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 | 2-10. Lacing
9/8/98
AC 43.13-1B
2-10. LACING.
a. Fabric should be attached to aircraft
components to prevent ballooning due to
aerodynamic forces, in the identical manner
and locations as used by the original aircraft
manufacturer. Any deviation from the original
method(s) of attachment, such as screws, riv
ets, wire clips, lacing cord, etc., are considered
a major alteration and in conflict with the air
craft type design data. Obtain FAA approval
on any deviation.
cial attention should be given to avoid interfer
ence with the routing of any control cable,
bellcrank, or any other movable item. To pre
vent chafing and cutting of the lacing cord,
control cables or any other movable items
should be tensioned or positioned to their
normal alignment before rib lacing and
checked afterwards to ensure adequate clear
ance. When a lace cord will be chafed by a
moving component, a blindstitch may be made
around the top and bottom rib caps as illus
trated in figure 2-11.
NOTE: When the type of rib lace
knot used by the original aircraft
manufacturer is not known, the modi-
fied seine knot shown in figure 2-4
through figure 2-9c will be used.
c. Stationary structures interfering with
needle routing may be circumvented by align
ing the needle forward or aft adjacent to the rib
cap. Pull the needle through the wing and then
return through the same hole and exit at the
desired adjacent location.
NOTE: The first lace on a wing rib
should be spaced from the leading
edge fairing no more than 1/2 the re-
quired lace spacing for the balance of
the rib.
FIGURE 2-4. Standard external modified seine knot used
for single and double rib lacing.
d. Both surfaces of fabric covering on
wings and control surfaces must be securely
fastened to the ribs by lacing cord or any other
method originally approved for the aircraft.
Care must be taken to insure that all sharp
edges against which the lacing cord may bear
are protected by tape in order to prevent abra
sion of the cord. Separate lengths of lacing
cord may be joined by the splice knot shown in
figure 2-10 or tied off. The first loop is tied
with a square knot as illustrated in figure 2-5
and figure 2-9a, and the knot secured with a
half hitch on each side after the lacing is pulled
tight around the rib. The needle is then routed
through the wing and around the rib cap at the
b. During the installation of lacing cord
through a wing or any other component, spe
Par 2-10
Page 2-11