FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 3. Fiberglass and Plastics | 1. Repair of Light Load Laminate Structures | 3-1. General
9/8/98
AC 43.13-1B
CHAPTER 3. FIBERGLASS AND PLASTICS
SECTION 1. REPAIR OF LIGHT LOAD LAMINATE STRUCTURES
3-1. GENERAL. There is a wide variation
in the composition and structural application
of laminates, and it is essential that these fac
tors be given major consideration when any
restoration activities are undertaken. To a
similar extent, there also exist many types of
laminate structure repairs that may or may not
be suitable for a given condition. For this rea
son, it is important that the aircraft or compo
nent manufacturer’s repair data be reviewed
when determining what specific type of repair
is permissible and appropriate for the damage
at hand.
NOTE: Review Material Safety Data
Sheets for material to be used. When
handling materials, prepreg fabrics,
or parts with prepared surfaces, ob-
serve shelf life. Latex gloves and ap-
proved masks must be worn.
a. The materials used in the repair of
laminate structures must preserve the strength,
weight, aerodynamic characteristics, or electri
cal properties of the original part or assembly.
Preservation is best accomplished by replacing
damaged material with material of identical
chemical composition or a substitute approved
by the manufacturer.
b. To eliminate dangerous stress con-
centrations, avoid abrupt changes in
cross-sectional areas. When possible, for scarf
joints and facings, make small patches round
or oval-shaped, and round the corners of large
repairs. Smooth and properly contour aerody
namic surfaces.
c. Test specimens should be prepared
during the actual repair. These can then be
subjected to a destructive test to establish the
quality of the adhesive bond in the repaired
part. To make this determination valid, the
specimens must be assembled with the same
adhesive batch mixture and subjected to curing
pressure, temperature, and time identical to
those in the actual repair.
3-2. FIBERGLASS LAMINATE RE-
PAIRS. The following repairs are applicable
to fiberglass laminate used for non-structural
fairing, covers, cowlings, honeycomb panel
facings, etc. Prior to undertaking the repair,
remove any paint by using normal dry sanding
methods. Bead blasting may be used but cau
tion must be exercised not to abrade the sur
faces excessively.
NOTE: Chemical paint strippers
must not be used.
NOTE: These repairs are not to be
used on radomes or advanced com-
posite components, such as graphite
(carbon fiber) or Kevlar.
CAUTION: Sanding fiberglass lami-
nates gives off a fine dust that may
cause skin and/or respiratory irrita-
tion unless suitable skin and respira-
tion protection is used. Sanding also
creates static charges that attract dirt
or other contaminants.
a. Check for voids and delamination by
tap testing. (See chapter 5.) When the surface
of a fiberglass laminated structure is scratched,
pitted, or eroded; first wash with detergent and
water to remove all of the dirt, wax, or oxide
film. Then scrub the surface with an accept
able cleaner. After the surface is thoroughly
cleaned, sand it with 280-grit sandpaper, and
again use an acceptable cleanser to remove any
sanding residue and moisture. This is
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