TM 1-1520-265-23
2-8 Change 2
Figure 2-4. Nonferrous Rotor System Bolts and Pins
2.5 MAIN ROTOR SHAFT NUT (MT).
2.5.1
Description (Figure 2-1, Index No. 5). The main rotor shaft nut threads onto the top of the
main rotor shaft and holds the shaft extension in place on the main rotor shaft.
2.5.2
Defects. Defects may occur anywhere on the surface of the main rotor shaft nut, especially
the inside diameter thread roots. No cracks are allowed.
2.5.3
Primary Method. Magnetic Particle.
2.5.3.1 NDI Equipment and Materials. (Refer to Appendix B.)
a. Magnetic Particle Inspection Probe/Yoke
b. Magnetometer
c. Black Light
d. Fluorescent Magnetic Particles, refer to Table 1-8
e. Consumable Materials, refer to Table 1-8
f. Aircraft Marking pencil, refer to Table 1-8
2.5.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance
and the main rotor shaft nut removed in accordance with the applicable technical manuals listed in
Table 1-1.
2.5.3.3 Access. Not applicable.
2.5.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or
Area for NDI, paragraph 1.4.4.
2.5.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.
2.5.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the
orientation of possible cracks. Positions required for this inspection are illustrated in Figure 2-5.
Figure 2-5. M ain Rotor Shaft Nut
