TM 1-1520-253-23
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.
3.13.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.
3.13.5 System Securing. Clean the aft 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 aft slider shaft requires installation in
accordance with the applicable technical manuals listed in Table 1-1.
AFT ROTOR SHAFT (MT).
3.14.1 Description (Figure 3-1. Index No. 14). The aft rotor shaft is splined to the top of the aft transmission. It
transmits input torque from the transmission to the aft rotary-wing head and rotor blades.
3.14.2 Defects. Defects may occur anywhere on the surface of the aft rotor shaft. No cracks are allowed.
3.14.3 Primary Method. Magnetic Particle.
3.14.3.1
NDI Equipment and Materials. (Refer to Appendix B.)
a.
Magnetic Particle Inspection Probe/Yoke
b.
Magnetometer
c.
Black Light
d.
Fluorescent Magnetic Particles
e.
Consumable Materials, refer to Table 1-8
f.
Aircraft Marking Pencil, refer to Table 1-8
NOTE
Hand-held coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.
3.14.3.2
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 aft rotor shaft shall be removed in accordance with the applicable
technical manuals listed in Table 1-1.
3.14.3.3
Access. Access is from the aft transmission work platform. See Figure 1-4 - CH-47: 27 and/or 34; MH-47:
17.
3.14.3.4
Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
