System Securing. Clean the main transmission tail rotor drive flange 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 main
transmission tail rotor drive flange requires installation in accordance with the applicable technical manuals listed in
MAIN ROTOR GEARSHAFT DRIVE GEAR TEETH (MT).
Description (Figure 3-1 . Index No. 17). The main rotor gearshaft is a semi-floating drive shaft mounted inside
the static mast. The main rotor gearshaft transmits power from the main transmission to drive the main rotor.
Defects. This inspection is used to verify crack indications found visually on the main rotor gearshaft drive gear
teeth. No cracks are allowed.
Primary Method. Magnetic Particle.
22.214.171.124 NDI Equipment and Materials. (Refer to Appendix B.)
Magnetic Particle Inspection Probe/Yoke
Fluorescent Magnetic Particles
Consumable Materials, refer to Table 1-8
Aircraft Marking Pencil, refer to Table 1-8
126.96.36.199 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main rotor
gearshaft drive gear teeth removed in accordance with the applicable technical manuals listed in Table 1-1.
188.8.131.52 Access. Not applicable.
184.108.40.206 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
220.127.116.11 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.
18.104.22.168 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 3-17.
Select AC on the AC/DC power switch.
Place probe/yoke on part in position 1 as shown.
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
Inspect for cracks using the black light.
Demagnetize before moving to the next position. Refer to paragraph 22.214.171.124.
Repeat steps a. through e. for position 2.