ELECTRICAL FLIGHT CONTROL SYSTEM (EFCS) - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General

EFCS General (A319) ** ON A/C NOT FOR ALL

EFCS General (A321) ** ON A/C NOT FOR ALL

EFCS General (A320) ** ON A/C NOT FOR ALL

The electrical flight control system (EFCS) is built around two types of digital computers :

2 ELACs (Elevator and Aileron Computers).
3 SECs (Spoiler and Elevator Computers).

These computers generate the surface deflection orders which correspond to the pilot orders and perform control of these surfaces through the electrically-controlled servocontrols.
These orders are monitored.
Another type of computer is provided :

2 FCDCs (Flight Control Data Concentrator)
They isolate the ELACs and the SECs from the other A/C systems and are used for maintenance tasks and data concentration.
The electrical flight control system (EFCS) performs several functions:
pitch control
lateral control
speedbrake function
ground spoiler function

The electrical flight control system uses the three A/C hydraulic systems.
In the event of complete loss of electrical supply:
Under these conditions, only the mechanical controls are available:

Rudder mechanical control from the pedals,
THS mechanical control from the trim control wheel.

** ON A/C NOT FOR ALL

2. Component Location

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C ALL
33CE1	SERVO CTL-L AILERON, INBD G	575AT	575	27-14-51
33CE2	SERVO CTL-R AILERON, INBD G	675AT	675	27-14-51
33CE3	SERVO CTL-L AILERON, OUTBD B	575KB	575	27-14-51
33CE4	SERVO CTL-R AILERON, OUTBD B	675KB	675	27-14-51
** ON A/C NOT FOR ALL
31CE1	SERVO CTL-SPLR1, L G	573BB	574	27-64-51
31CE2	SERVO CTL-SPLR1, R G	673BB	674	27-64-51
31CE3	SERVO CTL-SPLR2, L Y	575BB	582	27-64-51
31CE4	SERVO CTL-SPLR2, R Y	675BB	682	27-64-51
31CE5	SERVO CTL-SPLR3, L B	575DB	583	27-64-51
31CE6	SERVO CTL-SPLR3, R B	675DB	683	27-64-51
** ON A/C ALL
31CE7	SERVO CTL-SPLR4, L Y		584	27-64-51
31CE8	SERVO CTL-SPLR4, R Y		684	27-64-51
31CE9	SERVO CTL-SPLR5, L G		585	27-64-51
31CE10	SERVO CTL-SPLR5, R G		685	27-64-51
** ON A/C NOT FOR ALL
31CE1	SERVO CTL-SPLR1, L G		574	27-64-51
31CE2	SERVO CTL-SPLR1, R G		674	27-64-51
31CE3	SERVO CTL-SPLR2, L Y		582	27-64-51
31CE4	SERVO CTL-SPLR2, R Y		682	27-64-51
31CE5	SERVO CTL-SPLR3, L B		583	27-64-51
31CE6	SERVO CTL-SPLR3, R B		683	27-64-51
** ON A/C NOT FOR ALL
9CE	ACTUATOR-THS		311	27-44-51
** ON A/C NOT FOR ALL
9CE	ACTUATOR-THS	312AR	311	27-44-51
** ON A/C ALL
34CE1	SERVO CTL-L ELEVATOR, INBD G		335	27-34-51
34CE2	SERVO CTL-R ELEVATOR, INBD Y		345	27-34-51
34CE3	SERVO CTL-L ELEVATOR, OUTBD B		335	27-34-51
34CE4	SERVO CTL-R ELEVATOR, OUTBD B		345	27-34-51
2CE1	ELAC-1	83VU	127	27-93-34
2CE2	ELAC-2	84VU	128	27-93-34
3CE1	FCDC-1	83VU	127	27-95-34
3CE2	FCDC-2	84VU	128	27-95-34
3CE1	FCDC-1		127	27-95-34
3CE2	FCDC-2		128	27-95-34
3CE1	FCDC-1	83VU	127	27-95-34
3CE2	FCDC-2	84VU	128	27-95-34
1CE1	SEC-1	83VU	127	27-94-34
1CE2	SEC-2	84VU	128	27-94-34
1CC1	FAC-1	83VU	127	22-66-34
1CC2	FAC-2	84VU	128	22-66-34
** ON A/C NOT FOR ALL
4CE1	SSTU-ROLL CTL, CAPT	193VU	211	27-92-41
4CE2	SSTU-ROLL CTL, F/O	182VU	212	27-92-41
4CE3	SSTU-PITCH CTL, CAPT	193VU	211	27-92-41
4CE4	SSTU-PITCH CTL, F/O	182VU	212	27-92-41
** ON A/C ALL
7CE	XDCR UNIT-SPD BRK CTL	11VU	210	27-92-14
25CE1	XDCR UNIT-PEDAL POS, L		121	27-92-15
25CE2	XDCR UNIT-PEDAL POS, R		122	27-92-15
2CC	XDCR UNIT-YAW DAMPER POS	325BL	325	27-26-17
42WV	XDCR UNIT-RUDDER POS	325BL	325	27-25-17
12CE1	ACCLRM-1		131	27-92-16
12CE1	ACCLRM-1		131	27-92-16
12CE2	ACCLRM-2		132	27-92-16
12CE3	ACCLRM-3		131	27-92-16
12CE4	ACCLRM-4		132	27-92-16
10CE1	PRESS SW-B HYD, FLT CTL		195	27-92-17
10CE2	PRESS SW-G HYD, FLT CTL		145	27-92-17
10CE3	PRESS SW-Y HYD, FLT CTL		196	27-92-17
** ON A/C NOT FOR ALL
14CE1	PRESS XDCR-L Y LAF ACCU	575EB	500	27-92-19
14CE2	PRESS XDCR-R Y LAF ACCU	675EB	600	27-92-19
14CE3	PRESS XDCR-L G LAF ACCU	575GB	500	27-92-19
14CE4	PRESS XDCR-R G LAF ACCU	675GB	600	27-92-19
** ON A/C ALL
8KS1	CTL UNIT-THROTTLE, ENG 1	11VU	210	76-11-19
8KS2	CTL UNIT-THROTTLE, ENG 2	11VU	210	76-11-19
49CE1	XDCR UNIT-ELEV POS, L	344DB	345	27-92-13
49CE2	XDCR UNIT-ELEV POS, R	334DB	335	27-92-13
** ON A/C NOT FOR ALL
74CE	FTU-RUDDER PEDAL		121	27-92-27

** ON A/C NOT FOR ALL

3. System Description
The Electrical Flight Control System (EFCS) performs several functions :

EFCS Architecture

A. Flight Control Surfaces

EFCS Architecture

There is 1 aileron and 5 spoilers on each wing. The roll control is ensured by:

the 2 ailerons
the 4 outboard spoilers on each wing.
The spoilers 2, 3 and 4 of each wing ensure the speedbrake function.
All the spoilers ensure the ground spoiler function.
The pitch control is ensured by:
the 2 elevator control surfaces, each one actuated by 2 servocontrols.
1 trimmable horizontal stabilizer (THS) actuated by an electrohydraulic actuator.
The yaw control is ensured by the rudder which is actuated by 3 servocontrols mechanically controlled and simultaneously active.

