(b)
Removecenteravionicsconsoleand center floorboardsto gainaccess to the contactors.
(c)
Disconnectelectrical cables, bus bars and markto facilitate reinstallation.
(d)
Disconnect20 gauge jumperbetweencontactorcoils.
(e)
Disconnectannunciatorwire (with fuseholder).
(f)
Removescrews to contactor and remove unit.
16. Installationof Cross Start Relays
(a)
Positioncontactorson mounting plateand securewith appropriate screws.
(b)
Connectannunciatorwire, 20 gauge jumper,busbars andall marked electricalcablesto their appropriateterminalsandsecurewith lockwashers and nuts.
(c)
Reconnectbatteryor external powerandperformoperationalcheck.
17. Descriptionand Operation of Battery
The nickelcadmiumbatteriesmustbe keptcleanandchargedto remain airworthy.Serviceis requiredevery 100 hours or 60 days, whicheveroccursfirst. Water consumptionisdirectly proportionalto the overcharge currentsexperienced.Servicefrequencydependson operating conditions. Importantprecautions:
WARNING: SERIOUS INJURY CAN RESULT WHEN THE FOLLOWING PROCEDURES FOR CLEANING OR SERVICING A NICAD BATTERY ARE NOT FOLLOWED.
(a)
Removeall metal jewelry, i.e.rings,watchbands,and bracelets. Dueto very highcurrent capabilities,the battery canquicklymeltor fuse metal andcause severeburns.
(b)
Use only insulatedtools. Neveruse tools previouslyusedon leadacid batteries.
(c)
Thepotassiumhydroxide and waterbatteryelectrolyteis caustic andcancauseseverebums. Wearprotectiveclothing(rubber gloves, apron,eyeprotection,etc.)whilehandlingthe electrolyte. If contact occurs,flushimmediatelywith water and neutralizewith aceticacid, vinegar,lemonjuiceor a 10% solution of boricacid. Flusheyes with watercontinuouslyand
contactphysician immediately.
(d)
Hydrogenandoxygengasesdo generateand are highly explosive.Vent these gasesto the outsideair when charging. In case of chargingindoors with centralair conditioningpresent, thesegases can be circulated via the duct work throughout the building. Outside venting of the batteryserviceareaismandatory.
(e)
;Makesure all electrical connectionsare tight andsecureto prevent electricalarcswhichcould triggerand explosion.
(f)
Keepcell ventplugsin place at all timesexceptwheninspectingoradjustingelectrolytelevels.
EFFECTIVITY:
040-999 PAGE
13
24-30-00 Jan10/90
PIPERAIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL
A. DC Generation (continued)
18. Fault Isolation
CHART 3
FAULT ISOLATION (BATTERY)(Sheet1 of 3)
Fault Cause
Batterydisconnectsolenoid Opencircuit.
does not operate.
Dirty contact on
connectorplug.
Open-circuitedsolenoid
coil.
Plunger binding.
Batterydisconnectsolenoid Short-circuitedcoil. intermittentoperation. Looseelectrical connection.
Plunger binding.
Badlyburnedpoints.
Excessiveelectrolyte Electrolyteleveltoo high. spewage.
Vent caps loose or damaged.
Damagedcell case.
Chargingvoltagetoo high.
Remedy
Repair wiring.
Clean contacts.
Replaceunit.
Removeand wash plunger and housingthoroughlywith stoddardsolution. Change springcompressiononlyas a lastresort.
Replacecoil. Clean andtightenelectrical connections.
See remedypertainingto "Plungerbinding"under "Doesnotoperate."
Ifpointscannotbe dressed down,replacetheunit.
Cleanand adjustelectrolyte level.
Replaceortighten caps, recharge,andcheck electrolyteleveland clean.
Shortout all cellsto 0volts and clean, recharge,and checkelectrolytelevel. Replacedefectivecell.
Cleanandrecharge,check electrolytelevel,andcheck batterychargesystem.
EFFECTIVITY:
040-999
PAGE14 24-30-00 Jan 10/90
PIPERAIRCRAFT
PA-42-720(Advanced Trainer)
MAINTENANCEMANUAL
A. DC Generation (continued)
18. Fault Isolation (continued)
CHART 3 FAULTISOLATION(BATTERY)(Sheet2 of 3)
Fault
Excessuse of water by one or morecells.
Formingduring charge afterwateraddition.
Continuedfoamingduring charging.
Nobattery output.
Lossof capacity.
Below normal output
voltage.
Cause
Leakyordefectivecellor vent.
High charge voltage.
Lowconcentration electrolyte.
Oiland grease contamination inthe electrolyte.
Brokenor disconnected links.Loosebattery connector.Cell open internally.
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