TM 1-1520-265-23
a.
Select AC on the AC/DC power switch.
b.
Place probe/yoke on part in position 1 as shown.
c.
Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media
momentarily before removing the current. Current should be applied for no more than five seconds.
d.
Inspect for cracks using the black light.
e.
Demagnetize before moving to the next position. Refer to paragraph 3.8.3.8.
f.
Repeat steps a. through e. for position 2.
3.8.3.7 Marking and Recording of Inspection Results. Mark and record inspection results as required by paragraph 1.3.
3.8.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position
used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before
releasing the switch.
3.8.4 Backup Method. None required.
3.8.5 System Securing. Clean the oil cooler fan shaft thoroughly to remove all residual magnetic particle media. Refer
to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The oil cooler fan shaft, if removed,
requires installation in accordance with the applicable technical manuals listed in Table 1-1.
3.9 OIL COOLER FAN BLADES (ET).
3.9.1 Description (Figure 3-1. Index No. 9). The oil cooler fan blades are part of the transmission blower assembly.
The blower forces air through the oil cooler.
3.9.2 Defects. Defects may occur anywhere on the surface of the oil cooler fan blades. Particular attention shall be
given to the blade/hub area. No cracks are allowed.
3.9.3 Primary Method. Eddy Current.
3.9.3.1 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, 900 1/2 inch drop
d.
Cable Assembly
e.
Reference Block, three-notched aluminum (0.008, 0.020, 0.040 EDM notches)
f.
Teflon Tape, refer to Table 1-8
g.
Aircraft Marking Pencil, refer to Table 1-8
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