b1-11a aeroplane aerodynamics sr

7/25/2019 B1-11a Aeroplane Aerodynamics SR

1/42

Student Resource

SubjectB1-11a:AeroplaneAerodynamicsandFlight

Controls

Copyright 2008 Aviation Australia

Allrightsreserved.Nopartofthisdocumentmaybereproduced,transferred,sold,orotherwisedisposedof,withoutthewrittenpermissionofAviationAustralia.


2/42

ThisPageIntentionallyLeftBlank


3/42

Part 66 Subject

B1 11 Aeroplane Aerodynamics and Flight Control

IssueB:January2008 Revision1 Page1of6

CONTENTS

Page

Definitions 3

Study Resources 4

Introduction 5

AeroplaneAerodynamics 11.1.1-1

HighSpeedFlight 11.1.2-1

FlightControlsSystems 11.9-1


4/42

Part 66 Subject



ThisPageIntentionallyLeftBlank


5/42

Part 66 Subject



DEFINITIONS

Define

Todescribethenatureorbasicqualitiesof.

Tostatetheprecisemeaningof(awordorsenseofaword).

State

Specifyinwordsorwriting.

Tosetforthinwords;declare.

Identify

Toestablishtheidentityof.

List

Itemise.

Describe

Representinwordsenablinghearerorreadertoformanideaofanobjectorprocess.

Totellthefacts,details,orparticularsofsomethingverballyorinwriting.

Explain

Makeknownindetail.

Offerreasonforcauseandeffect.


6/42

Part 66 Subject



STUDYRESOURCES

JeppesenSandersonTrainingProducts:

A&PTechnicianGeneralTextbook.

A&PTechnicianAirframeTextbook.

B1-11aStudentHandout


7/42

Part 66 Subject



INTRODUCTION

Thepurposeofthissubjectistoexplainhowbasicaerodynamicsisappliedtoavarietyofdifferentaeroplanedesigns/typesandeffectsofhighspeedflight.Thepurpoise,functionand

opertionofbasicaeroplneflightcontrolsystemsandcomponents.

Oncompletionofthefollowingtopicsyouwillbeableto:

Topic 11.1.1 Aeroplane Aerodynamics

Describetheoperationandeffectsofthefollowingprimarycontrolsystems:

rollcontrol(aileronsandspoilers)

pitchcontrol(elevators,stabilators,variableincidencestabilisersandcanards)

yawcontrolandrudderlimiters

Describeflightcontrolusingelevonsandruddervators.

Describethefollowinghighliftdevices:

Slots

Slats

Flaps

Flaperons

Describetheoperationandeffectsof:

Draginducingdevices(spoilers,liftdumpersandspeedbrakes)

Wingfencesandsawtoothleadingedges

Describeboundarylayercontrolusing:

Vortexgenerators

Stallwedges

Leadingedgedevices.

Describetheoperationandeffectsofthefollowing:

Trimtabs

Balanceandantibalance(leading)tabs

Servotabs

Springtabs

Massbalance

Controlsurfacebias

Aerodynamicbalancepanels


8/42

Part 66 Subject


B:January2008 Revisi 1

Issue on Page6of6

Topic 11.1.2 High Speed Flight

Describethefollowing:

Speedofsound

Subsonicflight

Transonicflight

Supersonicflight

Machnumber

Criticalmachnumber

Compressibilitybuffet

shockwave

aerodynamicheating

arearule

Describetheairflowconditionsinengineintakesofhighspeedaircraftandthefactors

whichaffectthem.DescribetheeffectsofsweepbackoncriticalMachnumber.

Topic 11.9 Flight Control Systems

Identifythefollowingprimaryflightcontrolsandexplaintheiroperation:

Ailerons.

Elevators.

Rudders.

Spoilers.

Statethepurposeofthefollowingflightcontrolsystemsandexplaintheiroperation:

TrimControl.

ActiveLoadControl.

HighLiftDevices.

LiftDump.

SpeedBrakes.

Explaintheoperationofflightcontrolsbythefollowingmethods:

Manual.

Hydraulic.

