A320A320前轮转弯系统前轮转弯系统介绍和维护介绍和维护一、背景介绍Thesteeringsystemusesthegreenoryellowhydraulicsystemtooperateasteeringactuatingcylinder,whichchangesthedirectionoftheNLGwheels.飞机在地面滑行时的方向控制，几乎完全依赖于前轮转弯系统NWS来操作完成。如果前轮转弯系统出现故障，机组将无法掌控飞机的滑跑方向，从而使飞机偏离或冲出跑道、滑行道，轻则损伤飞机设备，严重的甚至会造成人员的重大伤亡。因此，对于前轮转弯系统相关故障，必须按手册谨慎处置。JetblueAirbusperformsalowpassfortheLGBtowerforanosegearJetblueAirbusperformsalowpassfortheLGBtowerforanosegearinspection,andasyoucanseethenosegearisina90-degreeinspection,andasyoucanseethenosegearisina90-degreeposition.Followingtheflyby,theaircraftspentthenext2hoursflyingposition.Followingtheflyby,theaircraftspentthenext2hoursflyingoverthePacificOceanjustoffLongBeachburningfuelbeforedivertingoverthePacificOceanjustoffLongBeachburningfuelbeforedivertingtoLAXforanemergencylanding,whichhappilywasasuccesfulonetoLAXforanemergencylanding,whichhappilywasasuccesfulonewithoutinjuries.withoutinjuries.JetblueA320-232(N536JB)前起落架减震支柱上支撑防转凸耳损伤被剪切断裂,导致前轮空中偏置90度，于LosAngelesairport(LAX)执行应急着陆。JetBlue292BUR-JFKmakesitsemergencylandingatJetBlue292BUR-JFKmakesitsemergencylandingatLAX.ThefrontgearwasturnedperpendiculartotheLAX.Thefrontgearwasturnedperpendiculartotherunwaycausingthesparksandsmoke.runwaycausingthesparksandsmoke.LTEInternationalAirwaysA320-214LTEInternationalAirwaysA320-214在着陆滑跑过程中因前在着陆滑跑过程中因前轮转弯系统故障，导致偏离跑道，前轮陷入跑道旁边的草地。轮转弯系统故障，导致偏离跑道，前轮陷入跑道旁边的草地。二、系统介绍SYSTEMOVERVIEWThesteeringsystemreceiveshydraulicpressureinthefollowingconditions:-A/SKID&N/W-A/SKID&N/WSTeeRinGswitchisinONSTeeRinGswitchisinONposition,position,-towingcontrolleverisin-towingcontrolleverisinnormalposition,normalposition,-atleastoneENG-atleastoneENGMASTERswitchisON,MASTERswitchisON,-aircraftisonground.-aircraftisonground.ThesteeringsystemiscontrolledbytheBSCU,whichreceivesorderfrom:-thesteeringhand-thesteeringhandwheels(ordersaddedwheels(ordersaddedalgebraically),algebraically),-therudderpedals,-therudderpedals,-theautopilot.-theautopilot.前轮转弯角度限制HandwheelsDuringDuringtaxitaxi,andmoregenerallyat,andmoregenerallyatlowlowspeedspeed,throughactiononahandwheel.,throughactiononahandwheel.Therearetwoidenticalhandwheels:Therearetwoidenticalhandwheels:onefortheCaptain,onefortheFirstonefortheCaptain,onefortheFirstOfficer.Officer.Intheeventofsimultaneousoperation,Intheeventofsimultaneousoperation,theordersthatthehandwheelsgivetheordersthatthehandwheelsgivearealgebraicallyadded.arealgebraicallyadded.ThemaximumtravelofthewheelsisThemaximumtravelofthewheelsisplusorminusplusorminus74deg74deg. .ThemaximumcorrespondingtravelofThemaximumcorrespondingtravelofthehandwheelisplusorminusthehandwheelisplusorminus75deg75deg. .ThelawbetweenthesetwotravelsisThelawbetweenthesetwotravelsisnotlinearnotlinear. .ThesteeringangleislimitedasafunctionoftheThesteeringangleislimitedasafunctionoftheaircraftspeed.aircraftspeed.（手轮偏转角度与前轮转弯角度比例关系）（手轮操作时前轮转弯角度与飞机速度的限制关系）20KTS以内，最大行程操作速度高于70KTS，使用手轮转弯无效RudderpedalsDuringtakeofforlanding,Duringtakeofforlanding,andmoregenerallyatandmoregenerallyathighspeedhighspeed：-eitherthroughactionof-eitherthroughactionoftheCaptain(orFirsttheCaptain(orFirstOfficer)ontherudderOfficer)ontherudderpedals,pedals,-orautomatically-orautomaticallythroughtheautopilot(yawthroughtheautopilot(yawcontrol).control).Intheeventofsimultaneousoperation,theordersthatthehandwheelsandpedalsgivearealgebraicallyadded.PEDALSDISC按钮可在以下情况脱开脚蹬对前轮转弯的控制：Duringruddergroundcheck.Therunwayisicy.Pilotcandisconnectthecontrolthroughthepedalsfromthesteeringcontrol.Whentheaircraftspeedisabove130knots,thesteeringisnotavailable（脚蹬操作时前轮转弯角度与飞机速度的限制关系）NoseWheelSteeringServo-Control(6GC)enhancedtype图示为增强型A320系列飞机，区别在于选择活门位置与classic不同,液压使用的是黄系统NoseWheelSteeringServo-Control(6GC)classictype传统型的6GC将选择活门作为部件嵌入到整体中。液压选用的是绿系统。NoseWheelSteeringServo-Control(6GC)SelectorvalveBleedscrewAnti-shimmyaccumulatorServovalveNoseWheelSteeringServo-Control(6GC)maincomponentsAnelectrically-operatedselectorvalveanditsslavedvalve.WhenAnelectrically-operatedselectorvalveanditsslavedvalve.Whentheselectorvalveisenergized,thepressureisappliedtothetheselectorvalveisenergized,thepressureisappliedtotheservovalve.servovalve.Aservovalveofthedeflection-jettype,equippedwithaLVDTAservovalveofthedeflection-jettype,equippedwithaLVDTsensorwhichdetectsthepositionoftheslidevalve.sensorwhichdetectsthepositionoftheslidevalve.AnadjustablediaphragmlocatedoneachoutputlineoftheAnadjustablediaphragmlocatedoneachoutputlineoftheservovalve,thisdiaphragmisusedtoadjusttheflowtoeachservovalve,thisdiaphragmisusedtoadjusttheflowtoeachactuatingcylinderchamberandconsequentlythewheelsteeringactuatingcylinderchamberandconsequentlythewheelsteeringspeed.speed.Aby-passvalvewhichinterconnectsthetwochambersoftheAby-passvalvewhichinterconnectsthetwochambersofthesteeringcylinderintheeventofhydraulicsystemdepressurization.steeringcylinderintheeventofhydraulicsystemdepressurization.Ananti-shimmyaccumulatorwithabuilt-inpressure-reliefvalve,ItAnanti-shimmyaccumulatorwithabuilt-inpressure-reliefvalve,Itcansupplyfluidpressurizedto15barsincaseofcavitationinonecansupplyfluidpres