1IntroductionHydraulicsystemsgivepowertooperatethelandinggear,flightcontrols,andotheraircraftsystems.AcceptableBMD3-11,TypeIVfluidssuchasskydrolcanbeused.Thethreehydraulicsystemsareidentifiedbythelocationoftheprimarycomponents.Theyaretheleft,right,andcentersystems.Theleftsystemcomponentsareintherightenginestrut.Therightsystemhas17gallonsofhydraulicfluid.Therightsystemcomponentsareintherightenginestrut.Therightsystemhas20gallonsofhydraulicfluid.Thecentersystemcomponentsareinorneartherightmainwheelwell.Thecentersystemhas40gallonsofhydraulicfluid.下一頁返回1IntroductionThethreesystemshavenoconnectionswitheachother.Theyhavedifferentcolor-codesontheirrelatedtubingforidentification.Therearetwoengine-drivenpumps（EDPs）,oneoneachengine.Thesearetheprimarypumpsintheleftandrightsystems.TherearefourACmotorpumps（ACMPs）.Twoaretheprimarypumpsinthecentersystem,andoneisthedemandpump（DP）inthecentersystem.Aircomesfromthepneumaticsystem.Thesearethesourcesforthisair：enginebleed,APU,groundsourcesuchasaircart.Aramairturbine（RAT）pumpinthecentersystemisanemergencysourceofhydraulicpressure.上一頁返回2PressureSourceTheprimarysourceofpowerfortheleftandrightsystemsisengine-drivenpumps（EDPs）ratedat37GPMattakeoffpower.Theprimarysourceofpowerfortheleftandrightsystemsistwoalternatingcurrentmotorpumps（ACMPS）ratedat7GPMeach.Secondary（demand）pumpscomeonwhentheprimarypumpscannotkeepsufficientpressure.TheleftandrightsystemshaveanACPMdemandpump.Theseareidenticaltoandinterchangeablewiththecentersystemprimarypumps.下一頁返回2PressureSourceThecentersystemusesanair-drivenpump（ADP）ratedat37GPMasademandpump.Thecentersystemalsohasanemergencyramairturbine（RAT）pumpratedat11.3GPM.Primaryflightcontrolactuatorsandautopilotservosgetthehydraulicpowerfromallthreehydraulicsystems.Thespoilersystemalsousesthepowerfromallthreesystems.Dualsystempowerissuppliedtothesesystems：thestabilizer,yawdampers,elevatorfeelsystem,andbrakes.Thesesystemsgetthehydraulicpowerfromonesource：thehighliftdevices,landinggear,rudderratiochanger,andhydraulicgeneratoroption.上一頁返回3SystemsDistributionPrimaryandsomesecondaryflightcontrolsgetthepowerfromtheleftandrightsystems.Thrustreversersalsogetthepowerfromthesesystems.Therightsystemsuppliespowertothenormalbrakes.Apitchenhancementsystem,thepowertransferunit（PTU）betweentheleftandrightsystems,suppliesathirdsourceofpowerforthehorizontalstabilizer.Thecentersystemsupplieshydraulicpowerforprimaryandsecondaryflightcontrols.Thesesystemsgethydraulicpowerfromthecentersystem：thelandinggear,nosewheelsteering,alternateandreservebrakes,andhydraulicmotorgeneratoroption.下一頁返回3SystemsDistributionTheseindependentsystemsgiveaircrafthydraulicpower.Eachsystemhasareservoirthatstoresandsupplieshydraulicpowertopumps.Eightpumpspressurizethehydraulicsystems.Eachpumphasafiltermoduletofiltermodulewithpressureandcasedrainlinefilters.Eachsystemhasareturnfiltermoduletofilterthefluidthatreturnstothereservoir.Oneheatexchangerineachsystemcoolspumpcasedrainfluidbeforeitreturnstothereservoir.Acentralfilllocationletsyouserviceallthreesystemsfromoneplace.