Pneumatic.

Electrical.

FlybyWire.

Explaintheoperationandeffectof:

ArtificialFeel.

YawDamper.

MachTrim.

RudderLimiter

Gustlocks.

Explainbalancingandriggingofflightcontrols.

Explaintheoperationofstallprotectionsystems.


9/42

Part 66 Subjec

t

B1 11.1 Aeroplane Aerodynamics and Flight Controls

B1-11.1.1:AeroplaneAerodynamics

IssueB:January2008 Revision2 Page1of 6

TOPIC11.1.1AEROPLANEAERODYNAMICS

Control About Two Axes

Ruddervators

AcombinationofrudderandelevatormountedonaVeetailwhichprovidessimultaneouslongitudinalanddirectionalcontrol

VeeTailisalsoknownasaButterflytail.

Control About Two Axes - Elevons

DELTA WINGS

Elevonsprovidesimultaneouscontrolaboutthelateralaxisandthelongitudinalaxisi.e.pitchandroll.


10/42

Part 66 Subjec

t


Aerodynamic Balancing And Trimming

Controlforcesdependontheairspeed2andareaofsurface,thelargerand/orfastertheaircraftthehighertheforcerequiredtomanoeuvre.

Forthisreasoncontrolsareoftenbalancedtoassistthepilotsinputforceduringmanoeuvres.(Reduceforces)

Trimminghowever,meansremovingallcontrolforcesduringsteadyflightusingaseparatecontrolinthecockpit.

Horn Balance

Aportionofthecontrolsurfaceisextendedoutaheadofthehingeline.Thisutilisestheairflowabouttheaircrafttoaidinmovingthesurface.Althoughverysimple,itdoescreatedrag.




11/42

Part 66 Subjec

t


Balance Panels

Thehingedbalancepanelmovesinsideasealedspaceaheadoftheaileron.

Whentheaileronisdeflectedupward,(asseenabove)theairoverthebottomsurfacespeedsupandproducesalowpressurebelowthebalancepanel.(Venturieffect)

Thislowpressurepullsthebalancepaneldownandputsaforceontheleadingedgeoftheaileroninsuchadirectionthatitassiststhepilotinholdingtheailerondeflectedupward.Thereisnoextradrag.

Drag Inducing Devices

Spoilers Lift Dumpers

Spoilersareflightcontrolsthatriseupfromtheuppersurfaceofthewingtodestroy,orspoil,lift.

Flightspoilersareusedathighspeedtodecreaseliftononewingandrolltheaircraft.

Asliftdumpers,theyareusedtodestroytheliftoftheaircraftaftertouchdowntoaidinslowingtheaircraft




12/42

Part 66 Subjec

t


Speed Brakes

Speedbrakes,alsocalleddivebrakes,arelargedragpanelsusedforairspeedcontrol.

Theycanalsobeusedtoslowanaircraftaftertouchdown,andreducethelandingroll.

Boundary Layer Control

Wing Fences

WING FENCE

Boundarylayercontroldevicesaredesignedtodelayairflowseparationoverthewing.

Wingfencesarefixedvanesthatextendchordwiseacrossthewingofsweptwingaircraft.

Theirpurposeistopreventairfromflowingoutwardalongthespanofthewing,forthisinturnislikelytocauseairflowseparationnearthewingtipsandsoleadtotipstallingandpitch-up




13/42

Part 66 Subjec

t


Vortex Generators

Saw Tooth Leading Edge

Tipseparationandstallcanalsobedelayedreducedbyintroducinganotchorsawtoothin

theleadingedge.

NOTCH

Eachnotchgeneratesastrongvortexwhichcontrolstheboundarylayerinthetipregion

Thesearesmallplatesorwedges,projectinganinchorsofromthetopsurfaceofthewing,Eachplategeneratesavortexaddingenergytotheboundarylayer.

Theboundarylayertravelsfurtheralongthesurfacebeforebeingslowedupandseparatingfromthewing.




14/42

Part 66 Subject


B:January2008 Revisi 2 Page


Issue on 6of 6

ThisPageIntentionallyLeftBlank.


