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PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCEMANUAL
B. MaintenancePractices(continued)
11. DeicerBoots (continued)
(i) WrinkledDeicers (Figure 404) (continued)
(4.) Check for intermittent open circuits by tensioning deicerstrap slightly while measuring resistance. Press lightly on deicer surface adjacent to strap retainer. Ensure resistance does not vary.
NOTE: Identify circuits in element by referring to resistance valves (See 30-20-00, Figures 1 & 2). Identification is necessary to cycle system properly and obtain correct amperage values during system operation. Minimum and maximum ohms between common ground and other terminals is 4.58 to 5.26 ohms.
(5.) Reconnect disconnected circuits and remove any paper shims.
(j) Installationof Propeller DeicerStraps and Wire Harness
(1.) Fasten deicer lead strip to bulkhead.
(2.) Attach deicer strap to studs on spinner bulkhead.
CAUTION: NEVER USE TYPE B STAR WASHER (TEETH ON OUTER DIAMETER) ADJACENT TO TONGUE OF DEICER TERMINALS.
(3.) Ensure no slack exists in deicer lead strap between terminals and clip. Conduct test on each propeller deicing system to ensure deicer lead straps are installed so propeller can be moved from full low pitch through feathering positionwithoutplacing tension on straps.
NOTE: Deicers must have plastic bonded to air side (shiny side) of deicer strap (Figure 405).
(4.) If damage occurs to slip ring wire harness, rubber spacers, or hose clamps, replace damaged parts.
Prop Deicer
Propeller Lead Strap Installation
Figure 405
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PIPERAIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL
B. MaintenancePractices (continued)
11. DeicerBoots (continued)
(k)
Balancing
Toassurea balancedpropellerassembly,reinstalloriginalbalancingweightsor equivalents. Positionweightsin originalpositionon propellerhub. Ensurerestrainerandweightsdo not interferewith propellerassembly. If balanceweightsare removed,reinstallsafetywireon screws.
(I)
FinalElectricalCheck
(1.) Ensureallterminalsaretight,not over-torqued.
(2.) Ensureallwiresareproperlyinsulated,especiallyin enginecompartments.
(3.) Ensureallwire tiesaretightand positionedto preventchafingor stoppageof moving
parts. (4.) Ensureallwiresaretightenedin connectorsand ensurenobarewireswill shorton nearby objects. (5.) Ensureinstalledwiresarenot sharplybent,pinched,or pulledtight.
(m)OtherComponents
Donotattemptinternalrepairsof timer,ammeter,or switches. If inoperative,replace componentswith properparts. Forotherrepairor maintenanceproblemsnotcoveredin this manual,inquireat Aerospaceand DefenseProductsDivisionofthe B. F.GoodrichCompany, Akron,Ohio 44318.
(n) PowerControlRelays (Figure406)
Bothleft and rightpowercontrolrelayssetaremountedin the accessorysectionof engine nacelles.
(o) Removalof the PowerControlRelays
(1.) Removetop cowlsfrom nacelle.
(2.) Relaysaremountedin accessorycompartmenton bulkheadby motorcontrolrelay. Identifywirecodesand noteattachmentpoints;disconnectthemfrom desiredrelay. (See 91-00-00forappropriatewiringdiagram.)
(3.) Removeappropriaterelaybe unscrewingtwo screwsfasteningunitto firewall.
(p) Installationof PowerControlRelay
(1.) Repositionrelayandsecurewith properscrews.
(2.) Reconnectwiresto appropriateterminal.
(3.) Completefollowingtestto determineproperinstallationandoperationof relay:
(a.) Turnon ice protectionswitch. Pushgroundtestswitch.
(b.) Ensurerelayactuates,causingtimerto startcyclinganddeicersto heat.
EFFECTIVITY:
040-999
30-60-00Jan
Jan 10/90
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