Repair Patch (Air Cure Method) - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
9-60
REPAIR PATCH (HEAT CURE METHOD) (continued)
CAUTION
Cover cement container between applications to maximize pot life.
k. Apply second coat of 5923C repair cement to cell and patch. If cement has become too thick to
brush, mix new batch of cement. (Refer to step 9.)
1. Allow cement to dry for 5 minutes.
m. Center repair patch over damaged area. Lay patch carefully by rolling action from center of patch
to edges to prevent trapping air. While surface is wet, slide repair patch by hand to improve lap
CAUTION
Be sure piece of cellophane is larger than cemented area and
remains in place. Ensure film obtains complete coverage.
n. Tape piece of cellophane over patch.
NOTE
Aluminum plates must be larger than patch.
o. Cover one side of aluminum plate with 0.25 inch fabric-backed airfoam (fabric side out). Tape air-
foam into place. Ensure airfoam covers edges of plate for protection.
p. Cut two backup boards larger than cemented area and smooth all edges.
CAUTION
Ensure cell is not folded between pressure plate and boards to
prevent permanent crease.
Ensure patch does not move when tightening clamp.
q. Fold cell next to patch. Place plate with airfoam over patch.
r. Place 2F1-3-2572 repair iron on center of plate. Cover iron with other backup board. Secure
assembly in place with C clamp. Wipe off any excess cement that flows from pressure plates.
s. Connect repair iron to 110/120 Vac. Set iron to 240°F and allow to cure for two hours.
t. Unplug iron and allow assembly to cool to the touch.
u. Dissemble cure iron, plate, and boards from cell. Dampen cellophane and remove from cell.
v. Check for complete seal of patch edges.
1. Trim loose edges if less than 1/8 inch.
2. Bond loose edges with cement and cure if more than 1/8/ inch.
w. Repeat steps 1 thru 22 for inside patch, except cut patch 1/4 inch to 1/2 inch smaller than outside
patch.
9-61
REPAIR PATCH (AIR CURE METHOD)
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 tem-
perature. Never attempt to air cure at temperatures below 60°F.
a. Follow the procedure for the heat cure method, except omit the following:
I. Omit cure iron from steps 18 and21.
2. Omit steps 19 and 21.
b. Refer to fuel cell repair limitations for curing time.
Revised:
3/3194
FUEL SYSTEM
2L10