acceptableto a depthof 0.015inch.)(4.) Iferosionequalsorexceedsamountsshownin Chart1,replaceigniter.
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PIPERAIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL
A. Distribution (continued)
1. Igniter Plugs (continued)
P&WC PARTNO. CHART1 SPARK IGNITER EROSIONLIMITS VENDOR NAME&PARTNO. DIMENSIOA N(INCHES) B
*3035102 Champion-CH34055 0.3000 N/A
*3031213 Bendix -10-390667-1 0.3000 N/A
*NOTE:Partsobtainedunder ordering Prattand Whitney p/n 3032096.
Dimension A
DimensionB
New Igniter AcceptableWear WornOut NOTE:FordimensionsA and B, refer to Chart1. IgniterPlug Figure601
(d) Cleaningof Igniter Plugs
(1.) Cap cableend of igniterplug to preventforeignmaterialfromenteringduringcleaning.
NOTE: Never cleanelectrodeend(firing) of igniter. Donot remove carbonfrom electrodeorannular gap areaas carbon depositsin gapareaaidigniter operation.
(2.) Usinga felt swab soaked in a petroleumsolventormethylalcohol,cleaninsidesurfaceof terminalwell. (3.) Dryigniterwith dry, compressedair.
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PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL
A. Distribution (continued)
2. IgnitionCables
The two ignition cable assemblies consist of electrical leads contained in flexible metal braiding with couplingnuts at each end and mounting flanges for attachment to engine fire seals. Refer to Pratt and WhitneyMaintenanceManual, p/n 3034342, Chapter 74 for complete service information.
Observeall safety precautionswhen working on ignition system.
(a)
Removalof Ignition Cables
NOTE: Refer to Pratt and Whitney Maintenance Manual, p/n 3034342, Chapter 74 for Removal of Ignition Cables.
(b)
Installation of Ignition Cables
NOTE: Refer to Pratt and Whitney Maintenance Manual, p/n 3034342, Chapter 74 for Installation of Ignition Cables.
(c)
Inspection of Ignition Cables
(1.) Clean ignition cables. (Refer to Cleaningof Ignition Cablesthis section.)
(2.) Inspect cablesfor signs of damage to braiding and for general condition.
(3.) Inspect cablecoupling nuts for signs of corrosion.
(4.) Inspect central conductor and insulation for damage.
(d)
Cleaning of Inspection Cables
(1.) Removeall corrosion residue with a stainlesssteel wire brush.
(2.) Clean affected areas with a methyl ethyl ketonedampenedcloth.
(3.) After cleaning, applya light film of fluorocarbon spraylubricant to affected area.
EFFECTIVITY:
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74-20-00 Jan10/90
PIPER AIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCE MANUAL
A. Distribution (continued)
3. Auto Ignition System
A separate auto ignition system is incorporated in each engine's ignition system. Each auto ignitionsystem is set to activate its ignition unit when engine torque is 400 foot-pounds or less.
Each auto ignition system is controlled by its respective ignition switch. For this system to operate, the condition lever must be at or past low idle detent and ignition switch in auto.
NOTE: Refer to Wiring Diagram Manual, p/n 761 853, section 74-20-01.
(a) Test of Ignition System
(1.) Test for proper annunciation and operation as follows:
(a.) Position enginecontrol levers for start. Place ignition switch in MANUALposition.
Amber annunciator light (R/L IGN ON) must illuminate. (b.) Move ignition switch to AUTO and ensure light remains on. (c.) With switch in auto, observe annunciator while increasing engine power. As torque
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