TM 1-1520-265-23
6.20.3.7. Marking and Recording of Inspection Results. Mark and record inspection results as required by paragraph
1.3.
6.20.3.8. 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.
6.20.4. Backup Method. None required.
6.20.5. System Securing. Clean the lateral bellcrank 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 lateral bellcrank, if removed, requires
installation in accordance with the applicable technical manuals listed in Table 1-1.
6.21. AFT BELLCRANK (MT).
6.21.1. Description (Figure 6-1. Index No. 21). The aft bellcrank, supported by the bellcrank support (bridge) in the
swashplate linkage installation, transfers flight control movements through a connecting servo link to the main rotor
swashplate. It is machined from a 4340 steel forging, cadmium plated, and protected by epoxy primer and polyurethane
paint.
6.21.2. Defects. This inspection is used to verify crack indications found visually on the aft bellcrank. Inspect all
reworked areas for cracks. Inspect aft bellcrank lug and rib surfaces. Visually inspect bellcrank flanged pivot bushings.
No cracks are allowed.
6.21.3. Primary Method. Magnetic Particle.
6.21.3.1. 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
NOTE
Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.
6.21.3.2. Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection
for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of
the installed part using applicable positions of this procedure. If required, the aft bellcrank shall be removed in
accordance with the applicable technical manuals listed in Table 1-1.
6.21.3.3. Access. Not applicable.
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