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 | 2-4. Aircraft Fabric-natural
AC 43.13-1B
9/8/98
2-4. AIRCRAFT FABRIC-NATURAL.
Physical specifications and minimum strength
requirements for natural fiber fabric, cotton
and linen, used to recover or repair compo
nents of an aircraft, are listed in table 2-1.
Tear resistance is an important factor when
considering aircraft fabric. A test method such
as ASTM D 1424 is recommended. Technical
Standard Order TSO-C15d, entitled Aircraft
Fabric, Grade A (AMS 3806D); and
TSO-C14b, Aircraft Fabric, Intermediate
Grade (AMS 3804C) current edition, respec
tively, describe the minimum standards that all
fabric must meet to qualify as aircraft covering
material.
2-5. RECOVERING AIRCRAFT. Re
cover or repair aircraft with a fabric of equal
quality and strength to that used by the original
aircraft manufacturer. It is recommended that
fabric conforming to TSO-C15d or TSO-C14b
be used to recover aircraft originally covered
with lower strength fabric conforming to
AMS 3802, current edition.
NOTE: Recovering or repairing air-
craft with any type fabric and/or
coating other than the type used by
the original aircraft manufacturer is
considered a major alteration. Obtain
approval from the FAA on fabric and
installation data. Cotton and linen rib
lacing cord, machine and hand-sewing
thread, and finishing tapes should not
be used with polyester and glass fabric
covering.
a. Reinforcing tape minimum tensile
strength is listed in table 2-2. Reinforcing tape
meeting specification MIL-T-5661, Type I,
current edition, is acceptable. Reinforcing tape
should have a minimum 40 lb. resistance with
out failure when static tested in shear against a
single rib lace, or a pull-through resistance
when tested against a single-wire clip, rivet,
screw, or any other type of fabric-to-rib
attachment. Reinforcing tape is used over the
rib cab on top of the fabric and for inter-rib
bracing.
b. Finishing Tape, sometimes referred to
as surface tape, should have the same proper
ties as the fabric used to cover the aircraft.
c. Lacing Cord shall have a minimum
breaking strength of 40 lb. Lacing cord meet
ing the specifications listed in table 2-2 is ac
ceptable. Rib lace cord should have a micro-
crystalline fungicidal wax, paraffin-free wax,
or beeswax coating, or other approved treat
ment to prevent wearing and fraying when
pulling through the structure.
d. Machine Thread shall have a mini
mum breaking strength of 5 lb. Thread meet
ing the specifications listed in table 2-2 is ac
ceptable.
e. Hand-Sewing Thread shall have a
minimum breaking strength of 14 lb. Thread
meeting the specifications listed in table 2-2, is
acceptable. When covering with STC-
approved fabric covering material, use the type
of sewing thread approved by the STC and
manufactured under the specific PMA.
f. Flutter Precautions. When re-covering
or repairing control surfaces, especially on
high performance airplanes, make sure that
dynamic and static balances are not adversely
affected. Weight distribution and mass bal
ance must be considered to preclude to possi
bility of induced flutter.
2-6. PREPARATION OF THE STRUC-
TURE FOR COVERING. One of the most
important items when covering aircraft is the
proper preparation of the structure. Before
covering, the airframe must be inspected and
approved by a FAA-certified mechanic or re
pair station.
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