TM 1-1520-265-23
Change 3
2-71
b. 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 vertical
signal when probe is passed over 0.040-inch notch in test block. (See the standard
instrument 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 to
obtain horizontal lift-off.
b. Inspect the part.
c. Any signal similar to the notches in the test block are cause for rejection.
NOTE
Either probe identified in paragraph 2.29.3.1 may be used depending primarily on the
ease of accessibility and user friendliness. If the probes are changed, steps 2.29.3.5
b. (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 as
required by paragraph 1.3.
2.29.4 Backup Method. None required.
2.29.5 System Securing. The pitch beam, if removed, requires installation in accordance with the
applicable technical manuals listed in Table 1-1.
2.30 TAIL ROTOR INBOARD/OUTBOARD RETENTION PLATES (ET).
2.30.1 Description (Figure 2-1, Index No. 30). The tail rotor inboard/outboard retention plates are
the attaching points for tail rotor blades.
2.30.2 Defects. Defects may occur anywhere on the surface of the inboard/outboard retention
plates. No cracks are allowed.
2.30.3 Primary Method. Eddy Current.
2.30.3.1 NDI Equipment and Materials. (Refer to Appendix B.)
a. Eddy Current Inspection Unit
b. Probe, straight, shielded surface, 2 MHz
c. Probe, right angle, shielded surface, 2 MHz, 90_ 1/2 inch drop
d. Cable Assembly
e. Adapter, Probe, MHz
f. Reference Block, three-notched titanium (0.008, 0.020, 0.040 EDM notches)
g. Teflon Tape, refer to Table 1-8
h. Aircraft Marking pencil, refer to Table 1-8
