Repair Patch (Heat Cure Method) - Piper Navajo PA-31 Service Manual

PIPER NAVAJO SERVICE MANUAL
a. Lap inside patches over defective edges 1.0 inch minimum in each direction.
b. Cut outside patches approximately 0.25 to 0.50 inch larger than inside patches.
c. Apply outside patches and allow to cure before applying inside patches
d. Apply both outside and inside patches for blisters between inner liner and fabric larger than 0.25 inch
in diameter.
e. Apply both outside and inside patches to repair holes and punctures. Apply both outside and inside
patches to repair separations between outer plies larger than 1.0 inches in diameter.
NOTE
Slits or tears are limited to 6.0 inches maximum in length.
f. Apply outside patch only to external abraded or scuffed areas without fabric damage.
g. Trim loose laps as necessary provided a 5.0 inch effective band remains.
CAUTION
For each 10
°
drop in temperature from 70°F, add 20 hours cure
time. Do not air cure repairs below 60°F.
h. Clamp repair patches when performing air cure repair. Cure at room temperature of 70°F undisturbed
for 72 hours.
i.Limit fitting repairs to loose flange edges, seal surface rework, and coat stock.
j.Do not exceed four heat cure repairs in the same area.
NOTE
Any damaged fuel cell that cannot be repaired using the above
procedures should be returned for repair to: Engineered
Fabrics. Corporation, 669 Goodyear Street, Rockmart, Georgia
3015 3-0548.
9-13a REPAIR PATCH (HEAT CURE METHOD)
CAUTION
Do not apply an outside and inside patch simultaneously Apply
outside patch first.
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 corners of patch. Ensure dull side or gum contact face of repair patch is the largest surface
after beveling.
b. Wash one square foot of cell wall beyond damaged area in all directions.
c. Wash contact side of patch using a clean cloth dampened with Methylelhylketone solvent.
d. Center repair patch over damaged area. Mark cell .50 beyond patch in all directions
CAUTION
Buff cell surface with care to avoid further damage.
e. Buff cell surface surrounding damaged area as marked and contact side of patch with fine emery cloth to
remove gloss.
f. Wash cell and patch surfaces two more times using a cloth dampened with MEK.
Revised: 2/18/94
FUEL SYSTEM
3B5