15/42

Part 66 Subjec

t


B1-11.1.2:HighSpeedFlight


TOPIC11.1.2HIGHSPEEDFLIGHT

Mach Number

Theratioofthespeedoftheairplanetothespeedofsoundinthesameatmosphericconditions.

True Airspeed

= Flight Mach No.

Local Speed of Sound

M=1iscalledSONICflow

HighspeedflightismeasuredintermsofMachNumber,whichistheratioofthespeedoftheaircrafttothespeedofsound.

WhentheaircraftisflyingatMach75itisflyingat75%ofthespeedofsoundattheambientairtemperature.

TheSpeedofSoundvarieswithtemperature,andthetempvarieswithaltitude.

SoaircraftreachMach1earlierathigheraltitudes.

Critical Mach Number Mcrit)

TheflightMachnumberatwhichthereisthefirstindicationofsonicairflow,overthewing.

AtMach0.5AllairflowovertheaircraftwingislessthanM=1.Astheaircraftaccelerates,theFlightMachNo.atwhichtheairflowoverthewing,(duetotheventurieffect),becomessonic,isknownastheCriticalMachNumber.


16/42

Part 66 Subjec

t




Shock Induced Stall

BeyondMcrit,theshockwavegrows.Airflowthroughthisregionundergoesasuddenstaticpressureincrease.

Theeffectofthesuddenpressureriseistocausetheboundarylayertoseparatefromthewingimmediatelybehindtheshock,takingwithitthelayersofairaboveit,soprecipitatingaShockStall.

Theshockwavecausesearlyairflowseparation.(partialstall)

TheShockStallandtheordinary\stall,althoughhavingdifferentcauseshavecertainpointsincommon:-

Asuddenincreaseindragoftenaccompaniedbycompressibilitybuffetingwhichincreasesinintensitywithgrowthofstall,andalossoflift.

Shock Induced Drag

Thesuddenextradragwhichisamarkedfeatureofshockstall,isofthesamenatureasformdragandskinfriction.

Overcomingthissuddendragrisegivesrisetotheexpression,breakingtheSoundBarrier.

Area Rule

Tominimisetheincreaseindragintransonicflighttheaircraftstotalcrosssectionalarea,alongitslengthshouldincreasegraduallytoamaximumandthendecreasejustasgradually.

Thefuselagecrosssectionareashoulddecreaseatthewingroot.Thecokebottleeffect.


17/42

Part 66 Subjec

t




Supersonic Intakes

Shockwavesareusedinthedesignofsupersonicaircraftjetintakestoaidengineperformance.AtMach1theairflowwithintheintakewillcausethecompressorsstallandtheenginetoflameout.Thisundesirableeffectiseliminatedbykeepingtheintakeairvelocitybelowsonic.

AsimplemethodtoslowdowntheairflowwithintheintakeistoinduceaNormalShockwaveinfrontofthecompressor,airflowbehindanormalshockwaveisalwayssubsonic.

Onemethodofachievingthisistobuildinadevicesuch,asamoveableplug,thatwillcauseaNormalShockwavetoform.Anothercommonmethodusedisthevariableconvergent/divergentintakeduct.Duringsupersonicflight,theNormalshockwavesformsintheconvergentsectionoftheductreducingtheintakevelocitytosubsonic,theairflowvelocityisthenfurtherreducedinthedivergentsectionbeforeenteringthecompressor.Dumpandspillvalvesintheintakekeeptheintakepressuretoanoptimum.


18/42

Part 66 Subject


B:January2008 Revisi 2 Page


Issue on 4of 4

ThisPageIntentionallyLeftBlank.


19/42

Part 66 Subjec

t


B1-11.9:FlightControls


TOPIC11.9FLIGHTCONTROLS

Load Alleviation

asystemofwingbendingreliefisdevisedforsomelargeraircrafttypes;

allowsmanufacturerstobuildlighterwingsandsavemoneyonconstruction;

allowaerodynamicstressestobealleviatedand,insometypes,istermedloadalleviationfunction(LAF).

passivewayofachievingloadalleviationistostorefuelinthewings.

