ailerons control the aircraft about the roll axis. They are used for the roll function plus the auxiliary functions. Three ailerons are attached onto each wing; the outboard ailerons are driven 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 each aileron operates in ACTIVE MODE, the other servocontrol operates in DAMPING MODE. After a failure occurs, the conventional servocontrol becomes in DAMPING MODE, and so, the other one becomes in ACTIVE MODE.


Elevators The elevators (with the THS) control the aircraft in the pitch axis. They are used for short-term actions. There are two elevators attached onto each side of the Trimmable Horizontal Stabilizer (THS). Each elevator is driven by one conventional servocontrol and one EHA. During normal operation, the elevator operation is as an aileron operation. During normal operation the conventional servocontrol operates in ACTIVE MODE, and the EHA operates in DAMPING MODE. After a failure of the conventional servocontrol, this one switches to DAMPING MODE and the EHA switches to ACTIVE MODE. Nevertheless, in case of high rate or deflection demands, both servocontrols of the same elevator can be activated simultaneously. PRIMARY FLIGHT CONTROLS PRESENTATION (1)

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A380 TECHNICAL TRAINING MANUAL Trimmable Horizontal Stabilizer (THS) The Trimmable Horizontal Stabilizer (THS) controls the aircraft about the pitch axis. The THS is only used for long-term actions. Three motors, two hydraulics, and one electrical actuate the THS through a gearbox. In normal operation, the green hydraulic motor is active, the yellow hydraulic is in standby, and the electrical motor is not electrically supplied. Both hydraulic motors can be simultaneously activated when a high rate is necessary. In case of failures of the hydraulic motors, the electrical motor is activated but it can be only used in AUTOMATIC MODE. When the AUTOMATIC MODE is available, this mode has the priority over the MANUAL MODE, and the pitch trim control switches are inhibited. If the AUTOMATIC MODE is lost, the pilots can control the THS via the pitch trim control switches, this mode is called MANUAL MODE.

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

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Spoilers The 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 spoilers are 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 the HYDRAULIC ACTIVE MODE. If a failure occurs, the spoiler operation is inhibited and the spoiler is lost and retracted to its zero position. For spoilers driven by an EBHA, during normal operation, the servocontrol operates in the HYDRAULIC ACTIVE MODE. In case of hydraulic failure, the EBHA switches to ELECTRICAL ACTIVE MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 31

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TYPE, LOCATION AND OPERATION OF THE SERVOCONTROLS - AILERONS ... SPOILERS MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


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PRIMARY FLIGHT CONTROLS PRESENTATION (1) Main Flight Control Functions This topic shows the main functions done inside the computers in NORMAL OPERATING MODE, and in addition in the ELECTRICAL BACKUP OPERATING MODE. This topic shows also the auxiliary functions.

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Lateral (Roll + Yaw) Function - Normal Operating Mode During the NORMAL OPERATING MODE, for the lateral function computation, in manual mode, the PRIMary systems and the SEcondary 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 trim control 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 SECs receive 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 do the roll/yaw coordination during turns. It also does the Dutch roll damping function.



Apr 18, 2006 Page 34

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MAIN FLIGHT CONTROL FUNCTIONS - LATERAL (ROLL + YAW) FUNCTION - NORMAL OPERATING MODE MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 35


PRIMARY FLIGHT CONTROLS PRESENTATION (1) Main Flight Control Functions (continued) Roll + Yaw Functions - Electrical Backup Operating Mode

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During the ELECTRICAL BACKUP OPERATING MODE, the PRIMary systems and the SEcondary Computers are inoperative. When the electrical backup system is activated, the two backup power supply units energize the backup control module. For roll and yaw control the backup control module controls and monitors: - the outer servocontrols of the inboard ailerons - the upper EBHA of both rudders The backup control module receives orders from dedicated transducers located inside: - the side sticks for the roll function, - the pedal feel and trim unit (gives the rudder pedal positions) for the yaw function. The "outer" control loop is done by the yaw rate gyrometer installed inside the module. There is no dedicated roll rate gyrometer. Even if the backup control module controls few surfaces, it still does the Dutch roll damping function.



