TM 1-1520-265-23Change 2 2--42.12.18A Bifilar Weight Bushings (PT)2.18A.1 Description(Figure2-1,IndexNo.18A). The bifilar weight bushings are installed withinthe body of the bifilar weight.2.18A.2 Defects. Inspect the inside diameter of the bushings for stress cracks along its edges.No cracks are allowed.2.18A.3 PrimaryMethod. Fluorescent Penetrant.2.18A.3.1 NDI Equipment and Materials. (Refer to Appendix B.) Inspection Equipment is listedin Table 1-7. AMS 2644 level 3 penetrant materials shall be selected from the approved list in Table1-8. Parts requiring flourescent penetrant inspection shall be cleaned prior to inspection with n--Propyl Bromide (vapor degreasing only)(Table 1--8), DS--108 (Table 1--8), Electron (Table 1--8),Positron (Table 1--8). DS--108, Electron, Positron must be followed by an acetone (Table 1--8) rinseor wipe: or drying until there is no visible solvent residue left on parts.2.18A.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground mainte-nance. A partial inspection for cause (visual indications, sites of mechanical damage, corrosion,etc.) may be performed on all exposed surfaces of the installed part using this procedure. The bifilarweight shall be removed in accordance with the applicable technical manuals listed in Table 1-1.2.18A.3.3 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.2.18A.3.4 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluores-cent Penetrant Method, paragraph 1.4.7 and Table 1-5. Apply penetrant with a brush to preventoverspray. Inspect area of concern.2.18A.3.5 Marking and Recording of Inspection Results. Mark and record inspection results asrequired by paragraph 1.3.2.18A.3.6 BackupMethod. None required.2.18A.3.7 SystemSecuring. Clean the bushings to remove inspection media. Refer to PostCleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The bifilar weight requiresinstallation in accordance with the applicable technical manuals listed in Table 1-1.Figure 2-18. Bifilar Weight (Sheet 2 of 3)
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