FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 1. Wood Structure | 4. Repairs | 1-50. Repairs to Double Curvature Plywood Skin
AC 43.13-1B
9/8/98
FIGURE 1-10. Method of reinforcing a longitudinal crack and/or local damage in a solid spar.
for determining which process of bending
should be used for the curvature being consid-
ered.
a. Plywood, after softening, may be bent
on a cold ventilated form, or it may be bent
over the leading edge near the area being
patched if space permits. In either method the
repair part should be allowed to dry completely
on the form. When bending plywood over a
leading edge, drying may be hastened by lay-
ing a piece of coarse burlap over the leading
edge before using it as a bending form. To
speed drying, a fan may be used to circulate air
around the repair part.
b. In bending pieces of small radii or to
speed up the bending of a large number of
parts of the same curvature, it may be neces-
sary to use a heated bending form. The surface
temperature of this form may be as high as
149 °C (300 �F), if necessary, without danger
of damage to the plywood. The plywood
should be left on the heated form only long
enough to dry to room conditions.
1-50. REPAIRS TO DOUBLE CURVA-
TURE PLYWOOD SKIN. The molded ply-
wood necessary for a repair to a damaged ply-
wood skin of double curvature cannot be made
from flat plywood unless the area to be re-
paired is very small or is of exceedingly slight
double curvature; therefore, molded plywood
of the proper curvature must be on hand before
the repair can be made. If molded plywood of
the proper curvature is available, the repair
may be made using the same procedure as on
single curvature skins.
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Par 1-49