TM 1-1520-264-23
3.9.3.7
Marking and Recording of Inspection Results. Mark and record the inspection results as
required by paragraph 1.3.
3.9.4
Backup Method. None required.
3.9.5
System Securing. The aft hanger bearing support, if removed, requires installation in
accordance with the applicable technical manuals listed in Table 1-1.
3.10 INTERMEDIATE GEARBOX CENTRIFUGAL FAN (ET).
3.10.1
Description (Figure 3-1. Index No. 10). The intermediate gearbox centrifugal fan is mounted to the
intermediate gearbox input flange. The centrifugal-fan maintains the intermediate gearbox assembly at normal operating
temperature.
3.10.2
Defects. This inspection is used to verify crack indications found visually on the intermediate gearbox
centrifugal fan. No cracks are allowed.
3.10.3
Primary Method. Eddy Current.
3.10.3.1 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
3.10.3.2 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 centrifugal fan shall be removed in
accordance with the applicable technical manuals listed in Table 1-1.
3.10.3.3 Access. Not applicable.
3.10.3.4 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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