Ata Chapter 27 Flight Controls

Dornier 328DORNIER LUFTFAHRT TRAINING MANUAL

LINE /BASE MAINTENANCE

Effectivity: - FOR TRAINING PURPOSES ONLY - Page: 27-1328-100 Mod.10 Issue: 08/95 ETM/ETX

TM-Flight Controls

ATA CHAPTER 27 FLIGHT CONTROLS

27-00 GENERAL 8GENERAL ................................................................................................................................................ 8

Primary Flight Controls......................................................................................................................... 9Secondary Flight Controls..................................................................................................................... 9Spoilers.................................................................................................................................................. 9Stall Warning and Prevention................................................................................................................ 9Gust Lock .............................................................................................................................................. 9

27-10 AILERON CONTROLS AND TRIM 10General ................................................................................................................................................ 10Aileron Controls.................................................................................................................................. 11Aileron Trim........................................................................................................................................ 11

INTERFACE TO OTHER SYSTEMS ................................................................................................... 11Roll Spoiler System............................................................................................................................. 11Indicating/Recording Systems............................................................................................................. 11Autoflight ............................................................................................................................................ 11

AILERON CONTROLS 12FUNCTIONAL DESCRIPTION ............................................................................................................ 12

LH and RH Control Wheels ................................................................................................................ 13Control Cables..................................................................................................................................... 13Pulleys ................................................................................................................................................. 14LH and RH Cable Tension Regulators................................................................................................ 14LH and RH Transition Units ............................................................................................................... 15Aileron Disconnect Unit...................................................................................................................... 15Quadrant Assembly ............................................................................................................................. 16Levers and Bellcranks ......................................................................................................................... 17Control Rods........................................................................................................................................ 17Aileron Disconnect Microswitch 7CW............................................................................................... 18LH and RH Aileron Position Transmitters 5CX and 4CX.................................................................. 18

OPERATION(refer to Fig. 3, Fig. 5, Fig. 7)........................................................................................... 18Power Supplies.................................................................................................................................... 18Aileron Controls.................................................................................................................................. 18Flight Compartment Controls.............................................................................................................. 18Flight Compartment to Upper Center Fuselage Control Run.............................................................. 18Regulation of Cable Tension in Fuselage Control Run....................................................................... 18Aileron Controls from Transition Units to Wing Roots...................................................................... 19Aileron Controls from Wing Root to Aileron ..................................................................................... 19

Dornier 328TRAINING MANUAL DORNIER LUFTFAHRTLINE /BASE MAINTENANCE

Page: 27-2 - FOR TRAINING PURPOSES ONLY - Effectivity:Issue: 08/95 ETM/ETX 328-100 Mod.10

TM-Flight Controls

RH Aileron Servo Tab .........................................................................................................................20LH Aileron Trim/Servo Tab ................................................................................................................20

SYSTEM INDICATIONS.......................................................................................................................21Aileron Position Indicating ..................................................................................................................21Aileron Disconnect Unit Monitoring ...................................................................................................21

AILERON TRIM 23FUNCTIONAL DESCRIPTION.............................................................................................................23

Aileron Trim Actuator 4CC (refer to Fig. 9) .......................................................................................23Trim Control Panel 10CC ....................................................................................................................24Main Aileron Trim Switch 2CC...........................................................................................................24Standby Aileron Trim Switch 12CC....................................................................................................25Aileron Trim Reset Switch/Light 17CC ..............................................................................................25Trim Test Switch 50CC .......................................................................................................................25

OPERATION...........................................................................................................................................25Power Supplies.....................................................................................................................................25System Power-Up ................................................................................................................................25Aileron Trim ........................................................................................................................................28

SYSTEM INDICATIONS.......................................................................................................................31Standby Trim/Main Lockout Circuit Status.........................................................................................31

27-20 RUDDER CONTROLS AND TRIM 32GENERAL...............................................................................................................................................32

Rudder Controls ...................................................................................................................................32Rudder Trim.........................................................................................................................................33

INTERFACE TO OTHER SYSTEMS....................................................................................................33Navigation System...............................................................................................................................33Communications ..................................................................................................................................33Autoflight.............................................................................................................................................33

RUDDER CONTROLS 34FUNCTIONAL DESCRIPTION.............................................................................................................34

LH and RH Rudder Pedal Assemblies.................................................................................................35LH and RH Pedal Adjustment Assemblies..........................................................................................35LH and RH Forward Quadrant Assemblies .........................................................................................36Pulleys..................................................................................................................................................36Control Rods ........................................................................................................................................36Levers and Bellcranks..........................................................................................................................37Pressure Bulkhead Fairleads ................................................................................................................37Aft Quadrant Assembly .......................................................................................................................37Spring Tab Lever Assembly ................................................................................................................38Rudder Limiter Actuator 7CL..............................................................................................................38TEST TAB LOCK Switch/Light 2CL .................................................................................................39RUD LIMIT Switch/Light 5CL...........................................................................................................40Current Detector 16CX........................................................................................................................40Rudder Position Transmitter 19CX......................................................................................................40

OPERATION...........................................................................................................................................40Power Supplies.....................................................................................................................................40




TM-Flight Controls

System Power-Up................................................................................................................................ 41Rudder Controls .................................................................................................................................. 41Electrical Control of Rudder Limiter .................................................................................................. 43

SYSTEM INDICATIONS ...................................................................................................................... 44Rudder Position Indicating.................................................................................................................. 44Rudder Limiter Monitoring................................................................................................................. 45

RUDDER TRIM 48FUNCTIONAL DESCRIPTION ............................................................................................................ 48

Rudder Trim Switch 22CC.................................................................................................................. 48Trim Test Switch 50CC....................................................................................................................... 49Rudder Trim Actuator 25CC............................................................................................................... 50

OPERATION .......................................................................................................................................... 50Power Supplies.................................................................................................................................... 50System Power-Up................................................................................................................................ 50Rudder Trim (refer to Fig. 27)............................................................................................................. 51

SYSTEM INDICATIONS ...................................................................................................................... 53T rim Position Indicating..................................................................................................................... 54Rudder Trim Selection Status.............................................................................................................. 54

27-30 ELEVATOR CONTROLS AND TRIM 55GENERAL .............................................................................................................................................. 55

Elevator Controls................................................................................................................................. 56Elevator Trim ...................................................................................................................................... 56

INTERFACE TO OTHER SYSTEMS ................................................................................................... 56Indicating/Recording Systems............................................................................................................. 56Navigation System .............................................................................................................................. 56Auto Flight System.............................................................................................................................. 56

ELEVATOR CONTROLS 57FUNCTIONAL DESCRIPTION ............................................................................................................ 57

LH and RH Control Column ............................................................................................................... 58LH and RH Cable Tension Regulator ................................................................................................. 59Control Cables..................................................................................................................................... 59Pulleys ................................................................................................................................................. 59Control Rods........................................................................................................................................ 59Levers and Bell cranks ........................................................................................................................ 59Pressure Bulkhead Fairleads ............................................................................................................... 59Quadrant Assembly ............................................................................................................................. 60Elevator Disconnect Unit .................................................................................................................... 61Elevator Disconnect Micro switch 8CW............................................................................................. 61LH and RH Elevator Position Transmitters 25CX and 26CX............................................................. 62

