Deep Scratches, Shallow Nicks, And Small Holes - Piper PA-44-180 SEMINOLE Maintenance Manual

When using a hot air gun, be careful not to overheat the
t h e rm oplastic.
2. Remove large dirt particles embedded in thermoplastic parts with a hot air gun capable of heating t o
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 51-4.)
A . Solvent cements will fit most applications. For small repairs make a satisfactory cement by
d i ssolving thermoplastic material of same type being repaired in solvent until desired paste-like
consistency is achieved.
B . Apply mixture to damaged area. When the solvent evaporates, the hard solids remaining can easily
be shaped to desired contour by filing or sanding.
C. Do not use solvent adhesives for highly stressed areas, thin walled parts, or for patching holes
greater than 1/4 inch in diameter.
D. For larger damages, use an epoxy patching compound. This type material is a two part, fast curing.
easy sanding commercially available compound.
Increase adhesion by roughing bonding surface with sandpaper and
by using as much surface area for bond as possible.
E. 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).
F. Use a mechanical sander after compound is cured. Keep sander in constant motion to prevent heat
buildup.
G. 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.
H. 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.
PIPER AIRCRAFT
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
—CAUTION—
Figure 51-3. Surfaces Scratches, Abrasions or Ground-In Dirt
— NOTE —
2L17
51-13-03
Page 51-09
Revised: June 20, 1995