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MAIN FLIGHT CONTROL FUNCTIONS - ROLL + YAW FUNCTIONS - ELECTRICAL BACKUP OPERATING MODE MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 37


PRIMARY FLIGHT CONTROLS PRESENTATION (1) Main Flight Control Functions (continued) Pitch Function - Normal Operating Mode

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During the NORMAL OPERATING MODE, for the pitch function computation, in manual mode, the PRIMary systems and the SEcondary Computers receive orders from: - the side sticks, - the pitch trim control switches. The pitch trim control switches are only used by the pilots in the MANUAL MODE, when the AUTOTRIM function done by the computers is lost. Only the PRIMs receive autopilot order from the FG. To fulfil the "outer" control (aircraft response) loop, the PRIMs and the 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.



Apr 18, 2006 Page 38

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MAIN FLIGHT CONTROL FUNCTIONS - PITCH FUNCTION - NORMAL OPERATING MODE MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 39


PRIMARY FLIGHT CONTROLS PRESENTATION (1) Main Flight Control Functions (continued) Pitch Function - Electrical Backup Operating Mode

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The electrical backup system is activated during the ELECTRICAL BACKUP 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 transducers located inside: - the side sticks, - the pitch trim control switches. The "outer" control loop is done through the pitch rate gyrometer installed inside the module.



Apr 18, 2006 Page 40

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MAIN FLIGHT CONTROL FUNCTIONS - PITCH FUNCTION - ELECTRICAL BACKUP OPERATING MODE MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 41


PRIMARY FLIGHT CONTROLS PRESENTATION (1) 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 aircraft and reduce the lift provided by the wings on aircraft touchdown. - aileron droop function, lowers the ailerons to increase the lift provided by the wings on aircraft approach. - Load Alleviation Function (LAF) uses the ailerons and some spoilers to reduce wing fatigue and bending moments. The auxiliary flight control functions are computed by the PRIMs only.

Speedbrake Function

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



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AUXILIARY FLIGHT CONTROL FUNCTIONS - SPEEDBRAKE FUNCTION MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


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PRIMARY FLIGHT CONTROLS PRESENTATION (1) Auxiliary Flight Control Functions (continued)

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Lift Dumping As soon as the aircraft touches down, the lift dumping function (also called 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 used The 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" of the lever. The wing and body landing gears give the speed wheels and, the information "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 systems compute the deployment orders of the surfaces. All the spoilers (1 to 8) and all ailerons are involved in the lift dumping function. PHASED LIFT DUMPING The phased lift dumping function activates during uneven aircraft touchdown. All of the spoilers and ailerons will partially deploy upon touchdown of one main landing gear to help the complete touchdown of the aircraft. Once all of the main gears have touched down full lift dumping will occur



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AUXILIARY FLIGHT CONTROL FUNCTIONS - LIFT DUMPING MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


Apr 18, 2006 Page 45


PRIMARY FLIGHT CONTROLS PRESENTATION (1) Auxiliary Flight Control Functions (continued) Aileron Droop Function

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


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PRIMARY FLIGHT CONTROLS PRESENTATION (1) Auxiliary Flight Control Functions (continued) Load Alleviation Function (LAF)

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The objective of the Load Alleviation Function (LAF) is to reduce the structural fatigue and the static loads on the wing. This function is automatically activated in flight above specific speed measured by the ADIRS, and vertical acceleration thresholds measured by 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 Load Alleviation Function.



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AUXILIARY FLIGHT CONTROL FUNCTIONS - LOAD ALLEVIATION FUNCTION (LAF) MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


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SECONDARY FLIGHT CONTROLS PRESENTATION (1) General

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The main functions of the SECONDARY flight controls give to the aircraft: - 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 droop function). The orders are sent to the SECONDARY FLIGHT CONTROL COMPUTERS. The orders are converted into surface positions and sent to the surfaces for deflection. The computers monitor the position of the surfaces and check that the surfaces have reached their correct positions. The aileron droop function helps the flaps and slats.


SECONDARY FLIGHT CONTROLS PRESENTATION (1)

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SECONDARY FLIGHT CONTROLS PRESENTATION (1) Secondary Flight Control Laws And Operation The computers controlling the slats and flaps are called Slat Flap Control Computers (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) but are functionally segregated operating on different power supplies. The channels can communicate each other. The SFCCs receive a pilot orders from the slat/flap control lever located on the center pedestal in the cockpit. The crew can select 5 positions ("0" position means surfaces fully retracted, to "Full" position means surfaces fully extended). The positions of the slats and the flaps are displayed on the two Primary Flight Displays (PFDs).