OPERATION .......................................................................................................................................... 62Power Supplies.................................................................................................................................... 62Elevator Controls................................................................................................................................. 62Flight Compartment to Vertical Stabilizer Control Run ..................................................................... 62LH and RH Elevator Tab..................................................................................................................... 63

SYSTEM INDICATIONS ...................................................................................................................... 63



TM-Flight Controls

Elevator Position Indicating.................................................................................................................63Elevator Disconnect Unit Monitoring..................................................................................................63

ELEVATOR TRIM 65FUNCTIONAL DESCRIPTION.............................................................................................................65

LH (RH) Elevator Trim Actuator 53CC (52CC) .................................................................................66Main Elevator Trim Switches 33CC....................................................................................................67Standby Elevator Trim Switch 63CC...................................................................................................68Elevator Trim Reset Switch/Light 69CC.............................................................................................68Trim Test Switch 50CC .......................................................................................................................68

OPERATION...........................................................................................................................................68Power Supplies.....................................................................................................................................68System Power-Up ................................................................................................................................68Trim Control ........................................................................................................................................69Main Trim Control...............................................................................................................................69Standby Trim Control and Main Trim Lockout...................................................................................69Actuator Speed Control........................................................................................................................72Main Trim Runaway Override.............................................................................................................73Runaway Override Test .......................................................................................................................73Main Trim Circuit Fault Protection .....................................................................................................74Standby Trim Circuit Fault Protection.................................................................................................74Auto-Trim ............................................................................................................................................75

SYSTEM INDICATIONS.......................................................................................................................75Trim Position Indicating ......................................................................................................................76Trim Synchronization ..........................................................................................................................76Trim Speed Mode Indicating ...............................................................................................................77Standby Trim/Main Lockout Circuit Status.........................................................................................79Trim Actuator Status............................................................................................................................79

27-33 STALL WARNING AND PREVENTION 80GENERAL...............................................................................................................................................80

Angle of Attack Information................................................................................................................81Stall Warning Computing ....................................................................................................................81Stick Shaker .........................................................................................................................................81Stick Pusher..........................................................................................................................................81System Inhibition on Ground and below 100 ft Radar altitude ...........................................................81Stick Pusher Disarm.............................................................................................................................82Autopilot Disengagement ....................................................................................................................82System Test..........................................................................................................................................82System Monitoring and Indicating.......................................................................................................82

INTERFACE TO OTHER SYSTEMS....................................................................................................83Auto Flight System (Chapter 22).........................................................................................................83Communications (Chapter 23).............................................................................................................83

FUNCTIONAL DESCRIPTION.............................................................................................................83LH (RH) AOA Sensor 2WH (12WH)..................................................................................................84LH (RH) Stick Shaker 6WH................................................................................................................85Stick Pusher 25WH..............................................................................................................................85LH (RH) Stall Warning Test Switch 7WH (17WH)............................................................................86Pusher Disarm Switch/Light 22WH ....................................................................................................87Pusher Reset Switch 24WH.................................................................................................................87




TM-Flight Controls

OPERATION .......................................................................................................................................... 87Power Supplies.................................................................................................................................... 87System Power-Up................................................................................................................................ 87Power-Up Test..................................................................................................................................... 89System Test ......................................................................................................................................... 89Stall Warning Computing.................................................................................................................... 90Stick Shaker Operation........................................................................................................................ 91Stick Pusher Operation........................................................................................................................ 91

SYSTEM INDICATIONS ...................................................................................................................... 93General ................................................................................................................................................ 93AOA Sensor Status.............................................................................................................................. 93AOA Comparison................................................................................................................................ 93Shaker Status ....................................................................................................................................... 94Pusher Status ....................................................................................................................................... 94

27-50 FLAPS 97GENERAL .............................................................................................................................................. 97INTERFACE TO OTHER SYSTEMS ................................................................................................... 98

Hydraulic Power (Chapter 29) ............................................................................................................ 98Landing Gear (Chapter 32).................................................................................................................. 98Navigation (Chapter 34)...................................................................................................................... 98Indicating/Recording Systems (Chapter 31) ....................................................................................... 98

FUNCTIONAL DESCRIPTION ............................................................................................................ 98Flap Control Unit 2CG........................................................................................................................ 99Flap Control Switch 3CG.................................................................................................................. 101Flap Control Valve Manifold 4CG.................................................................................................... 102LH and RH Flap Actuators................................................................................................................ 103LH (RH) Flap Position Feedback Sensor 5CG (6CG) ...................................................................... 103Torque Shaft...................................................................................................................................... 104Relay 8CG......................................................................................................................................... 104

OPERATION ........................................................................................................................................ 104Electrical Power Supplies.................................................................................................................. 104Hydraulic Power Supplies................................................................................................................. 104System Power-Up.............................................................................................................................. 106Power-Up Test................................................................................................................................... 106Flap Operation................................................................................................................................... 107

SYSTEM INDICATIONS .................................................................................................................... 108General .............................................................................................................................................. 108System Operating Status Monitoring ................................................................................................ 109System Reset ..................................................................................................................................... 109Flap Position Indicating..................................................................................................................... 109

27-60 SPOILERS 111GENERAL ............................................................................................................................................ 111

Ground Spoilers (optional)................................................................................................................ 112Roll Spoilers...................................................................................................................................... 112Indications ......................................................................................................................................... 112

INTERFACE TO OTHER SYSTEMS ................................................................................................. 112Hydraulic Power (Chapter 29) .......................................................................................................... 112



TM-Flight Controls

GROUND SPOILERS (OPTIONAL) 113FUNCTIONAL DESCRIPTION...........................................................................................................113

Valve Manifold 10CS ........................................................................................................................113Ground Spoiler Actuators ..................................................................................................................115Restrictor Relief Valves.....................................................................................................................116Ground Spoiler Arm/Disarm Switch/Light 2CS................................................................................117Microswitches 3CS/5CS/7CS/8CS ....................................................................................................117Proximity Sensors 3CW/5CW (refer to Fig. 64)................................................................................118

OPERATION.........................................................................................................................................118Electrical Power Supplies ..................................................................................................................118Hydraulic Power Supplies..................................................................................................................118System Power-Up ..............................................................................................................................118System Pre-Takeoff Test....................................................................................................................118Spoiler Inflight Inhibition ..................................................................................................................119Landing Gear Circuit .........................................................................................................................119Power Lever Circuit...........................................................................................................................119Spoilers Disarm/Arm .........................................................................................................................122Auto-Deployment on Landing ...........................................................................................................122Auto-Deploy on Aborted Takeoff......................................................................................................122Auto-Stow..........................................................................................................................................122Spoiler Lockout During Ground Manoeuvring..................................................................................122

SYSTEM INDICATIONS.....................................................................................................................123Ground Spoiler Position Indicating....................................................................................................123Spoiler Proximity Sensor Monitoring................................................................................................123Ground Spoiler not Stowed................................................................................................................123Ground Spoiler Control Circuit Armed .............................................................................................123

