Piper Navajo PA-31 Service Manual page 600

PIPER NAVAJO SERVICE MANUAL
9-13a
REPAIR PATCH (HEAT CURE METHOD) (continued)
NOTE
Rapid stirring or shaking will cause air bubbles to form. Air bub-
bles in cement can result in repair voids, pits, blisters, and leak
paths.
j.
Apply one even coat of 5923C cement on buffed area of cell to within 1/4 inch of edge and on buffed
side of patch. Allow to dry for 15 minutes.
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 airfoam
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.
Revised: 2/18/94
FUEL SYSTEM
3B8