Anactivemethodofloadalleviationisforhydraulicactuationtorapidlymovetheaileronsand/orspoilersinresponsetoturbulencesensedbyaflightmanagementcomputer.

YawdampercomponentsintheruddersystemautomaticallyinputruddermovementtopreventDutchRoll.

Mach Trim.

Asthemachincreases,sothecentreofpressuremovesaftandthenoseoftheaircraftwilltendtodrop.(machtuck).

Someaircrafthaveasystemthatwillincreasetheangleofattacktopreventmachtuck.

Iftheaircraftapproachesthiscondition,theautopilotwillinputtotheelevatororstabtrimtoliftthenoseoftheaircraft.Operation:-machinformationreceivedfromairdatacomputerisusedbym/tcouplertogenerateamachtrimservopositioncommandsignalwhichisroutedtom/tactuator[signalmodified/cancelledifflapnotfullup].theactuatorchangeselevatorpositionthruelevatorfeelandcenteringunitandelevatorpcuinordertomaintaincorrectpitchattitude.


20/42

Part 66 Subjec

t




Spoiler/Speedbrakes.

Airbus fly by wire system.

Allpanelsareusedforgroundspoilers.

Panels2.3and4usedasspeedbrakes.

Panels2,3,4and5plusaileronsareusedforrollcontrol..

Panel4and5plusaileronsareusedforloadalleviationfunction(LAF).

ELACsandSECsarethecomputersthatarecontrollingthepanelmovement.

BlueGreenorYellowhydraulicsystems.


21/42

Part 66 Subjec

t




B737

Thespeedbrakeleverisconnectedtorodswhichoperateaquadrantandcablesystem.

Thecablesruntoaspoilercontrolvalvewhichallowshydraulicpowertobeportedtothespeedbrake/spoileractuators.

Ifairloadsareexcessiveonthepanelthenitwillblowdownviaacheckvalve.

Lastpartoftravelissnubbedtopreventdamageofpiston.


22/42

Part 66 Subjec

t




Boeing:

Whentakingoff,leverselectedtodowndetent,uponreversethrustbeingselected(rejectedtakeoffabove60knots)thespeedbrakeleverwillbeliftedbyacamandtheelectricactuator

willdrivetheleverandcableruntodeployallgroundspoilers.Whenlanding(leversettoARMinflight)ifawheelspeedissensed(60knotsB737)andthethrottlesareretarded,spoilerswillbedeployed.Absenceofwheelspeedsensingwillmeanthatthesystemwillsensesquatswitchongroundanddeployspoilers.

Advancingeitherthrottleretractsspoilers.


23/42

Part 66 Subjec

t




Lateralcontrol,providedbytheailerons,isinitiatedbycontrolwheelorstickmovement.

Inthisschematicthepistonisfixed,thecylindermovesandrepositionsitselfwiththespooltherebyfollowingupandcancellinghydraulic inputwhendesiredtravelofcontrolsurfacehasbeenachieved.

Ifspoolisdisplacedtotherightbycablemovement,thiswillopenR/Hpxportandalsoopen

returnforL/Hsideofactuator.PxwillflowtoR/Hsideofactuatoranditwillmovetotheright(panelwillraise).Asthishappensthepressureandreturnportswillbeblockedoffagain(willcatchuptothespool).

Outboardaileronsonlyabletobeusedduringlowspeedflight.On747thisiswhenflapsarenotup,andon767aircraftspeedisusedtolockoutoutboardaileron.

Yaw damper components in the rudder system automatically input rudder movement toprevent Dutch Roll:- (directional and lateral oscillation that swept back wings aresusceptible to.) Flight management computers sense uncommanded roll and pitchmovementsthenwillinputtorudder.

Mach Trim:

Someaircrafthaveasystemthatwillincreasetheangleofattacktopreventmachtuck.

Iftheaircraftapproachesthiscondition,theautopilotwillinputtotheelevatororstabtrimtoliftthenoseoftheaircraft.(MachTuck:-asthemachincreases,sothecentreofpressuremovesaftandthenoseoftheaircraftwilltendtodrop).