ROLL SPOILERS 125FUNCTIONAL DESCRIPTION...........................................................................................................125

LH and RH Roll Spoiler Actuators....................................................................................................125LH (RH) Roll Spoiler Position Sensor 21CX (22CX).......................................................................127Double Shuttle Valve.........................................................................................................................127

OPERATION.........................................................................................................................................128Hydraulic Power Supplies..................................................................................................................129Roll Spoiler Control...........................................................................................................................129

SYSTEM INDICATIONS.....................................................................................................................130Spoiler Position Indicating.................................................................................................................130

27-70 GUST LOCK AND DAMPER 132GENERAL.............................................................................................................................................132

Aileron and Elevator Control Gust Locks..........................................................................................132Rudder Damper..................................................................................................................................133

FUNCTIONAL DESCRIPTION...........................................................................................................133Gust Lock Lever, Flexible Cables and Distribution Box...................................................................133Aileron Controls Gust Lock...............................................................................................................134Elevator Controls Gust Lock..............................................................................................................134Rudder Damper..................................................................................................................................135




TM-Flight Controls

INDEX 137

LIST OF ILLUSTRATIONS 138



TM-Flight Controls

27-00 GENERAL

GENERAL

RudderTrim Tab

Spring Tab

Aileron

Servo Tab

Flap

Flap

Groundspoiler(Option)

Roll Spoiler

Trim/Servo Tab

Aileron

Elevator

TrimTabs

Roll Spoiler

TrimTabs

Elevator

Groundspoiler(Option)

Fig. 1 Flight Controls - General Arrangement




TM-Flight Controls

This chapter provides information on those units and components which furnish a means of manuallycontrolling the flight attitude of the aircraft. The chapter is divided into sections containing detailedinformation on the following flight control subsystems:

- Aileron Controls and Trim- Rudder Controls and Trim- Elevator Controls and Trim- Stall Warning and Prevention- Flaps- Spoilers- Ground Spoilers (Option)- Roll Spoilers- Gust Lock and Damper

Primary Flight Controls

The aircraft primary controls consist of conventional ailerons, elevators and rudder. The primary controlsurfaces are moved manually by linkage systems consisting of cables, pulleys, levers and rods. Dualcontrols are installed for the three primary controls. The elevator and aileron control runs are eachequipped with a disconnect unit. This allows the captain's and first officer's controls to be disconnectedfrom each other should one control run become jammed. The rudder pedals drive a Flettner-type springtab on the trailing edge of the rudder. At airspeeds up to 160 knots the rudder is deflected by aerodynamicservo reaction from the tab. The rudder itself is not connected to the rudder pedals directly except atairspeeds above 160 knots.

Secondary Flight Controls

The secondary flight controls consist of aileron, elevator and rudder trim systems and trailing edge flaps.The aircraft is trimmed in the three axes by electro-mechanical actuators driving trim tabs. Roll trim isachieved by a single actuator driving a tab on the left aileron. Pitch trim is achieved by a tab on eachelevator, each tab having its own actuator. Yaw trim is achieved by a single actuator driving a tab on thetrailing edge of the rudder. The flaps consist of one flap section on the trailing edge of each wing half.The two sections are mechanically linked and are driven hydraulically.

Spoilers

For improved performance roll spoilers and ground spoilers are installed. The roll spoilers assist theailerons. Both sets of spoilers are located on the top surface of the wing and are driven hydraulically.

Stall Warning and Prevention

A stall warning and prevention system (stick shaker and stick pusher) is installed.Gust Lock

The ailerons and elevators can be locked for parking by a lever in the flight compartment. The ruddercontrol system is equipped with a hydraulic gust damper which prevents damage to the structure when theaircraft is parked in gusty conditions



TM-Flight Controls

27-10 AILERON CONTROLS AND TRIM

General

RH Ail

eron P

osition

Transm

itter

Aileron

Discon

nect Un

it

LH Aile

ron Po

sition

Transm

itter

Control

Wheels

Cable T

ension

Regulat

ors

EICAS

position

status

position

30

25

30

25

Servo T

ab

Trim/Se

rvo Ta

b

Fig. 2 Aileron - General ArrangementThis section provides information on that portion of the flight control system which controls the aileronsand the aileron trim tab. Also included are the aileron and trim tab position indicating systems and theaileron disconnect indicating system.The section is divided into subsections containing detailed information on the following aileron and tabsubsystems:

- Aileron Controls- Aileron Trim




TM-Flight Controls

Aileron Controls

The aircraft is controlled about the roll axis by a conventional aileron control system. Two ailerons areinstalled, one on the outboard trailing edge of each wing. The ailerons are manually operated by dualcontrol wheels. The linkage from the control wheels to the ailerons is by an arrangement of pulleys,cables, quadrants, push-pull rods, levers and bellcranks. The maximum aileron movement is 30 up and25 down. The captain's and first officer's aileron control runs are joined by a disconnect unit. This unitallows the two control runs to be separated by the application of higher than normal input forces shouldone control run become jammed.Aileron Trim

The aircraft can be trimmed about the roll axis by a Trim/Servo-tab located on the inboard trailing edge ofthe left aileron. The tab is driven by an electrically powered linear actuator installed in the trailing edge ofthe wing. Due to the actuator attachment geometry the tab also functions as a servo tab to provideaerodynamic assistance to flight crew roll commands.The actuator is powered by two separate DC motors and controlled by either a main or a standby ailerontrim switch. Override circuits are provided to protect against a trim runaway. Test facilities are providedfor the override circuits.

INTERFACE TO OTHER SYSTEMS

Roll Spoiler System

The roll spoiler control actuators are connected by push-pull rods to the aileron control system.

Indicating/Recording Systems

The following functions of the aileron and tab subsystem are indicated on the electronic indicating,caution and advisory system EICAS:

- the position of each aileron- the status of the aileron disconnect unit- the position of the aileron trim actuator.

Autoflight

Signals from the automatic flight control system (AFCS) are used to operate the ailerons when the aircraftis flying under automatic control. Refer to (Chapter 22 - AUTO FLIGHT) for further details.



TM-Flight Controls

AILERON CONTROLS

FUNCTIONAL DESCRIPTION

The aileron control subsystem consists of the following components:FIN Component Panel Zone Access Door

LH and RH control wheels 210 211-FZF212-EZF

LH and RH cable tension regulators 120 211-LFZ212-KFZ

LH and RH fairlead brackets 120 221-MFZ222-EFZ

control cables 120130210

various+

furnishingpulleys 220 panels

control rods 220530630

various

levers and bellcranks 530630

various

LH and RH transition units 220 251-bt252-bt

furnishingpanels

aileron disconnect unit 250 251-btquadrant assembly 252-bt

7CW aileron disconnect microswitch4CX RH aileron position transmitter 632 632-JB5CX LH aileron position transmitter 532 532-JB




TM-Flight Controls

LH and RH Control Wheels

A

A

Double Pulley

Transition Unit

Turnbuckle

Pulley Cable Tension Regulator

Control Cable

Fig. 3 Aileron - Control Wheels to Transition UnitsThe control wheels are of the horn type and are mounted with splined shafts on the top of the controlcolumns. Wheel movement is transmitted to the aileron control cable tension regulators beneath the flightcompartment floor by cables and pulleys.