** ON A/C NOT FOR ALL

4. Power Supply

A. Hydraulic Power Supply

Flight Control Hydraulic Power Supply

There are three independent hydraulic systems:

the Blue system pressurized by an electric pump.
the Green system pressurized by a pump driven by the left engine.
the Yellow system pressurized by a pump driven by the right engine.
On the ground, an electric pump can pressurize directly the Yellow system.
A reversible power transfer unit (PTU) can pressurize the Yellow or Green system from the other system.
A ram air turbine (RAT) can pressurize the Blue system in the event of an ultimate-emergency electrical supply.

B. Electrical Power Supply

(1) General
Schematic diagram

Electrical Power Supply (General)

Electrical Power Supply (EFCS) ** ON A/C NOT FOR ALL

The main power supply system has two generators. Each one is located on one engine . A third generator, of equivalent power and driven by the APU can be used on the ground or in flight to replace a main generator.
In normal configuration, each main generator supplies its side which has:

a three-phase 400 Hz 115VAC main busbar
a transformer rectifier unit (TRU)
a 28VDC main busbar.

The two sides are completely separated.
The AC and DC essential busbars are connected to the side 1.
If a main generator fails, an automatic switching facility enables the simultaneous supply of the two main AC busbars by the other main generator.
However, the TRUs keep the two DC sides isolated.
If a main TRU fails, the essential DC busbars are automatically isolated from the rest of the DC network and are supplied by the AC busbar 1XP through a third TRU.
The main DC busbars are simultaneously connected together and supplied through the remaining TRU.
If the AC busbar 2XP is failed, the sequence is the same.
If the AC busbar 1XP is failed, the DC and AC essential busbars will be connected to the side 2 after action of the crew.
In the event of a power supply loss on the two sides (standby power configuration) :

the RAT extension command is generated
the AC and DC essential busbars are immediately supplied by the batteries.
after 7s the AC and DC essential busbars are supplied by the standby generator.
The RAT extension can be manually controlled.

(2) Interface with the EFCS
The ELAC1 and the SEC1 are supplied from a DC essential busbar (4PP for the ELAC1 and SEC1), the battery 1 taking over instantaneously through a dedicated diode device (Power Supply Decoupling Unit) when the voltage level drops below the battery output voltage.

ELAC 1 and SEC 1 Power Supplies - Principle ** ON A/C NOT FOR ALL

A relay ensures the battery supply line breaking on the ground 30s after the second engine is shut down. (after the third hydraulic pressure drop down).
The ELAC2, and the THS motor 1 are normally supplied from a DC normal busbar 2PP.
In case of loss of this busbar (particularly after loss of both main generation channels, or after a double main TRU failure),these supplies are automatically switched over to the battery 2 by means of two relays, for a fixed period of 30s.

ELAC 2 Power Supply - Principle ** ON A/C NOT FOR ALL

These relays are automatically re-energized if later on the Blue hydraulic pressure to falls, and during the landing phase as soon as the nose landing gear is extended.
On each of these four supply lines must be added the solenoid valves associated with the computer and one of the four accelerometers, with the following distribution:

-------------------------------------

! COMPUTER ! ACCELEROMETER !

!---------------!-------------------!

! ELAC 1 ! 1 !

! SEC 1 ! 2 !

! ELAC 2 ! 3 !

! SEC 2 ! 4 !

-------------------------------------

The SEC 2, SEC 3, the THS electric motor 3, and the FCDC 2 are supplied from the DC normal busbar 2PP. The THS electric motor 2 is supplied from the DC essential busbar 4PP. The FCDC 1 is supplied from the DC essential busbar 8PP.

(3) Interface with the EFCS
The ELAC1 and the SEC1 are supplied from a DC essential busbar (4PP for the ELAC1 and SEC1), the battery 1 taking over instantaneously through a dedicated diode device (Power Supply Decoupling Unit) when the voltage level drops below the battery output voltage.

ELAC 1 and SEC 1 Power Supplies - Principle ** ON A/C NOT FOR ALL

ELAC 2 Power supply - Principle ** ON A/C NOT FOR ALL

-------------------------------------

! COMPUTER ! ACCELEROMETER !

!---------------!-------------------!

! ELAC 1 ! 2 !

! SEC 1 ! 1 !

! ELAC 2 ! 3 !

! SEC 2 ! 4 !

-------------------------------------

** ON A/C NOT FOR ALL

5. Functions Performed in Normal Configuration
This section briefly describes the functions of the electrical flight controls in normal mode, i.e without failures which cause law degradation.

A. Pitch Control

(1) General
The C* law is the fundamental mode of manual pitch control.
The law generates a load factor demand from the position of the side stick and the inertial feedbacks.
Protection against excessive load factor, Mach or speed or angle of attack pitch attitude are also provided.

(2) Pitch control law

Flight Control Laws ** ON A/C NOT FOR ALL

Three phases are considered:

flight,
flare,
ground.

These phases are determined by the computers and consolidated by the information below :

radioaltimeter altitude,
R and L L/G compressed signals from the LGCIUs,
Pitch attitude from the ADIRS,
wheel speed and spoiler activation from the SECs.

(a) Flight law

Flight Normal Law ** ON A/C NOT FOR ALL

The C* law is activated. It combines the elevator control and the THS controls (AUTOTRIM function).
It generates a load factor demand as a function of the position of the side sticks and inertial feedbacks.
The gains depend on the speed (Vc) and center of gravity.
The main characteristics of the C* law are:

load factor demand,
inclusion of the AUTOTRIM function,
compensation of the lateral attitude up to 33°,
A/C response independent from the speed, weight and center of gravity.
The maximum surface deflection controlled by the computers are:
Elevator deflection: +15, -30 deg
THS deflection: +3.5, -11 deg.

(b) Flare law

Flare Normal Law ** ON A/C NOT FOR ALL

This law generates a longitudinal attitude value as a function of the side stick demand, Nz feedbacks and pitch rate. The gains are function of the speed (Vc) and center of gravity.
The purpose of this law is to restore the behaviour of a conventional aircraft down to the ground.

