NOTE: For control of door valve solenoid, fabricatean electric harness (Figure502). This harness,when connected to 24-volt battery, allows control of electrical current to door valve solenoid permitting hydraulicdoor circuits to operate.
EFFECTIVITY: 040-999
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PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCEMANUAL
A. Main (continued)
58. Bleedingthe Hydraulic System.
(a)Jack airplane (refer to 7-10-00).
(b)
Ensurereservoiris full.
(c)
Connecthydraulictestunit to airplane.
(d)
Cyclelandinggearsystemthroughseveralcycles.
(e)
Ensurehydraulicreservoiris full.
(f)
Disconnecthydraulictestunit.
(g)
Ensurelandinggearselectorhandle is in down,neutralposition,and landing gearis down and locked.
(h)
Removeairplanefromjacks.
59. Removaland Installation ofHydraulicLines
lineby disconnecting brackets (Figure3). Providesmallcontainerfor draining line. Install newor replaced lineby connecting fittings at each end and connecting brackets.Refillpower pack with hydraulic fluid.
Removedamagedhydraulic fittingsateachend and disconnecting
NOTE: Whenusingstraightthreadtype fittings, locknutsmustbe tightenedso O-ring seals are on non-threaded portion of fitting.
60.RemovalandInstallationofHydraulicFilters.
The hydraulic filters,locatedon lower right forward sideof each enginefirewall,areremovedas
follows:
(a)
Removeturtle back skinaftof cowlingsto gain accesstoforwardandaftsidesof firewall.
(b)
Disconnectfilterinlethoseandoutletlinefromfilter.
(c)
Removefilter from firewallby holding bolts at aft side of firewall andremovingnut at filter.
(d)
Thefilter is installed in reverse order.
(e)
Afterrunningengine,checkfor leaks.
of Filter Elements.(Figure409) 61. Replacement
(a)
Removeturtlebackskinaft of cowlings to gain accessto forward and aft sidesof firewall.
(b)
Cutsafetywire,unscrewbowl,andremovefilterelement.
(c)
Cleanfilterbowlwithsuitablecleaningsolventanddry.
(d)
Replacefilterelementand O-ring onbowl.
(e)
Halffillfilter bowl to minimize trappedair in hydraulic systemandreplace bowl.
andreplace
(f)
Safety filter bowlwith safety wire(MS20995C20) cowl.
(g)
Afterrunningengine,checkforleaks.
EFFECTIVITY:
040-999 29-10-00Jan 1
29-10-00U Jan 10/90
PIPERAIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL
A. Main(continued)
1.Body,Filter 2. -RingSeal 10. O-Ring Seal9. Screw PressureScrewPressure
3.O-RingSeal 8. Spring
17. Valve,By-Pass
4. Filter
5.Spring
6.Bowl
HydraulicFilter Figure409
62. HydraulicPumpOperationalCheck.
Todetermineoperationalconditionof eachhydraulicpump,conductfollowingcheck:
(a) Startone engine andallow to stabilize at idle.
(b)With engine operatingat52%gasgeneratorspeed,movegear selector handleto gear down
position. One pump must build up pressurein hydraulic system and return selectorhandleto neutralposition within 3 to 9 seconds. Againselect down positionandcheckhandlereturn time.
(c)
Shutenginedown and repeat precedingstepsfor other engine.
(d)
If selector handledoesnot return to neutral during operationcheckforone pump, but does returnwithin required timeduring check of other,removepumpand determine causeof malfunction.
63. ProcedureafterHydraulicPump Failure.
Ifpumpbreakageoccurs,metal particles couldexistin hydraulic system. To rectifycondition,flush hydraulicsystemas follows:
(a)
Replacedefectiveengine-drivenhydraulicpumpandprimeit. Do not connectpump to hydraulicsystemuntilsystemis flushed.
(b)
Flushsystem.
(c)
Removefilter elements andcheckfor metal particles. Ifmetal particles are found in filter, clean filterbowlwith dry cleaningsolvent. Dry with compressed air and installnew filter elements.
EFFECTIVITY:
PAGE 28 040-999
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PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCEMANUAL
A. Main (continued)
64. Removalof Hydraulic Pump.
(a)
Removeupperandlowerengine cowls by releasing skin fasteners and separating two halves.
(b)
Place drip pan under engine to catch spillage.
(c)
Disconnecttwo hydraulic hosesfrom end of pump. Cap hoses to prevent contamination.
(d)
Disconnectdrainhose from bottom of pump.
(e)
Removefour nuts, lock washers, andflat washers from base of pump.
(f)
Removepump from engine housing.
(g) 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：夏延飞机维护手册 Cheyenne IIIA PA-42-720 AMM 2(6)