Control Cables

The aileron control cables transmit the movement of the control wheels to the tension regulators and fromthere to the transition units located on the passenger compartment roof between frames 25 and 26. Thecables are 7 x 19 flexible steel wire ropes made from corrosion resistant steel and have a nominaldiameter of 3.2 mm (0.13 in.).The LH and RH aileron control runs each consist of eight separate cable sections. Each control wheel isconnected to its associated tension regulator by four sections. Each tension regulator is connected to itsassociated transition unit by a further four sections. Cable sections are joined by turnbuckles andterminated by swaged end fittings.



TM-Flight Controls

Pulleys

The control cables are guided by pulleys equipped with cable guards. The pulleys are made of a phenolicmaterial and run in sealed ball bearings.A double pulley connected to the control wheel at the top of each control column and two single pulleysat the base of the control column guide the cable run from the control wheel to the associated tensionregulator. The cable run from each tension regulator to the associated transition unit is guided by a totalof fifteen pulleys.

LH and RH Cable Tension Regulators

Notch for Aileron Gust Lock

(LH Side Only)

Input Pulley

Lower Arm

Compression Springs

Sliding Lever Assembly

Compression Springs

Upper Arm

Fig. 4 Aileron - Cable Tension RegulatorThe tension of the control cables installed in the flight control system must be maintained within specifiedtolerances. Temperature effects cause the cables and the aircraft structure to expand and contract. Theexpansion coefficient of the aluminium structure is higher than that of the steel cables. This means thatthe cables tighten at high ambient temperatures and slacken at low ambient temperatures. Control cabletension regulators compensate for these effects.A control cable tension regulator is installed below the flight compartment floor in the captain's and firstofficer's aileron control runs. The two tension regulators are identical in operation. Each regulatorautomatically regulates the tension of the control cables between the regulator output quadrant and theassociated cable termination quadrants in the upper center fuselage. The tension regulator consists of ashaft to which an input pulley and a spring compensator mechanism are firmly attached. An outputquadrant with separate upper and lower sections is installed on but not attached to the shaft. The twosections are connected to each other by the compensator mechanism but are otherwise free to rotate onthe shaft. The compensator mechanism consists of two compression springs which act on a sliding leverassembly. The sliding lever is connected to the upper and lower sections of the output quadrant by twoarms. If the control cables become tight the cables pull the two sections of the output quadrant towardsthe shaft against the force of the springs. This effectively shortens the length of the cable run. If the cablesbecome slack the springs push the quadrant sections in the other direction to take up the slack.The aileron gust lock engages with a notch in the LH (captain's) tension regulator.




TM-Flight Controls

LH and RH Transition Units

The transition units are installed in the roof section of the passenger compartment between frames 25 and26. The units have two functions:

- they act as a connection point between the LH (RH) cable run in the fuselage and the rods in the LH(RH) wing

- they act as pressure seals at the point where the control run exits the pressure compartment.Each unit consists of a cable quadrant located in the pressure compartment and an output lever located inthe fairing between the fuselage and the wing. The quadrant and the lever are mounted on a commonshaft . The shaft bearing is installed in the passenger compartment roof and acts as the pressure seal. Thequadrant accepts the control inputs from the fuselage control cables and the lever transmits the movementinto the control rod run in the wing.

Aileron Disconnect Unit

A

A

Rod to RH Aileron Control

LH/RH Interconnect Rod

Autopilot Roll Servo Actuator

Cable Quadrant

Lever Assembly

Rod to LH Aileron

Lever Assy Drive Rod

Quadrant Output Lever

Roll Disconnect Unit

Quadrant Assembly

Fig. 5 Aileron - Transition Units to the Wingroot



TM-Flight Controls

Output to RH Aileron

Transverse Rod to LH Control Circuit

Rear Half

Command Input from RH Control Circuit

Front Half

Fig. 6 Aileron - Disconnect UnitThe captain's and first officer's aileron control cable runs are routed completely separately along the leftand right sides of the fuselage respectively. They are joined by an interconnect rod in the wing centersection and an aileron disconnect unit located in the trailing edge section of the RH wing root. Undernormal circumstances the movement of one control wheel moves both ailerons and the other controlwheel. Should one aileron control become jammed the two control circuits can be separated by theapplication of a higher than normal force to a control wheel.The unit has two halves which are held engaged by a spring and cam arrangement. The front half haslevers for two push-pull rods. The lower lever is for the command input from the RH aileron controlcircuit. The upper lever is for the output rod to the RH aileron. The rear half has a single lever for theinterconnect rod that joins the LH and RH control circuits. Under normal operating conditions the twohalves of the unit are firmly engaged and move together as a single unit. Should one of the aileron controlcircuits jam, the two halves can be disconnected from each other by the application of a higher thannormal force at a control wheel. The disconnect force is 39 daN (87.7 lb). The applied force causes thecam to override the spring force and move out of its detent. The two halves of the unit are nowdisengaged, effectively isolating the jammed control circuit. In this situation the captain's control circuit isconnected to the left aileron only. The first officer's control circuit is connected to the right aileron only.The aircraft can be controlled about the roll axis using the free control wheel. Once activated, thedisconnect unit can only be reset on the ground.The unit has an integral microswitch 7CW which is operated if the disconnect unit is activated. Theswitch sends a signal to EICAS

Quadrant AssemblyThe quadrant assembly is installed in the trailing edge section of the LH wing root at rib 2. The assemblyconsists of three levers and a cable quadrant all mounted on a common shaft. The lower lever accepts thecontrol inputs from the LH transition unit. The forward upper lever is the drive lever for the LH aileroncontrol run. The aft upper lever forms the connection point for the LH/RH aileron control interconnectrod. The cable quadrant is the connection point for the autopilot roll servo to the aileron control run.The control cable from the autopilot roll servo is connected to cable arms that extend from the upper andlower sections of the cable quadrant. Because the control cable has no turnbuckles, the arms can beadjusted with screws for setting the cable tension.




TM-Flight Controls

Levers and Bellcranks

R 3

R 4

R 5

R 6

R 7

R 8

R 9

R 10

R 11

R 12

R 12

R 13

R 14

R 15

R 16

R 17

R 18

R 19R 20

R 0

A1

7

2

3

4

5

LH SIDE SHOWN, RH SIDE SIMILAR.

6

A

Fig. 7 Aileron - Wing Root to AileronThe control rods in the wing are supported by idler levers and bellcranks running in sealed ball bearings.The connection points for the rod clevis ends are formed by self-aligning sealed ball bearings.

Control Rods

The aileron control run from the transition units in the upper center fuselage to their associated aileron isformed by a series of aluminium push-pull control rods. Another rod forms the interconnection betweenthe LH (captain's) and RH (first officer's) aileron controls. The Servo-tab on each aileron is alsocontrolled by rods. Rod ends are either of the clevis or eye type. Eye type rod ends are equipped with self-aligning sealed ball bearings.

