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 reserved
No 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.
A380 TECHNICAL TRAINING MANUAL
LEVEL I - ATA 27 FLIGHT CONTROLS
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Flight Controls System Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 2
"Fly by wire" Philosophy Presentation . . . . . . . . . . . . . . . . . . . . . . . 10
Primary Flight Controls Presentation . . . . . . . . . . . . . . . . . . . . . . . . 24
Secondary Flight Controls Presentation . . . . . . . . . . . . . . . . . . . . . . 50
Flight Controls System Maintenance (1) . . . . . . . . . . . . . . . . . . . . . . 58
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
TABLE OF CONTENTS
Mar 21, 2006
Page 1
A380 TECHNICAL TRAINING MANUAL
FLIGHT CONTROLS SYSTEM INTRODUCTION
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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
FLIGHT CONTROLS SYSTEM INTRODUCTION
Mar 15, 2006
Page 2
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A380 TECHNICAL TRAINING MANUAL
GENERAL
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
FLIGHT CONTROLS SYSTEM INTRODUCTION
Mar 15, 2006
Page 3
A380 TECHNICAL TRAINING MANUAL
FLIGHT CONTROLS SYSTEM INTRODUCTION
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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
FLIGHT CONTROLS SYSTEM INTRODUCTION
Mar 15, 2006
Page 4
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A380 TECHNICAL TRAINING MANUAL
GENERAL ARCHITECTURE OF THE FLIGHT CONTROL SYSTEM - FLIGHT CONTROL SURFACES
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
FLIGHT CONTROLS SYSTEM INTRODUCTION
Mar 15, 2006
Page 5
A380 TECHNICAL TRAINING MANUAL
FLIGHT CONTROLS SYSTEM INTRODUCTION
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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
FLIGHT CONTROLS SYSTEM INTRODUCTION
Mar 15, 2006
Page 6
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A380 TECHNICAL TRAINING MANUAL
GENERAL ARCHITECTURE OF THE FLIGHT CONTROL SYSTEM - CONTROL AND INDICATING
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
FLIGHT CONTROLS SYSTEM INTRODUCTION
Mar 15, 2006
Page 7
A380 TECHNICAL TRAINING MANUAL
FLIGHT CONTROLS SYSTEM INTRODUCTION
"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).
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
FLIGHT CONTROLS SYSTEM INTRODUCTION
Mar 15, 2006
Page 8
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A380 TECHNICAL TRAINING MANUAL
"FLY BY WIRE" PHILOSOPHY
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
FLIGHT CONTROLS SYSTEM INTRODUCTION
Mar 15, 2006
Page 9
A380 TECHNICAL TRAINING MANUAL
"FLY BY WIRE" PHILOSOPHY PRESENTATION
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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
Page 10
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A380 TECHNICAL TRAINING MANUAL
GENERAL
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
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A380 TECHNICAL TRAINING MANUAL
"FLY BY WIRE" PHILOSOPHY PRESENTATION
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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
Page 12
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A380 TECHNICAL TRAINING MANUAL
COMPUTATION PHILOSOPHY - COMPUTER FUNCTIONS & COMPUTER MASTER/SLAVE CONFIGURATION
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
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A380 TECHNICAL TRAINING MANUAL
"FLY BY WIRE" PHILOSOPHY PRESENTATION
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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
Page 14
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A380 TECHNICAL TRAINING MANUAL
FLIGHT CONTROL LAWS - LAW RECONFIGURATION + LAW IMPLEMENTATION
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
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"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
Page 15
A380 TECHNICAL TRAINING MANUAL
"FLY BY WIRE" PHILOSOPHY PRESENTATION
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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
Page 16
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A380 TECHNICAL TRAINING MANUAL
SYSTEM AND LAW ENGAGEMENT LOGIC - RULE 1: LAW ENGAGEMENT PRIORITY ORDER & RULE 2: SYSTEM ENGAGEMENT
PRIORITY ORDER
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
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"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
Page 17
A380 TECHNICAL TRAINING MANUAL
"FLY BY WIRE" PHILOSOPHY PRESENTATION
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".
