Technical data

13773-001
51-20
Page 12 30 Nov 2000
G. Ply Orientation
Each ply has a fiber orientation. Fiber orientation, is the direction that the 0° axis fibers point. The
glass-fabric used for repair in this airplane is Hexcel 7781-F16 fabric (the number 7781-F16 denotes
the weave style and the fiber type). For repair purposes, 7781 is considered a balanced cloth, meaning
that approximately 50% of the fibers run parallel to warp, and approximately 50% run perpendicular to
warp. Fibers that run parallel to the edge are the 0° axis fibers. (See Figure 51-202)
Generally, the 0° axis is parallel to the ground and centerline of the fuselage when the aircraft is level.
For example: the main spar in most wings run perpendicular to the 0° axis. Draw the 0° reference line
alongside the damage, position the line so it intersects the center of the damage. This line will be used
for positioning the repair plies.
When cutting a ply, if fiber orientation of a ply is 0°, position the template on the fabric with the 0° refer-
ence line parallel with the edge of the cloth. If orientation is 45°, turn the template so the 0° reference
line is at a 45° angle to the cloth edge.