1. Interconnection Rod2. Quadrant Assembly3. Position Transducer4. Aileron Drive Rod5. Bellcrank6. Rollspoiler Drive Rod7. Disconnect Unit



TM-Flight Controls

Aileron Disconnect Microswitch 7CW

A microswitch located in the aileron disconnect unit monitors the status of the unit and sends a discretesignal to the EICAS when the disconnect unit is activated. The switch contacts are connected to groundunder normal operating conditions and open under aileron disconnect conditions.

LH and RH Aileron Position Transmitters 5CX and 4CX

An aileron position transmitter is installed for each aileron. The transmitters are installed on theirassociated wing rear spar between ribs 17 and 18. Each transmitter is driven by a short rod connected tothe outboard idler lever in the aileron control run. The transmitters are identical 0 to 10 k W three-wirepotentiometers whose resistance changes as a function of the aileron position. They send a variableresistance signal to the EICAS for aileron position indicating.

OPERATION(refer to Fig. 3, Fig. 5, Fig. 7)

Power Supplies

Electrical power is not required for the aileron control system. Power for the indicating part of the systemis provided by the EICAS

Aileron Controls

Note:The LH (captain's) and RH (first officer's) aileron controls from the flight compartment to the uppercenter fuselage are similar. The operation of the LH side is described. Differences for the RH side arecovered in the text or given in brackets.

Flight Compartment Controls

The Control wheel movement is transmitted through the pulleys by a cable to the cable tension regulatorlocated at frame 9. The tension of this short cable run can be adjusted by turnbuckles. A notch is providedin the aft portion of the LH cable tension regulator between the upper and lower quadrants. The ailerongust lock engages with this notch to lock the aileron controls for gust protection when the aircraft isparked.

Flight Compartment to Upper Center Fuselage Control Run

From the cable tension regulator, the control movement is continued aft below the flight and passengercompartment floor by control cables and pulleys. The cables pass through guides in some frames underthe floor. Cable fairleads equipped with small pulleys are used to guide the cables through the machinedpart of frame 24. The cable run is virtually straight as far as a point between frames 25 and 26. At thispoint the cables are routed outboard and then upwards. The cable run now passes between the fuselageskin and the passenger compartment furnishing panels and terminates at a transition unit on the passengercompartment roof just left (right) of the aircraft centerline.Regulation of Cable Tension in Fuselage Control Run

The continuous cable run from the cable tension regulators to the cable quadrants on the passengercompartment roof is approximately 9.5 m (31 ft) long. Approximately 6.5 m (21 ft) of this is a virtuallystraight horizontal run. The expansion coefficient of the aluminium structure is higher than that of thesteel cables. This means that the cables tighten at high ambient temperatures and slacken at low ambienttemperatures. The control cable tension regulators compensate for these effects.




TM-Flight Controls

The shaft of the tension regulator (and thus the regulator mechanism) is rotated by flight crew commandsacting on the input pulley. The movement is transmitted to the upper and lower sections of the outputquadrant by the arms of the regulator mechanism. The control cable is a two-part cable, each part beingattached to its associated quadrant section by a nipple. The two sections of the output quadrant are thusallowed to move in relation to each other.Under high ambient temperature conditions the control cables tighten. The cable tension pulls on the twosections of the output quadrant and moves them in opposite directions on the shaft. The movement actsthrough the arms and pulls the sliding lever assembly towards the shaft against the force of twocompression springs. This effectively shortens the length of the cable run. The sliding motion continuesuntil the spring compression is equal to the cable tension.If the ambient temperature is low the cables slacken. The springs push the two sections of the outputquadrant in the other direction to take up the slack.

Aileron Controls from Transition Units to Wing Roots

The shaft of the transition unit on the LH side of the passenger compartment roof exits the fuselagethrough a pressure tight fitting. A lever is fixed to the shaft out-side the fuselage. A push-pull rodconnected to the lever transmits the aileron commands to the quadrant assembly at LH wing station Y 600(rib 2). A cable quadrant shares a common shaft with three levers on the quadrant assembly. The autopilotroll servo is connected by a control cable to the aileron control run at this quadrant.Two push-pull rods are connected to the upper levers of the quadrant assembly. The aft rod connects tothe aileron disconnect unit (at RH wing station Y 600 (rib 2). This rod forms the interconnection betweenthe LH (captain's) and RH (first officer's) aileron controls. The forward rod is the first of six push-pullrods which form the control run from the wing root to the aileron drive bellcrank at LH wing station Y7345.4 (between ribs 19 and 20).The RH side is similar to the LH. The differences are:

- the disconnect unit replaces the quadrant assembly- the control run starts with rod from the disconnect unit- the interface to the autopilot is connected through the disconnect unit.

Aileron Controls from Wing Root to Aileron

Six push-pull rods - supported at intervals by idler levers and a bellcrank - form the control run from thequadrant assembly in the LH wing root to the LH aileron drive bellcrank. The six rods are routed alongthe aft face of the rear spar. A further push-pull rod is connected to the idler lever located on the rear sparbetween ribs 15 and 16. This is the drive rod for the LH roll spoiler actuator. A short push-pull rodconnects the aileron drive bellcrank to the aileron control horn. The horn is attached to the underside ofthe aileron.The aileron position transmitter is driven by the outboard idler lever and indicates the aileron position onthe flight control system page on EICAS.The control run in the RH wing starts with rod at the disconnect unit. Otherwise it is similar to the LHwing control run.



TM-Flight Controls

RH Aileron Servo Tab

A

BB

Servo Tab Push-Pull Rods

Servo Tab Push-Pull Rods

Connection to Wing Trailing Edge

Reduction Lever in AileronLeading Edge

Connection to Servo Tab

Fig. 8 Aileron - Servo TabA Flettner-type servo tab is installed on the inboard trailing edge of the RH aileron. The tab is connectedby four short push-pull rods and a reduction lever to the structure of the wing trailing edge atapproximately station Y 6880 (just outboard of rib 18). The reduction lever is installed in the leading edgeof the aileron. The tab moves in the opposite direction to the aileron to provide aerodynamic assistancefor reduced pilot effort.

LH Aileron Trim/Servo Tab

A

Connection to Trim Tab

Aileron Trim Actuator

Connection to Wing Trailing Edge

Trim Tab Drive Rods

Reduction Lever in AileronLeading Edge

Fig. 9 Aileron - Trim/Servo Tab




TM-Flight Controls

An aileron trim tab is installed on the inboard trailing edge of the LH aileron. The dual-shaft trim actuatoris installed in the trailing edge of the wing. The actuator drives the tab through a reduction lever installedin the leading edge of the aileron. The reduction lever is connected to the trim tab by twin push-pull rods.Due to this attachment geometry the trim tab also functions as a Flettner-type servo tab in addition to itsfunction as a trim tab.

SYSTEM INDICATIONS

Certain components of the aileron control system send signals to EICAS. The signals are sent to dataacquisition units (DAUs) and are used:

- to display the position of the ailerons by synoptics- to indicate the status of the aileron disconnect unit by a synoptic- to display a caution message if the aileron disconnect unit is activated.