ELACs "on" , 2 or 3 ADIRUs "on" and SECs "off".
* If Vc < 70 kts, the deflection is + 15, - 30°.
* If Vc > 70 kts, the deflection is + 15, - 20°.
ELACs "on" , ADIRUs "off" and SECs "off".
* Fixed Vc = 80 kts, the deflection is + 15, - 20°.
SECs "on" and ELACs "off", the deflection is + 15, - 30°.

(3) Pitch control law

Flight Control Laws ** ON A/C NOT FOR ALL

Three phases are considered:

flight,
flare,
ground.

These phases are determined by the computers and consolidated by the information below :

radioaltimeter altitude,
R and L L/G compressed signals from the LGCIUs,
Pitch attitude from the ADIRS,
wheel speed and spoiler activation from the SECs.

(a) Flight law

Flight Normal Law ** ON A/C NOT FOR ALL

load factor demand,
inclusion of the AUTOTRIM function,
compensation of the lateral attitude up to 33°,
A/C response independent from the speed, weight and center of gravity.
The maximum surface deflection controlled by the computers are:
Elevator deflection: +15, -30 deg
THS deflection: +3.5, -11 deg.

(b) Flare law

Flare Normal Law ** ON A/C NOT FOR ALL

ELACs "on" , 2 or 3 ADIRUs "on" and SECs "off".
* If Vc < 70 kts, the deflection is + 15, - 30°.
* If Vc > 70 kts, the deflection is + 15, - 20°.
ELACs "on" , ADIRUs "off" and SECs "off".
* Fixed Vc = 80 kts, the deflection is + 15, - 20°.
SECs "on" and ELACs "off", the deflection is + 15, - 30°.

(d) Pitch rate law at rotation (theta°)
To limit the pitch rate for take-off in order to avoid tail strike in normal operation, a positive (nose-down) demand reduces the direct law order.
This demand is function of the pitch rate and side stick position.

(4) THS control
The elevator orders are progressively transferred to the THS through a low-speed integrator to decrease the drag. This is the AUTOTRIM function. The THS movement is inhibited:

under 50 ft in manual mode (100 ft in AP mode),
when the high-speed and Mach protection is active,
in case of manual action on the hand wheel,
when the load factor is lower than 0.5 g,
in case of abnormal condition law.

The THS movement is limited in up direction:

when the alpha protection is active,
when the load factor is higher than 1.25g,
when the bank angle is above 33 deg,
in case of low speed protection (alternate law).

(5) Protections

(a) Alpha (A0A) protection
In the normal law, when an angle-of-attack threshold is reached (ALPHA PROT), the C* law is replaced by an alpha protection law.
In this case, an angle-of-attack value, proportional to the side stick position, is calculated.
The ALPHA PROT value is associated to a null order of the side stick.
The ALPHA MAX value is associated to a full nose-up order of the side stick.
This protection is de-activated by a pitch-down side stick order.

(b) High-speed protection
If a Vc or Mach threshold is reached, a positive load factor demand is added to the C* law.
This positive load factor demand is proportional to the difference between the actual Vc or Mach and the related threshold.
This value is limited and decreases the pilot's authority in nose down direction.
This protection is active from takeoff to landing.

(c) Longitudinal attitude protection
Pilot pitch-up commands are reduced linearly from a factor of 1 (theta max - 5°) to zero at (theta max and above). Similarly, pitch-down commands are factored from 1 at (theta min + 5°) to zero at (theta min and below). Pitch attitude feedback is phased in outside (theta min/theta max).
theta max = 30° at conf. 0 to 3
theta max = 25° in full.

(d) Load factor limitation
A maneuver protection is introduced in the C* law and restricts the load factor within the limits below :

clean configuration : - 1 g, + 2.5 g, (CONF 0 - CONF 1)
flaps extended : 0, + 2g. (CONF 1+F, 2, 3, F)

(6) Operation in normal conditions
The pitch laws are activated as described in the table below.

Pitch Normal Law

-------------------------------------------------------------------------------

! ! ! NORMAL LAW ! ! !

! PHASE !TRANSITION!---------------------------! ! !

! ! ! GROUND ! FLARE ! C* LAW ! THS ! A0A !

! ! ! LAW ! LAW ! ! COMMAND !PROTECTION !

!---------------!----------!----------!-------!--------!----------!-----------!

! GROUND ! ! YES ! ! ! 0° ! !

! ! ! ! ! ! ! FINAL ! !

! ! ! ! ! ! ! MANUAL ! !

! !Take off ! ! ! ! ! SETTING ! !

! ! ! ! ! ! ! ! !

! FLIGHT ! FLIGHT ! SMOOTHLY ! !SMOOTHLY! AUTOTRIM ! AUTHORIZED!

! ! ! AND ! WASHED ! !INTRODU-! WHEN ! 1s AFTER !

! ! !Theta > 8°! OUT OVER ! !CED OVER! z > 50 ft! FLIGHT !

! ! ! ! 5s ! ! 5s ! ! !

! ! ! ! ! ! ! ! !

! BEFORE ! z < 50ft ! ! YES ! ! INHIBITED! !

! LANDING ! ! ! ! ! ! !

! ! ! ! ! ! ! ! !

! !Landing ! ! ! ! ! ! !

! ! ! ! ! ! ! ! !

! GROUND ! GROUND ! YES ! ! ! 0° ! !

! ! ! CONFIRMED! ! ! ! ! !

! ! ! 5s AND ! ! ! ! ! !

! ! !Theta < ! ! ! ! ! !

! ! ! 2.5° ! ! ! ! ! !

! ! ! ! ! ! ! ! !

! GO AROUND ! ! ! YES ! ! FROZEN ! !

! BELOW ! ! ! ! ! ! !

! 50 ft ! z > 50ft ! ! !SMOOTHLY! ! !

! ! ! ! !RESTORED! ! !

! ! ! ! !OVER 5s ! ! !

-------------------------------------------------------------------------------

B. Lateral Control

(1) General
The normal law for the lateral control includes the roll and yaw axis control.
The ailerons and the spoilers 2, 3, 4 and 5 are the roll control surfaces. The main characteristics of the lateral control law are as follows:

side stick movement in roll processed as a roll rate demand,
turn coordination automatically ensured,
lateral attitude limitation provided.

(2) Lateral normal law
Two phases must be considered:

flight,
ground.

The ground law is activated 0.5s after landing with longitudinal attitude lower than 8°.
The flight law is activated 0.5s after take-off with longitudinal attitude higher than 8°.

(a) Flight law
The side stick movement in roll controls a roll rate in which the gains are function of Vc and of the configuration. The maximum roll rate is 15°/s.
The characteristics of the roll law are:

in turn configuration, lateral attitude maintained up to 32° with side stick at zero,
lateral attitude limited to 67° for full side stick deflection,
automatic turn coordination,
Dutch roll damping,
minimization of sideslip.

