FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 4. Metal Structure, Welding, and Brazing | 5. Welding and Brazing | 4-91. Repair of Tubular Members
AC 43.13-1B CHG 1
9/27/01
melts, the copper iron is drawn slowly along
the seam. As much solder as necessary is
added without raising the soldering copper iron
from the job. The melted solder should run
between the surfaces of the two sheets and
cover the full width of the seam. Work should
progress along the seam only as fast as the sol
der will flow into the joint.
4-89. AIRCRAFT PARTS NOT TO BE
WELDED.
a. Brace Wires and Cables. Do not weld
aircraft parts whose proper function depends
upon strength properties developed by cold-
working. Among parts in this classification
are streamlined wire and cables.
b. Brazed and Soldered Parts. Do not
weld brazed or soldered parts as the brazing
mixture or solder will penetrate and weaken
the hot steel.
c. Alloy Steel Parts. Do not weld alloy steel
parts such as aircraft bolts, turnbuckle ends,
etc., which have been heat treated to improve
their mechanical properties.
d. Nos. 2024 and 7075 Aluminum. Do not
weld these two aluminum alloys (that are often
used in aircraft construction) because the heat
from the welding process will cause severe
cracking. The 2024 aluminum is most often
used in wing skins, fuselage skins, and in most
structured airframe parts. The 7075 aluminum
is most often used in machined fittings such as
wing-spar attachments, landing-gear attach
ments, and other structural parts.
4-90. WELDING ROD SELECTION.
Most aircraft repair shops that are prepared to
make weld repairs should have the basic se
lection of welding rods available. The best
rods to stock, the metals they weld, and the
AWS specification number are shown in ta
ble 4-15.
4-91. REPAIR OF TUBULAR MEM
BERS.
a. Inspection. Prior to repairing tubular
members, carefully examine the structure sur
rounding any visible damage to insure that no
secondary damage remains undetected. Sec
ondary damage may be produced in some
structure, remote from the location of the pri
mary damage, by the transmission of the dam
aging load along the tube. Damage of this na
ture usually occurs where the most abrupt
change in direction of load travel is experi
enced. If this damage remains undetected,
subsequent normal loads may cause failure of
the part.
b. Location and Alignment of Welds.
Unless otherwise noted, welded steel tubing
may be spliced or repaired at any location
along the length of the tube. To avoid distor
tion, pay particular attention to the proper fit
and alignment.
c. Members Dented at a Cluster. Repair
dents at a steel-tube cluster joint by welding a
specially formed steel patch plate over the
dented area and surrounding tubes. (See fig
ure 4-34.) To prepare the patch plate, cut a
section of steel sheet of the same material and
thickness as the heaviest tube damaged. Trim
the reinforcement plate so that the fingers ex
tend over the tubes a minimum of 1.5 times the
respective tube diameter. (See figure 4-34.)
Remove all the existing finish on the damaged
cluster-joint area to be covered by the rein
forcement plate. The reinforcement plate may
be formed before any welding is attempted, or
it may be cut and tack-welded to one or more
of the tubes in the cluster joint, then heated
and formed around the joint to produce a
smooth contour. Apply sufficient heat to the
plate while forming so that there is generally a
gap of no more than 1/16 inch from the con-
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