The position of the ailerons and the status of the disconnect unit are displayed on the FLIGHTCONTROL page. The caution message is displayed on the CAS field of the primary EICAS page and onthe FLIGHT CONTROL page.

Aileron Position Indicating

An aileron position transmitter is installed for each aileron. Each transmitter is a three-wire potentiometerwhose resistance changes as a function of the aileron position. The LH transmitter sends resistance signalto DAU 1 in the EICAS system for processing. The RH transmitter sends an identical signal DAU 2. Theresistance values correspond to the following aileron deflections:

- 0.5 kW corresponds to an aileron up deflection of -30- 5 kW corresponds to aileron neutral- 9.5 kW corresponds to an aileron down deflection of +25 .

The position of each aileron is indicated by a blue synoptic on the FLIGHT CONTROL page of theEICAS. If the transmitter signal is invalid, the blue synoptic is replaced by an amber X. Under normaloperating conditions the LH and RH aileron synoptics are joined by a white bar. The bar changes toamber if the aileron disconnect unit is activated below.

Aileron Disconnect Unit Monitoring

A micro switch 7CW in the aileron disconnect unit monitors the status of the unit. It sends a discreteground or open signal to DAU 1 for processing. The signal line is connected to ground under normaloperating conditions and open circuit if the disconnect unit is activated. If the captain's and first officer'saileron control runs are disconnected:

- an amber AIL DISCONNECT caution message is displayed on the CAS field of the primary EICASpage and on the FLIGHT CONTROL page

- on the FLIGHT CONTROL page the white bar which connects the LH and RH aileron synopticschanges to amber.

CAS FIELD Indication MFD PAGE Indication Fault or ConditionAMBER

AIL DISCONNECTAMBER

AIL DISCONNECTAMBER Bar

Aileron disconnect unit activated

- blueLH (RH) aileron synoptic

Invalid synoptic replaced byan amber X RH aileron similar

Indicates position of Aileron

white pointer against whiteaileron scale


Indicates aileron trim settings



TM-Flight Controls

RUDDER LIMITED

TRIM SPEED FAST

FLAP ASYM

ELEV DISCONNECT

Honeywell

SYSTEM 1 / 3HYDR ENGINE FUEL NEXTFLIGHT

CONTROL

ROLL ROLL

0 0

NU

ND

AIL

RUD

ELEV

TRIM

RUDDERAILERON

ELEVATORLH RH

FLAPS

1220

AIL DISCONNECT

32

Fig. 10 Aileron - EICAS Indications - MFD System Page




TM-Flight Controls

AILERON TRIM

FUNCTIONAL DESCRIPTION

The aileron trim subsystem consists of the following components:FIN Component Panel Zone Access Door

1CC/11CC circuit breaker 12VE 2101CX circuit breaker 18VE 2102CC main aileron trim switch 10CC 2104CC aileron trim actuator 532 532-JB5CC trim runaway interlock relay LH 23VE 2106CC trim runaway override relay LH 23VE 2107CC trim runaway override relay RH 23VE 2108CC trim runaway interlock relay RH 23VE 2109CC aileron trim test relay 23VE 21010CC trim control panel 21012CC standby aileron trim switch 10CC 21014CC15CC

diodes 10CC 210

16CC standby aileron trim control relay 23VE 21017CC aileron trim reset switch/light 10CC 21050CC trim test switch 30VE LH 210

Aileron Trim Actuator 4CC (refer to Fig. 9)The aileron trim actuator is installed in the left wing trailing edge at approximately station Y 6880 (justoutboard of rib 18). The actuator has two separate DC motors (main and standby). The main motor iscontrolled by the main trim switch 2CC and the standby motor by the standby trim switch 12CC. Onlyone motor can operate at a time. An external electrical lockout circuit prevents the main motor fromoperating when the standby motor is active. Internal limit switches for both motors stop actuatormovement before the mechanical limits are reached.The rotary output of each motor is converted in a reduction gearbox to a dual shaft linear output. Totalshaft travel between the electrical limits is 26.8 mm (1.05 in.). The twin shafts of the actuator areconnected to a reduction lever arrangement in the leading edge of the aileron. Two push-pull rodsconnected to the output side of the reduction lever transmit the actuator movement to the tab.An integral synchro-type position transmitter in the actuator sends an aileron trim position indicatingsignal to the EICAS.



TM-Flight Controls

Trim Control Panel 10CC

RESET

ELEV

STBY

TRIM

UP

RH

RUD

LH

AILSTBY

OFF

PRESSTO

RESET

STBYELEV

UP

RHLH AILRHLH AIL

DN

NH OVSPENGLH

LHFITEST

OFF

1

TEST

PLA FI

PLA FI

ENGRH

SSEC DISABLE

MADC 2

TRIM TEST

Fig. 11 Aileron Trim Controls - Trim ControlThe trim control panel is installed in the aft LH section of the center pedestal. The panel interfaces withthe aileron, rudder and elevator trim circuits and has the following switches:

- main aileron trim switch 2CC- standby aileron trim switch 12CC- aileron trim reset switch/light 17CC- rudder trim switch- rudder trim on/off switch/light- elevator trim reset switch/light- standby elevator trim switch

Main Aileron Trim Switch 2CC

The main aileron trim switch is installed in the forward LH section of the trim control panel. The switchis labelled LH AIL RH and contains two three-position center biased rocker switches. Both rockerswitches must be activated together to operate the aileron trim actuator. The two switches have a total ofeight sets of contacts (four per switch). Each contact of one rocker switch is connected in either series orparallel with a contact in the other switch, making a total of four contact pairs.




TM-Flight Controls

Standby Aileron Trim Switch 12CC

The standby aileron trim switch is installed in the forward RH section of the trim control panel. Theswitch is labelled LH AIL RH and is identical to the main trim switch 2CC. It controls the standby motorof the aileron trim actuator. A lockout circuit is activated when the standby trim switch is operated. Thiscircuit disables the main motor of the aileron trim actuator. The main motor remains disabled until thereset switch/light 17CC is pressed.

Aileron Trim Reset Switch/Light 17CC

A lockout circuit disables the main trim motor when the standby trim motor is operated. The lockoutcircuit remains active even after the trim operation has been completed. The main trim motor can be re-enabled by pressing an aileron trim reset switch/light. The switch is labelled PRESS TO RESET and isinstalled in the trim control panel between the two aileron trim switches . A white STBY AIL annunciatorin the front face of the switch comes on to indicate when the standby trim circuit - and thus the lockoutcircuit - is active. The switch is guarded by a transparent spring-loaded cover.

Trim Test Switch 50CC

The trim test push switch is installed in the LH engine/propeller test panel 30VE located in the forwardLH section of the center pedestal. The switch is labelled TRIM TEST and is used to test the trim runawayoverride circuits of the following systems:

- aileron trim actuator main motor- rudder trim system- elevator trim system

To test the aileron trim runaway override circuit, press and hold the TRIM TEST switch and then pressthe main aileron trim switch to LH and then RH. If the runaway override circuits of the actuator mainmotor are serviceable, the actuator will operate in the reverse direction to that commanded. When the testswitch is released the motor will start again in the commanded direction.

