Flight Controls Flashcards
The fly-by-wire system was designed and certified to render the new generation of aircraft even more
safe, cost effective, and pleasant to fly.
Flight control surfaces are all :
‐ Electrically-controlled, and
‐ Hydraulically-actuated.
The stabilizer and rudder can also be mechanically-controlled.
Pilots use sidesticks to fly the aircraft in pitch and roll (and in yaw, indirectly, through ___
turn coordination).
However, when in normal law, regardless of the pilot’s input, the computers will prevent excessive maneuvers and exceedance of the safe envelope in pitch and roll axis.
However, as on conventional aircraft, the __ has no such protection.
rudder
___ flight control computers process pilot and autopilot inputs according to normal, alternate, or direct flight control laws.
Seven
FLIGHT CONTROLS COMPUTERS
2 ELACs : (Elevator Aileron Computer)
Normal elevator and stabilizer control. Aileron control.
FLIGHT CONTROLS COMPUTERS
3 SECs : (Spoilers Elevator Computer)
Spoilers control.
Standby elevator and stabilizer control.
FLIGHT CONTROLS COMPUTERS
2 FACs : (Flight Augmentation Computer)
Electrical rudder control.
FLIGHT CONTROLS
COMPUTERS
2 FCDC
Flight Control Data Concentrators (FCDC) acquire data from the ELACs and SECs and send it to
the electronic instrument system (EIS) and the centralized fault display system (CFDS).
Two elevators and the Trimmable Horizontal Stabilizer (THS) control the aircraft in pitch. The maximum elevator deflection is
30 ° nose up, and 17 ° nose down. The maximum THS deflection is 13.5 ° nose up, and 4 ° nose down.
‐ In normal operations, ___ controls the elevators and the horizontal stabilizer, and the green and yellow hydraulic jacks drive the left and right elevator surfaces respectively. The THS is driven by N° 1 of three electric motors.
ELAC2
‐ If a failure occurs in ELAC2, or in the associated hydraulic systems, or with the hydraulic jacks, the system shifts pitch control to
ELAC1. ELAC1 then controls the elevators via the blue hydraulic jacks and controls the THS via the N° 2 electric motor.
‐ If neither ELAC1 nor ELAC2 is available, the system shifts pitch control either to
SEC1 or to SEC2, (depending on the status of the associated circuits), and to THS motor N° 2 or N° 3.
Mechanical control of the THS is available from the pitch trim wheel at any time, if either
the green or yellow hydraulic system is functioning.
Mechanical control from the pitch trim wheel has priority over electrical control.
One aileron and four spoilers on each wing control the aircraft about the roll axis. The maximum deflection of the ailerons is ___
25 °.
The ailerons extend ___ down when the flaps are extended (aileron droop).
The maximum deflection of the spoilers is ___ .
5 ° / 35 °
(The purpose of aileron droop is to use the ailerons as wing flaps. Wing flaps increase the lift generated by the wings at low speed.)
‐ The ___ normally controls the ailerons.
If ELAC1 fails, the system automatically transfers aileron control to ELAC2. If both ELACs fail, the ailerons revert to the ___ .
ELAC 1 / damping mode
(Damping Mode: Servojack follows surface movement.)
‐ SEC3 controls the N° 2 spoilers, SEC1 the N° 3 and 4 spoilers, and SEC2 the N° 5 spoilers. If a SEC fails, the spoilers it controls are ___
automatically retracted.
The flight crew controls the speedbrakes with the speed brake lever. The speedbrakes are
spoilers 2, 3 and 4.
Speedbrake extension is inhibited, if one of the following occurs:
6 points
‐ SEC1 and SEC3 both are faulty, or
‐ An elevator (L or R) is faulty, or
‐ ANGLE-OF-ATTACK PROTECTION IS ACTIVE, OR
‐ FLAPS ARE IN CONFIGURATION FULL (3 or FULL A321) , OR
‐ THRUST LEVERS ARE ABOVE MCT POSITION, OR
‐ ALPHA FLOOR IS ACTIVATED.
If an inhibition occurs when the speedbrakes are extended, they retract automatically and stay retracted until the inhibition condition disappears and the flight crew resets the lever (the speedbrakes can be extended again ___ after the lever is reset).
