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Title: Flight Controls Note Part 3
Description: EASA PART 66 MODULE 11 - FLIGHT CONTROLS NOTES PART 3
Description: EASA PART 66 MODULE 11 - FLIGHT CONTROLS NOTES PART 3
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3/15/2014
Trim Tabs Controls
• Rotation of Hand wheel (trim wheel) in the
cockpit move control cables
• Control cables rotate screw jack assembly
• Screwjack extend or retract a push pull rods
that move the trim tab
...
• Q FEEL IS USED TO PREVENT THE AIRCREW FROM
DAMAGING THE AIRCRAFT BY PULLING EXCESSIVE G
FORCES
...
• Increase the control column centralising forces in
proportion to the square of the airspeed
...
• Simple feel unit consist of spring catridges as centering
mechanism and opposing force as feel
• More advance spring feel system can compensate the
spring forces porpotional to the changes in airspeed
• Hydraulic “Q” feel system use hydraulic forces to create
feel
MECHANICAL Q FEEL
MECHANICAL Q FEEL IS DONE THROUGH A SPRING FEEL
UNIT
...
WITH THIS SYSTEM HOWEVER THE EFFECTIVE FORCE
PROVIDED BY THE SPRING UNIT IS ADJUSTED FOR A
GIVEN AIRSPEED
...
4
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MECHANICAL Q FEEL
THE BELLCRANK LEVER ATTACHES TO A SLOTTED
“BANANA SLOT” LEVER WHICH IS DIRECTLY CONNECTED
TO THE FLYING CONTROL RODS AT ONE END AND THE
SPRING FEEL UNIT AT THE OTHER
...
A FOLLOW UP POTENTIOMETER PROVIDES A FEEDBACK
TO THE AIRSPEED SENSOR WHEN THE ACTUATOR
REACHES THE REQUIRED POSITION
...
THIS MOVEMENT SHORTENS THE DISTANCE FROM THE
FULCRUM ARM ROLLER TO THE SPRING RELATIVE TO
THE CONTROL RODS
...
AS THE AIRSPEED INCREASES THE FULCRUM ARM
MOVES FURTHER AWAY FROM THE SPRING UNIT GIVING
MORE FEEL TO THE SYSTEM
...
THE PRINCIPLE OF OPERATION IS THAT THE PRESSURE OF THE
HYDRAULIC FLUID WITHIN THE FEEL SERVO JACK IS
PROPORTIONAL TO THE AMOUNT OF FORCE NECESSARY AT
THE STICK TO OVERCOME IT
...
WITHIN THE SERVO, PITOT STATIC PRESSURES ARE FED TO
EITHER SIDE OF A FLEXIBLE DIAPHRAGM
...
AT ZERO AIRSPEED THE SERVO VALVE PISTON WILL BE
FULLY UP AS THERE WILL BE NO PITOT PRESSURE ACTING
AGAINST IT
...
HYDRAULIC Q FEEL
AS AIRSPEED INCREASES THE DOWWARDS FORCE ON THE
DIAPHRAGM ALSO INCREASES
...
THIS INCREASED EFFORT GIVES THE SYSTEM THE FEEL AND
THIS FEEL INCREASES IN PROPORTION TO THE SQUARE OF
THE AIRSPEED
...
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HYDRAULIC Q FEEL
MACH
CORRECTION
CAPSULE
PITOT
DIAPHRAGM
STATIC
EXHAUST
CONTROL
COLUMN
PRESSURE
INLET
INPUT TO PFCU
Q FEEL JACK
MACH CORRECTION
THE CAPSULE IS SEPARATED BY A DIAPHRAGM WITH
PITOT AND STATIC PRESURES ACTING ON IT
...
A LINK CONNECTS TO THE CAPSULE WHICH ACTS
AGAINST THE SERVO VALVE
...
8
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MACH CORRECTION
AS THE CRITICAL MACH NUMBER IS REACHED THE PITOT
PRESSURE INCREASES IN RELATION TO THE STATIC
...
THE MACH CAPSULE EXPANDS CAUSING THE LINKAGE TO
PUSH UP THE SERVO VALVE
...
MACH TRIM
AS THE AIRCRAFT APPROACHES THE CRITICAL MACH
NUMBER CHANGES TO THE CENTER OF PRESSURE, LIFT
AND DRAG WILL CAUSE PITCH CHANGES, NORMALLY
NOSE DOWN
...
THE MACH TRIM SYSTEM WILL NORMALLY OPERATE IN
THE SPEED RANGE MACH 0
...
84
...
INDICATOR LIGHTS ON THE INSTRUMENT PANEL INDICATES THAT
THE SYSTEM IS WORKING OR IS FAULTY
...
