in conventional aircraft the movement of the control column is transferred along cables and pulleys until it reaches the control surface to be moved in the a320 family the cables and pulleys have been replaced by electrical wires this has the advantage of saving weight on the aircraft however there are even greater advantages as the video clip will demonstrate the electrical signals created by sidestick movement travel through flight control computers before being passed to the surface hydraulic actuators also named servo controls the pilots use the side sticks to fly the aircraft computers interpret the pilots inputs and move the flight control surfaces as necessary preventing excessive maneuvers and flight outside the safe flight envelope pilots input is converted into an aircraft control objective no direct relationship between stick and surface the aircraft is servo looped this has advantages over conventional systems it makes the aircraft extremely stable enhances safety reduces the pilots workload the movements of the flight control surfaces are managed by seven computers these are two elevator and aileron computers ELAC three spoiler and elevator computers SEC two flight augmentation computers FAC which managed the rudder movements the flight control system is designed to incorporate several redundancy and safety concepts each computer is able to control the aircraft in flight each computer is divided into two physical units which are programmed in two different software languages segregated power supply control source and signaling lanes extensive monitoring within each computer allows detection of failures and controls computers and sensors with the basic configuration no single failure computer electrical system hydraulic system sensors will cause a degradation of the normal functions to flight control data concentrators F CDC's are installed they receive data from ELAC and SEC computers for indication recording and maintenance purposes the F CDC stores the maintenance data and delivers failure indications eg stored failures failure history troubleshooting guidance etc as well as failed LR use to the centralized fault display interface unit CF Diu the F CDC's interface with ECAM system surface position computer status surface status and interface with the d FD are flying parameter recording however the data from both facts is directly sent to the EIS three independent hydraulic systems are used to power all the flight control surfaces the flight control system incorporates ailerons each aileron is powered by two servo controls from independent hydraulic systems in normal operation one servo control is active through the elac the other one being damped surface position indication is displayed on the ekm display unit elevators each elevator is actuated by two independent hydraulic servo controls in normal operation one servo control is active through the ELAC second backup the other is damped in the event of total electrical control loss the servo controls are automatically switched to a centering mode and will hold the surface in the neutral position surface position indication is displayed on the ECAM display unit a trimmable horizontal stabilizer ths for pitch trim the THS is actuated by a failsafe ball screw jack driven by two independently supplied hydraulic motors manual control of the ths is achieved through the interconnected hand wheels located on the Center pedestal on the ground the ths setting must be performed through the manual control as soon as the aircraft is airborne the ths automatically engages in electrical control mode the mechanical control can override the electrical control in case of auto trim runaway automatic pitch trim is achieved with the ths through the ELAC when the auto trim function is engaged any movement of the elevators will be followed by a ths movement in order to align the surfaces for drag reduction fuel saving the ths position indication is displayed on the ECAM display unit and is also indicated in degrees on a scale adjacent to each trim hand wheel a rudder the single piece rudder is actuated by three independently supplied hydraulic servo controls mechanically signaled from the pedals and the yaw damper actuators the rudder position indication is displayed on the ECAM display unit and finally ground spoilers speed breaks each spoiler is driven by a single servo control through one of the three six for redundancy the hydraulic supply from the three systems is distributed among the spoilers servo controls in case of failure detected by the sec the corresponding spoiler retracts automatically and is held in that position the spoiler position indication is displayed on the ECAM display unit now let's introduce the ECAM flight control page you can see that all the flight control surfaces we have talked about are displayed we will now see them in more detail the movements of both ailerons and both elevators are symbolized by a green index moving in front of a white scale the servo control status displayed on the side of the white scale will become amber when the corresponding actuator is not available hydraulic low-pressure electrical control failure computer failure etc ailerons the ailerons are shown in neutral position note the indication below corresponds to the new neutral position when the flaps are extended aileron droop automatic function elevators in case of elevator failure the deflection of the remaining elevator is limited by the computer to avoid excessive asymmetrical loads on the horizontal tail plane or rear fuselage the green rudder symbol is used as an index to display the movements of the rudder on a white scale the servo control status is displayed on top of the rudder indication the rudder trim is indicated by a small blue line below the scale when used the rudder trim will move the neutral point of the rudder surface and change the rudder pedals position the hydraulic systems which actuate each control surface are indicated on the ECAM flight control page by G B and Y for example the rudder is powered by the green blue and yellow hydraulic systems note that the rudder and the pedal deflections are limited via a rudder travel limiter at high speed rudder travel is limited as a function of airspeed the facts control electric motors coupled with a variable stop mechanism the high speed position is indicated by small white ticks on the rudder scale the pitch trim position is indicated by ths deflection and degrees up or down the pitch trim hydraulic motor status is displayed on top of the ths position indication the spoilers have several functions speedbrakes use the three central surfaces on the ekm flight control page