10 s or more
When the aircraft is flying faster than 315 kt or M 0.75 with the autopilot engaged, the speedbrake retraction rate is reduced (retraction from FULL to CLEAN takes about ___ ).
25 s
The maximum speedbrake deflection in manual flight is:
- 40 ° for spoilers 3 and 4
- 20 ° for spoiler 2.
(A321 The maximum deflection for the spoilers 2, 3 and 4 is 25 °)
The maximum speedbrake deflection with the autopilot engaged is:
- 25 ° for spoilers 3 and 4
- 12.5 ° for spoiler 2.
(A321 The maximum deflection for the spoilers 2, 3 and 4 is 25 °)
For these surfaces (which perform both roll and speedbrake functions) the ___ has priority: When the sum of a roll order and a simultaneous speedbrake order on one surface is more than the maximum deflection available in flight, the symmetric speedbrake on the other wing is retracted until the difference between the two surfaces is equal to the roll order.
roll function
The ground spoiler function involves ___
all spoilers (full extension)
FULL EXTENSION – REJECTED TAKEOFF PHASE
▪ If the ground spoilers are armed and the wheel speed exceeds 72 kt, the ground spoilers will automatically extend as soon as
both thrust levers are reset to idle.
FULL EXTENSION – REJECTED TAKEOFF PHASE
▪ If the ground spoilers are not armed and the wheel speed exceeds 72 kt, the ground spoilers will automatically extend as soon as
reverse is selected on one engine (the other thrust lever remains at idle).
FULL EXTENSION - LANDING PHASE
The ground spoilers will automatically extend when the following conditions are met:
‐ Speed brake lever not in the retracted position or ground spoilers armed and:
‐ Speed brake lever in the retracted position but ground spoilers not armed and:
- Both main landing gears on ground,
- Both thrust levers at or below Idle position, or Reverse selected on at least one engine
(and the other thrust lever below MCT position). - Reverse selected on at least one engine (and the other thrust lever below MCT position).
PARTIAL EXTENSION
In order to accelerate the full spoiler extension, the Phased Lift Dumping (PLD) function allows the ground spoilers to deploy with a reduced deflection.
When landing in crosswind conditions or on contaminated runways.
- One main landing gear on ground,
- Both thrust levers at or below Idle position.
- Reverse selected on at least one engine (and the other thrust lever below MCT position).
PARTIAL EXTENSION
In order to reduce the bounce severity at landing in the case of an inappropriate thrust lever handling during flare, ground spoilers are also partially deployed when the following conditions are met:
‐ Ground spoilers armed,
‐ Both main landing gears on ground,
‐ BOTH THRUST LEVERS AT OR BELOW THE CLIMB POSITION.
The ground spoilers retract:
- After landing, when the ground spoilers are disarmed
- After a rejected takeoff, when the ground spoilers are disarmed
- DURING A TOUCH AND GO, WHEN AT LEAST ONE THRUST LEVER IS ADVANCED ABOVE 20 °.
The yaw damping and turn coordination functions are automatic.
The ___ compute yaw orders for coordinating turns and damping yaw oscillations, and transmit them to the FACs.
ELACs
There is no feedback to the ___ from the yaw damping and turn coordination functions.
rudder pedals
In the case of a failure that causes loss of the Rudder Travel limit system, the rudder deflection limit stops at the last value reached. At ___ , full rudder travel authority is recovered.
slats extension
LOW SPEED vs. HIGH SPEED logic for LOW SPEED MAX RUDDER DEFLECTION
RELATIONSHIP BETWEEN SIDESLIP/RUDDER DEFLECTION/RUDDER PEDAL TRAVEL
Regardless of the aircraft speed, therefore the maximum rudder deflection, full rudder pedal travel remains available. However, except at low speed, maximum rudder deflection is achieved before reaching
maximum rudder pedal travel.
RUDDER TRIM
The two electric motors that position the artificial feel unit also trim the rudder. In normal operation, motor N° 1 (controlled by FAC1), powers the trim, and FAC2 with motor N° 2 remains synchronized as a backup.
