TM 1-1520-265-234.6VIBRATION ABSORBER STRUCTURAL FITTINGS (ET).4.6.1 Description(Figure4-1.IndexNo.6). The vibration absorber structural fittings attach the vibration absorbers tothe helicopter structure. Due to similarity, this procedure is applicable to cabin and nose fittings.4.6.2 Defects. This inspection is used to verify crack indications found visually on the vibration absorber fittings. Nocracks are allowed.4.6.3 PrimaryMethod. Eddy Current.4.6.3.1NDI 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 1-84.6.3.2Preparation 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 fittings using this procedure. If required, the fittings shall be removed in accordance with the applicabletechnical manuals listed in Table 1-1.4.6.3.3Access. Remove cabin ceiling soundproofing for access to cabin fitting. Access nose fitting through fairing(Figure 1-4, Item 1 B-GS-A-1).4.6.3.4Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,paragraph 1.4.4.4.6.3.5NDI Equipment Settings.a.Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9e".Frequency F1- 200 KHzF2- offHdB- 57.0VdB- 69.0Rot- 56°Probe drive- midLPF- 100HPF- 0H Pos- 80%V Pos-20%4-16
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