TM 1-1520-253-23
2.6.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.
2.6.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the
Am orientation of
possible cracks. Position required for this inspection is illustrated in Figure 2-6.
a. Select AC on the AC/DC power switch.
b. Place probe/yoke on part 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.
2.6.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by
2.6.3.8 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.
2.6.4 Backup Method. None required.
2.6.5 System Securing. Clean the vertical hinge pin flanges thoroughly to remove all residual magnetic particle media.
Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. If removed, the vertical hinge pin
flanges require installation in accordance with the applicable technical manuals listed in Table 1-1. Secure the forward
and aft transmission work platforms.
2.7.1 Description (Figure 2-1. Index No. 7). The pitch varying shaft bore liner is the bearing surface for the horizontal
pin and the attach point for the tie bar assembly.
2.7.2 Defects. Defects may occur anywhere on the surface of the pitch varying shaft bore liner. No cracks are allowed.
2.7.3 Primary Method. Magnetic Particle.
2.7.3.1 NDI Equipment and Materials. (Refer to Appendix B.)
a.
Magnetic Particle Inspection Probe/Yoke
b.
Magnetometer
c.
Black Light
d.
Fluorescent Magnetic Particles
e.
Consumable Materials, refer to Table 1-8
f.
Aircraft Marking Pencil, refer to Table 1-8
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