TM 1-1520-264-23
2.8.3.3 Access. Accessibility of the main rotor mast varies considerably. Refer to Figure 1-4 and Table 1-2 to locate
applicable access provisions.
2.8.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
paragraph 1.4.4.
2.8.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.
2.8.3.6 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 2-8.
a.
Select AC on the AC/DC power switch.
b.
Place probe/yoke on part in typical position 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.
2.8.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph
1.3.
2.8.3.8 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.
2.8.4
Backup Method. None required.
2.8.5
System Securing. Clean the main rotor mast thoroughly to remove all residual magnetic particle media. Refer to
Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main rotor mast, if removed, requires
installation in accordance with the applicable technical manuals listed in Table 1-1.
2.9
MAIN ROTOR MAST RETAINING RING (MT).
2.9.1
Description (Figure 2-1, Index No. 9). The main rotor mast retaining ring secures the main rotor mast retention
nut to the main rotor mast.
2.9.2 Defects. This inspection is used to verify crack indications found visually on the main rotor
mast retaining ring. No cracks are allowed.
2.9.3 Primary Method. Magnetic Particle.
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