(b) Ground law
All feedbacks are inhibited. The side stick movement directly controls the roll control surfaces (ailerons and spoilers).
The rudder is mechanically controlled by the pedals with the yaw damper function always active.

(3) Roll control surface Kinematics
Full authority of surfaces is:

+ or - 25 deg for the ailerons,
maximum deflection of 35 deg for the spoilers.
The spoilers 2, 3, 4 and 5 use the same deflection; from configuration 0 to configuration 3, a threshold is included to minimize the drag.
A 5 deg downward deflection of the ailerons (droop) is active when the flaps are extended. This position is identified by an index on the AIL scale of the ECAM F/CTL page (Ref 31-51).
The aileron droop function is ensured by each ELAC.
The aileron droop function is active on ground or in flight when the flaps are extended; in that case, a 5 deg downward deflection of the ailerons is ordered by the ELAC1 (or by the ELAC2 if it is active on the control of the ailerons).
The aileron droop function is available as long as one ELAC is able to control the ailerons.
The ailerons are normally controlled by the ELAC1 through the left Blue and the right Green servo-controls (active mode). The ELAC2 is in stand-by, and the associated servo-controls are in damping mode.
In case of ELAC1 failure, the control of the ailerons is automatically transferred to the ELAC2 which becomes active through the left Green and right Blue servo-controls; in that case, the servo-controls dedicated to the ELAC1 revert to the damping mode.
In case of double ELAC failure, or Blue and Green hydraulic low pressure, all ailerons servo-controls are in the damping mode.

(4) Roll control surface Kinematics
Full authority of surfaces is:

+ or - 25 deg for the ailerons,
maximum deflection of 35 deg for the spoilers (7 deg limitation for spoiler 3).
The spoilers 2, 3, 4 and 5 use the same deflection; from configuration 0 to configuration 3, a threshold is included to minimize the drag.
A 5 deg downward deflection of the ailerons (droop) is active when the flaps are extended. This position is identified by an index on the AIL scale of the ECAM F/CTL page (Ref 31-51).
The aileron droop function is ensured by each ELAC.
The aileron droop function is active on ground or in flight when the flaps are extended; in that case, a 5 deg downward deflection of the ailerons is ordered by the ELAC1 (or by the ELAC2 if it is active on the control of the ailerons).
The aileron droop function is available as long as one ELAC is able to control the ailerons.
The ailerons are normally controlled by the ELAC1 through the left Blue and the right Green servo-controls (active mode). The ELAC2 is in stand-by, and the associated servo-controls are in the damping mode.
In case of ELAC1 failure, the control of the ailerons is automatically transferred to the ELAC2 which becomes active through the left Green and right Blue servo-controls; in that case, the servo-controls dedicated to the ELAC1 revert to the damping mode.
In case of double ELAC failure, or Blue and Green hydraulic low pressure, all ailerons servo-controls are in the damping mode.

(5) Rudder control
The pedals mechanically control the rudder position. The maximum rudder deflection is plus or minus 25° limited by the TLU. The trim authority is plus or minus 20° and its deflection rate is 1°/s.
The yaw orders from the roll normal law are sent to the yaw damper servo-actuators and added to the servocontrol mechanical input.
Authority of these orders is given in the table below:

-------------------------------------------------------------------------------

! ! Less than or ! ! ! !

! V Cas (kts) ! equal to 160 ! 200 ! 300 ! 380 !

!----------------!--------------!--------------!---------------!--------------!

! ! plus ! plus ! plus ! plus !

! ! or ! or ! or ! or !

! ! minus ! minus ! minus ! minus !

! Max. authority ! 20.8° ! 10.8° ! 4.8° ! 2.7° !

-------------------------------------------------------------------------------

The limitation of the rudder maximum deflection is given in the table below:

-------------------------------------------------------------------------------

! V Cas (kts) ! Less than ! 200 ! 240 ! 320 ! 380 !

! ! 160 ! ! ! ! !

!----------------!--------------!-----------!-----------!-----------!---------!

! ! plus ! plus ! plus ! plus ! plus !

! ! or ! or ! or ! or ! or !

! ! minus ! minus ! minus ! minus ! minus !

! Max. authority ! 25° ! 14.5° ! 8.8° ! 4.8° ! 3.4° !

-------------------------------------------------------------------------------

(6) Rudder control
The pedals mechanically control the rudder position. The maximum rudder deflection is plus or minus 28 deg limited by the TLU. The trim authority is plus or minus 21 deg and its deflection rate is 1 deg/s.
The yaw orders from the roll normal law are sent to the yaw damper servo-actuators and added to the servocontrol mechanical input.
Authority of these orders is given in the table below:

-------------------------------------------------------------------------------

! V Cas (kts) ! Less than or! 200 ! 240 ! 320 ! 380 !

! ! equal to 160 ! ! ! ! !

!----------------!--------------!-----------!-----------!-----------!---------!

! ! plus ! plus ! plus ! plus ! plus !

! ! or ! or ! or ! or ! or !

! ! minus ! minus ! minus ! minus ! minus !

! Max. authority ! 21 deg ! 10.8 deg ! 6.6 deg ! 3.6 deg ! 2.4 deg !

-------------------------------------------------------------------------------

The limitation of the rudder maximum deflection is given in the table below (TLU activated):

-------------------------------------------------------------------------------

! V Cas (kts) ! Less than ! 200 ! 240 ! 320 ! 380 !

! ! 160 ! ! ! ! !

!----------------!--------------!-----------!-----------!-----------!---------!

! ! plus ! plus ! plus ! plus ! plus !

! ! or ! or ! or ! or ! or !

! ! minus ! minus ! minus ! minus ! minus !

! Max. authority ! 25 deg ! 13 deg ! 7.9 deg! 4.3 deg! 2.9 deg!

-------------------------------------------------------------------------------

(7) Rudder control
The pedals mechanically control the rudder position. The maximum rudder deflection is plus or minus 30 deg limited by the TLU. The trim authority is plus or minus 25 deg and its deflection rate is 1 deg/s.
The yaw orders from the roll normal law are sent to the yaw damper servo-actuators and added to the servocontrol mechanical input.
Authority of these orders is given in the table below:

-------------------------------------------------------------------------------

! V Cas (kts) ! Less than or! 200 ! 240 ! 320 ! 380 !

! ! equal to 140 ! ! ! ! !

!----------------!--------------!-----------!-----------!-----------!---------!

! ! plus ! plus ! plus ! plus ! plus !

! ! or ! or ! or ! or ! or !

! ! minus ! minus ! minus ! minus ! minus !

! Max. authority ! 25 deg ! 12 deg ! 7.3 deg ! 4 deg ! 2.8 deg !

-------------------------------------------------------------------------------

The limitation of the rudder maximum deflection is given in the table below (TLU activated):

-------------------------------------------------------------------------------

! V Cas (kts) ! Less than ! 200 ! 240 ! 320 ! 380 !

