Download - Airbus A320 Flight Controls Laws
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AutopilotAutopilot(Master FMGC)(Master FMGC)
Fly-Through-ComputerFly-Through-ComputerFly-Through-ComputerFly-Through-Computer
FAC 2FAC 2
FAC 1FAC 1
Flight Augmentation Computers
ELAC 2ELAC 2
ELAC 1ELAC 1
ELevator Aileron Computers
SEC 3SEC 3
SEC 2SEC 2
SEC 1SEC 1 Spoiler Elevator Computers
OR
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ELAC 2ELAC 2
ELAC 1ELAC 1
FAC 2FAC 2
FAC 1FAC 1
SEC 3SEC 3
SEC 2SEC 2
SEC 1SEC 1
Fly-Through-ComputerFly-Through-ComputerFly-Through-ComputerFly-Through-Computer
SEC 1 & 2 provide backup THSSEC 1 & 2 provide backup THSand elevator control.and elevator control.
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The flight control laws are the manufacturer’s built in computer instructions defining flight control movement, flight characteristics, and aircraft limitations.
The flight control laws are a series of instructions that are executed by the flight control computers.
For safety and redundancy there are three flight control laws:
• NORMAL LAW
• ALTERNATE LAW
• DIRECT LAW
Mechanical backup control of the THS and rudder is always available.
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Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
PITCHPITCH ROLLROLL YAWYAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
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NORMAL LAWThe flight control law in use during normal operations when
all, or nearly all, aircraft systems are operational.
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Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
=NORMAL==NORMAL= PITCHPITCH ROLLROLL YAWYAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
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=NORMAL==NORMAL= PITCHPITCH
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Load Factor Demand
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LOAD FACTOR DEMAND
Neutral Stick – Requests NO CHANGE in Gs
The flight control computers maintain approximately 1GPitch attitude remains relatively constant.
Aft Stick – Requests a positive G CHANGE
The flight control computers order the elevators to move the required amount to provide the requested G change, resulting in the nose pitching up.
Forward Stick - Requests a negative G CHANGE
The flight control computers order the elevators to move therequired amount to provide the requested G change, resulting in the nose pitching down.
A specific pitch input results in the same G change regardless of the current airspeed.
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=NORMAL==NORMAL= PITCHPITCH
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Load Factor Demand
Automatic Pitch Trim
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The Trimmable Horizontal Stabilizer (THS) is trimmed up or down to provide pitch trim.
The THS is a much more active part of the pitch control system on the Airbus than on many other aircraft.
When a G change (pitch change) is commanded, the elevatorsinitially move to provide the commanded change.
If the desired pitch attitude requires the elevators to remaindisplaced, THS movement is commanded until the elevatorsare centered with the THS. Pilot manual pitch trim inputs are not required.
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=NORMAL==NORMAL= PITCHPITCH
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Load Factor Demand
Automatic Pitch Trim
Ground ModeFlight ModeLanding Mode
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GROUND MODE OF NORMAL LAW
A direct stick to flight control relationship exists.
This enables the pilot to:• Check the flight controls • Rotate the aircraft for takeoff
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FLIGHT MODE OF NORMAL LAW
• Load factor demand in pitch • All protections are available
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LANDING MODE OF NORMAL LAW
The landing mode was created to give the flare and touchdown a “conventional feel”.
At 50 feet AGL (measured by the RAs) the ELACs memorize the pitch attitude
At 30 feet AGL the ELACs add a gentle nose down command to the memorized pitch attitude, which the pilot counters with an aft stick input.
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=NORMAL==NORMAL= PITCHPITCH
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Load Factor Demand
Automatic Pitch Trim
Ground ModeFlight ModeLanding Mode
Maneuver Protection
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Maneuver protection prevents aircraft damage due to overstressing the aircraft. The flight control computers prevent flight control surface movement that would cause the aircraft to exceed preset G limits.
NOTE: MAX = +2.0G IF FLAPS EXTENDED
NOTE: MAX = 0.0G IF FLAPS EXTENDED
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=NORMAL==NORMAL= PITCHPITCH
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Load Factor Demand
Automatic Pitch Trim
Ground ModeFlight ModeLanding Mode
Maneuver ProtectionPitch Protection
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NO FLY
NO FLY
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=NORMAL==NORMAL= PITCHPITCH
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Load Factor Demand
Automatic Pitch Trim
Ground ModeFlight ModeLanding Mode
Maneuver ProtectionPitch Protection
High Speed Protection
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High speed protection prevents aircraft damage High speed protection prevents aircraft damage due to excessive speed.due to excessive speed.
