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 | 5-48. Magnetization
9/27/01
AC 43.13-1B CHG 1
c. Residual Magnetization Method. In
this method, the part is magnetized and the
magnetizing current is then cut off. If the am-
perage has been correctly calculated and qual-
ity indicator has verified the technique, then
one shot will correctly magnetize the part. The
magnetic particles are applied to the part after
the magnetization. This method is dependent
upon the retentiveness of the part, the strength
of the applied field, the direction of magneti-
zation, and the shape of the part.
5-48. MAGNETIZATION.
a. Circular. Circular magnetization is in-
duced in the part by the central-conductor
method or the direct-contact method. (See fig-
ure 5-11.)
(1) Indirect Induction (central-conduc-
tor method). Pass the current through a central
conductor that passes through the part. When
several small parts are examined at one time,
provide sufficient space between each
piece to permit satisfactory coverage (with
particles), magnetization, and examination.
(2) Direct Induction (contact method).
Pass current through the part mounted hori-
zontally between contact plates. As an exam-
ple, circular magnetization of a round steel bar
would be produced by placing the ends of the
steel bar between the heads of the magnetic in-
spection machine and passing a current
through the bars. Magnetic particles applied
either during or after passage of the current, or
after passage of the current in magnetically-
retentive steels, would disclose discontinuities
parallel to the axis of the bar.
NOTE: Exercise extreme caution to
prevent burning of the part at the
electrode contact areas. Some causes
of overheating and arcing are: insuffi-
cient contact area, insufficient contact
pressure, dirty or coated contact ar-
eas, electrode removal during current
flow, and too high an amperage set-
ting.
FIGURE 5-11. Circular magnetization.
Par 5-47
Page 5-23