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.
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51-10-00 Page 51-10 Issued: April 1, 1997
3B22
GENERAL THERMOPLASTIC REPAIRS
— WARNING —
COMMON SAFETY PRECAUTIONS MUST BE FOLLOWED WHEN USING THE MATERIALS AND TOOLS FOR THESE REPAIRS.
Thermoplastic material is used throughout the airplane. Check the following list of materials and vendors to aid in thermoplastic repairs.
CHART 5101. LIST OF MATERIALS FOR THERMOPLASTIC REPAIR
ITEMS DESCRIPTIONS SUPPLIERS
Buffing and Rubbing Compounds. Automotive Type - DuPont #7. Ram Chemical #69 x 1. Mirror Glaze #1. DuPont Company Wilmington. Del. 19898 Ram Chemicals Gardena, CA 90248 Mirror Bright Polish Co., Inc. Irvin, CA 92713
Cleaners. Fantastic Spray. Perchlorethylene. VM&P Naphtha (lighter fluid). Local suppliers
ABS-Solvent Cements. Solarite #11 Series. Solar Compounds Corp. Linden, N.J. 07036
Solvents. Methylethylketone. Methylene Chloride. Aceyone Local suppliers
Epoxy Patching Compound. Solarite #400. Solar Compounds Corp. Linden, N.J. 07036
Hot Melt Polyamids Adhesives and Hot Melt Gun. Stick Form 1/2 in. dia., 3 in. long. Sears Roebuck & Co. or local hardware stores.
Hot Air Gun. Temp. Range 300° to 400° F. Local suppliers.
SURFACE PREPARATION:
1.
Remove surface dirt and paint from item being repaired. Household cleaners are effective in removing surface dirt.
2.
Cleaning damaged area with perchlorethylene or VM&P Naptha will give a good bond between epoxy compounds and thermoplastic.
SURFACE SCRATCHES (Refer to Figure 51-2)
1. Shallow scratches and abraded surfaces are repaired using conventional automotive buffing and rubbing compounds.
51-10-00 Page 51-11 Issued: April 1, 1997
—CAUTION— WHEN USING A HOT AIR GUN, BE CAREFUL NOT TO OVERHEAT THE THERMOPLASTIC.
2.
Remove large dirt particles embedded in thermoplastic parts with a hot air gun capable of heating to 300° to 400° F (149° to 204° C). Hold nozzle of gun about 1/4 inch away from surface and apply heat with a circular motion until area is sufficiently soft to remove dirt particles.
3.
Thermoplastic will return to its original shape upon cooling.
DEEP SCRATCHES, SHALLOW NICKS, AND SMALL HOLES: (Less than 1 inch in diameter.) (Refer to Figure 51-3.)
1.
Solvent cements will fit most applications. For small repairs make a satisfactory cement by dissolving thermoplastic material of same type being repaired in solvent until desired paste-like consistency is achieved.
2.
Apply mixture to damaged area. When the solvent evaporates, the hard solids remaining can easily be shaped to desired contour by filing or sanding.
3.
Do not use solvent adhesives for highly stressed areas, thin walled parts, or for patching holes greater than 1/4 inch in diameter.
3.
For larger damages, use an epoxy patching compound. This type material is a two part, fast curing. easy sanding commercially available compound.
— Note — Increase adhesion by roughing bonding surface with sandpaper and by using as much surface area for bond as possible.
4.
Mix patching compound in equal portions on a hard flat surface (use a figure eight motion). Clean damaged area with perchlorethylene or VM&P naphtha prior to applying compound (figure 51-5).
5.
Use a mechanical sander after compound is cured. Keep sander in constant motion to prevent heat buildup.
6.
For repairs in areas involving little or no shear stress, use hot melt adhesives (polyamids) supplied in stick form. This type of repair has a low cohesive strength factor.
7.
For repairs in areas involving small holes, indentations, or cracks in material where high stress is apparent, or thin walled sections are used with the welding method.
51-10-00 Page 51-12 Issued: April 1, 1997
8.
The welding method requires a hot air gun and ABS rods. To weld, hold gun to direct the flow of hot air into repair zone. Heat damaged area and rod simultaneously. Move the gun continuously in a fanning motion to prevent discoloration of material. Pressure must be maintained on rod to ensure good adhesion (Refer to Figure 51-5).
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