OPERATION

Power Supplies

The aileron trim subsystem is supplied with 28 VDC and 26 VAC electrical power as follows:Component BUS circuit breaker No.

trim actuator main motor control andpower circuit

ESSENTIAL BUS 3PP AIL TRIM 1CC

trim actuator standby control and powercircuit

BUS 1 2PP STBY AIL TRIM 11CC

trim actuator position indicating circuit AC BUS 4XP AIL TRIM IND 1CX

System Power-Up

The trim tab control and indicating circuits are energized when 28 VDC and 26 VAC are applied to theaircraft bus system.



TM-Flight Controls

10 11 124 5 6 7 8 91 2 3

210

C O T

3

C O T 5

C O T1

4

6C O T

9

C O T 8

11

AILTRIMRH

B8

B6

A8

A6

2CCAILTRIMLH

B2

B4

A2

A4

2CC4CC

B

FILTER

M

R

LH RH

NORMAL OPERATIONBr

AILTRIMACTR

AILTRIMLH2CC

A1

A3

B1

B3

ESS BUS-3PP

3A 1CCAIL TRIM

A5

A72CC

AILTRIMRH B5

B7

A2

A1A38CC

A2

A1A39CC

B2

B1B3

C2

C1C3

8CC

5CCX1

X26CC

X1

X2

A1

7CCA3

A2

A3

6CCA1

A2

A1

A2

A3 B1

B2

B3

A2

A1A3

7CCX1

X2

B2

B1B3

8CCX1

X2

(9) (11) (5) (4) 5CCB2

B1B3

C2

C1C39CC 5CC (3)

16CC(18)

7

9CCX1

X2

A1

A2A3

TRIMMTEST

50CC

G3G2

50CCG1

C = closesO = opensT = change over(transition)

5

74 8

6

3

1 2

A

5

74 8

6

3

1 2

B

Electrical Schematic for:

Main Trim Switch 2CC andStby Trim Switch 12CC

Fig. 12 Aileron Trim - Electrical Diagram (Sheet 1 of 3)




TM-Flight Controls

13 14 15 16 17 18 19 20

56

C O T

141518

AILTRIMSTBYRH

B8

B6

A8

A6

12CC

4CC

B

FILTER

M

R

LH RH

STBY OPERATION

16CCX1

X2

E

16CCE1

E2

E3

17CC

A2

A3

A1

RESET

2LF

STBYAIL

2CX

6CX3CX

LAMPTEST

D/N

A5

A712CC

AILTRIMSTBYRH B5

B7

16CCD1 D3

D2

C1 C3

C2

B2

B4

A2

A4

AILTRIMSTBYLH

12CC

AILTRIMSTBYLH

12CC

A1

A3

B1

B3

BUS 1-2PP

3A 11CCSTBYAILTRIM




TM-Flight Controls

21 22 23 24 25

26VAC-BUS-6XP

1A 1CXAIL TRIM

IND

4CC

R1

R2

ACTR POSIT SENSOR

S3BK/W

S1S2

L W H

SIGN 41

1TU

H L

SIGN 34

DAU 1

AIL POSIT POTILH

CWCCW

W

5CX

R

H W L

SIGN 609

11TU DAU 2

AIL POSIT POTIRH

CWCCW

W

4CX

26 27


Aileron Trim

Main Trim CircuitThe main motor of the aileron trim actuator is controlled by the main aileron trim switch 2CC. Ifboth rockers of the switch are held to LH (left wing down), the following contacts operate:

- series contacts A1/A3 and B1/B3 close and supply 28 VDC to the left wing down circuit- parallel contacts A2/A4 and B2/B4 open and remove the ground from the right wing down

circuit.28 VDC is now supplied to the left wing down side of the motor through:




TM-Flight Controls

- contacts A3/A2 of relay 7CC- contacts A2/A3 of relay 16CC- the contacts of the actuator LH internal limit switch.

The ground circuit for the motor is provided by either:- the contacts of the actuator RH internal limit switch (and then direct to ground if the actuator is

at its maximum RH travel)or by the following series circuit:- the contacts of the RH internal limit switch- contacts B3/B2 of relay 16CC- contacts A2/A3 of relay 6CC- contacts B2/B3 of relay 9CC- the parallel contacts B8/B6 and A8/A6 of the main trim switch 2CC.

The motor runs in the commanded direction (drives the trim tab down) until either the trim switch isreleased or until the LH internal limit switch operates. The operation sequence is similar in reversewhen right wing down is commanded.

Main Trim Runaway Override CircuitsAn electrical fault in the actuator control circuitry, such as sticking contacts in the main trim switch,could cause a trim runaway. Override circuits ensure that a main trim motor runaway can be stoppedand reversed by instinctive operation of the main trim switch in the opposite direction to therunaway.The following example describes the operation of the circuit in the event of a runaway towards leftwing down.Relay 5CC is the LH trim runaway interlock relay. It is energized when the main trim switch is heldto the LH position. If contacts A1/A3 and B1/B3 of the main trim switch 2CC stick closed when theswitch is released, the trim actuator will run uncommanded towards left wing down and relay 5CCwill remain energized. The relay has three sets of contacts:

- contacts C2/C1 close and arm the test circuit- contacts B2/B3 open and disable the coil circuit of relay 8CC (8CC is the RH trim runaway

interlock relay)- contacts A2/A1 close and arm the coil circuit of the trim runaway override relay 7CC.

The trim runaway will be indicated to the flight crew by the continuing left roll and by the ailerontrim position indicator on the EICAS. The runaway can be stopped and reversed by holding the maintrim switch to the RH position. This action energizes relay 7CC through contacts A2/A1 of 5CC.The contacts of 7CC replace the 28 VDC power supply to the left wing down side of the main trimmotor with a ground connection. 28 VDC is now supplied to the right wing down side of the motorthrough:

- contacts A5/A7 and B5/B7 of the main trim switch 2CC- contacts A3/A2 of relay 6CC- contacts B2/B3 of relay 16CC- the contacts of the actuator RH internal limit switch.

The ground circuit for the motor is provided by either:- the contacts of the actuator LH internal limit switch (and then direct to ground if the actuator is

at its maximum LH travel) or by the following series circuit:- the contacts of the LH internal limit switch- contacts A3/A2 of relay 16CC- contacts A2/A1 of relay 7CC.

The motor drives the trim tab up (right wing down) until either the trim switch is released or until theRH internal limit switch operates. If the fault still exists on the main trim switch when the switch isreleased, the actuator will again run uncommanded towards left wing down. The main motor can bedisabled by momentarily operating the standby trim switch 12CC to LH or RH .

The operation sequence is similar in reverse if the trim runaway is to the right.