上一頁返回4FlowPathFluidgoestotheengine-drivenpump（EDP）throughareservoirstandpipe.Asupplyshutoffvalveoperatedbythefireswitchisinthissupplyline.Itclosestostopfluidtotheengine-drivenpumpifthereisanengineshutdownduetofire.TheEDPprovides3,000psihydraulicfluidtooperateleftsystemcomponents.EDPcasedrainfluidisusedtolubricateandcoolthepump.Pressureandcasedrainoutputsarefilteredinthesamemodule.Casedrainfluidisinaheatexchangerintheleftwing.Anelectricpump（ACMP）isademandsourceofsystempressure.下一頁返回4FlowPathAseparatefiltermodulefiltersACMPcasedrainandpressureoutput.Pumppressureandsystempressurearemonitoredbypressureswitches.SystempressureisalsomonitoredbyapressuretransducerandtransmittedtotheEICAScomputers.Thesystem’sfluidthatreturnstothereservoirgoesthroughareturnfilter.ApowertransferunitpumppressurizestheleftsystemreturnfluidandprovidesittothestabilizertrimcontrolmodulewhenthePUDison.上一頁返回5LoadsThelefthydraulicsystemsuppliespowerforthesefunctions：primaryflightcontrols,somesecondarycontrols,andthrustreversers.Thehydrauliclinestothetail（empennage）areaandthewingunitshaveisolationvalvesformaintenanceuse.Thecheckvalvesandfusesareintheleftsystemrudderandelevatorpressureandreturnlinestoprotectthelefthydraulicsystemifthereisafailureofthehydrauliclinesinthehorizontalorverticalstabilizer.Therighthydraulicsystemissimilartotheleftsystem.下一頁返回5LoadsTherightsystempressureisprovidedtothesecomponents,ailerons,spoolers,rudderandelevator,autopilots,LCCAsandPCAs,normalbrakesystem,thrustreverser,andpowertransferunitmotor.上一頁返回6ReservoirFillYouservicetheleftsystemreservoirthroughaservicingfittingandselectorvalveintherightfairingarea,aftoftherightmainwheelwell.Groundservicedisconnects（quickdisconnects）areontheEDPandreturnfiltermodulesintheaftpartoftheenginestrut.下一頁返回7ReservoirsEachreservoirispressurizedtomakesurethereisfluidsupplytothepumps.Thepressureiscontrolledto40psiwithairfromthepneumaticsystem.Theairgoesthroughthepressurizationmodulewhichcontainsthesecomponents：twofilters,twocheckvalves,manualbleedvalve,andcappedtest.Thereservoirsarealuminumweldments.AstandpipesuppliesfluidtotheEDPandtheACMPdrawsfluidfromthebottomofthereservoir.Thereservoirholdseightgallons,butisservicedto4.77gallonstoallowforairvolumenecessaryforheadpressure.下一頁返回7ReservoirsAhydraulicquantityindicatingsystemgivesreservoirfluidleveldataforeachsystem.Acapacitanceprobeineachreservoirmeasuresthefluidlevel.Asthefluidlevelchanges,theamountoftheprobeinfluidchanges.Thischangestheprobecapacitance.Theprobesintheleftandrightreservoirareinterchangeable.Alargerprobeisusedinthecentersystemreservoir.Avariableresistancetemperaturetransmitterisoneachhydraulicreservoir.TheEICAScomputershowsthetemperatureonthelowerEICASdisplay.ThereservoirservicestationisintherightaftbodyfairingareaaftoftheRHwheelwell.上一頁下一頁返回7ReservoirsThereservoirservicestationgivessinglepointservicingforchecksandforthemaintenanceoffluidlevelsinthreehydraulicreservoirs.Afour-positionselectorvalveandswitchiscontrolledbyoneleverthatselectsthereservoirtobeservicedandtoshowonthehydraulicquantityindicator.NOTE：Togetaproperfluidlevelinthereservoirs,thereservoirsmustbeservicedwithalllandinggearsdown,geardoorsclosed,steeringandflightcontrolsneutral.Whenservicingtherightsystem,thebrakeaccumulatorpressureindicatormustreadatleast2,500psi.上一頁下一頁返回7ReservoirsThehydraulicquantityindicatoriscalibratedinpercentoffullincrements（110percent