A gentle pitch up is produced by the flight control computers to limit further acceleration
Acceleration is limited even if full forward stick is applied.
If high speed protection activates, automatic pitch trim in the nose down direction is deactivated and the autopilot, if engaged, disengages.
Activates just above Vmo/Mmo
VMO / MMO
High speed protection activation
It is always possible to overspeed the aircraft. The fight control computers merely limit the maximum attainable speed to within safe limits.
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=NORMAL==NORMAL= PITCHPITCH
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Load Factor Demand
Automatic Pitch Trim
Ground ModeFlight ModeLanding Mode
Maneuver ProtectionPitch Protection
High Speed Protection
Angle of Attack Protection
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(ALPHA) = Angle of Attack = the angular difference between the relative wind and the attitude of the aircraft
Relative Wind
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= The angle of attack where the flight control computers intervene to prevent alpha fromreaching a stall alpha.
At Alpha Prot:
• Pitch command logic changes from load factor demand to commanding an angle of attack.
• Additional nose up trim is inhibited - nose down trim is still available.
• The autopilot, if engaged, disengages.
• A lowering of pitch attitude occurs.
If the pilot persists and pulls the stick further aft, eventuallythe angle of attack will reach . . . . . . . . .
Alpha Prot
VLS
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= The highest angle of attack that the ELACs will allow.
ALPHA MAX is a lower alpha than ALPHA STALL; therefore, it is nearly impossible to stall the aircraft in normal law.
If autothrust is available, the airspeed is unlikely to reach Alpha Max because Alpha Floor will probably activate prior to reaching it.
NOTE: Although the FACs continuously compute the airspeeds corresponding with the various alpha protection values and display them on the airspeed tape, these speeds are for pilot reference only.
The actual angles of attack that correspond with Alpha Prot and Alpha Max are computed by the ELACs based on angle of attack, not airspeed.
Alpha Prot
Alpha Max
VLS
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Alpha Floor:
Is a predictive function of the autothrust system. It activates based on the current trend if it predicts thrust will be required.
Is normally available from immediately after takeoff throughout the flight down 100 feet RA in configuration 1 or greater.
Is only available in normal law.
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Excessive high angles of attackIndirectly as a result of
windshear
Excessive high nose up attitudes combined with specific
sidestick inputs
Alpha floor uses the autothrust system to automatically provide TOGA thrust if any of the following conditions occur:
• Excessive high angles of attack.
• Indirectly as a result of windshear.
• Excessive nose up attitudes combined with specific sidestick inputs.
Alpha Floor is predictive and can be triggered at any airspeed; therefore it is NOT depicted on the airspeed tape.
It is independent of Alpha Prot and Alpha Max. In other words, Alpha Floor can be triggered at airspeeds significantly higher than Alpha Prot.
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A. FLOOR
If Alpha Floor activates, TOGA thrust is automatically applied, regardless of thrust lever position.
Alpha Floor activation DOES NOT require that autothrust be ENGAGED, but it must be AVAILABLE (i.e., operational).
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Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
=NORMAL==NORMAL= PITCHPITCH ROLLROLL YAWYAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
Load Factor Demand
Automatic Pitch Trim
Ground Mode
Flight Mode
Landing Mode
Maneuver Prot
Pitch Protection
Hi Speed Prot
of Attack Prot
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=NORMAL==NORMAL= ROLLROLL
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Roll Rate
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Neutral Stick – Requests zero roll rate.
The aircraft essentially maintains the currentbank angle.
ROLL RATE
Full Stick Deflection – Requests 15 / sec roll rate.
Stick Slightly Left / Right of Center- Requests a between 15 and 0 / sec roll rate.
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=NORMAL==NORMAL= ROLLROLL
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Roll Rate
Pitch Trim < 33
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Automatic pitch trim is available up to 33 of bank to assist the pilot in maintaining altitude during turns.
