FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 8. Engines, Fuel, Exhaust, and Propellers | 4. Repair of Metal Propellers | 8-72. Steel Blades
9/27/01
AC 43.13-1B CHG 1
SECTION 4. REPAIR OF METAL PROPELLERS
8-71. GENERAL. Reject damaged blades
with model numbers which are on the manu-
facturer’s list of blades that cannot be repaired.
Follow the propeller manufacturer’s recom-
mendations in all cases, and make repairs in
accordance with latest techniques and best in-
dustry practices.
NOTE: Title 14 of the Code of Fed-
eral Regulations, 14 CFR, part 65 does
not allow an airframe and power
plant mechanic to perform major re-
pairs to propellers.
8-72. STEEL BLADES. Due to the critical
effects of surface injuries and their repair on
the fatigue life of steel blades, all repairs must
be made in accordance with the manufacturer’s
instructions.
8-73. ALUMINUM PROPELLER RE-
PAIRS. Aluminum-alloy propellers and
blades with dents, cuts, scars, scratches, nicks,
leading-edge pitting, etc., may be repaired,
provided the removal or treatment does not
materially affect the strength, weight, or per-
formance of the blade. Remove these damages
or otherwise treat as explained below, unless it
is contrary to the manufacturer’s instructions
or recommendations. More than one injury is
not sufficient cause alone for rejection of a
blade. A reasonable number of repairs per
blade may be made and not necessarily result
in a dangerous condition, unless their location
with respect to each other is such to form a
continuous line of repairs that would materi-
ally weaken the blade. Suitable sandpaper or
fine-cut files may be used for removing the
necessary amount of metal. In each case, the
area involved will be smoothly finished with
#00 sandpaper or crocus cloth, and each blade
from which any appreciable amount of metal
has been removed will be properly balanced
before it is used. Etch all repairs. To avoid
removal of an excessive amount of metal, local
etching should be accomplished at intervals
during the process of removing suspected
scratches. Upon completion of the repair,
carefully inspect the entire blade by etching or
anodizing. Remove all effects of the etching
process with fine emery paper. Blades identi-
fied by the manufacturer as being cold-worked
(shot-blasted or cold-rolled) may require
peening after repair. Accomplish repair and
peening operations on this type of blade in ac-
cordance with the manufacturer’s instructions.
However, it is not permissible in any case to
peen down the edges of any injury wherein the
operation will lap metal over the injury.
a. Flaws in Edges. Round out nicks,
scars, cuts, etc., occurring on the leading edge
of aluminum-alloy blades as shown in fig-
ure 8-24 (view B). Blades that have the lead-
ing edges pitted from normal wear in service
may be reworked by removing sufficient mate-
rial to eliminate the pitting. In this case, re-
move the metal by starting a sufficient distance
from the edge, as shown in figure 8-25, and
working forward over the edge in such a way
that the contour will remain substantially the
same, avoiding abrupt changes in contour.
Trailing edges of blades may be treated in sub-
stantially the same manner. On the thrust and
camber face of blades, remove the metal
around any dents, cuts, scars, scratches, nicks,
and pits to form shallow saucer-shaped depres-
sions as shown in figure 8-24 (view C). Exer-
cise care to remove the deepest point of the
injury and also remove any raised metal
around the edges of the injury as shown in fig-
ure 8-24 (view A). When repairing blades,
figures 8-26 and 8-27 show the maximum re-
duction in width and thickness that is allow-
able below the minimum dimensions required
by the blade drawing and blade manufacturing
specification.
Beyond the 90
Par 8-71
Page 8-29