TM 1-1520-264-23
a.
Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal lift-
off.
b.
Inspect the part.
c.
Any signal similar to the notches in the test block is cause for rejection.
NOTE
Either probe identified in paragraph 2.11.3.1 may be used depending primarily on the ease of accessibility and user
friendliness. If the probes are changed, steps 2.11.3.5 b. (1), (2), and (3) shall be repeated each time a change is
made.
2.11.3.7
Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph
1.3.
2.11.4
Backup Method. None required.
2.11.5
System Securing. The main rotor head (hub), if removed, requires installation in accordance with the applicable
technical manuals listed in Table 1-1.
2.12 MAIN ROTOR LEAD LAG LINK (DAMPER LINK) (ET).
2.12.1
Description (Figure 2-1. Index No. 12). The four lead lag links are titanium mounts that provide a mounting point
for each of the main rotor blade assemblies.
2.12.2
Defects. This inspection is used to verify crack indications found visually on the lead lag ink (damper link). No
cracks are allowed.
2.12.3
Primary Method. Eddy Current.
2.12.3.1
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 titanium (0.008, 0.020, and 0.040 EDM notches)
f.
Teflon Tape, refer to Table 1-8
g.
Aircraft Marking Pencil, refer to Table 1-8
2.12.3.2
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 lead lag link shall be removed in accordance with the applicable
technical manuals listed in Table 1-1.
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