C. Air InletLip Deicer System
1. OperationalCheck
(a)
Remove top engine cowl. Unplug lip deicer boot at plug and ground dead disconnect.
(b)
With auxiliary power plugged in and deicer switch on, check for proper operation of ice deflector door underneath air inlet screen by looking back through air inlet and down around each engine side. Also check operation of bypass door on underside of bottom engine cowl at rear of engine.
EFFECTIVITY:
040-999
30-20-00 PAGE5
Jan 10/90
PIPERAIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL
C. Air Inlet Lip Deicer System (continued)
1. OperationalCheck (continued)
CAUTION: THE LIP CAN BE DESTROYED WITH THE COMBINATION OF THE PARTING STRIP ELEMENT BEING ON CONTINUOUSLY ANDTHE HEAT INTENSITY OF THE LIP DEICER ELEMENTS. OBSERVE LIP CLOSELY WHILE TESTING FOR OVERHEATING.
(c) Threeways to safety check operation of the lip deicer are as follows:
(1.) Disconnect deicerplug. Using a precisionmeter, check the following resistances for each heating element. (a.) Shed Area I Resistance isapproximately
1.10
ohms. (b.) Shed Area II Resistance is approximately
1.10
ohms. (c.) The Parting Strip Resistanceis approximately 1.00 ohms.
(2.) Obtain 28 Vdc power source capable of supplying 30 amps. Connect negative lead to deicerground leads and touch positive lead individually to 3 terminalsofdeicer plug.
(3.) Have 1 person in the cockpit position masterwith deicer switcheson. Activate ground test switchwhile an assistant connectsdeicerplug to mating plug. Supply systempower long enoughto complete check. Finally, disconnect plug and wait until second lip deicer phase begins.
CAUTION: DO NOT HOLD CONNECTION SO DEICER BECOMES TOO HOT TO TOUCH.
NOTE:The timer only operates as long as the ground test switch is activated.
(d)Temperaturerise of the boots must be noticeable.If local hot spots are apparent, boot is damaged and must be replaced.
2. Removalof Inlet Deicers
If inlet deicer lip becomes damagedor defective, requiringremovalofunit from lower cowl assembly,proceedas follows:
(a) Removeupper and lower engine cowling (see 71-10-00).
(b)Locate inlet deicer cannon plugconnector.Removewiresfrom connector.
(c) Removeclampsecuring inlet deicerwire harness to lower cowl assembly.
(d)Removemachinescrewsfrom inner and outer edges of inlet deicer.
(e)Pullinlet deicer away from lowercowl assembly far enough to allow accessto wire harness.
(f) Gentlypull inlet deicer wire harnessthrough fireshield tube. Remove deicerassemblyfrom aircraft.
3. Installation of Inlet Deicers
(a)Whileholding inlet deicerin position, run end of inlet deicer wire harnessthroughfireshield tube.
(b)Positioninletdeicerassemblyon cowl assembly.Securewithappropriatemachinescrews.
(c)
Securewireharnessto cowl assemblywith clamp.
(d)
Reattachinletdeicer wire harnessto cannon plug connector.
(e)
Install lower and upper cowl assemblies(see 71-10-00).
EFFECTIVITY: 040-999
Jan 10/90GE
630-20-00
Jan 10/9030-20-00
PIPERAIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL
4. Electrical Check of Inlet Deicers
Ammeter(ForReferenceOnly)
Wiring Diagram,LeftPropeller and EngineAir Inlet Lip Deicing System Figure 1
(For Reference Only) Ammeter
WiringDiagram,Right Propeller and EngineAir Inlet Lip DeicingSystem
Figure 2
EFFECTIVITY:
040-999
PAGE7
30-20-00
30-20-00 Jan 10/90
PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL
4. Electrical Check of Inlet Deicers
(a)
Check air inlet deicers by disconnecting harness plug and ground connection inside lower engine cowl and removing upper cowl.
(b)
Check electrical resistanceof each element betweeneach pin in plug and ground lead. Pin C and E is the parting strip element; Pin D and F is shedding area (I) element and Pin B and F is the shedding area (II) element. (See Figures 1 & 2 and Chart 2.)
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