TM-Flight Controls

Runaway Override Test CircuitThe TRIM TEST push switch 50CC is used to test the trim runaway override circuits of thefollowing systems:

- aileron trim actuator main motor- rudder trim system- elevator trim system

To test the aileron trim runaway override circuit, press and hold the TRIM TEST switch and thenpress the main aileron trim switch 2CC to LH and then RH. If the runaway override circuits of theactuator main motor are serviceable, the actuator will operate in the reverse direction to thatcommanded. When the test switch is released the motor will start again in the commanded direction.The following example describes the operation of the circuit when the test switch is pressed and themain aileron trim switch held to LH.When the TRIM TEST switch is held pressed the trim test relay 9CC energizes. Relay 9CC has twosets of contacts, one for the LH circuit and one for the RH. If the main trim switch is now held to theL position, relay 5CC energizes. The RH trim runaway override relay 7CC energizes through thefollowing series circuit:

- contacts C2/C1 of relay 5CC- contacts B1/B2 of relay 9CC- contacts A2/A1 of relay 5CC.

The contacts of 7CC remove the 28 VDC power supply from the left wing down side of the maintrim motor and replace it with a ground connection. The actuator stops. 28 VDC is now supplied tothe right wing down side of the motor through:

- the same circuit as the coil of relay 7CC (see above)- contacts A3/A2 of relay 6CC- contacts B2/B3 of relay 16CC- the contacts of the actuator RH internal limit switch.

The ground circuit for the motor is provided by either:- the contacts of the actuator LH internal limit switch (and then direct to ground if the actuator is

at its maximum LH travel)or by the following series circuit:- the contacts of the LH internal limit switch- contacts A3/A2 of relay 16CC- contacts A2/A1 of relay 7CC.

The motor now starts in the reverse direction and trims the aileron tab up (right wing down) untileither:

- the TRIM TEST switch 50CC is releasedor

- the main aileron trim switch 2CC is releasedor

- the RH internal limit switch operates.The test sequence is similar in reverse when the main trim switch is held to RH.

Main Trim Motor Lockout CircuitIf for any reason the aileron main trim circuit is unserviceable, it can be disabled. This is done bymomentarily pressing the standby trim switch 12CC to either LH or RH. The standby aileron trimcontrol relay 16CC energizes and self-latches through its contacts E2/E1. The ground circuit for therelay coil is provided through the RESET switch/light 17CC.In addition to the contacts for the self-latching circuit, relay 16CC has four other sets of contacts.Contacts C and D complete the circuits to the left and right wing down sides of the standby trimmotor. Contacts A and B disable the left and right wing down sides of the main trim motor . Themain motor is thus locked out until relay 16CC is de-energized by pressing the RESET switch/light.This re-enables the main motor and disables the standby motor.A white STBY AIL annunciator in the aileron trim reset switch/light indicates when the standbyaileron trim subsystem is active. The annunciator is controlled by contacts E2/E1 of relay 16CC .




TM-Flight Controls

Standby Trim CircuitThe standby motor of the aileron trim actuator is controlled by the standby aileron trim switch 12CC.If both rockers of the switch are held to LH (left wing down), the following contacts operate:

- series contacts A1/A3 and B1/B3 close and supply 28 VDC to the left wing down circuit- parallel contacts A2/A4 and B2/B4 open and remove the ground from the right wing down

circuit.The standby aileron trim control relay 16CC energizes and latches, disabling the main trim circuitand switching on the STBY AIL annunciator as previously described.28 VDC is now supplied to the left wing down side of the motor through:

- contacts C2/C1 of relay 16CC- the contacts of the actuator LH internal limit switch.

The ground circuit for the motor is provided by:- the contacts of the actuator RH internal limit switch (and then direct to ground if the actuator is

at its maximum RH travel) or by the following series circuit:- the contacts of the RH limit switch- contacts D1/D2 of relay 16CC- the parallel contacts B8/B6 and A8/A6 of the standby trim switch 12CC.

The motor runs in the commanded direction until either the trim switch is released or until the LHinternal limit switch operates. The operation sequence is similar in reverse when right wing down iscommanded.

SYSTEM INDICATIONS

The aileron trim actuator has an integral synchro-type position transmitter. The transmitter sends anaileron trim position signal to data acquisition unit 1 (DAU 1) in the EICAS system for processing.The aileron trim setting is indicated by a white pointer against an analogue scale on the primary andFLIGHT CONTROL pages of the EICAS.

CAS FIELD Indication MFD PAGEIndication

Fault or Condition


Scale has white tic marksevery 25%.

white pointer againstwhite aileron scaleScale has white ticmarks every 25%.

Indicates aileron trim settings

Standby Trim/Main Lockout Circuit Status

A STBY AIL annunciator in the front face of the RESET switch/light 17CC indicates when the standbytrim circuit and the main trim lockout circuit are active.



TM-Flight Controls

27-20 RUDDER CONTROLS AND TRIM

GENERAL

Rudder Pedal Assemblies

Spring Tab Lock Actuator

Autopilot Servo

Spring Tab Drive Mechanism

Rudder Trim Actuator

Quadrant Assembly

Rudder Position Transmitter

Cable Quadrants

-24 20

Fig. 15 Rudder - General ArrangementThis section provides information on that portion of the flight control system which controls the positionand movement of the rudder and the rudder trim tab. Also included are the indicating systems for therudder position, the rudder limiter status and the trim tab position.The section is divided into subsections containing detailed information on the following rudder and tabsubsystems:

- Rudder Controls- Rudder Trim

Rudder Controls

The aircraft is controlled about the yaw axis by a rudder control system. At airspeeds below 160 knots thedual rudder pedal assemblies are connected to a Flettner-type tab on the lower trailing edge of the rudderthrough a torsion bar and lever assembly. Movement of the rudder pedals drives the tab in the oppositesense to the yaw command and aerodynamic effects from the tab move the rudder in the commandedsense.




TM-Flight Controls

At speeds above 160 knots the lever assembly is locked by an actuator controlled by micro air datacomputers 1 and 2. The pedal assemblies are then effectively connected directly to the rudder and flightcrew commands are not assisted by the tab. This limits the rudder deflection at high airspeeds andprevents structural overload conditions. The tab can be unlocked and the limiter actuator disabled bymanually operating a switch in the flight compartment. A facility is provided for testing the actuator.The linkage from the pedal assemblies to the rudder and tab is by an arrangement of pulleys, cables,quadrants, push-pull rods, levers and bellcranks. The control cables exit the pressure compartmentthrough pressure fairleads at the rear pressure bulkhead. Maximum rudder deflection is 24 right and 20 left.

Rudder Trim

The aircraft can be trimmed about the yaw axis by a trim tab located on the trailing edge of the rudderimmediately above the spring tab. The tab is driven by an electrically powered linear actuator installed inthe leading edge of the rudder.The actuator is powered by a DC motor and controlled by a rudder trim switch in the flight compartment.Override circuits are provided to protect against a trim runaway. Test facilities are provided for theoverride circuits.The rudder trim actuator can be disabled and re-enabled by a switch/light in the flight compartment.

INTERFACE TO OTHER SYSTEMS

Navigation System

The micro air data computers MADC 1 and 2 send discrete airspeed signals to the rudder limiter controlcircuit.

Communications

An amber RUDDER LIMITED caution message is displayed on page 2 of the radio management unit(RMU) if the rudder limiter is active at airspeeds lower than 155 knots.Indicating /Recoording SystemThe following functions of the rudder and tab subsystem are indicated on EICAS:

- the position of the

Documents

Ata Chapter 27 Flight Controls