TM 1-1500-204-23-11
REPAIR PROCEDURES
7-1. GENERAL. This chapter provides detailed pro-
to ensure that the repair is performed correctly. Each
cedures for repairing damaged advanced composite
process should be reviewed and understood prior
parts. Each repair includes an equipment list, mate-
to beginning the repair. A description of generally
rials list and process low diagram for accomplishing
applicable repair techniques for advanced composites
the repair. The processes in the low diagram are
structures is listed in 7-1.
listed in the order in which they are to be performed
General Description of Different Repair Types
Constraints and
Description
Application
Type of Repair
Limitations
Resin Injection
Holes drilled partially into
Most types of thick
Broken ibers or remnants
laminate area of void or
laminates.
of cured resin in the
delamination. Liquid resin
void area may affect
injected with a syringe
the quality of the bond.
through a vacuum duct
Dificult to ascertain if the
into one of the holes.
delamination has been
Vacuum applied to draw
corrected. If vacuum is
the resin outward from the
used, surface laminate
point of insertion through
must be relatively lat and
the delamination region.
accessible.
Pressure and heat applied
to restore the bond.
Limited structural
Wet Layup (Simple Patch)
Concentric circular or
All types of laminated and
capability. Used primarily
rectangular patches cut
sandwich panel facings.
for thin laminates with
from woven aramid,
non-directional layups.
iberglass, and/or carbon
Not usable where close
fabric. Patches laid up
tolerance control of
over damaged area and
surface or mold line is
impregnated with two-part
required. Usually no
epoxy/resin mixed at the
requirement to orient
repair site and applied by
iber direction relative to
hand. Patches stacked
the parent structure. If
for multiple ply repairs.
hybrid patch, stacking
Pressure applied with
sequence generally not
weight or vacuum device.
critical. One-sided access
Repair is then cured at
generally adequate.
room temperature or
elevated temperature,
depending on the curing
agent or resin system.
All laminates and
Wet Layup (External
Same as the simple wet
Good structural capability.
sandwich panel facings.
Stepped Patch)
layup repair described
May not be usable where
Usually conined to thicker
above except the repair
close tolerance control
laminates with directional
plies are stepped (made
of surface or mold line is
layups requiring a more
successively smaller in
required. Prescribed
structural repair than a
diameter for smoother
ply orientation and
simple patch.
load transition).
stacking sequence usually
required.