A MACH TRIM CONTROLLER IS SUPPLIED WITH HEIGHT AND
AIRSPEED SIGNALS FROM THE PITOT STATIC SYSTEM AND
GENERATES CONTROL SIGNALS TO THE TRIM ACTUATOR WHICH
ADJUSTS THE TAILPLANE INCIDENCE TO KEEP THE AIRCRAFT
STRAIGHT AND LEVEL
...
THE SYSTEM ENSURES THAT ONLY ONE OF THE ACTUATORS
IS DRIVING AT ANY ONE TIME
...
IT IS OFTEN CONNECTED TO THE TAILPLANE TRIM WHEELS
TORQUE SHAFT BY A CHAIN LINK
...
THE SYSTEM BECOMES ACTIVE AS SOON AS THE AIRCRAFT
ENTERS THE MACH TRIM SPEED RANGE
...
IT THEN RE-ENGAGES WHEN THE TRIM WHEELS ARE
RELEASED
...
68
MOTOR
AMPLIFIER
ALTITUDE AND
MACH SENSOR
MACH NUMBER
TRANSMITTER
MACH TRIM CONTROLLER
12
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RUDDER LIMITING
• Use at high speed to limit rudder travel
• Reduce aerodynamic loading to prevent structural
damage
• Use a “Q” Limiter to restrict rudder movements
RUDDER LIMITING STOP
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RUDDER LIMITING
• The stepped stop extends into a clawed stop on the
rudder
...
• As airspeed increases caused the stepped stop to extend
into the claw stop
...
YAW DAMPER
The yaw damper is used to improved directional stability
To prevent “dutch roll”
...
Yaw damper system differ from one aircraft to another
...
14
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GUST LOCKS
A GUST LOCK SYTEM IS USED TO LOCK THE PRIMARY
FLIGHT CONTROL SURFACES IN A NEUTRAL POSITION
FOR TOWING, TAXIING, PARKING OR MOORING THE
AIRCRAFT
...
EACH SECTION WILL INCORPORATE A SOLENOID WEIGHT
ON WHEELS LOCK (SNIB) WHICH PREVENTS THE LOCKS
FROM ENGAGING IN FLIGHT
GUST LOCKS
WHEN THE CONTROLS ARE SELECTED “LOCKED” ON THE
GROUND A THROTTLE INTERLOCK IS ALSO ENGAGED TO
LIMIT THE ENGINE POWER DURING TAXIING
...
W
...
WHEN THE CONTROLS ARE GROUND LOCKED
...
IN THIS
CONDITION THE SOLENOID STRUT WILL ENGAGE INTO
THE “LOCK” SELECTOR LEVER AND PREVENT IT FROM
BEING OPERATED
...
ON THE GROUND SELECTION OF THE LOCK LEVER WILL
ENERGISE AN ELECTRICAL LOCK ACTUATOR
...
WHEN THE CONTROLS ARE IN THE NEUTRAL POSITION THE LOCK
PINS ENGAGE IN THE LOCK STRUTS
...
CONTROL LOCK
CONTROL BELLCRANK
LOCK STRUT
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GUST LOCK
17
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GUST LOCK
GUST LOCK
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GUST LOCK
Rigging and Balancing Controls
Rigging – Introduction
• Truing and checking the flight control system to ensure
they are working correctly
• Objective is to ensure cockpit controls and control
surfaces are both in neutral
• Pilot’s control in correct relationship with the control
surfaces
• Control surfaces move in the correct sense and to it’s
max travel position in either direction
• Cable tension within acceptable limits
• Friction in the system within acceptable limits
19
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When do you perform flight control
riggings?
• After assembly in the factory
• As specified by the manufacturer or operators’
maintenance schedule
• Once the control system has been disturbed
(i
...
after component change or controls
system adjustment)
• Flight control related defects as reported by
pilot
• Hard landing
Checks Before Rigging
• No obstruction around control surfaces and
warn maintenance personnel working in the
vicinity
• Put aircraft in rigging position- level aircraft as
necessary
• Ensure all parts of the control systems are
serviceable
20
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Rigging Procedure
• All control systems are peculiar to each
aircraft type
• Always refer to the latest applicable
maintenance manual before you proceed in
any rigging tasks
• Observe all applicable safety warnings in the
AMM and aircraft placards
• Refer to the correct configuration or
modification status
Establishing Neutral Setting
• Lock cockpit control in neutral
• By means of rigging pins
• Sometimes leveling bar required on control
column to neutralize aileron
• In absence of rigging pin holes, rudder pedal can
be neutralized by clamping a straight bar across
the pedals
• Generally control surface in neutral position are
usually fair with the main or adjacent surface
• Some ailerons are set in droop position
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Bellcrank locking tool for rigging
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Straight edge tool to lock aileron
9
...
3
...
