FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 5. Nondestructive Inspection (NDI) | 4. Magnetic Particle Inspection | 5-47. Application of Magnetic Particles
AC 43.13-1B CHG 1
9/27/01
5-45. PREPARATION OF SURFACE.
a. Remove protective coatings according
to the manufacturer’s instructions if necessary.
Unless otherwise specified, magnetic particle
examination should not be performed with
coatings in place that could prevent the detec-
tion of surface defects in the ferro-magnetic
substrate. Such coatings include paint or
chromeplate thicker than 0.003 inch, or ferro-
magnetic coatings such as electroplated nickel
thicker than 0.001 inch.
b. Parts should be free of grease, oil,
rust, scale, or other substances which will in-
terfere with the examination process. If re-
quired, clean by vapor degrease, solvent, or
abrasive means per the manufacturer’s in-
structions. Use abrasive cleaning only as nec-
essary to completely remove scale or rust. Ex-
cessive blasting of parts can affect examination
results.
c. Exercise extreme care to prevent any
cleaning material or magnetic particles from
becoming entrapped where they cannot be re-
moved. This may require extracting compo-
nents such as bushings, bearings, or inserts
from assemblies before cleaning and magnetic
particle examination.
d. A water-break-free surface is re-
quired for parts to be examined by water sus-
pension methods. If the suspension com-
pletely wets the surface, this requirement is
met.
e. Magnetic particle examination of as-
sembled bearings is not recommended because
the bearings are difficult to demagnetize. If a
bearing cannot be removed, it should be pro-
tected from the magnetic particle examination
materials and locally magnetized with a mag-
netic yoke to limit the magnetic field across
the bearing.
5-46. METHODS OF EXAMINATION.
Magnetic particle examination generally con-
sists of: the application of magnetic particles;
magnetization; determination of field strength;
special examination techniques; and demag-
netization and post-examination cleaning.
Each of these steps will be described in the
following paragraphs.
5-47. APPLICATION OF MAGNETIC
PARTICLES. The magnetic particles used
can be nonfluorescent or fluorescent (depend-
ent on the examination required) and are ap-
plied suspended in a suitable substance. Fluo-
rescent particles are preferred due to their
higher sensitivity.
a. Wet Continuous Method. Unless oth-
erwise specified, use only the wet continuous
method. In the wet continuous method, the
particle suspension is liberally applied to wet
all surfaces of the part. The magnetizing cur-
rent is applied at the instant the suspension is
diverted from the part. Apply two shots of
magnetizing current, each at least 1/2 second
long.
(1) Wet suspensions of fluorescent par-
ticles, either in water or oil, should be used for
most overhaul and in-service examinations ex-
cept where the material, size, or shape of the
part prohibits its use.
(2) Water, with a suitable rust inhibitor
and wetting agent, may be used as a liquid ve-
hicle, provided that magnetic examination
equipment is designed for use or is satisfacto-
rily converted for use with water.
b. Dry Continuous Method. This
method is not recommended for use on aero-
space components because of its lower sensi-
tivity level.
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