TM 1-1520-264-23
e.
Consumable Materials, refer to Table 1-8
f.
Aircraft Marking Pencil, refer to Table 1-8
NOTE
Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.
2.23.3.2
Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main rotor
hub lower plate shall be removed in accordance with the applicable technical manuals listed in Table 1-1.
2.23.3.3
Access. Not applicable.
2.23.3.4
Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
paragraph 1.4.4.
2.23.3.5
NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.
2.23.3.6
Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of
possible cracks. The position required for this inspection is illustrated in Figure 2-23.
a.
Select AC on the AC/DC power switch.
b.
Place probe/yoke on part in position 1 as shown.
c.
Press the test switch and apply a light coat of magnetic particle media at the same time.
Remove the media momentarily before removing the current. Current should be applied for no more than five
seconds.
d.
Inspect for cracks using the black light.
2.23.3.7
Marking and Recording of Inspection Results. Mark and record the inspection results as required by
paragraph 1.3.
2.23.3.8
Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same
position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet
before releasing the switch.
Figure 2-23. Main Rotor Hub Lower Plate
2-53
