Piper Arrow IV Turbo Maintenance Manual page 485

5. Cover a piece of cardboard or metal with cellophane. Tape it to the outside of the structure covering
the hole completely. The cellophane should face 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 contour may be placed over the area. The
aluminum should also be covered with cellophane.
6. Prepare a patch of fiberglas mat and cloth to cover an area two inches larger than the hole.
7. Mix a small amount of resin and catalyst, enough to be used for one step at a time, according to kit
instructions.
8. 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.
9. 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.
10. 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.
11. Mask area around hole with tape and paper to protect surface. Cut a piece of fiberglas mat about one
inch larger than the hole and one or more pieces of fiberglas cloth two inches larger than the hole. Brush
catalyzed resin over hole, lay mat over hole and wet out with catalyzed resin. Use a daubing action with brush.
Then apply additional layer or layers of fiberglas cloth to build up patch to the surface of structure. Wet out
each layer thoroughly with resin.
12. With a squeegee or broad knife, work out all air bubbles in the patch. Work from center to edge,
pressing patch firmly against the structure. Allow patch to cure for 15 to 20 minutes.
13. As soon as the patch begins to set up, 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. Using dry 80-grit sandpaper on a power sander or sanding block, smooth patch and blend with
surrounding 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 resand.
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 resand.
17. Brush or spray a coat of catalyzed resin to seal patch. Sand patch, finish by priming, again sanding and
applying color coat.
Brush and hands may be cleaned in solvents such as acetone or
methylethylketone. If solvents are not available, a strong solution
of detergent and water may be used.
THERMOPLASTIC REPAIRS.
The following procedure will assist in making field repairs to items made of thermoplastic which are used
throughout the airplane. A list of material needed to perform these repairs is given along with suggested
suppliers of the material. Common safety precautions should be observed when handling some of the materials
and tools used while making these repairs.
PIPER AIRCRAFT
PA-28RT-201 / 201T
MAINTENANCE MANUAL
—NOTE—
2I14
51-10-04
Page 51-05
December 1, 1978