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.)4.6.3.6Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-6.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 4.6.3.1 may be used depending primarily on the ease ofaccessibility and user friendliness. If the probes are changed, steps 4.6.3.5 b. (1), (2), and (3)shall be repeated each time a change is made.4.6.3.7Marking and Recording of Inspection Results. Mark and record inspection results as required by paragraph1.3.4.6.4 BackupMethod. None required.4.6.5 SystemSecuring. The vibration absorber fittings, if removed, require installation in accordance with the applicabletechnical manuals listed in Table 1-1.4.7ROLL VIBRATION ABSORBER (PT).4.7.1 Description(Figure4-1.IndexNo.7). A roll vibration absorber is installed under each drag beam support fairing.The absorbers are tuned to reduce roll vibrations.4.7.2 Defects. This inspection is used to verify crack indications found visually on the roll vibration absorber. No cracksare allowed.4.7.3 PrimaryMethod. Fluorescent Penetrant.4.7.3.1NDI Equipment and Materials. (Refer to Appendix B.) Inspection equipment is listed in Table 1-7. MIL-1-25135 level 3 penetrant materials shall be selected from the approved list in Table 1-8.4.7.3.2Preparation 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 roll vibration absorber shall be removed in accordance with theapplicable technical manuals listed in Table 1-1.4-17
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