Adding Layers To Undamaged Areas - Piper PA-44-180 SEMINOLE Maintenance Manual

8. Thoroughly wet mat and cloth with catalyzed resin. Daub resin to mat, then to cloth. Mat must be
placed on structure surface with cloth on top. Use enough fiberglass cloth and mat reinforcements to
maintain the original surface strength. Use extra layers of cloth if the damage was a stress crack.
9. Lay patch over hole (inside of structure). Cover with cellophane, and squeegee from center to edges to
remove all air bubbles. Air bubbles will show white and must all be worked out to edge. Remove
excess resin before it gels. Allow patch to cure completely.
10. Remove cardboard or aluminum sheet from outside of hole and rough-sand patch and hole edge.
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. Cut 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. Brush with a daubing
action. Then apply additional layer or layers of fiberglass cloth to build up patch to surface of struc-
ture. Wet out each layer thoroughly with resin.
12. Work out all air bubbles in patch using a squeegee or broad knife. Work from center to edge pressing
patch firmly against structure. Allow patch to cure 15 to 20 minutes.
13. As soon as the patch begins to set up, but while it is still rubbery, use a sharp knife and cut away extra
cloth and mat. Cut on outside edge of feathering. Strip cut edges of structure 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 sur-
rounding surface. Should air pockets appear while sanding, puncture and fill with catalyzed resin. A
hypodermic needle may be used to fill cavities. Let cure and sand.
15. Mix catalyzed resin and work into patch with fingers. Smooth carefully and work into crevices.
16. Cover with cellophane and squeegee smooth. Cure completely before removing cellophane. Sand the
area.
17. Brush or spray catalyzed resin to seal patch. Sand and finish by priming. Sand again and apply color
coat.
Clean brush and hands in solvent such as acetone. Use a strong
solution of detergent and water if solvents are not available.

ADDING LAYERS TO UNDAMAGED AREAS.

1. Rough sand area to be laminated with 80 grit dry sandpaper.
2. Thoroughly clean area to be laminated with acetone, MEK, or equivalent.
3. Mix resin and catalysts according to the manufacturers instructions. Mix only enough to be used one
step at a time.
4. Thoroughly wet fiberglass cloth with catalyzed resin. Lay cloth on part and squeegee from center to
edges of cloth to remove all air bubbles, and to assure adhesion. Air bubbles will show white and all
should be worked out to the edge. Remove excess resin before it gels on the part.
5. Repeat step d until the desired number of cloth layers have been added.
6. Allow parts to cure for 24 hours at room temperature.
7. After part has cured it may be sanded and painted as required.
PIPER AIRCRAFT
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
—NOTE—
2L15
51-12-04
Page 51-07
Revised: June 20, 1995