TM 1-1520-265-23a.Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal lift-off.b.Inspect the part.c.Any signal similar to the notches in the test block are cause for rejection.NOTEEither probe identified in paragraph 3.10.3.1 may be used depending primarily on the ease ofaccessibility and user friendliness. If the probes are changed, steps 3.10.3.5 b. (1), (2), and (3)shall be repeated each time a change is made.3.10.3.7 Marking and Recording of Inspection Results. Mark and record inspection results as required by paragraph 1.3.3.10.4 BackupMethod. Fluorescent Penetrant, refer to paragraph 1.4.7.3.10.5 SystemSecuring. The tail gearbox, if removed, requires installation in accordance with the applicable technicalmanuals listed in Table 1-1.3.11 TAIL GEARBOX MOUNT FITTING (ET).3.11.1 Description(Figure3-1.IndexNo.11). The tail gearbox mount fitting is a structural component of the pylon. Itserves as the attaching point for the tail gearbox assembly.3.11.2 Defects. Defects may occur anywhere on the surface of the tail gearbox mount fitting. Particular attention shallbe given to the joining area with the fitting to front spar caps in the area of high strength fasteners. No cracks areallowed.3.11.3 PrimaryMethod. Eddy Current.3.11.3.1 NDI Equipment and Materials. (Refer to Appendix B.)a.Eddy Current Inspection Unitb.Probe, straight, shielded surface, 100 KHz-500 KHzc.Probe, right angle, shielded surface, 100 KHz-500 KHz, 900 1/2 inch dropd.Cable Assemblye.Reference Block, three-notched aluminum (0.008, 0.020, 0.040 EDM notches)f.Teflon Tape, refer to Table 1-8g.Aircraft Marking Pencil, refer to Table 1-83.11.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspectionfor cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces ofthe installed part using this procedure. If required, the tail rotor gearbox shall be removed in accordance with theapplicable technical manuals listed in Table 1-1.3-23
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