TM 1-1520-264-23
NOTE
Either probe identified in paragraph 3.19.3.1 may be used depending primarily on the ease of accessibility
and user friendliness. If the probes are changed, steps 3.19.3.5 b. (1), (2), and (3) shall be repeated each
time a change is made.
3.19.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph
1.3.
3.19.4
Backup Method. None required.
3.19.5
System Securing. The intermediate gearbox, if removed, requires installation in accordance with the applicable
technical manuals listed in Table 1-1.
3.20
INTERMEDIATE GEARBOX RETAINERS (ET).
3.20.1
Description (Figure 3-1. Index No. 20). The intermediate gearbox retainers maintain the bearings and seals
within the intermediate gearbox assembly.
3.20.2
Defects. This inspection is used to verify crack indications found visually on the intermediate gearbox
retainers. No cracks are allowed.
3.20.3
Primary Method. Eddy Current.
3.20.3.1 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 magnesium (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
3.20.3.2 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 intermediate gearbox retainers shall be removed in accordance
with the applicable technical manuals listed in Table 1-1.
3.20.3.3 Access. Access is through the vertical stabilizer fairings (Figure 1-4, Items R510 and L51 0).
3.20.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
paragraph 1.4.4.
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