Piper Arrow IV, Руководство по обслуживанию

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D. For larger damages an epoxy patching compound is recommended. This type material is a two
part, fast curing, easy sanding commercially available compound.
E. Adhesion can be increased by roughing the bonding surface with sandpaper and by utilizing as
much surface area for the bond as possible.
F. The patching compound is mixed in equal portions on a hard flat surface using a figure eight
motion. The damaged area is cleaned with perchlorethylene or VM&P Naptha prior to applying
the compound. (Refer to Figure 51-4.)
G. A mechanical sander can be used after the compound is cured, providing the sander is kept in
constant motion to prevent heat buildup.
H. For repairs in areas involving little or no shear stress, the hot melt adhesives, polyamids which are
supplied in stick form may be used. This type of repair has a low cohesive strength factor.
I. For repairs in areas involving small holes, indentations or cracks in the material where high stress
is apparent or thin walled sections are used, the welding method is suggested.
J. This welding method requires a hot air gun and ABS rods. To weld, the gun should be held to
direct the flow of hot air into the fusion (repair) zone, heating the damaged area and rod
s i m u l t a n e o u s l y. The gun should be moved continuously in a fanning motion to prevent
discoloration of the material. Pressure must be maintained on the rod to insure good adhesion.
(Refer to Figure 51-5.)
K. After the repair is completed, sanding is allowed to obtain a surface finish of acceptable
appearance.
4. Cracks: (Refer to Figure 51-6.)
A. Before repairing a crack in the thermoplastic part, first determine what caused the crack and
alleviate that condition to prevent it recurring after the repair is made.
B. Drill small stop holes at each end of the crack.
C. If possible, a double plate should be bonded to the reverse side of the crack to provide extra
strength to the part.
D. The crack should be “V” grooved and filled with repair material, such as solvent cement, hot melt
adhesive, epoxy patching compound or hot air welded, whichever is preferred.
E. After the repair has cured, it may be sanded to match the surrounding finish.
5. Repairing Major Damage: (Larger than 1 inch in diameter.) (Refer to Figure 51-7.)
A. If possible a patch should be made of the same material and cut slightly larger than the section
being repaired.
B. When appearances are important, large holes, cracks, tears, etc., should be repaired by cutting out
the damaged area and replacing it with a piece of similar material.
C. When cutting away the damaged area, under cut the perimeter and maintain a smooth edge. The
patch and/or plug should also have a smooth edge to insure a good fit.
D. Coat the patch with solvent adhesive and firmly attach it over the damaged area.
E. Let the patch dry for approximately one hour before any additional work is performed.
F. The hole, etc., is then filled with the repair material. A slight overfilling of the repair material is
suggested to allow for sanding and finishing after the repair has cured. If patching compound is
used the repair should be made in layers, not exceeding a 1/2 inch in thickness at a time, thus
allowing the compound to cure and insuring a good solid buildup of successive layers as required.
6. Stress Lines: (Refer to Figure 51-8.)
A. Stress lines produce a whitened appearance in a localized area and generally emanate from the
severe bending or impacting of the material. (Refer to Figure 51-9.)
B. To restore the material to its original condition and color, use a hot air gun or similar heating
device and carefully apply heat to the affected area. Do not overheat the material.
51-10-04
Page 51-09
December 1, 1978
2I18
PIPER AIRCRAFT
PA-28RT-201 / 201T
MAINTENANCE MANUAL