TM 1-1500-204-23-11
Table 7-1.
General Description of Different Repair Types -- Continued
Constraints and
Description
Application
Type of Repair
Limitations
Bonded Pre-cured
Flat or gently contoured
Patch usually must be
Structural repair.
Composite (Simple
laminates.
oriented with respect
Pre-cured iber/epoxy
External Patch)
to the parent structure.
laminated patch made
Care needed to avoid
from woven and/or
preloading during
unidirectional aramid,
installation. Uniform
iberglass, and/or carbon.
pressure, temperature,
Geometry and size
and cure cycle are
tailored to a speciic
important. Adhesive
structural coniguration,
bond may have poorer
stiffness, and loading
strength properties than
condition. Circular or
a wet layup or pre-preg
rectangular patch. Patch
repair. Adhesive should
applied to structure with
not be overly sensitive to
ilm or paste adhesive. A
contamination and should
relatively thick and elastic
possess elastic properties
bond-line is desirable.
similar to an elastomer,
Similar to lat pattern
especially in areas which
pre-preg with respect to
experience high strain
preparing the damaged
rates or interlaminar
part and curing the repair.
shears. If the laminate
thickness permits, rivets
may be installed prior to
adhesive cure to ensure
good surface contact
and to provide fail-safe
strength in case of bond
deterioration. Provides
no opportunity to form
repair parts to it structural
contours as with metals.
Bonded Pre-cured
Flat, gently contoured,
Same as the simple
Same as simple bonded
Composite (External
thick laminates requiring
external bonded patch
patch except for the added
Stepped Patch)
greater structural
except the patch is tapered
complications associated
capability than a simple
by stepping the plies to
with scaring the damaged
patch provides.
successively smaller or
structure to match the
larger diameters. May be
taper of the patch.
installed as a lush repair
by scaring the parent
material to match the
taper of the patch.
7-3