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 | 4-74. General
9/27/01
SECTION 5. WELDING AND BRAZING
AC 43.13-1B CHG 1
4-74. GENERAL. This section covers weld
repairs to aircraft and component parts only.
Observe the following procedures when using
such equipment as gas tungsten arc welding
(GTAW), gas metal arc welding (GMAW),
plasma arc welding, and oxyacetylene gas
welding. When repairs of any of these
flight-critical parts are required, it is extremely
important to make the weld repairs equal to the
original weld. Identifying the kind of metal to
be welded, identifying the kind of welding pro
cess used in building the part originally, and
determining the best way to make welded re
pairs are of utmost importance.
e. Finally, after the weld is completed, the
weld must be inspected for defects. All these
things are necessary in order to make an air
worthy weld repair.
f. Aircraft welding Qualifications. Four
groups of metals a person can be certified and
qualified to use are:
(1) Group 1, 4130 Steel.
(2) Group 2, Stainless Steel.
(3) Group 3, Aluminum
(4) Group 4, Titanium.
a. Welding is one of the three commonly
used methods of joining metals without the use
of fasteners. Welding is done by melting the
edges of two pieces of metal to be joined and
allowing the molten material to flow together
so the two pieces will become one.
b. Brazing is similar to welding in that heat
is used to join the material; but rather than
melting, the metal is heated only enough to
melt a brazing rod having a much lower melt
ing point. When this brazing rod melts, it wets
the surfaces to be joined, and when it cools
and solidifies, it bonds the pieces together.
c. Soldering is similar to brazing except that
brazing materials normally melt at tempera
tures above 425 °C (800 °F), while solders
melt at temperatures considerably lower.
d. The next step in making airworthy weld
repairs is to decide the best process to use,
considering the available state-of-the-art
welding equipment, and then deciding the cor
rect weld-filler material to use. Before any
weld repairs can be made, the metal parts to be
welded must be cleaned properly, fitted and
jigged properly, and all defective welds must be
removed to prepare for an aircraft quality weld
repair.
g. For other group listing of metal the welder
may qualify, refer to Mil-Std-1595A.
h. Most large business or agencies conduct
their own certification tests, or they have an
outside testing lab validate the certification
tests.
4-75. EQUIPMENT SELECTION. Use
the welding equipment manufacturer’s infor
mation to determine if the equipment will sat
isfy the requirements for the type of welding
operation being undertaken. Disregarding
such detailed operating instructions may cause
substandard welds. For example, when using
GTAW equipment, a weld can be contami
nated with tungsten if the proper size electrode
is not used when welding with direct current
reverse polarity. Another example, the deple
tion of the inert gas supply below the critical
level causes a reduction in the gas flow and
will increase the danger of atmospheric con
tamination.
(a) Electric welding equipment versatility
requires careful selection of the type current
and polarity to b used. Since the composition
and thickness of metals are deciding
Par 4-74
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