The scarfed method of repair for punctures is the
same as that used for damage extending into the core,
with the exception that the opposite side of the
sandwich is provided with a temporary mold or block to
hold the core in place during the first step. See view C in
After the first facing repair is cured completely, the
mold and the shim (temporarily replacing the facing on
the opposite side) are removed. The repair is then
completed by repeating the procedure used in the first
step. When this facing is cured, the surface should be
sanded down to the original contour and the repair area
lightly sanded in preparation for refinishing.
When you use the stepped method of repair, the
damaged area is first trimmed out to a round or oval
shape or to a rectangular or square shape (preferably
having rounded corners).
The individual plies are then cut out as shown in
figure 5-14. Each ply is "stepped" back 1 1/2 inches and
trimmed out by using a sharp knife. The sides of the
repair should be parallel with the weave of the cloth, if
Figure 5-14.--Stepped repair method.
NOTE: Do not cut through more than one layer of
one-half inch over the undamaged facing. The repair
cloth. If the layer of cloth underneath is scratched, the
area is then covered with a sheet of cellophane to apply
strength of the repair will suffer.
pressure, and then it is allowed to cure. The inner facing
The opposite facing is shimmed and backed up
is then replaced in the same manner as the outer facing.
with a mold, and the core material is inserted as
After the inner repair has been cured, the entire repair
previously described. The outer repair plies are soaked
area should be sanded to the original contour and
in the resin and laid over the damaged area. An extra
prepared for refinishing.
layer of thin cloth is laid over the repair area to extend
FOAM CORE.--When the puncture penetrates
the entire wall, remove the damaged core and face
laminates to one-fourth inch past the perimeter of the
hole on the inner face. Make a plaster support to replace
the removed core, conforming to the curvature of the
inside layer of the inner face. Figure 5-15 shows a
punctured repair with a plaster support.
After repair to the inner face has been completed,
remove the plaster support and continue the repair on
the opposite side.
Finishing Repaired Areas
In the repair of reinforced plastic parts, the final
step is to refinish the part with a finish identical to the
original, or an acceptable substitute. In refinishing
radomes and other surfaces that enclose electronic
equipment, consult NAVAIR 01-1A-22. Do not use
metallic pigmented paints or other electronic
reflective-type materials because of undesirable
Figure 5-13.--Scarfed repair method.