! ! 140 ! ! ! ! !

!----------------!--------------!-----------!-----------!-----------!---------!

! ! plus ! plus ! plus ! plus ! plus !

! ! or ! or ! or ! or ! or !

! ! minus ! minus ! minus ! minus ! minus !

! Max. authority ! 30 deg ! 14.5 deg! 8.8 deg! 4.8 deg! 3.4 deg!

-------------------------------------------------------------------------------

(8) Operation in normal conditions
The lateral laws are activated as described in the table.

Activation of flight/ground laws in lateral

-------------------------------------------------------------------------------

! ! ! NORMAL LAW ! !

! PHASE ! TRANSITION !-----------------------------! DISPLAY ON !

! ! ! GROUND LAW ! FLIGHT LAW ! PFD !

!---------------!------------!--------------!--------------!------------------!

! GROUND ! ! YES ! ! LATERAL !

! ! ! ! DECREASED ! ! LOAD FACTOR !

! ! ! ! AUTHORITY ! ! !

! ! ! ! WITH INCREA-! ! !

! ! ! ! SED SPEED ! ! !

! ! ! ! ! ! !

! ! TAKE ! ! YAW DAMPING ! ! !

! ! OFF ! ! ! ! !

! ! ! ! ! ! !

! FLIGHT ! FLIGHT AND ! WASHED OUT ! PHASED IN ! SIDE SLIP !

! ! ! Theta > 8° ! OVER 0.5s ! OVER 0.5s ! !

! ! ! ! ! ! !

! ! LANDING ! ! ! ! !

! ! ! ! ! ! !

! GROUND ! GROUND ! PHASED IN ! PHASED OUT ! LATERAL LOAD !

! ! ! OVER 0.5s ! OVER 0.5s ! FACTOR !

! ! ! ! ! !

! ! ! YAW DAMPING ! ! !

-------------------------------------------------------------------------------

C. Speedbrake Function

Speedbrake Order Generation ** ON A/C NOT FOR ALL

(1) General
The speedbrake function is ensured by the spoilers 2, 3 and 4 and the associated SECs.
The speedbrake deflection order is dependent upon the speedbrake control lever position.
Extension of the spoilers 2 is half the extension of the spoilers 3 and 4.
The speedbrake order is combined with roll orders.
In flight, when the aircraft speed is more than 315 knots or Mach 0.75 with the autopilot engaged, the speedbrake retraction rate decreases (approximately 25 seconds are necessary to retract the speedbrakes from FULL to IN).

(2) Speedbrake order
The speedbrake order comes from the order received from the speedbrake lever received by the SEC.
The speedbrake control order is inhibited:

if the monitoring of the speedbrake control transducer unit has detected a failure (by means of the transducer unit range monitoring or COM/MON comparison),
if the alpha protection is active,
if in FULL configuration,
in case of single elevator configuration,
in case of loss of the Blue and Green hydraulic pressures.
if at least one throttle lever is above MCT (Maximum Continous Thrust) or
if full back stick associated with pitch altitude protection,

The deflection rate is limited to 5°/sec.
In order to do the test of the spoiler 1 on the ground, a 6° extension of the spoiler 1 is possible with the speedbrake control lever.

Logic Conditions for Spoiler 1 Extension on the ground ** ON A/C NOT FOR ALL

(3) General
The speedbrake function is ensured by the spoilers 2, 3 and 4 and the associated SECs.
The speedbrake deflection order is dependent upon the speedbrake control lever position:
Splr 4: 25 deg, Splr 3: 25 deg, Splr 2: 25deg for SPD BRK lever fully deflected.
The speedbrake order is combined with roll orders.
In flight, when the aircraft speed is more than 315 knots or Mach 0.75 with the autopilot engaged, the speedbrake retraction rate decreases (approximately 25 seconds are necessary to retract the speedbrakes from FULL to IN).

(4) Speedbrake order
The speedbrake order comes from the order received from the speedbrake lever receveid by the SEC.
The speedbrake control order is inhibited:

if the monitoring of the speedbrake control transducer unit has detected a failure (by means of the transducer unit range monitoring or COM/MON comparison),
if the alpha protection is active,
if in FULL configuration or configuration 3.
in case of single elevator configuration,
in case of loss of the Blue and Green hydraulic pressures.
if at least one throttle lever is above MCT (Maximum Continous Thrust) or
if full back stick associated with pitch altitude protection.

The deflection rate is limited to 3°/sec.
In order to do the test of the spoiler 1 on the ground, a 6° extension of the spoiler 1 is possible with the speedbrake control lever.

Logic Conditions for Spoiler 1 Extension on the ground ** ON A/C NOT FOR ALL

(5) General ,
The speedbrake function is ensured by the spoilers 2, 3 and 4 and the associated SECs.
The speedbrake deflection order is dependent upon the speedbrake control lever position:
Splr 4: 25 deg; Splr 3: 25 deg; Splr 2: 17.5 deg CONF 0/1/2, 12.5 deg CONF 3 for SPD BRK lever fully deflected.
The speedbrake order is combined with roll orders.
In flight, when the aircraft speed is more than 315 knots or Mach 0.75 with the autopilot engaged, the speedbrake retraction rate decreases (approximately 25 seconds are necessary to retract the speedbrakes from FULL to IN).

(6) Speedbrake order
The speedbrake order comes from the order received from the speedbrake lever receveid by the SEC.
The speedbrake control order is inhibited:

if the monitoring of the speedbrake control transducer unit has detected a failure (by means of the transducer unit range monitoring or COM/MON comparison),
if the alpha protection is active,
if in FULL configuration or configuration 3.
in case of single elevator configuration,
in case of loss of the Blue and Green hydraulic pressures.
if at least one throttle lever is above MCT (Maximum Continous Thrust) or
if full back stick associated with pitch altitude protection.

The deflection rate is limited to 3°/sec.
In order to do the test of the spoiler 1 on the ground, a 6° extension of the spoiler 1 is possible with the speedbrake control lever.

Logic Conditions for Spoiler 1 Extension on the ground ** ON A/C NOT FOR ALL

(7) Pitch precommand
To reduce pitch effect at speedbrake movement.

D. Ground Spoiler Function

(1) General
The ground spoiler function is ensured by all the spoilers.
The surface deflection is 50 deg with an extension rate of 20 deg/s (in autopilot or manual mode).

(2) Activation of the ground spoiler function.