33 to 67
Beyond 67
NO FLY
33 to 67
0 to 33 0 to 33
Automatic pitch trim is available
Automatic pitch trim is available
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=NORMAL==NORMAL= ROLLROLL
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Roll Rate
Pitch Trim < 33
Bank Angle Hold < 33
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33 to 67
Beyond 67
NO FLY
33 to 67
0 to 33 0 to 33
If the stick is released to neutral, a 0 / second roll rate is commanded.
The aircraft essentially maintains a constant bank angle, unless commanded otherwise.
“Bank angle hold” 0-33°
“Bank angle hold” 0-33°
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=NORMAL==NORMAL= ROLLROLL
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Roll Rate
Pitch Trim < 33
Bank Angle Hold < 33
Positive Spiral Stability > 33
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33 to 67
Beyond 67
NO FLY
33 to 67
0 to 33 0 to 33
If the bank angle exceeds 33 and the stick is released, bank angle returns to 33.
This called positive spiral stability.
Positive spiral stability
NOTE: Positive spiral stability returns the bank angle to 0° if high speed protection is active.
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=NORMAL==NORMAL= ROLLROLL
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Roll Rate
Pitch Trim < 33
Bank Angle Hold < 33
Positive Spiral Stability > 33
BANK ANGLE PROTECTION
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33 to 67
Beyond 67
NO FLY
33 to 67
0 to 33 0 to 33
Bank angle protection
In normal, the flight control computes will not allow bank angles in excess of 67.
NOTE: Bank angle is limited to 45° if high speed protection or angle of attack protection is active (the limit marks do not move).
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Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
=NORMAL==NORMAL= PITCHPITCH ROLLROLL YAWYAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
Load Factor Demand
Automatic Pitch Trim
Ground Mode
Flight Mode
Landing Mode
Maneuver Prot
Pitch Protection
Hi Speed Prot
of Attack Prot
Roll Rate
Pitch Trim
Bank Angle Hold
Pos Spiral Stab
Bank Angle Protection
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=NORMAL==NORMAL= YAWYAW
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Turn Coordination
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Yaw orders associated with bank are…
ELAC 2ELAC 2
ELAC 1ELAC 1
…processed by the ELACs then...
The FACs direct the rudder to rudder’shydraulic servos to move the rudder.
Turn coordination is automatic, requiring no pilot rudder input.
There is no rudder pedal movement resulting from turn coordination.
FAC 2FAC 2
FAC 1FAC 1
…transmitted to the FACs.
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=NORMAL==NORMAL= YAWYAW
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Turn Coordination
Yaw Damping
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YAW DAMPINGYAW DAMPING
Two yaw dampers are installed.
A yaw damper moves the entire rudder as necessary to dampen yaw oscillations.
Either yaw damper is capable of providing full yaw damping authority.
There is no rudder pedal movement resulting from yaw damping.
Yaw DampActuators
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=NORMAL==NORMAL= YAWYAW
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Turn Coordination
Yaw Damping
Rudder Trim
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RUDDER TRIM RUDDER TRIM
Rudder trim commands are sent from the FACs to one of two rudder trim motors which move the entire rudder surface. Trim tabs are not used.
When an autopilot is engaged, rudder trim needs are computed by the FACs and automatically carried out. Manual rudder trim is deactivated.
With the autopilots off, the rudder may be trimmed using the RUD TRIM knob on the pedestal.
As the rudder is trimmed (either manually or automatically), the rudder pedals ARE symmetrically displaced.
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=NORMAL==NORMAL= YAWYAW
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Turn Coordination
Yaw Damping
Rudder Trim
Manual Rudder (HYD)
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Backup mechanical control of the rudder is always available via cables from the rudder pedals to the rudder servos if at least one hydraulic system is available.
Rudder Pedals
Mechanical Connection
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=NORMAL==NORMAL= YAWYAW
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Turn Coordination
Yaw Damping
Rudder Trim
Manual Rudder (HYD)
Rudder Limiting
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RUDDER LIMITINGRUDDER LIMITINGThe FACs, using airspeed inputs from the ADRs, limit rudder surface movement at high speeds to prevent excessive airframe loads and yaw responses.
The two rectangular symbols on the rudder travel indication represent the unrestricted rudder travel limit at low speeds.
NOTE: On some Spirit aircraft the high speed rudder travel limit depiction on the F/CTL page is fixed and does not move with changes in the rudder travel limit.
