FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 1. Wood Structure | 5. Finishing Wood Structures | 1-71. Sealing of Bolt Holes
9/8/98
AC 43.13-1B
1-70. FINISHING WITH FABRIC OR
TAPE. A number of systems for exterior fin-
ishing have STC approval and are manufac-
tured under a PMA. Follow the product manu-
facturer's instructions for the system used.
a. If the finish surrounding the repair is
a traditional dope system, seal the wood grain
with a suitable solvent resistant one-part var-
nish, commonly described as “dope proof,” or
a two-part epoxy varnish. Follow with two
coats of clear dope, and allow sufficient drying
time between coats.
b. Apply a third coat of clear dope and
lay a piece of pinked-edge airplane cloth into
the wet film. All air bubbles should be worked
out by brushing to ensure maximum adhesion.
When dry, apply one brush coat, to ensure
proper penetration, and at least one spray coat
of clear dope. The dried spray coat may be
sanded with fine sandpaper to obtain a
smoother finish. Complete the refinishing of
the surface by application of a topcoat as re-
quired to match the adjacent area.
1-71. SEALING OF BOLT HOLES. Bolt
holes in wooden structure provide a vulnerable
entry point for moisture. Variations in mois-
ture content around bolt holes can lead to de-
cay or splitting. In addition, excessive mois-
ture at bolt holes promotes corrosion of the
bolts. Sealing of the wood surfaces in bolt
holes can be accomplished by application of
varnish or other acceptable sealer into the open
hole. The sealer must be allowed to dry or
cure thoroughly prior to bolt installation.
1-72.1-79. [RESERVED.]
Par 1-70
Page 1-37 (and 1-38)