Piper COMANCHE PA-24-180 Service Manual page 117

PIPER COMANCHE SERVICE MANUAL
cellophane and allow to cure completely for 30 minutes to an hour. The patch will shrink slightly
below the structure surface as it cures. (If wax paper is used, ascertain wax is removed from
surface.)
g. Rough up the bottom and edges of the hole with the electric bun attachment or rough sand
paper. Feather hole into surrounding gel coat, do not undercut.
h. Pour out a small amount of resin, add catalyst and mix thoroughly, using a cutting motion
rather than stirring. Use no fibers.
i. Using the tip of a putty knife or finger tips, fill the hole to about 1/16 inch above the
surrounding surface with the gel cost mixture.
i. Lay a piece of cellophane over the patch to start the curing process. Repeat step f,
trimming patch when partially cured.
k. After trimming the patch, immediately place another small amount of gel cot on one edge
of the patch and cover with cellophane. Then, using a squeegee or the babk of a razor blade,
squeegee level with area surrounding the patch; leave the cellophane on patch for one to two
hours or overnight, for complete cure.
1. After repair has cured for 24 hour, sand patched area, using a sanding block with fine
wet sandpaper. Finish by pnming, again sanding and applying color coat.
4-46. Fibergls
Frecture And Patch Repairs.
a. Remove wax, oil and dirt from around the damaged area with acetone, methylethylketone
or equivalent.
b. Using a key hole saw, electric saber saw, or sharp knife cut away ragged edges. Cut
back to sound material.
c. Remove paint three inches back from around damaged area.
d. Working inside the structure, bevel the edges to approximately a 30 degree angle and
rough-sand the hole and the area around it, using 80 grit dry paper. Feather back for about two
inches all around the hole. This roughens the surface for strong bond with patch.
e. Cover a piece of cardboard or metal with cellophane. Tape it to the outside of the struc-
ture, covering the hole completely. The cellophane shouldface toward the inside of the structure.
If the repair is on a sharp contour or shaped area, a sheet of aluminum formed to a similar con-
tour may be placed over the area. The aluminum should also be covered with cellophane.
f. Prepare a patch of fiberglas mat and cloth to cover an area two inches larger than the
hole.
g. Mix a small amount of resin and catalyst, enough to be used for one step at a time, ac-
cording to kit instructions.
h. Thoroughly wet mat and cloth with catalyzed resin. Daub resin on mat first, and then on
cloth. Mat should be applied against structures surface with cloth on top. Both pieces may be
wet out on cellophane and applied as a sandwich. Enough fiberglas cloth and mat reinforcements
should be used to at least replace the amount of reinforcements removed in order to maintain
the original strength. If damage occurred as a stress crack, an extra layer or two of cloth may
be used to strengthen area.
i. Lay patch over hole on inside of structure, cover with cellophane, and squeegee from
center to edges to remove all air bubbles and assure adhesion around edge of hole. Air bubbles
will show white in the patch and they should all be worked out to the edge. Remove excess resin
before it gels on the part. Allow patch to cure completely.
. Remove cardboard or aluminum sheet from outside of hole and rough-sand the patch and
edge of hole. Feather edge of hole about two inches into-undamaged area.
STRUCTURE
ISSUED: 8/18/72
IE21