Piper Comanche PA-24 Service Manual page 228

4-44. Fiberglas Repairs.
The repair procedure in this manual will describe the methods for the repair of fiberglas reinforced
structures. Paragraph 4-45 describes Touch-up and Surface Repairs such as blisters, open seams,
delaminations, cavities, small holes and minor damages that have not harmed the fiberglas cloth
material. Paragraph 4-46 describes Fracture and Patch Repairs such as puncture, breaks and holes that
have penetrated through the structure and damaged the fiberglas cloth. A repair kit, part number 756-
729, that will furnish the necessary material for such repairs is available through Piper Aircraft
Distributors.
NOTE: Very carefully follow resin and catalyst mixing instructions furnished with repair kit.
4-45. Fiberglas Touch-Up And Surface Repairs.
A. Remove wax, oil and dirt from around the damaged area with acetone, methylethylketone or
equivalent and remove paint to gel coat.
B. The damaged area may be scraped with a fine blade knife or a power drill with a burr attachment to
roughen the bottom and sides of the damaged area. Feather the edge surrounding the scratch or
cavity. Do not undercut the edge. (If the scratch or cavity is shallow and penetrates only the surface
coat, continue to step H.)
C. Pour a small amount of resin into a jar lid or on a piece of cardboard, just enough to fill the area
being worked on. Mix an equal amount of milled fiberglas with the resin, using a putty knife or
stick. Add catalyst, according to kit instruction, to the resin and mix thoroughly. A hypodermic
needle may be used to inject gel into small cavities not requiring fiberglas millings mixed with the
gel.
D. Work the mixture of resin, fibers and catalyst into the damaged area, using the sharp point of a putty
knife or stick to press it into the bottom of the hole and to puncture any air bubbles which may be
present. Fill the scratch or hole above the surrounding undamaged area about 1/16 inch.
E. Lay a piece of cellophane or waxed paper over the repair to cut off air and start the cure of gel
mixture.
F. Allow the gel to cure 10 to 15 minutes until it feels rubbery to the touch. Remove the cellophane
and trim flush with the surface, using a sharp razor blade or knife. Replace the 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 burr 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 coat mixture.
J. 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 coat on one edge of the
patch and cover with cellophane. Then, using a squeegee or the back 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.
IV - STRUCTURES
PIPER COMANCHE SERVICE MANUAL
1E20
04/01/09