TM 1-1520-265-23
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.
6.8.3.7 Marking and Recording of Inspection Results. Mark and record inspection results as required by paragraph 1.3.
6.8.3.8 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.
6.8.4 Backup Method. None required.
6.8.5 System Securing. Clean the collective boost and yaw boost servo 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 collective boost
and yaw boost servo, if removed, requires installation in accordance with the applicable technical manuals listed in Table
1-1.
6.9 YAW/PITCH COUPLING LINK (ET).
6.9.1 Description (Figure 6-1. Index No. 9) . The yaw/pitch coupling link is a component of the mixer assembly which
is part of the collective control system.
6.9.2 Defects. This inspection is used to verify crack indications found visually on the yaw/pitch coupling link. No
cracks are allowed.
6.9.3 Primary Method. Eddy Current.
6.9.3.1 NDI Equipment and Materials. (Refer to Appendix B.)
a.
Eddy Current Inspection Unit
b.
Probe, straight, shielded surface, 100 KHz-500 KHz
c.
Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop
d.
Cable Assembly
e.
Reference Block, three-notched aluminum (0.008, 0.020, 0.040 EDM notches)
f.
Teflon Tape, refer to Table 1-8
g.
Aircraft Marking Pencil, refer to Table 1-8
6.9.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection
for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of
the installed part using this procedure. If required, the yaw/pitch coupling link shall be removed in accordance with the
applicable technical manuals listed in Table 1-1.
6.9.3.3 Access. Access is through the controls/accessories sliding cover (Figure 1-4, Item 3T-4T-2).
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