24/42

Part 66 Subjec

t




Rudder Limiter.

Someaircraftneedtolimittheamountofruddertravelathighspeedtoavoidoverstress.

Thisisusuallyaccomplishedbyalteringtheamountofmechanicalinputbasedonairspeed.

Anelectricactuatoralterstheamountofmechanicalinputthattherudderpedalscancause.Ona747atabout165knots,therudderdeflectioncapabilitygoesfrom25degto5deg.

Highspeedaircraftneedamorecomplicatedfeelcomputerthanthesimplespringduetoseveralfactors:

variationinCofGandgrossweight;

variationinaltitude.ThereisconsiderablevariationinelevatoreffectivenessbetweenanaftCofGandaforwardCofG.Toachieveaconstantstickforce,thefeelsystemmustbuildinstiffnessforaftCofGandreducethestiffnessforaforwardCofG.

Feel computers have inputs from two hydraulic systems, pitot / static air pressure andstabiliserposition.

AvariablefeeliscreatedasCofGchangesduringfuelburn,andatdifferingairspeedsandaltitudes.

Thefeelistransmittedasahydraulicresistancetothepilotcontrolinputs.


25/42

Part 66 Subjec

t




Trim, Centre Feel Mechanism.

Lefthanddiagramshowscontrolwheelinputwithcontrolcablesmovingquadrantwithfeelgainedbyrollerridingupcamagainstspringpressure.Whencontrolwheelisreleasedthespringreturnswheeltocentre(neutral).

Rightdiagramistriminput,whereactuatorextendsorretractsandthecammoveswiththecam follower (aileron system friction forces are less than spring force) toproduceanewneutralposition.Controlwheelmoves.

Triminputwithouthydraulicswillhavethesameeffectasfeelintheaboveschematics.Thesystem will be ready to move as soon as hydraulics are applied, causing dangeroussituation.

(B737)

Duringflight,ifsmalllateralcontrolmovementsareneeded,thepilotwilltrimtheaircraft.

Ailerontriminthissystemisprovidedbyanelectricactuatordisplacingthecontrolquadrant.

Trim;

Electricactuatorcontrolledbythetwoswitchesrepositionstheaileroncableswhichcauseaninputtotheaileronhydraulicactuator.

Feel;

Cablesoperateagainstthespringtogivethepilotfeel.


26/42

Part 66 Subjec

t




Trailing Edge Flaps.

Hydraulicmotorsinthewheelwelldrivetorquetubesalongthewing.Thetorquetubesdrivegearboxeswhichrotatejackscrews.Thejackscrewsdrivetheflappanelviatheballnut.Theflap drivesystem alsonormally incorporates an electricmotorwhich can drive the same

torquetubesintheeventofhydraulicpowerfailure.Atanyflappositionorwhileintransit,theleftandrightflappositionsarecompared.

Ifadifferenceisdetectedthentheflapasymmetryprotectionsystemisactivated.Theflapswillbede-activatedorlockoutifonesideissensedtobemovingatadifferentratetotheotherside.


27/42

Part 66 Subjec

t




Movementoftheflapleverpositionsthecontrolvalvewhichportshydraulicfluidtooneportofthehydraulicmotor.Thelinkageisalsomovedbutasthemotorturnsthefollowupdrumis rotated which repositions the cam on the linkage and nulls the input at the positionselected.(followup)

Theloadlimiterisadevicethatwillmovetheflapsfrom40unitsto30units(737)toprotect

thetrailingedgeflapsagainstexcessiveairloads.


28/42

Part 66 Subjec

t




Theseaircraftuseanelectronicstallwarningsystem.

A stall warning computer uses airspeed,angle of attack, flap position and enginepowersettingtodetermineapproachingstall andwillactivateastick shakerandprovidemaster

warningwithauraltones.Withlargeaircraftthemarginbetweenpre-stallbuffetandactualstallisverysmall.Somemanufacturers incorporateasticknudger,whichwillpush the controlcolumn forward ifastallisimminent.

