TM 1-1520-265-23b.Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:(1)Null probe on test block.(2)Adjust phase as required to obtain horizontal lift-off.(3)Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal whenprobe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure1-7.)3.2.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-2.a.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 3.2.3.1 may be used depending primarily on the ease ofaccessibility and user friendliness. If the probes are changed, steps 3.2.3.5 b. (1), (2), and (3)shall be repeated each time a change is made.3.2.3.7 Marking and Recording of Inspection Results. Mark and record inspection results as required by paragraph 1.3.3.2.4 BackupMethod. None required.3.2.5 SystemSecuring. The main transmission, if removed, requires installation in accordance with the applicabletechnical manuals listed in Table 1-1.3.3 INTERMEDIATE GEARBOX (ET).3.3.1 Description(Figure3-1.IndexNo.3). The intermediate gearbox is mounted at the base of the pylon. Theintermediate gearbox carries main transmission torque to the tail gearbox.3.3.2 Defects. This inspection is used to verify crack indications found visually on the intermediate gearbox. All areaswhere rework has been performed shall be inspected for cracks. No cracks are allowed.3.3.3 PrimaryMethod. Eddy Current.3.3.3.1 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 1-83-4
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