Ground Spoiler Activation ** ON A/C NOT FOR ALL

The activation of the ground spoiler function is dependent upon:

the function preselection, or one throttle lever at reverse
the two engines at low rate
wheel speed information (of both main gears)
the main landing gear wheel rotation more than 72kts

NOTE: Condition on wheel speed is inhibited after GND/FLT transition.
The condition is rearmed if wheel rotation stops.
Consequently after an A/C bounce (A/C airborne):
- the spoilers remain extended with thrust lever at idle
- the spoilers retract if thrust is increased above idle (GA), and extend again after the next touch down.

elevator pre command at the extension of the ground spoilers (manual only)
the both main landing gears compressed while the altitude less than 6ft
The preselection is made with the speedbrake control lever. The lever position must be lower than - 2 deg.
This preselection can also be made through the selection of reverse thrust on both throttle control levers, or only one throttle control lever with the other control lever in position less than 20 deg.
The "two throttle levers at low rate" information is given when the position of the two throttle control levers is less than 20 deg.

(3) Partial lift dumping
This function, elaborated in the SECs, is actived at reverse selector if only one main landing gear is depressed. The spoilers 1 thru 5 are partially deflected in order to impact the second gear and consequently to activate the ground spoiler function.

(4) General
The ground spoiler function is ensured by all the spoilers.
The surface deflection is 50 deg with an extension rate of 20 deg/s (in autopilot or manual mode).

(5) Activation of the ground spoiler function.

Ground Spoiler Activation ** ON A/C NOT FOR ALL

The activation of the ground spoiler function is dependent upon:

the function preselection, or one throttle lever at reverse
the two engines at low rate
wheel speed information (of both main gears)
the main landing gear wheel rotation more than 72kts

elevator pre command at the extension of the ground spoilers (autopilot and Manual)
the both main landing gears compressed while the altitude less than 6ft
The preselection is made with the speedbrake control lever. The lever position must be lower than - 2 deg.
This preselection can also be made through the selection of reverse thrust on both throttle control levers, or only one throttle control lever with the other control lever in position less than 20 deg.
The "two throttle levers at low rate" information is given when the position of the two throttle control levers is less than 20 deg.

(6) Partial lift dumping
This function, elaborated in the SECs, is actived at reverse selector if only one main landing gear is depressed. The spoilers 1 thru 5 are partially deflected in order to impact the second gear and consequently to activate the ground spoiler function.

(7) General
The ground spoiler function is ensured by all the spoilers.
The surface deflection is 50 deg.

(8) Activation of the ground spoiler function.

Ground Spoiler Activation ** ON A/C NOT FOR ALL

The activation of the ground spoiler function is dependent upon:

(a) The function preselection:

speedbrake control lever in ARMED position, or in extended position while the altitude is less than 6ft or one throttle control lever in reverse position.

(b) The two engines at low rate.

(c) The main landing gear wheel rotation is more than 72kts or both main landing gears compressed while the altitude is less than 6ft.

NOTE: The wheel speed condition is inhibited after GND/FLT transition and is rearmed when the wheel rotation stops.
Therefore, after an aircraft bounce (aircraft airborne):
- the spoilers remain extended with the throttle control lever at idle
- the spoilers retract if thrust increases above idle (GA), and extend again after the next touchdown.
The preselection can also be made through the selection of reverse thrust:

on both throttle control levers, or
on only one throttle control lever with the other lever at a position less than 20 deg or speedbrake control lever in extended position while the altitude is less than 6ft.
The "two throttle levers at low rate" information is given when the position of the two throttle control levers is less than 20 deg, or one throttle lever is in REV position and the other is at less than CLB.

(9) Partial lift dumping
This function, computed in the SECs, is activated when reverse thrust is selected if one main landing gear is not compressed or if both main landing gears are compressed but retard is not achieved (throttle lever at CLB or below) while the altitude is less than 6ft.
Spoilers 1 thru 5 are partially deflected in order to push down on the landing gears and thereforre facilitate activation of the ground spoiler function.

E. Speedbrake Deflection Limitation and Aileron Rigging in the Up Position

(1) Speedbrake deflection limitation
On A320, to improve the loads in continous turbulence condition, the speedbrake maximum deflection is reduce in clean configuration in relation to aircraft weight.
The deflection of spoiler 2, 3 and 4 is given in the table below:

Spoiler Deflection Mode	Spoiler deflection values
1/2 deflection in manual mode	12.5°/25°/25° for W<MLW+2t
	8°/16°/16° for W>MLW+4t
Full deflection in manual mode	20°/40°/40° for W<MLW+2t
	12.5°/25°/25° for W>MLW+4t
1/2 deflection in AP mode	12.5°/25°/25°
Full deflection in AP mode	12.5°/25°/25°

(2) Aileron rigging in the up position
The speedbrake defection limitation is also related to a permanent rigging of the ailerons in the up position.
When the speedbrake are deflected, the ailerons are symmetrically deflected up by 6°, in relation to the current speedbrake deflection and the aircraft weight.

F. Load Alleviation Function (LAF)

(1) General
The load alleviation function is used to alleviate the loads on the wings.
This is done through the upward deflection of the control surfaces:

The two ailerons only, or
The two ailerons associated with spoilers 4 and 5.

The LAF has two sub-functions:

One that is activated during a stable maneuver (aileron deflections only)
One that is activated during discrete gust detection (aileron and spoiler deflections).

The LAF is available in clean configuration and in normal law only, with the autopilot engaged or not.
The LAF orders are added to those generated by the normal law.
The LAF generates surface deflection orders in relation to load factors from:

Gust,
Acceleration because of a bank,
Acceleration because of a side stick order in pitch.

(2) LAF (maneuver function) (deflection of the ailerons only)

(a) Control surfaces
The LAF (maneuver function) uses the two ailerons only with an upward deflection of 15° maximum (phased out with the speedbrake deflection).

(b) Inhibition conditions
The LAF is not available when:

The flight control law is not the "normal law"
The slat/flap is not in clean configuration
The wing tip brake is ON
There is one-elevator configuration if there is a double hydraulic failure (Blue and Yellow)
There is a failure of one aileron
There is a double accelerometer failure in ELAC 1.

(c) Deflection logic
The ailerons are deflected in relation to the Nz measured and thresholds.
Then, when the ailerons are deflected, they stay deflected for a minimum of 2.5 seconds (hold time).

(3) LAF (discrete gust function) (deflection of the ailerons and spoilers)

(a) Control surfaces
The LAF (discrete gust function) uses:

The two ailerons with an upward deflection of 10° maximum, and
Spoilers 4 and 5 with a deflection of 10° maximum

(b) Inhibition conditions
The LAF is not available when:

The flight control law is not the "normal law"
The slat/flap is not in clean configuration
The wing tip brake is ON
There is a one-elevator configuration if there is double hydraulic failure (Blue and Yellow)
There is a failure of one aileron
There is a double accelerometer failure in ELAC 1.