The maximum rudder travel available at the current speed is indicated by small L shaped indications next to the rudder travel arc.
Rudder PEDAL travel is never restricted. Only rudder SURFACE travel.
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Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
=NORMAL==NORMAL= PITCHPITCH ROLLROLL YAWYAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
Load Factor Demand
Automatic Pitch Trim
Ground Mode
Flight Mode
Landing Mode
Maneuver Prot
Pitch Protection
Hi Speed Prot
of Attack Prot
Roll Rate
Pitch Trim
Bank Angle Hold
Pos Spiral Stab
Bank Angle Protection
Turn Coordination
Yaw Damping
Rudder Trim
Manual Rudder
Rudder Limiting
x ALTERNATE x
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ALTERNATE LAWA single failure WILL NOT cause the flight control system to degrade
from NORMAL to ALTERNATE LAW.
A minimum of TWO or MORE failures must occur for the flight controls to degrade from NORMAL LAW, usually in the following systems:
x x
Flight Control Computers
SEC 3ELAC 2
ELAC 1
FAC 2
FAC 1SEC 2
SEC 1
Hydraulic Systems
AADD
IIRR
AADD
IIRR
AADD
IIRR
ADIRUs
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Two failures may not cause the flight control system to degrade.
For example:
The aircraft remains in normal law and the autopilots are operational.
SEC 3ELAC 2
ELAC 1
FAC 2
FAC 1SEC 2
SEC 1
ALTERNATE LAWx x
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F / CTL ALTN LAW (PROT LOST) MAX SPEED . . . . . . . . . . . . . . 320 KT
This statement ismisleading.
X X
ALTERNATE LAWx x
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Load Factor Demand
Automatic Pitch Trim
Ground Mode
Flight Mode
Landing Mode
Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
PITCHPITCH ROLLROLL YAWYAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
Maneuver Prot
Pitch Protection
Hi Speed Prot
of Attack Prot
Roll Rate
Pitch Trim
Bank Angle Hold
Pos Spiral Stab
Bank Angle Protection
Turn Coordination
Yaw Damping
Rudder Trim
Manual Rudder
Rudder Limiting
x ALTERNATE x
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x ALTERNATE x PITCHPITCH
Flight CharacteristicsFlight Characteristics
ProtectionsProtections
Load Factor Demand
Automatic Pitch Trim
Flight Mode
Maneuver Protection
High Speed Protection
of Attack Protection
Stability
Lo Speed Stability
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Stabilities are flight control commands that smoothly attempt to change pitch to prevent an overspeed or a low speed (stall) condition.
Pilots can manually override either stability with stick movement, causing an or a to occur.
activates at a speed slightly below VMO/MMO.
activates if the speed decreases to within a few knots of the stall warning.
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Load Factor Demand
Automatic Pitch Trim
Flight Mode
Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
PITCHPITCH ROLLROLL YAWYAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
Maneuver Prot
Hi Speed Stab
Lo Speed Stab
Roll Rate
Pitch Trim
Bank Angle Hold
Pos Spiral Stab
Bank Angle Protection
Turn Coordination
Yaw Damping
Rudder Trim
Manual Rudder
Rudder Limiting
x ALTERNATE x
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Load Factor Demand
Automatic Pitch Trim
Flight Mode
Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
PITCHPITCH YAWYAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
Maneuver Prot
Hi Speed Stab
Lo Speed Stab
Turn Coordination
Yaw Damping
Rudder Trim
Manual Rudder
Rudder Limiting
ROLLROLL
ROLL DIRECTA direct stick to flight control surface relationship in roll
x ALTERNATE x
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Load Factor Demand
Automatic Pitch Trim
Flight Mode
Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
PITCHPITCH YAWYAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
Maneuver Prot
Hi Speed Stab
Lo Speed Stab
Yaw Damping
Rudder Trim
Manual Rudder
Rudder Limiting
USE MAN PITCH TRIM
*
*Assuming a double FAC failure was not the cause of the degradation.
x ALTERNATE x x DIRECT x ROLLROLL
ROLL DIRECTA direct stick to flight control surface relationship in roll
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x DIRECT LAW xx DIRECT LAW x
It is possible for the flight control system to degrade from
NORMAL law straight to DIRECT law (e.g., dual radar altimeter
failure).
The primary reason that DIRECT law is reached is because
the aircraft is in ALTERNATE law and the landing gear is
lowered in preparation for landing.