the spoiler extended position is indicated by small arrows this is the case for the speed brakes speed brakes are used to decrease the aircraft speed and to increase the rate of descent speed breaks inhibition the computers will automatically retract the speed brakes or keep them retracted in the following conditions aircraft and high angle of attack condition flaps full configuration selected landing computer failure roll spoilers to compliment the ailerons action the roll spoilers are deployed automatically by the computers on the same side as the aileron which is deflected upward they remain retracted on the other wing and proportionately to this aileron deflection the computers are able to mix the speed breaks function with the roll spoilers look at the video carefully roll control uses the four outer surfaces on the video look at the left spoilers as they deploy then at the right ones as the wings are leveled ground spoilers use all surfaces at their maximum deflection the ground spoilers are used to maintain the aircraft on the ground ground lift dumper and to reduce the speed ground spoilers will remain extended during bounces ground spoilers are automatically extended after touchdown or in case of rejected takeoff when specific ground conditions are fulfilled pre selections have to be made through the speed brake control lever located on the Center pedestal they will retract when deselected with the speed brake control lever or one engine thrust lever is advanced above idle position on the video watch all the spoilers deploy a touchdown the status of the LX and sex is indicated on the ekm flight control page the other computers are not displayed pilots control pitch and roll through two side sticks the side stick advantages are improved crew interface system simplification weight and room saving each side stick sends independent electrical signals to the flight controls computers when both side sticks are used at the same time their inputs are algebraically added by the computers when the autopilot is engaged both side sticks are locked in the neutral position by a solenoid system each side stick is fitted with a red push-button which is used for autopilot manual disconnection deactivation of the other stick when this push-button is kept pressed to take priority in case of crew in capacitance or during flight training for rigging purposes the side stick can be held in neutral position by a single rigging pin aileron spoiler elevator servo control adjustments there are associated sidestick priority lights manual control of the ths is achieved through the interconnected hand wheels located on the Center pedestal the trim position is indicated in degrees on a scale adjacent to each trim wheel the normal range is marked by a green band note crew action on the pitch trim wheel does not disconnect the île acts they remain synchronized with the manually selected position following touchdown the pitch trim is automatically reset to zero when the pitch trim is engaged in electrical mode a feedback movement is sent to the wheels via the mechanical Channel there are two sets of conventional rudder pedals these pedals are adjustable for pilot comfort the two sets of pedals are mechanically interconnected when the autopilot is engaged the rudder pedals are locked in neutral position a rudder trim panel is located on the pedestal manual trim orders are received from a switch located on the Center pedestal an automatic reset function is initiated through a push-button switch and allows the trim position to be nulled the position indicator displays the rudder trim direction left or right and value the rudder trim rotary switch is not active when the autopilot is engaged as the rudder trim is controlled by the autopilot system a speed brake lever is located on the left side of the pedestal to select speed brakes the lever has to be pushed down and set to the required position to arm the ground spoilers the lever must be pulled up one in retracted position upon ground spoiler deployment there is no movement of the lever as it is an electrical control in addition there are two panels located on the overhead panel to control the flight control computers switching off then on reset the corresponding computer the ELAC 1 and SEC 1 are normally supplied by the essential bus but can be supplied by the hot bus in case of electrical failure now we will introduce the lift augmentation devices high-lift control is achieved on each wing by five leading edge slats two trailing edge flaps one aileron aileron droop function slots and flaps are driven through similar hydro-mechanical systems consisting of power control units pchew differential gearboxes and torque shafts rotary actuators there are five slots on each leading edge and two flaps on trailing edge note the a321 has double-slotted flaps the slats and flaps power control units are hydraulically actuated they are electrically controlled via two slot flap control computers SFCC the SF CCS monitor the slats and flaps operation through physician pickoff units PP use located on the PC use and at the end of the transmission torque shafts the slats and flaps operate with protection functions such as asymmetry runaway over speed uncommanded movement HFS CC has two channels one for the flaps and one for the slats each channel can drive its associated surfaces the flaps and slats information is shown on the engine warning display the system data acquisition concentrators s tax receive slat and flap positions from feedback PP use through SF CCS to generate appropriate ECAM displays the flap and slot positions are indicated by white dots here the surfaces are extended to the full position this is the flap zero indication notice there is no labeling with this setting the flap lever located on the right side of the pedestal operates the slats and flaps before selection of any position the lever must be pulled out of the detent moreover bulks are provided at position one and three to avoid excessive flap slat travel demand by a single pilot action the flap lever has the following positions zero one two three and full ile AK one sec one fac-1 and FC dc1 are located in rack 83 vu e left by sec - fact - and FC DC - are located in rack 84 vu SFCC one is located in rack 85 vu SFCC two is located in rack 86 vu SEC three is located in rack 93 vu the LX sex and s fcc's bite memories can be read and test triggered on the MTD you through flight control key the facts and data to the CFD I you their bite memories can be read and test triggered through the MCD UAFS menu the LX and six send data to the CFD I you through the F CDC's the s FCC's send data directly to the CFD I you you