in the below video and article we will talk about the A320 family enhanced electric rudder modification

A320 flight control overview


As all pilots and engineers dealing with A320 know that A320 is the first fully fly by wire commercial aircraft all the flight control surfaces are
hydraulically operated by actuators that receive electrical signals from the computers.


Figure 1: A320 Fly by Wire Flight Control System

Figure 2: System overview - reconfiguration priority

the rudder and the trimmable horizontal stabilizer can also be mechanically controlled normally in flight the pilot can fly the aircraft only using the side sticks without any need to use rudder pedals or stabilizer trim wheel but in case of complete loss of electrical power or flight control computer failure the mechanical backup control signals let the aircraft be still controllable in mechanical backup control system longitudinal control is achieved using the trim wheels to control the THS as the elevators are kept at zero deflection, lateral control is achieved from the rudder pedals but remember hydraulic power is still needed to operate the surfaces of the THS and the Rudder.

Figure 3: A320 Fly by Wire Flight Control System

Figure 4: Mechanical backup

Figure 5: Mechanical backup

The flight control computers include 7 computers for controls and 2 computers for indication and maintenance as follows:

  • 2 elevator aileron computers ELAC 1 and 2 for pitch and roll control
  • 3 spoiler elevator computers SEC 1,2 and 3 for pitch and roll control,
  • 2 flight augmentation computers FAC 1 and 2 for yaw control
  • 2 flight control data concentrator FCDC for indication and maintenance tests

Figure 6: A320 Flight Control Computers

Rudder mechanical control system

Figure 7:Rudder mechanical control

The two pairs of rudder pedals are connected together, they are linked by a cable loop to the mechanical summing point which in turn is connected to the hydraulic rudder actuators via differential unit the rudder is powered by three hydraulic actuators operating in parallel each actuator mechanically controlled through spring rod for jamming protection the following component connected to the rudder mechanical control system
2 Yaw damper actuators for yaw damping and turn coordination electrical orders 1 rudder trim unit for rudder trim including 2 electric trim motors1 rudder traveling limitation unit RTLU for rudder travel limitation with airspeed including 2 electric motors

Figure 8: Rudder trim and travel limitation

The modified electric rudder system

by the end of 2021, Airbus will deliver the first A320 family aircraft named e-rudder.

What changes?

Figure 9:

It will be fitted with electric control of the rudder instead of current mechanical control in E-rudder system flight control computers
will be 4 only instead of 7 :

  • SEC3,  FAC 1, and 2 will be deleted,
  •   only ELAC 1 and  2 and the SEC 1 and 2 will control the flight controls system

Figure 10: A320 “E-rudder”

And in the case of flight control computer failure or its power supply failure the radar is still controllable through Backup Control Module BCM which is electrically supplied by the backup power supply unit.

The backup power supply unit is hydraulically operated by the yellow hydraulic power.

the deleted equipment are:

  • FAC 1, FAC 2, and SEC 3,
  •   yaw damper actuators
  • rudder trim actuators
  • rudder travel limitation unit.
  • rudder mechanics and equipment,
  • one rudder position sensor. Fly by Wire Flight Control System.jpg

Figure 11: Deleted equipment

The added equipment are:

  • rudder and brake pedal unit,
  • BCM or backup control module BPS or backup power supply,
  • two rudder position sensors for ELAC, SEC and BCM Fly by Wire Flight Control System.jpg

Figure 12: New equipment

What E-rudder added value for A320 family operators?

  • weight-saving about 40 kilograms leading to fuel saving,
  • operational interruption reduction,
  • maintenance cost reduction,
  • rudder trim failure no longer impacts autopilot availability as you see FAC 1 and 2 deleted from 80 VU and BCM replace SEC 3 in 90 VU. Fly by Wire Flight Control System.jpg

Figure 13: Avionics Compartment Arrangement

When E-rudder will be first introduced?

E-Rudder will be introduced on A319 neo, A320 neo, and A321 neo. the first aircraft will be delivered in December 2021

E-rudder will become the default standard for A320 family  A320 CEO will not be proposed for E-rudder, E-rudder is not retrofittable

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