TM 1-1520-265-23Change 3 2-71b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:(1) .Null probe on test block.(2) .Adjust phase as required to obtain horizontal lift-off.(3) .Move probe over all three notches in test block. Adjust gain to obtain a three block verticalsignal when probe is passed over 0.040-inch notch in test block. (See the standardinstrument display shown in Figure 1-7.)2.29.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-29.a. Place probe on a good area in the inspection location and null. Adjust phase as required toobtain horizontal lift-off.b. Inspect the part.c. Any signal similar to the notches in the test block are cause for rejection.NOTEEither probe identified in paragraph 2.29.3.1 may be used depending primarily on theease of accessibility and user friendliness. If the probes are changed, steps 2.29.3.5b. (1), (2), and (3) shall be repeated each time a change is made.2.29.3.7 Marking and Recording of Inspection Results. Mark and record inspection results asrequired by paragraph 1.3.2.29.4 BackupMethod. None required.2.29.5 SystemSecuring. The pitch beam, if removed, requires installation in accordance with theapplicable technical manuals listed in Table 1-1.2.30 TAIL ROTOR INBOARD/OUTBOARD RETENTION PLATES (ET).2.30.1 Description(Figure2-1,IndexNo.30). The tail rotor inboard/outboard retention plates arethe attaching points for tail rotor blades.2.30.2 Defects. Defects may occur anywhere on the surface of the inboard/outboard retentionplates. No cracks are allowed.2.30.3 PrimaryMethod. Eddy Current.2.30.3.1 NDI Equipment and Materials. (Refer to Appendix B.)a. Eddy Current Inspection Unitb. Probe, straight, shielded surface, 2 MHzc. Probe, right angle, shielded surface, 2 MHz, 90_ 1/2 inch dropd. Cable Assemblye. Adapter, Probe, MHzf. Reference Block, three-notched titanium (0.008, 0.020, 0.040 EDM notches)g. Teflon Tape, refer to Table 1-8h. Aircraft Marking pencil, refer to Table 1-8
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