Why?
Because ALTERNATE law does not provide a landing mode.
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DIRECT law results in a direct stick to flight control surface
relationship. What does that really mean?
Stick inputs are still processed by the flight control computers
and transferred to the flight control surfaces.
The computers, however, carry out pilot orders exactly as they
are signaled.
Unlike NORMAL or ALTERNATE laws, the computers have no
authority to modify or override the stick inputs, thus NO
protections OR stabilities are provided.
x DIRECT LAW xx DIRECT LAW x
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USE MAN PITCH TRIM
F / CTL DIRECT LAW (PROT LOST)MAX SPEED . . . . . . . . 320 KT/ .77MANEUVER WITH CAREUSE SPEED BRAKE WITH CARE
This statement is more accurate.
No pitch or roll protections are provided in DIRECT law.
x DIRECT LAW xx DIRECT LAW x
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Load Factor Demand
Automatic Pitch Trim
Flight Mode
Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
PITCHPITCH YAWYAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
Maneuver Prot
Hi Speed Stab
Lo Speed Stab
Yaw Damping
Rudder Trim
Manual Rudder
Rudder Limiting
USE MAN PITCH TRIM
x DIRECT x ROLLROLL
ROLL DIRECTA direct stick to flight control surface relationship in roll
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Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
YAWYAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
Yaw Damping
Rudder Trim
Manual Rudder
Rudder Limiting
USE MAN PITCH TRIM
x DIRECT x ROLLROLL
ROLL DIRECTA direct stick to flight control surface relationship in roll
PITCHPITCH
PITCH DIRECTA direct stick to flight control relationship in pitch.
Manual THS Input
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Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
YAWYAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
Yaw Damping
Rudder Trim
Manual Rudder
Rudder Limiting
USE MAN PITCH TRIM
x DIRECT x ROLLROLL
ROLL DIRECTA direct stick to flight control surface relationship in roll
PITCHPITCH
PITCH DIRECTA direct stick to flight control relationship in pitch.
Manual THS Input
Mech. Backup
MAN PITCH TRIM ONLY
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Mechanical BackupMechanical Backup
Mechanical backup control of the THS and rudder is always
available.
Mechanical backup is the only way to maintain aircraft control if
all the flight control computers fail or there is a TOTAL loss of
electrical power.
It either occurs, the sidesticks are inoperative and the aircraft is
controlled using the trim wheels, rudder pedals, and engine
thrust.
Mechanical backup provides a means of aircraft control until a
higher law can be restored.
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No ECAM message specifically indicates that mechanical backup is active.
X X
Mechanical BackupMechanical Backup
F/CTL L + R ELEV FAULT MAX SPEED. . . . . . . . . . . 320/.77 - MAN PITCH TRIM . . . . . . . . USE - SPD BRK . . . . . . . . DO NOT USE
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PITCHPITCH
Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
YAWYAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
Manual Rudder
ROLL DIRECTA Direct Stick to Flt Control Surface Relationship in Roll
Manual THS Input
MAN PITCH TRIM ONLY
Mech. Backup ROLLROLL
PITCH MECHANICAL
PITCH
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Flight Control LawsFlight Control LawsFlight Control LawsFlight Control Laws
YAW
FLIGHT CHARACTERISTICS
FLIGHT CHARACTERISTICS
PROTECTIONSPROTECTIONS
LAW: A predetermined set of rules which govern flight characteristicsLAW: A predetermined set of rules which govern flight characteristics
Manual Rudder
Manual THS Input
YAW MECHANICAL
YAW
PITCH MECHANICAL
PITCH
MAN PITCH TRIM ONLY
Mech. Backup
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If extreme conditions cause the aircraft to leave the protected envelope (e.g. severe turbulence), and exceed a normal law limit, abnormal attitude law becomes active.
Abnormal attitude law is alternate law without protections and stabilities except for load factor protection.
This is a safety feature to ensure that the flight control computers never prevent the pilots from recovering from an abnormal attitude.
After recovery, the flight controls remain in alternate law without protections but with auto trim. There is no reversion to direct law when the gear is extended.
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Flight Control System Page Flight Control System Page Flight Control System Page Flight Control System Page
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Flight Control System Page Flight Control System Page Flight Control System Page Flight Control System Page
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