AILERON DRAG/DIFFERENTIAL AILERONS

The aileron thatmovesdownward createsbothmore liftanddrag,and thisdragwayoutnearthewingtippullsthenoseoftheairplanearoundinthedirectionoppositetothewaytheairplaneshouldturn.

ToovercomethisproblemtheaileronmovingupwardtravelsagreaterdistancethantheonemovingdownwardandarecalledDifferential Ailerons.


29/42

Part 66 Subjec

t




Airbus System

Aileron Servocontrol

1. SolenoidValve

2.

PressureLineClosingValve

3.

ReturnLineClosingValve

4. Servovalve

5. ModeSelectorValve

6. DampingOrifice

7. CheckValve

8. ReturnReliefValve

9. FluidReserve

10 FeedbackTransducer

11.ModeSelectorValveTransducer

ThisisanAirbusflybywireaileronservocontrol.Hydraulicpressuregoestoaservowhichisthesameprincipleastheantiskidservo.Howmuchsidestickdeflectionismeasuredbyadisplacementtransducerwhichissentasasignaltoacomputerandthenontotheservo.Theamountof flapperdeflectioninservoiscontrolledbythecoilinservo,whichdisplacesthespoolandmovesaileron.Movementofaileronispickedupbythefeedbacktransducer

andwhen inputsignal andoutput signalmatch, the spoolwillbebackin null.This istheprincipleofallairbusflightcontrols.Internalstopsfortravelthrowsandathumbwheelateyeendforrigging.


30/42

Part 66 Subjec

t




Balancing of Flight Controls.

Ingeneral,controlforceswhichthepilothastoexertinordertomovethecontrols,dependontheairspeedandareaofsurface.Thelargerand/orfastertheaircraft,thehighertheforcerequiredtomanoeuvre.Forthisreasoncontrolsareoftenbalancedtoassistthepilotsinputforceduringmaneuvers.(Reduceforces)

Flight,especiallyhighspeedflight,demandsthatallcontrolsurfacesbewellalignedandbalanced.

Surfacesareaerodynamicallyandstatically/massbalanced.

Aerodynamicbalancingmakesiteasierforpilotstooperatethecontrolsinflightrequireslessinputforce.

Staticbalancingpreventscontrolsurfaceflutterandsubsequentvibration.

Oneformofaerodynamicbalanceiswhenaportionofthecontrolsurfaceoftheaircraftisextendedoutaheadofthehingeline.TheportionisknownasaHornBalance.Thisutilisestheairflowabouttheaircrafttoaidinmovingthesurface.

Mass Balance

Thecontrolsurfaceisbalancedonaknife-edgemandrel.Aslidingweightofknownweightismovedalongagraduatedscaleuntiltheflightcontrolisbalanced(usespiritlevel).

Theweightmustbeacertaindistancefromthehingetoachieveequilibrium.

Forexample,iftheweightisonepoundanditmustbepositionedoneinchforwardofthe

hingetoachieveequilibrium,themomentarmissaidtobeoneinchpound.

Twopoundsplacedhalfaninchforwardofthehingewillachievethesameresult.


31/42

Part 66 Subjec

t





32/42

Part 66 Subjec

t




Therefore,itisnecessarytoknowthedistancefromthehingethattheprovisionforinstalling

thebalanceweightsisonthecontrolsurface.

Aformulacanthenbeusedforbalanceweightsrequired:

M1 x S1 = M2 x S2,

whereM1isthemassusedalongtheslidingscaleandM2isthemasstobeinstalled

onthecontrolsurface.

S1isthedistanceofthebalanceweightfromthehingelineandS2isthedistancefromthe

hingethattheweightsaremountedonthecontrolsurface.

IfS2isknownalready(forexample,2inches),theformulacannowread:

M1 x S1 = M2

2

If,ontheslidingscale,amassof0.5poundsatadistanceof1inchfromthehingeachieved

balance,then:

0.5 x 1 = M2

2

0.25 = M2

Therefore,amassof0.25poundsisinstalledtobalancethiscontrolsurface.

Rebalanceisrequiredafteranyrepairorrepaintandshouldbecarriedouttoaircraft

manufacturersspecifications.


