TM 1-1520-265-23
4.27.3.7. Marking and Recording of Inspection Results. Mark and record inspection results as required by paragraph
1.3.
4.27.3.8. 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.
4.27.4. Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.
4.27.5. System Securing. Clean the main landing gear brake 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 landing gear brake
requires assembly and installation in accordance with the applicable technical manuals listed in Table 1-1.
4.28. MAIN LANDING GEAR BRAKE HOUSING (ET).
4.28.1. Description (Figure 4-1. Index No. 28). The main landing gear brakes are self-adjusting, double disc, three-
cavity brake assembly, which includes a visual-brake lining wear indicator. The housing contains the pistons.
4.28.2. Defects. Defects may occur anywhere on the surface of the main landing gear brake housing. No cracks are
allowed.
4.28.3. Primary Method. Eddy Current.
4.28.3.1. 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, 900 1/2 inch drop
d.
Cable Assembly
e.
Reference Block, three-notched aluminum (0.008, 0.020, 0.040 EDM notches)
f.
Teflon Tape, refer to Table 1-8
g.
Aircraft Marking Pencil, refer to Table 1-8
4.28.3.2. Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the brake
assembly removed and disassembled in accordance with the applicable technical manuals listed in Table 1-1.
4.28.3.3. Access. Not applicable.
4.28.3.4. Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
paragraph 1.4.4.
4-66
