FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 6. Corrosion, Inspection, and Protection | 7. Basic Corrosion Removal Techiques | 6-115. Fairing or Blending Reworked Areas
9/8/98
AC 43.13-1B
SECTION 7. BASIC CORROSION REMOVAL TECHNIQUES
6-113. GENERAL. When active corrosion
is found, a positive inspection and rework pro
gram is necessary to prevent any further dete
rioration. The following methods of assessing
corrosion damage and procedures for rework
of corroded areas could be used during cleanup
programs. In general, any rework would in
volve the cleaning and stripping of all finish
from the corroded area, removal of corrosion
products, and restoration of surface protective
film.
(1) Remove battery(s), liquid oxygen
generator container (if installed), and external
hydraulic and electric power.
(2) Install all applicable safety pins,
flags, and jury struts.
e. Protect the pitot-static ports, louvers,
airscoops, engine opening, wheels, tires, mag
nesium skin panels, and airplane interior from
moisture and chemical brightening agents.
a. Repair of corrosion damage includes
removal of all corrosion and corrosion prod
ucts. When the corrosion damage is severe
and exceeds the damage limits set by the air
craft or parts manufacturer, the part must be
replaced.
b. If manufacturer information and
limits are not available, then a DER must be
consulted before the aircraft or part is returned
to service.
6-114. PREPARATIONS FOR REWORK.
All corrosion products should be removed
completely when corroded structures are re
worked. Before starting rework of corroded
areas, carry out the following:
a. Document corrosion damage.
b. Position the aircraft in a wash rack or
provide washing apparatus for rapid rinsing of
all surfaces.
c. Connect a static ground line from the
aircraft to a grounding point.
d. Prepare the aircraft for safe ground
maintenance.
f. Protect the surfaces adjacent to rework
areas from chemical paint strippers, corrosion
removal agents, and surface treatment materi
als.
6-115. FAIRING OR BLENDING RE-
WORKED AREAS. All depressions result
ing from corrosion rework should be faired or
blended with the surrounding surface. Fairing
can be accomplished as follows:
a. Remove rough edges and all corrosion
from the damaged area. All dish-outs should
be elliptically shaped with the major axis run
ning spanwise on wings and horizontal stabi
lizers, longitudinally on fuselages, and verti
cally on vertical stabilizers. (Select the proper
abrasive for fairing operations from table 6-1.)
b. In critical and highly stressed areas,
all pits remaining after the removal of corro
sion products should be blended out to prevent
stress risers that may cause stress corrosion
cracking. (See figure 6-14.) On a non-critical
structure, it is not necessary to blend out pits
remaining after removal of corrosion products
by abrasive blasting, since this results in un
necessary metal removal.
Par 6-113
Page 6-21