The flap load relief protection function commands a flap retraction to the next lower position if the airspeed exceeds the maximum speed necessary for the currently selected configuration. When the airspeed drops below this maximum speed, the flaps are automatically restored to their initial positions. The flap auto command protection function hass two alternative flap settings depending on the airspeed when the slat/flap control lever is in the position 1. The slat/flap cruise baulk protection function retains all the surfaces in their fully retracted position if the crew accidentally moves the slat/flap control lever to the 1 position during the cruise phase.

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Laws There are two types of command: - manual command and, - automatic command. A manual command on the slat/flap control lever position corresponds to a position of the slats and flaps. But, the SFCCs can automatically modify the position of the slats and flaps 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 slats at high angle of attack of the aircraft. The slat baulk protection function prevents retraction at low aircraft airspeed. MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


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SECONDARY FLIGHT CONTROL LAWS AND OPERATION - LAWS MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


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SECONDARY FLIGHT CONTROLS PRESENTATION (1) Architecture

Position Pick-off Units (PPU)

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

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 the flap PCU. Each FPPU is linked to the two SFCCs, they provide positional data for system control and monitoring. Four Asymmetry Position Pick-off Units (APPUs) are installed at each end 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 as monitoring by sending data of the transmission system position. The positional data sent by the two APPUs and the FPPU (belonging to the same system) are permanently compared in the SFCCs for failure detection. For example, an asymmetry of one transmission system.

Power Control Units (PCU)

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

Slat PCU

Flap Interconnection Struts

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

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

Flap PCU The flap PCU has two hydraulic drive units. The green hydraulic pressure supplies one hydraulic unit and the yellow hydraulic pressure supplies the other one. MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls

Wing Tip Brakes (WTB) There are four Wing Tip Brakes. Two are installed at each end of the slat transmission system, and two at the end of the flap transmission system. Each WTB is connected to the two SFCCs. They make sure that the systems 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 of one transmission system). The WTBs are of pressure-off type; the slat WTBs are electrically released and the flap WTBs are hydraulically released.



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ARCHITECTURE ... WING TIP BRAKES (WTB) MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


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FLIGHT CONTROLS SYSTEM MAINTENANCE (1)

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Flight Control Safety Items When you work on the flight control system, make sure that you obey all the AMM safety precautions. This will prevent injury to persons and/or damage to the aircraft. Here is an overview of main safety precautions relative to the flight control system. When you are working near or on the flight controls, you have to be aware that the flight control surfaces can move. Before any maintenance operations, make sure that all the safety devices and all the warning notices are in position. Before any maintenance operations, due to the fact that either hydraulic or electrical power supplies the servocontrols , make sure that all the power 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 high and, the Trimmable Horizontal Stabilizer (THS) is at around 9 meters high. Thus, for safety reasons, any people who need to work on flight control surfaces must use a harness connected to the dedicated attachment points. Related also to the aircraft dimensions, the servocontrols are now bigger and heavier. For example, each rudder Electrical Backup Hydraulic Actuator (EBHA) weighs around 100 kg and the top EBHA of the upper rudder is at around 20 meters high. By consequence, the servocontrol removal/installation tasks require specific tooling.



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


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FLIGHT CONTROLS SYSTEM MAINTENANCE (1) Flight Control Ground Support Equipment

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The flight control maintenance tasks need some Ground Support Equipment (GSE). As an example, a GSE used for flight control maintenance is the EBHA removal/installation tool. This tool is used to hold an EBHA during the removal and the installation tasks. 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 the complete list of tools.



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FLIGHT CONTROL GROUND SUPPORT EQUIPMENT MAINTENANCE COURSE - T1 & T2 (RR / Metric) LEVEL I - ATA 27 Flight Controls


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AIRBUS S.A.S. 31707 BLAGNAC cedex, FRANCE STM REFERENCE L1W06161 APRIL 2006 PRINTED IN FRANCE AIRBUS S.A.S. 2006 ALL RIGHTS RESERVED AN EADS JOINT COMPANY WITH BAE SYSTEMS

LEVEL I - ATA 27 Flight Controls

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