In manual flight, the pilot can apply rudder trim via the rotary RUD TRIM switch on the pedestal. The pilot can use a button on the RUD TRIM panel to reset the rudder trim to zero.
With the autopilot engaged, the ___ computes the rudder trim orders. The rudder trim rotary switch and the rudder trim reset pushbutton are not active.
FMGC
The normal flight control laws provides:
‐ Aircraft control on the 3 axis
‐ Flight envelope protection
‐ Alleviation of maneuver loads.
Despite system protections, the PF must not deliberately exceed the normal flight envelope. In addition, these protections are not designed to be
structural limit protections (e.g. opposite rudder pedal inputs).
NORMAL LAW Protection
5 points
Pitch Attitude
Load Factor
High Speed
High Angle of Attack
Bank Angle
LOW ENERGY AURAL ALERT ( IF INSTALLED)
FLIGHT CONTROL SYSTEM - NORMAL LAW
Pitch Control Modes
4 points
Ground Mode
Rotation Mode
Flight Mode
Flare Mode
FLIGHT CONTROL SYSTEM - NORMAL LAW
Lateral Control Modes
2 points
Ground Mode
Flight Mode
Flight > Ground Transition
Once the flight crew set the THR lever to a position more than CLB, the Rotation Mode activate after a transition phase of
2 s.
Ground mode is a direct relationship between sidestick deflection and elevator deflection.
There is no auto trim. The THS is automatically set at 0 ° (inside the green band). However, when the flight crew enters manually a THS setting to adjust the CG, this one has priority for
the take off.
During the take off roll, the system reduces the maximum up elevator deflection from 30 ° to
20 °.
The objective of the rotation mode is to provide a homogeneous rotation for all possible weight, CG and configurations, while minimizing the risk of
a tail strike.
The rotation mode is a pitch rate demand control law, providing tail strike protection.
The flight crew can override the tail strike protection.
The rotation mode depends on:
- The pitch rate
- The tail clearance
- The sidestick position.
The rotation mode is active from 70 kt during takeoff roll until
10 s after lift-off and pitch attitude is above 8 °.
The normal-law flight mode is a ___ mode with automatic trim and protection throughout the flight envelope.
load-factor-demand
With the sidestick at neutral, wings level, the system maintains ___ in pitch (corrected for pitch attitude), and there is no need for the flight crew to trim by changing speed or configuration.
1 g
If the flight crew senses an overcontrol, the sidestick should be released.
Automatic pitch trim freezes in the following situations:
‐ The flight crew enters a manual trim order
‐ The radio height is below 50 ft (100 ft with autopilot engaged) ‐ The load factor goes below 0.5 g
‐ The aircraft is in high-speed or high-Mach protection.
When angle-of-attack protection is active, the THS setting is limited between the setting at entry of the aircraft into this protection and ___ nose down. Neither the flight crew nor the system can apply additional nose-up trim.
4 °
When the load factor is higher than 1.25 g or when the aircraft exceeds 33 ° of bank, the THS setting is limited to values between the current setting and ___ nose down.
3.5 °
The flight crew can also disconnect the autopilot when they push the rudder pedals ( ___ out of trim), or they move the pitch trim wheel beyond a certain threshold.
10 °
CONTROL WITH AUTOPILOT ENGAGED
‐ All protections of normal laws remain effective except
pitch attitude protection.
FLARE MODE A320
When the aircraft passes ___ RA, the THS is frozen and the normal flight mode changes to flare mode as the aircraft descends to land. Flare mode is essentially a ___ relationship
50 ft / direct stick-to-elevator
The system memorizes the aircraft’s attitude at 50 ft, and it becomes the initial reference for pitch attitude control.
FLARE MODE A320
As the aircraft descends through 30 ft, the system begins to reduce the pitch attitude to ___ . Consequently, to flare the aircraft, a gentle nose-up action by the pilot is required.
-2 °nose down over a period of 8 s
FLARE MODE A321
When passing ___ RA, the THS is frozen and the normal flight mode changes to flare mode as the aircraft descends to land.
The flare mode is a direct stick-to-elevator law without ___ , with some damping provided by load factor and pitch rate feedback. The flare law provides full elevator authority.
The flare law does not compensate the ___
100 ft / auto trim / ground or thrust effect