TM 1-1520-264-23
4.15.3.6
Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-15.
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 4.15.3.1 may be used depending primarily on the ease of accessibility and user
friendliness. If the probes are changed, steps 4.15.3.5 b. (1), (2), and (3) shall be repeated each time a change is
made.
4.15.3.7
Marking and Recording of Inspection Results. Mark and record the inspection results as required by
paragraph 1.3.
4.15.4
Backup Method. None required.
4.15.5
System Securing. The nacelle carry-through post assembly, if removed, requires installation in accordance with
the applicable technical manuals listed in Table 1-1. Secure opened access doors.
4.16
WING ATTACHMENT FITTINGS ON WING AND FUSELAGE (ET).
4.16.1
Description (Figure 4-1. Index No. 16).
The wing attach fittings on the wings and fuselage are located at F.S.
199.75, F.S. 214.50, and WL 139.34, and 129.2. All of the attach fittings are made from aluminum alloy.
4.16.2
Defects. This inspection is used to verify crack indications found visually on the wing attach fittings. No cracks
are allowed.
4.16.3
Primary Method. Eddy Current.
4.16.3.1
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, and 0.040 EDM notches)
f.
Teflon Tape, refer to Table 1-8
g.
Aircraft Marking Pencil, refer to Table 1-8
4.16.3.2
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 wing shall be removed in accordance with the
applicable technical manuals listed in Table 1-1.
4-38
