FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 2. Fabric Covering | 1. Practices and Precautions | 2-3. Aircraft Fabric-synthetic
9/8/98
CHAPTER 2. FABRIC COVERING
AC 43.13.1B
SECTION 1. PRACTICES AND PRECAUTIONS
2-1. GENERAL. Cotton and Irish linen fab
rics were the airframe coverings of choice
from WWI through the 1950’s. However, in
creases in cost and the short lifespan of natural
fabrics became the driving factors which re
sulted in almost 100 percent replacement of
original airframe fabrics by man-made,
STC-approved, polyester, and glass filament
fabric.
2-2. PROBLEM AREAS.
a. Deterioration. Polyester fabric dete
riorates only by exposure to ultraviolet radia
tion as used in an aircraft covering environ
ment. When coatings completely protect the
fabric its service life is infinite. Therefore, it is
very important to thoroughly protect the
structure from deterioration before covering
and provide adequate inspection access to all
areas of fabric-covered components to allow
inspection for corrosion, wood rot, and mice
infestation. Multiple drain holes in the lower
ends of all fabric-covered sections also provide
needed ventilation to remove condensation.
b. Tension. Polyester fabric obtains
maximum tension on an airframe at 350 ºF,
and will not be excessive on aircraft originally
covered with natural fabric and 12 coats of
Nitrate or Butyrate Dope. However, dope ap
plied over full heat-tauted fabric can develop
excess tension after aging and damage light
aircraft structures. Coatings other than dope
will not increase fabric tension after aging.
The heat-tauting instructions given in the
manual of each STC-approved covering proc
ess should be followed.
2-3. AIRCRAFT FABRIC-SYNTHETIC.
a. STC-Approved Covering Materials.
There is a wide selection of STC-approved
covering materials available which utilize
synthetic fabric falling within the generic class
“Polyester” and may vary in characteristics.
Difference in the fabric may be denier, tenac
ity, thread count, weight, shrink, tension, and
weave style.
b. Polyester Filaments. Polyester Fila
ments are manufactured by polymerization of
various select acids and alcohols, then extrud
ing the resulting molten polymers through
spinnerets to form filaments. The filaments
are heat stretched to reduce to the desired
denier or size. It is the heat stretching that im
parts a memory in the filaments causing them
to try and return to their original shorter length
when reheated at a controlled temperature.
Overheating will cancel the memory and melt
the filaments.
c. Covering Procedures. Coating types,
covering accessories, and covering procedures
also may vary; therefore, the covering proce
dures given in the pertinent manuals must be
followed to comply with the STC. The FAA
STC-approved installation takes precedence
over instructions in this advisory circular.
d. Installation. Initial installation of
polyester fabric is similar to natural fabric.
The fabric is installed with as little slack as
possible, considering fittings and other protru
sions. It may be sewn into an envelope, in
stalled as a blanket, or installed by cementing
to the airframe with a fabric cement. Each
STC may differ in the cement seam overlap,
type of sewn seam, heat shrinking procedures,
and temperature.
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