• Reinsert all the rigging pins again to ensure they
fit in easily
• This steps ensure the system had been adjusted
satisfactorily
• Finally, ensure ALL the rigging pins are removed
after completion of the task, failure to do so may
cause damage to the aircraft and injury or death
to personnel
Rigging Pins
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Using a Tensiometer
1
...
3
...
5
...
17
...
17
...
THE STOPS MAY BE PHYSICAL STOPS WITHIN THE CONTROL
RUN OR WITHIN THE HYDRAULIC SERVO JACK
...
CONTROL STOPS
THE SERVO JACK STOPS COULD BE THE FULLY EXTENDED
OR RETRACTED RAM POSITIONS
...
IN POWERED CONTROL SYSTEMS THE CONTROL STOPS
ARE NORMALLY FOUND ON THE CONTROLS FROM THE
CONTROL COLUMN THUS LIMITING THE SYSTEM
MOVEMENT FROM THAT POSITION
...
Align the zeroes
2
...
3
...
4
...
5
...
6
...
7
...
8
...
9
...
Aileron Travel Check Video
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9
...
6 Checking For Static and Running Friction
• Minimum Breakout
Force
• Running Friction
• Check for proper
lubrication, seize
or worn pulleys,
cable binding or
chafing, abnormal
wear and tear
Fitting Protractor to Control Column
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9
...
7 Checks After Rigging
• All rigging pins removed
• Turnbuckles, control rods, end fittings, limit stop
secured and wire-locked
...
17
...
• AN 51 (Malaysia DCA)
– A duplicate inspection of all control systems in an aircraft shall be
made after initial assembly and before a Certificate of Release to
Service has been issued after overhaul, repair, replacement,
modification or adjustment and in any case before the first flight
...
Carry out checks before rigging per AMM 27-xx-xx
...
Slacken control cable throughout the system
...
Lock’s the pilot column in neutral and ensure that the
control chains shown are equally disposed around the
top and bottom sprockets
...
Set the aileron operating sprockets to neutral using
rigging pins as necessary
...
Ensure that the chains are correctly positioned and then
adjust the turnbuckles evenly to tension the control
cables; a tension meter may or may not be required to
check the cable tension, depending on whether or not
the system is a regulated one
...
Adjust the operating rods until the ailerons are in line
with the trailing edge of the main plane or as specified (
or the neutral setting on the setting gauge if one is
provided)
...
Remove the control column locking device and also the
rigging pins, if fitted
...
Operate the ailerons, checking for freedom of
movement and that they move in the correct sense
relative to the control column movement
...
Measure the range of movement of the ailerons and
adjust the limit stops until the range is as specified in
the maintenance manual
...
10
...
11
...
12
...
Flight Control Cable/Chain
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Example of Rigging
Tube Operated Control System
1
...
2
...
3
...
4
...
5
...
Example of Rigging
Tube Operated Control System
6
...
Remove the cockpit control locking device and rigging
pins
...
Operate the control, checking for freedom of
movement and that it moves in the correct sense in
relation to the control surface
...
Measure the range of movement and, as necessary,
adjust the limit stops
...
Check the system for friction
...
Carry out the necessary checks after rigging
...
Carry out duplicate inspection
...
Disconnect all control tubes and set the pilot’s control
to neutral
...
2
...
Continue to build up the system in the cockpit,
connect various control tubes to their corresponding
lever, adjusting as necessary; fit the subsidiary pins in
their correct positions, locking the levers in neutral
...
Set the control lever on the cable tension
regulator vertical by inserting a subsidiary pin
...
Set the artificial units as describe in the AMM
...
Set the trim actuator to neutral and connect to
the artificial feel unit
...
Fit the control cables to the cable tension
regulator, and run the cables around their
pulleys
...
Connect the cables to the tie rods and feed the
cables around their pulleys to the rear part of
the fuselage
...
Connect the cables to the cable quadrant and to their respective
tie rods
...
Set the cable quadrant to neutral by inserting a subsidiary rigging
pin
...
The yaw damper can now be connected into the system, control
tubes connecting this unit to the cable quadrant and to the PFCU
...
Adjust the system as necessary per AMM
...
Connect the link rod to the rudder operating lever and adjust as
necessary
6
...
7
...
8
...
Carry our the necessary checks after rigging
...
Carry our duplicate inspection
Example of Rigging
Trim Tab System
1
...
2
...
3
...
4
...
5
...
6
...
7
...
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Example of Rigging
47
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B727 Rudder Rigging
Tension Regulator
48
Title: Flight Controls Note Part 3
Description: EASA PART 66 MODULE 11 - FLIGHT CONTROLS NOTES PART 3
Description: EASA PART 66 MODULE 11 - FLIGHT CONTROLS NOTES PART 3