TM 1-1520-253-23
3.11.3.7
Marking and Recording of Inspection Results. Mark and record the inspection results as necessary per
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.
3.11 4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.
3.11.5 System Securing. Clean the forward transmission slider 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 forward transmission
slider shaft requires installation in accordance with the applicable technical manuals listed in Table 1-1.
FORWARD TRANSMISSION OUTSIDE SURFACE (ET).
3.12.1 Description (Figure 3-1. Index No. 12). The forward transmission receives input torque from the combining
transmission through its forward driveshafting. It then transmits the torque directly to the forward rotary-wing head and
rotor blades through an integral shaft.
3.12.2 Defects. Defects may occur anywhere on the surface of the forward transmission. Any damaged areas shall be
inspected both before and after repair to ensure there are no cracks. No cracks are allowed.
3.12.3 Primary Method. Eddy Current.
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, 901/2 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
3.12.3.2
Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. 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 forward transmission shall be removed in accordance with the.
applicable technical manuals listed in Table 1-1.
3.12.3.3
Access. Access is from the forward transmission work platform. See Figure 1-4-CH-47: 9; MH-47: 16.
3.12.3.4
Preparation of Part. The forward transmission outside surface shall be thoroughly cleaned.
Refer to
Preparation of Part or Area for NDI, paragraph 1.4.4.
