(a.) Equipmentrequired: 1 Thermogunheating tool Model CV-5000, Model500A. 2 Heat reflector TG-24 (Raychem P/N 991023). 3 Pressurefeed-throughseals.
NOTE: Two types of nuts may be used dependingupon installation. TypeA nut is pressed into openingin the bulkhead fromthe same side that the feedthroughseal will be installed. Type B nut is installed fromthe bulkheadside opposite thefeedthroughseal.
EFFECTIVITY:
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PIPER AIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL
A Processes (continued)
1. Sealing Procedures (continued)
Fitting Halves
View C
Fillet Excess Sealant After Installation of Fitting Halves
View B
MaskingTape 1-1/2"Width
Masking Tape 3/4" Width
WireHarnessSeals
Figure208 (Sheet 1 of 2)
String
EFFECTIVITY:
040-999
Jan 10/9051-20-00
PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL
A Processes (continued)
1. Sealing Procedures (continued)
NOTE:
RecoverableEnd. Apply Heat in This Area
Type "A' Nut
O-Ring
Coating Side View End View
Pressure Bulkhead
Type Nut
Type "B" Nut
PressureBulkhead
HeatReflector
Type"A" Nut Installation
3
3
PressureBulkhead Type"B" Nut Installation
Wire Harness Seals Figure 208 (Sheet 2 of 2)
EFFECTIVITY:
040-999
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51-20-00 Jan 10/90
PIPERAIRCRAFT
PA-42-720(Advanced Trainer)
MAINTENANCEMANUAL
A Processes (continued)
1. Sealing Procedures (continued)
(b) FuselageSealing (continued)
(14.)SealingElectrical Harnesses with heat shrinkable coverings (Figure 208) (continued)
(b.) Installation. 1 Installnut (type A or B) in the pressurebulkhead. 2 Insertwire or cable through feedthrough, 3 Ensure O-ring is positioned in groove of feedthrough. Screw feedthrough into
nut. Tighten to approximately (10) foot pounds torque. 4 Usingrecommendedheatingdeviceand heat reflector, apply heat to recoverable end of feedthrough seal. (Shown in Figure 208.1 5 Aftershrinking, inspect to ensure neck of feedthrough is generally rounded and has uniform wall thickness.
(15.)Applicationof Release Agent
Edges and faying surfaces of removable or hinged panels must receive at least two. coats of release agent (Polyvinyl Alcohol PVA) applied approximately 0.50 inch wider than the mating flange proper to sealant application. The panel must be allowed to air dry between coats. Only removable covers requiring a formed-in-place gasket receive an application of release agent. Sealant must be applied to prepared surface within 2 hours after completion of surface preparation. Surfaces not sealed within this time must be prepared again.
CAUTION: DO NOT USE POLYVINYL ALCOHOLAS A RELEASE AGENT NEAR ACRYLIC(PLEXIGLAS)WINDOWS. IT WILL CRAZE ACRYLIC PLASTICS.
(16.)Sealing Formed-in-Place Gaskets NOTE: This type of seal is used on the radome lock handle cover of the airplane.
Unless otherwise specified, apply heavy bead of class B-2 sealant to mating surfaces not coatedwith a release agent. Spread evenly until coating is approximately 0.062 inch thick. While sealant is still fluid, secure access cover and smooth excess sealant flush with top of cover. Allow to fully cure for 48 hours at 70°F and 50% relative humidity. After curing, trim excess sealant from around cover; pry one comer of panel open, using care not to damage the gasket. Slowly free the rest of panel. Remove all release agent and excesssealant from panel and mating surface.
NOTE: Release agents can be removed with water.
NOTE: Do not pressure test the fuselage until sealing compound has thoroughly cured.
(17.) Removal of Sealant
Whenit is necessary to remove fillets or beads of sealant due to rework or repair, scrape sealantoff with scrapers madeof hardwood or plexiglas. Removeonly major portion of fillets or beads. After rework, clean, reseal and test the area for leaks.
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