(c) Deflection logic
The two ailerons and spoilers 4/5 are deflected up when the vertical acceleration is more than 1.3g and the gust detector algorithm is active.
When activated, ailerons and spoilers stay deflected for a minimum of 2.5 seconds (hold time).

G. Normal Configuration

(1) Computers
Each computer is active as follows:

ELAC 2:
normal law in pitch with associated protections
elevator control
control of THS electric motor No. 1.
ELAC 1:
normal law in lateral
aileron control.
SEC1, 2 and 3:
control of their related spoilers from the orders from the normal lateral law of the ELAC 1
speedbrake function,
ground spoilers.

The FAC1 controls the rudder with the yaw damper servo-actuator 1 from the orders elaborated in the ELAC 1.

(2) Servocontrols

(a) Elevators
Each elevator can be actuated by two different servocontrols.
In normal operation, one servocontrol per surface is active, the other is in the damping mode.
On the left elevator, the Green servocontrol is active.
On the right elevator, the Yellow servocontrol is active.
On the two elevators, the Blue servocontrols are in damping mode.

(b) THS actuator
The THS can be actuated by three different electric motors.
In normal operation, the electric motor No. 1 controls the two hydraulic motors respectively supplied by the Green and Yellow systems. The ELAC 1 performs a ground setting through the electric motor No. 2.

(c) Ailerons
Each aileron can be actuated by two different servocontrols. In normal operation, one servocontrol per aileron is active, the other is in damping mode. On the left aileron, the Blue servocontrol is active.
On the right aileron, the Green servocontrol is active.
The servocontrols, controlled by the ELAC 2, Green on the left side and Blue on the right side are in the damping mode.

** ON A/C NOT FOR ALL

6. Functional Reconfiguration
The functions available in normal configuration can be degraded depending on the failures which may affect the system. The resulting functional reconfigurations depend on:

the level of redundancy of the external information necessary for the normal laws,
predetermined functional status,
inclusion of laws in the computers.

A. Law Reconfiguration

(1) Pitch control

(a) Alternate law
When the information necessary for the normal law can no longer be consolidated, the alternate law is activated.
This law can also be activated after certain system failures.
The basic idea is to reduce the authority of the parameters required for the law, while keeping the main characteristics of the normal law.
The gains are now dependent upon the configuration.
The pitch rate is limited to 5°/s.
The flare law is replaced by the direct law upon landing gear extension.
The longitudinal attitude protection is no longer activated. The alpha protection is replaced by a low-speed protection when Vc becomes lower than a threshold (Vc PROT) a negative load factor demand is added to the pilot command.
The high-speed and Mach protection is included as for the normal law, except for decreasing of pilot nose down authority.

(b) Direct law
When the information required for the C* law is no longer valid or upon landing gear extension when the alternate law is active, the direct law in pitch is activated.
The side stick movement directly controls the elevator position.
The THS is mechanically controlled from the trim control wheel.
No protection is included.

(c) Mechanical control
When the electrical flight controls are lost, the THS is mechanically controlled from the trim control wheel.
The elevators are centered.

(2) Lateral control
After the loss of the normal pitch law or after certain system failures, the direct lateral law is activated. The side stick movements directly control the position of the ailerons and the spoilers 4 and 5.
In the event of loss of these surfaces, reconfigurations are introduced to keep a sufficient roll rate:

if the two ailerons are no longer available, the spoilers 2 and 3 become active in direct law,
if the spoilers 4 are no longer available, the spoilers 3 become active.

After the loss of the normal lateral law, the yaw alternate law activated in the FACs ensures the Dutch-roll damping function.

(3) Abnormal condition law
If the main aircraft parameters (Theta, phi., Vc, M, alpha) exceed predetermined limits, the abnormal condition law is activated i.e.:

in pitch control, the alternate law is active without autotrim,
in lateral control, the direct law is active,
the rudder control is mechanical.

If the aircraft returns to level flight (0.9 g < Nz lower than or = to 1.2 g) during 18s, the autotrim function is again active and the alternate law for the rudder control is active. There is no reversion to direct law when landing gear is extended.

B. Law Distribution in the Computers
The distribution of the laws in the computers is as follows:

-------------------------------------------------------------------------------

! COMPUTER ! LAW ! CONTROL !

!-----------------------------------------------------------------------------!

! ! - PITCH NORMAL LAW ! - 2 ELEVATORS !

! ! - PITCH ALTERNATE LAW ! - 1 THS MOTOR !

! ELAC ! - PITCH DIRECT LAW ! - 2 AILERONS !

! ! - LATERAL DIRECT LAW ! !

!----------------------!---------------------------!--------------------------!

! SEC ! - PITCH ALTERNATE LAW ! - 2 PAIRS OF SPOILERS !

! ! - PITCH DIRECT LAW ! - 2 ELEVATORS !

! ! - LATERAL DIRECT LAW ! - 1 THS MOTOR !

!----------------------!---------------------------!--------------------------!

! FAC ! - YAW ALTERNATE LAW ! !

-------------------------------------------------------------------------------

C. Functional Statuses
The various functional statuses possible are:

"normal law" status: the normal laws are active in pitch and lateral control,
"alternate law" status: the laws, alternate in pitch and direct in lateral are active,
"direct law" status: the direct laws are active in pitch and lateral control.

Upon loss of all the EFCS control laws, standby mechanical controls in pitch and yaw are possible.

D. Logic of Transition between Different Statuses
The purpose of this logic is, after failure, to force law degradations in a computer and take into account the functional statuses then possible in all the computers.
The "normal law" status can only be authorized when:

the ELAC having priority in lateral meets the requirements for engagement of the lateral normal laws,
the ELAC having priority in pitch meets the requirements for engagement of the pitch and lateral normal laws.

If one ELAC with priority on one axis no longer meets the requirements for the normal law, the "alternate law" status is adopted.
If the computer which has priority in pitch does not meet the requirements for engagement of the alternate law, the "direct law" status is adopted.

** ON A/C NOT FOR ALL

7. System Reconfiguration Logic
A computer is engaged on one axis if:

it has priority,
it has the capability to ensure control on this axis.

This capability is related to:

its status,
the status of its servoloops,
the status of the hydraulic systems,
the status of the external sensors.

A. Switching Logics
The switching logics are as follows:

pitch control ELAC 2 ------> ELAC 1 ------> SEC 2 ------> SEC 1,
lateral control ELAC 1 ----> ELAC 2.

For this switching logic, discrete links are included from each computer to the lower level computers.
These links are:

looped,
permanently monitored.

B. Conditions Related to the Computer Status
The EFCS computers can operate normally when:

the engagement pushbutton switch is pressed,
the self-test results are satisfactory.

C. Conditions Related to Servoloops
All the failures detected by the servoloop monitorings are self-held until the next computer reset through action on the pushbutton switch or power supply rise.