33/42

Part 66 Subjec

t




Control System Rigging.

Acommoncharacteristicisthatallcontrolsystemsneedtoberigged,takingintoaccount:

correctcontrolsystemrouting,

wearanddamageofanysystemhardware,

correctadjustmentandtensionofadjustablecomponents,

safetyofalladjustablecomponents,

correctsense,thatis,thecontrolinputdoeswhattheoperatorwantstoachieve(instinctivecontrol).

correctneutralfairingandcorrecttravel(throw)ofallcontrolsurfacesand,

freedomofmovementofthewholesystem.

Thefollowingpagesexaminethesesevenpointstoconsiderwhenriggingacontrolsystem.


34/42

Part 66 Subjec

t




1. Correct system routing

Meansthatallhardwarecomponentsareintheircorrectlocationwithrespecttoothercomponents.Forexample,itisveryimportantforacableruntopassthecorrectwayover

pulleysandcableguards,fairleadsandcabledrums.Ifthesecablespicturedabovewereroutedthewrongsideofthecableguard,thecablewouldgrindontheguard,causingprematurewearandroughsystemoperation,possiblyleadingtocablebreakage.

Anyroughnesswhenoperatingacablesystemiscausetocheckforcorrectroutingalongtheentirecablerun.

2. Wear and damage of any system hardware

Shouldbeassessedwhencarryingoutanysystemriggingoradjustment.


35/42

Part 66 Subjec

t




3. Correct adjustment and tension of adjustable components

Isrequiredtoensurecorrectsystemoperation.Adjustmentofcableandchainends,push-pullrodendsandadjustablestopswilldeterminecableandchaintension,controlsurface

neutralpositionandcontrolsurfacetravel.Cabletensiometerisreadonthescaleandthenconvertedtocabletensioninpounds.Eachunithasacalibratedcardandthescalereadingisconverteddependingontheriserbeingusedandthegaugeofthecable.


36/42

Part 66 Subjec

t




4. Safety of all adjustable components

Itisessentialtoensurethesystemcomponentsdonotloosenoff.Thiswillfirstlyaffectsystemlengthortensionandeventuallycompromisesystemintegrity.Lockwiringon

turnbucklesmustbeterminatedwithatleastfourwrapsaroundtheshankoftheturnbuckle.Ifacablerunhasbecomeloose,orthereislostmotioninacontrolrun,itisimportanttocheckthatallturnbucklesandendfittingsarestillsecure.Precautionsforensuringthatpush-pullrodadjustableeyeendsandcableturnbucklesaresecure

5. Correct sense

Isabsolutelycriticaltoaircraftoperation.Imaginetheconsequencesifacontrolrunwasriggedsothattheaircraftstartedtoclimbwhenthecontrolcolumnwaspushedforward,ratherthandescendorrolledtotheleftwhenthepilotwantedtorolltotheright.


37/42

Part 66 Subjec

t




6. Correct neutral fairing and correct travel (throw)

Isimportantbecauseanydeviationofacontrolsurfacefromastreamlinedpositionwill:

Causeanetresultsimilartoacontrolmovementinthatdirection,e.g.ifanelevatorissittingbelowitsnormalfairedposition,theaircraftwilladoptaconstantnose-downattitude.Pilotsmustactivelycorrectthis.

Causeincreasedfuelburnbecauseofincreaseddrag

Causeundueaerodynamicstressontheairframe.

Controlsystemriggingisusuallydoneinaneutralpositionandpartsofthesystemmaybeheldintheneutralbytheuseofrigpins.

Rigpinsareusedtoeasilysetportionsofthecontrolsysteminneutral.Theremaybeapintobefittedatthecontrolcolumnoratitsbase,forexample,thenanotherinabellcrankorpulleyhalfway throughthesystem. Finally,theremaybearigpinorriggingboardtobefittedatthecontrolsurfacetolockitatneutralortoadjustthebiasofthesurfacetheamountitshouldsitawayfromneutral,ifapplicable.

