Thermoplastic Repairs - Piper Dakota Maintenance Manual

6. Prepare a patch of fiberglass mat and cloth to cover area two inches larger than hole.
7. Mix small amount of resin and catalyst according to kit instructions.
8. Thoroughly wet mat and cloth with catalyzed resin. Apply mat to structures surface with cloth on top.
Both pieces may be wet out on cellophane and applied as a sandwich. Use enough fiberglass cloth and
mat reinforcements to at least replace amount of reinforcements removed. If damage occurred as a
stress crack, an extra layer or two of cloth may be used to strengthen area.
9. Lay patch over hole on inside of structure, cover with cellophane. Squeegee from center to edges to
remove all air bubbles and assure adhesion around edge of hole. Air bubbles will show white in patch
and they should all be worked out to edge. Remove excess resin before it gels on part. Allow patch to
cure completely.
10. Remove cardboard or aluminum sheet from outside of hole and rough-sand patch and edge of hole.
Feather edge of hole about two inches into undamaged area.
11. Mask area around hole with tape and paper to protect surface. Cut a piece of fiberglass mat about one
inch larger than hole and one or more pieces of fiberglass cloth two inches larger than hole. Brush
catalyzed resin over hole. Lay mat over hole and wet out with catalyzed resin. Apply additional layer
or layers of fiberglass cloth to build up patch to surface of structure. Wet out each layer thoroughly
with resin.
12. With a squeegee or broad knife, work out all air bubbles in patch. Work from center to edge, pressing
patch firmly against structure. Allow patch to cure for 15 to 20 minutes.
13. As soon as patch begins to set, but while still rubbery, take a sharp knife and cut away extra cloth and
mat. Cut an outside edge of feathering. Strip cut edges of structure. Do this before cure is complete to
save extra sanding. Allow patch to cure overnight.
14. Use dry 80-grit sandpaper on a power sander or sanding block to smooth patch and blend with
surrounding surface. Should air pockets appear while sanding, puncture and fill with catalyzed resin.
Use a hypodermic needle to fill cavities. Let cure and re-sand.
15. Mix catalyzed resin and work into patch with fingers. Smooth carefully and work into any crevices.
16. Cover with cellophane and squeegee smooth. Allow to cure completely before removing cellophane.
Let cure and re-sand.
17. Brush or spray a coat of catalyzed resin to seal patch. Sand patch. Finish by priming, again sanding
and applying color coat.
Clean brush and hands in solvent such a acetone. Use a strong
solution of detergent and water if solvents are not available.

THERMOPLASTIC REPAIRS

The following procedure will aid in making field repairs to items made of thermoplastic. A list of material
needed to perform these repairs is given along with suggested suppliers of the material.
PIPER AIRCRAFT
PA-28-236
MAINTENANCE MANUAL
—NOTE—
2F3
51 - 12 - 00
Page 51 - 07
Reissued: August 1, 1986