(1) Pitch servoloop
An ELAC can be engaged in pitch if its 3 pitch servoloops are valid.
An SEC can be engaged in pitch if one of the surface servoloops is valid.
An elevator servoloop is declared valid by a computer if the result of the monitorings below is satisfactory:

monitoring of the servovalve current,
monitoring of the servovalve selector valve,
monitoring of the position of the servovalve spool valve,
monitoring of the servocontrol position transducers,
monitoring of the mode selector valve,
monitoring of the mode selector valve position,
automatic tests launched at the third hydraulic rise.

A THS servoloop is declared valid by a computer if the result of the monitorings below is satisfactory:

monitoring of the servomotor current,
monitoring of the THS position,
monitoring of the THS position transducers.
automatic test results:
monitoring of the relay ensuring cutoff of the electric motor,

(2) Aileron servoloops
An ELAC can be engaged in lateral if at least one of the two aileron servoloops is valid.
If the ELAC 1 can only drive one aileron, the ELAC 2 drives the other aileron from the order computed by the ELAC 1.
An aileron servoloop is declared valid when the result of the monitorings below is satisfactory:

monitoring of the servovalve current,
monitoring of the servovalve failures,
monitoring of the servocontrol position transducer,
monitoring of the discrete links between ELAC 1 and ELAC 2 (performed in the ELAC 1 only).
result of automatic (launched or third hydraulic rise) test:
monitoring of the mode selector valve transducer ,
monitoring of the servocontrol modes.

(3) Spoiler servoloops
A SEC can be engaged on a pair of spoilers when the two servoloops are validated.
The servoloops of a pair of spoilers are validated when:

the result of the monitorings below is satisfactory:
monitoring of position transducers,
monitoring of servovalve currents,
monitoring of positions.

D. Conditions Related to Hydraulic Systems
The ELAC 2 can drive in pitch if the Green and Yellow hydraulic systems are available or upon a dual hydraulic failure, including the Blue system.
The ELAC 1 can drive in pitch if the Blue hydraulic supply is available.
In lateral, a servoloop can only be validated if the related hydraulic power source is available.

E. Conditions Related to Sensor Status

(1) In pitch:

ELAC 2 loses priority because of the failure of:
. One of the four side-stick transducer units related to it
. The two accelerometers related to it (in normal electrical condition)
. The pedal-position transducer unit
. The two radio-altimeters (only detected by ELAC 2).
ELAC 1 loses priority in pitch because of the failure of one of the four side-stick transducer units which are related to it.

(2) In lateral:

ELAC 1 loses priority because of the failure of:
. One of the four side-stick transducer units
. The pedal-position transducer unit.
ELAC 2 has no longer priority because of the failure of one of the four side-stick transducer units.

** ON A/C NOT FOR ALL

8. Miscellaneous Logics

A. "Priority between Side-Sticks" logic
The CAPT and F/O stick orders are algebraically added.
The takeover and priority pushbutton switch on the side stick is used to take over and to disconnect the auto pilot.
The takeover and priority logic is described below:

the last pilot who presses the pushbutton switch takes over and cancels the order from the other pilot.
If the pilot releases the P/BSW within the 30s which follow the takeover, his priority is cancelled.
If the pilot releases the P/BSW more than 30s after his takeover, he keeps his takeover.
This takeover can be cancelled through action on the P/BSW of any side stick.
Indications related to takeover:
a red light comes on in front of the pilot who has lost priority,
a green light comes on in front of the pilot who has priority as long as the stick which has not priority is not at zero.

The CAPT and F/O stick orders are algebraically added.
The takeover and priority pushbutton switch on the side stick is used to take over and to disconnect the auto pilot.
The takeover and priority logic is described below:

the last pilot who presses the pushbutton switch takes over and cancels the order from the other pilot.
If the pilot releases the P/BSW within the 30s which follow the takeover, his priority is cancelled.
If the pilot releases the P/BSW more than 30s after his takeover, he keeps his takeover.
This takeover can be cancelled through action on the P/BSW of any side stick.
Indications related to takeover:
a red light comes on in front of the pilot who has lost priority,
a green light comes on in front of the pilot who has priority as long as the stick which has not priority is not at zero.
In case of simultaneous action on Captain and First Officer side sticks, the green CAPT and F/O legends located on SIDE STICK PRIORITY/CAPT and SIDE STICK PRIORITY F/O (130, 131VU) flash at the same time.

B. Elevator-Servocontrol Simultaneous-Pressurization Logic
the four servocontrols can be simultaneously active (the two servo controls which are normally in damping mode become active in addition to the two normally active ones) in the cases below:

elevator demand amplitude greater than a threshold function of Vc,
in flare law or landing direct law if the deflection demand is greater than 30°/s
in case of undetermined mode detection (not in active, not in damping).

The three possible configurations are:
when the ELAC2 has priority

ELAC 2 commands the active mode to the other servocontrol which is controlled by the ELAC 1,
ELAC 2 commands the active mode to the other servocontrol which is controlled by the SEC 1,
when the ELAC1 has priority
ELAC 1 commands the active mode to the other servocontrol which is controlled by the SEC 2,
When the four servocontrols become active, the surface deflection rate can reach 50°/s.
When SEC 2 has priority
SEC 2 commands the active mode to the other servocontrol which is controlled by the SEC 1.

C. Elevator Oscillation Detection
The ELACs include a function to monitor specific oscillations of elevator surfaces in order to protect the aircraft structure.
If this system is activated the elevator deflection is limited to few tenths of a degree around zero and both servocontrols are simultaneously pressurized (on one surface only) when speed is above 170 kts. Full authority is progressively restored from 170 kts to 150 kts. If the protection is activated it remains latched until next ELAC long autotest (ELAC low hydraulic reset).

D. Detection of a Manual Action on the Pitch-Trim Control Wheel
If the pilot acts on the pitch-trim control wheel he forces the position commanded to the THS. (Electrical control is overriden by the mechanical control).
The electrical control has again priority as soon as the pilot releases the control wheel.

NOTE: In direct law, in normal law, in alternate law and in autotrim the THS is manually controlled.

E. THS Ground-Setting Logic
5s after landing the ELAC 1 set the THS in the 0° position.
The priority logic for the ground setting function is as follows:
E1 ------> E2 ------> S2 ------> S1.

F. Flight/Ground Logic computed in the ELACs

Flight/Ground Logic ELAC

The Ground information is validated:

if both main landing gears are seen compressed (left LGCIU1 and left LGCIU2 and right LGCIU1 and right LGCIU2),
or
if at least two of above four information are seen compressed and radio altimeter information (consolidated data) is lower than 50 ft,
or
if the ground spoilers are extended from at least 2 SECs.

[Rev.10 from 2021] 2026.04.01 06:53:47 UTC