CAUTION: TO PREVENT CEMENT FROM STICKING CELL WALLS TOGETHER, ENSURE CELLOPHANE PLACED INSIDE CELL REMAINS IN PLACE.
(g)
Tape a piece of cellophane inside the cell over the injury.
(h)
Fold cell so repair can be completed without repositioningcell.
WARNING: CEMENTS AND SOLVENTS ARE FLAMMABLE. MIX AND APPLY CEMENT IN WELL VENTILATED AREA.
WARNING: REPAIR CEMENT 5923C SHELF LIFE IS ONE YEAR FROM DATE ON CONTAINER. DO NOT USE OUT DATED CEMENT.
NOTE:Mix and apply cement at minimum temperatureof 70°F. Pot life of mixed cementis 20 minutesto one hour.
(i) Mix repair cement 5923Casfollows:
(1.) Shake contentsof part 2. (2.) Pour contents of part 2 into part 1. Stir thoroughly, makingsure entire contentsof both containersare are blended completely.
EFFECTIVITY:
28-10-00Jan10/90
PIPERAIRCRAFT
PA-42-720(Advanced Trainer)
MAINTENANCEMANUAL
A. Storage(continued)
NOTE: Rapidstirringor shaking will cause air bubbles to form. Air bubbles in cement can resultin repair voids, pits, blisters,andleak paths.
(j) Apply one even coatof 5923C cementon buffed area of cell to within 1/4inch of edge and on buffedside of patch. Allowtodry for 15 minutes.
CAUTION: COVERCEMENTCONTAINERBETWEENAPPLICATIONSTO MAXIMIZE POT LIFE.
(k)
Applysecond coat of 5923C repair cement to cell and patch. If cement has become too thick to brush, mix new batch ofcement.[Referto step (i).]
(I)
Allowcementto dry for 5 minutes.
(m)Centerrepairpatchover damaged area. Lay patchcarefullyby rolling actionfrom center of patchto edges to prevent trappingair. While surface is wet, sliderepairpatchby hand to improvelap
CAUTION: BESURE PIECEOF CELLOPHANE IS LARGER THANCEMENTEDAREA AND REMAINSIN PLACE. ENSUREFILMOBTAINSCOMPLETECOVERAGE.
(n) Tapepieceof cellophane over patch.
NOTE: Aluminumplatesmustbe largerthanpatch.
(o) Cover one side ofaluminumplatewith0.25 inch fabric-backed
airfoam(fabricsideout). Tape airfoamintoplace. Ensureairfoamcoversedges of plate forprotection.
(p)Cut two backup boardslargerthan cemented areaand smooth all edges.
CAUTION: ENSURECELLIS NOT FOLDEDBETWEENPRESSUREPLATEAND BOARDS TO PREVENTPERMANENTCREASE.
CAUTION: ENSUREPATCH DOES NOTMOVEWHENTIGHTENINGCLAMP.
(q)
Foldcell next to patch. Place plate with airfoamoverpatch.
(r)
Place2F1-3-2572repairironon center of plate. Coveriron with otherbackupboard. Secure assemblyinplace with C clamp. Wipeoff any excesscementthat flows from pressureplates.
(s)
Connectrepair iron to 110/120Vac. Set ironto 240°F and allow to cure for two hours.
(t)
Unplugiron and allowassemblyto cool to the touch.
(u)
Dissemblecure iron, plate, and boards from cell. Dampen cellophaneand remove from cell.
(v)
Checkforcompleteseal of patch edges.
(1.) Trim looseedgesif less than 1/8 inch.
(2.) Bond loose edges with cement and cure if more than 1/8/ inch.
(w)Repeatsteps (a) thru (v) for inside patch, except cut patch 1/4 inch to 1/2 inch smaller than outsidepatch.
EFFECTIVITY: PAGE20 040-999
Jan10/9028-10-00
PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL
A. Storage (continued)
17. Repair Patch (Air Cure Method)
CAUTION: DO NOT APPLY AN OUTSIDE AND INSIDE PATCH SIMULTANEOUSLY. APPLY OUTSIDEPATCH FIRST.
NOTE: A minimum of 72 hours curing time at 70°F is required per patch. A minimum of 144 hours is required to install an outside and inside patch. Add 20 hours cure time for each 10°F drop in temperature. Never attempt to air cure at temperatures below 60°F.
(a)
Cut a patch from FT -227 repair fabric to the size required to ensure a proper lap over the injury in all directions.
(1.) Hold shears at an angle to produce a beveled edge (feather) on the patch. (2.) Round comersof patch. Ensure dull side or gum contact face of repair patch is the largest surface after beveling.
(b)
Washone square foot of cell wall beyond damagedarea in all directions.
solvent.
(c)
Wash contact side of patch using a clean cloth dampened with Methylethylketone
(d)
Centerrepair patch over damaged area. Mark cell 0.50 inch beyond patch in all directions
CAUTION: BUFF CELL SURFACE WITH CARE TO AVOID FURTHER DAMAGE.
(e)
Buffcell surface surroundingdamagedarea as marked and contact side of patch with fine emerycloth to remove gloss.
(f)
Wash cell and patch surfaces two more times using a cloth dampened with MEK.
CAUTION: TO PREVENT CEMENT FROM STICKING CELL WALLS TOGETHER, ENSURE CELLOPHANEPLACED INSIDE CELL REMAINSIN PLACE.
(g) Tapea piece of cellophane insidethe cell over the injury.
cell.