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
Page 18
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A380 TECHNICAL TRAINING MANUAL
SYSTEM AND LAW ENGAGEMENT LOGIC - RULE 1 + RULE 2: NORMAL + ALTERNATE MODES
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
Page 19
A380 TECHNICAL TRAINING MANUAL
"FLY BY WIRE" PHILOSOPHY PRESENTATION
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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
Page 20
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A380 TECHNICAL TRAINING MANUAL
SYSTEM AND LAW ENGAGEMENT LOGIC - DIRECT MODE
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
Page 21
A380 TECHNICAL TRAINING MANUAL
"FLY BY WIRE" PHILOSOPHY PRESENTATION
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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
Page 22
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A380 TECHNICAL TRAINING MANUAL
NEW FLIGHT CONTROL SERVOCONTROLS - CONVENTIONAL SERVOCONTROL ... ELECTRICAL BACKUP HYDRAULIC ACTUATOR
(EBHA)
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"FLY BY WIRE" PHILOSOPHY PRESENTATION
Mar 15, 2006
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A380 TECHNICAL TRAINING MANUAL
PRIMARY FLIGHT CONTROLS PRESENTATION
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).
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
Page 24
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A380 TECHNICAL TRAINING MANUAL
GENERAL
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
Page 25
A380 TECHNICAL TRAINING MANUAL
PRIMARY FLIGHT CONTROLS PRESENTATION
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.
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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).
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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A380 TECHNICAL TRAINING MANUAL
ARCHITECTURE - NORMAL OPERATING MODE & MONITORING MODE
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
Page 27
A380 TECHNICAL TRAINING MANUAL
PRIMARY FLIGHT CONTROLS PRESENTATION
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
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
Page 28
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A380 TECHNICAL TRAINING MANUAL
ARCHITECTURE - ELECTRICAL BACKUP OPERATING MODE
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PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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A380 TECHNICAL TRAINING MANUAL
PRIMARY FLIGHT CONTROLS PRESENTATION
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.
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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
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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
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LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
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TYPE, LOCATION AND OPERATION OF THE SERVOCONTROLS - AILERONS ... SPOILERS
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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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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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
PRIMARY FLIGHT CONTROLS PRESENTATION
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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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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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
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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A380 TECHNICAL TRAINING MANUAL
MAIN FLIGHT CONTROL FUNCTIONS - PITCH FUNCTION - NORMAL OPERATING MODE
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
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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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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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
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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PRIMARY FLIGHT CONTROLS PRESENTATION
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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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A380 TECHNICAL TRAINING MANUAL
AUXILIARY FLIGHT CONTROL FUNCTIONS - SPEEDBRAKE FUNCTION
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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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
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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AUXILIARY FLIGHT CONTROL FUNCTIONS - LIFT DUMPING
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
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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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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AUXILIARY FLIGHT CONTROL FUNCTIONS - AILERON DROOP FUNCTION
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
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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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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AUXILIARY FLIGHT CONTROL FUNCTIONS - LOAD ALLEVIATION FUNCTION (LAF)
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
PRIMARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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SECONDARY FLIGHT CONTROLS PRESENTATION
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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
SECONDARY FLIGHT CONTROLS PRESENTATION
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GENERAL
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LEVEL I - ATA 27 Flight Controls
SECONDARY FLIGHT CONTROLS PRESENTATION
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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
SECONDARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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A380 TECHNICAL TRAINING MANUAL
SECONDARY FLIGHT CONTROL LAWS AND OPERATION - LAWS
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LEVEL I - ATA 27 Flight Controls
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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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
SECONDARY FLIGHT CONTROLS PRESENTATION
Mar 15, 2006
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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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
FLIGHT CONTROLS SYSTEM MAINTENANCE (1)
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FLIGHT CONTROL SAFETY ITEMS
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LEVEL I - ATA 27 Flight Controls
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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.
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
FLIGHT CONTROLS SYSTEM MAINTENANCE (1)
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FLIGHT CONTROL GROUND SUPPORT EQUIPMENT
MAINTENANCE COURSE - T1 & T2 (RR / Metric)
LEVEL I - ATA 27 Flight Controls
FLIGHT CONTROLS SYSTEM MAINTENANCE (1)
Mar 15, 2006
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AIRBUS S.A.S.
31707 BLAGNAC cedex, FRANCE
STM
REFERENCE L0Y06082
MARCH 2006
PRINTED IN FRANCE
AIRBUS S.A.S. 2006
ALL RIGHTS RESERVED
AN EADS JOINT COMPANY
WITH BAE SYSTEMS