Rigginganycontrol system requires thatstep-by-stepmethodicalproceduresbe followed

fromtheaircraftmaintenancemanual.Thebasicmethodhasmorestepswithincreasingaircraftcomplexitybutfollowsthesameformat:


38/42

Part 66 Subjec

t




Lockthecockpitcontrol,bellcranksandcontrolsurfacesintheneutralposition.

Adjustthecabletension,maintainingtherudder,elevatorsoraileronsintheneutralposition.

Adjustthecontrolstopstolimitthecontrolsurfacetraveltothedimensionsgiven.

Whenalladjustmentshavebeenmade,checkthattherigpinsarenotundertension,shouldbeabletoberemovedeasily,indicatingthatthecableorpush-pullrodadjustmenthasnotdisturbedthesystemawayfromitsoriginalneutralposition.

The control surfaces themselves move through an arc which is determined by themanufacturer.Maximumdeflectionfromneutralmaybemeasuredindegreesbyusingan

inclinometer.


39/42

Part 66 Subjec

t




Thesetwotypesofinclinometersorprotractorsaremountedonthecontrolsurface.Asthesurfacemoves either way from neutral, the vernier graduationswill show the amount ofdeflectionindegrees.Anothermethodofcheckingmaximumcontrolsurfacedeflectionisby


40/42

Part 66 Subjec

t




measuringthelineardistancefromthetrailingedgeofthecontrolsurfacetothetrailingedgeof the surface on which the control is mounted e.g. elevator trailing edge to horizontalstabilisertrailingedge.

It is important for the primary stops to contact first then, with further control columnmovement,thesecondarystopstocontact.

Thisfurthercontrolcolumnmovementistermedspringback.

Thisensuresfulltravelofthesurfacewillbeachievedbeforefullcontrolcolumndeflection.Ifacontrolsurfacedoesnotachieveitsspecifiedtravelrange,primaryandsecondarystopsmustbecheckedforcorrectdimension.

Also,assumingcable riggingiscorrectandrigpinsareeasilyremoved,ensureanypush-pullhardwareinthesystemnearthecontrolsurfaceisthecorrectlength.


41/42

Part 66 Subjec

t




7. Freedom of movement

isthefinalchecktobemadeonacontrolsystemafteranyworkhasbeencarriedout.

Thecontrolsystemshouldbeoperatedthroughthewholerangeofmovementinallmodesofoperatione.g.hydraulicpoweronandoff.

Anybinding,grinding, restrictionsinmovementor failureof thecontrolsystemtoreturntoneutralmustbeinvestigated.

Check for correct routingofsystem elements and excessive deflectionofcables as theypassthroughfairleadsetc.

Look, also, for any worn, rusted or seized bearings, either quadrant and bellcrank pivotbearingsorpush-pullrodeyeendbearings.

8. Duplicate Inspections

Oncompletionofallriggingandbeforeflight,aduplicateinspectionmustbecarriedout.

DuplicateinspectionsarerequiredbyallRegulatoryAuthoritiesafterassemblyoradjustmentofaircraftofflightandenginecontrols,airlinesmayrequiresduplicateinspectionsofothersystemsincluding:

fuel,

landinggear

andothersystemsvitaltoaircraftsafety.


42/42

Part 66 Subject


Sample Rig.

Hereisasimplecontrolsystem.Torigthissystem,thelogicalsequencewouldbe:

Lockthecontrolcolumninneutral

Lockanyintermediatehardwarei.e.bellcrankinneutral

Lockthecontrolsurfaceinneutralorinstallaninclinometerorriggingboard

Adjustcableandchaintensionstospecifiedvaluesandlockallturnbuckles

Adjustthepush-pulltubelengthtoconnectthebellcrankandthecontrolsurfaceandlocktheadjustableeyeends

Removeallrigpins

Operatethesystemthroughitsentirerangeandcheckforspecifiedcontrolsurfacedeflection.Adjustprimary/secondarystopsifrequired.

Removeanyinclinometersorriggingboards.

Ensureduplicateinspectioncarriedoutandcertifiedfor.

b1-11a aeroplane aerodynamics sr

Documents