TM 1-1520-265-23
2--42.2
Change 2
2.18B BIFILAR WEIGHT TAPERED WASHERS (PT).
2.18B.1 Description (Figure 2-1, Index No. 18B). The bifilar weight washers are installed within
the body of the bifilar weight.
2.18B.2 Defects. Inspect the washers for stress cracks. No cracks are allowed.
2.18B.3 Primary Method. Fluorescent Penetrant.
2.18B.3.1
NDI Equipment and Materials. (Refer to Appendix B.) Inspection Equipment is listed
in Table 1-7. AMS 2644 level 3 penetrant materials shall be selected from the approved list in Table
1-8. Parts requiring flourescent penetrant inspection shall be cleaned prior to inspection with n--Pro-
pyl Bromide (vapor degreasing only)(Table 1--8), DS--108 (Table 1--8), Electron (Table 1--8), Posi-
tron (Table 1--8). DS--108, Electron, Positron must be followed by an acetone (Table 1--8) rinse or
wipe: or drying until there is no visible solvent residue left on parts.
2.18B.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 wash-
ers shall be removed from the bifilar weight in accordance with the applicable technical manuals
listed in Table 1-1.
2.18B.3.3
Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.
2.18B.3.4
Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluores-
cent Penetrant Method, paragraph 1.4.7 and Table 1-5. Inspect area of concern.
2.18B.3.5
Marking and Recording of Inspection Results. Mark and record inspection results as
required by paragraph 1.3.
2.18B.3.6
Backup Method. None required.
2.18B.3.7
System Securing. Clean the washers to remove inspection media. Refer to Post
Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The washers require installa-
tion in accordance with the applicable technical manuals listed in Table 1-1.
Figure 2-18. Bifilar Weight (Sheet 3 of 3)
