TM 1-1520-265-23
Change 2 3-25
Figure 3-11. Tail Gearbox Mount Fitting
3.11.3.7 Marking and Recording of Inspection Results. Mark and record inspection results as
required by paragraph 1.3.
3.11.4 Backup Method. None required.
3.11.5 System Securing. The tail gearbox mounting fitting, if removed, requires installation in
accordance with the applicable technical manuals listed in Table 1-1.
3.12 TAIL ROTOR GEARBOX INNER/OUTER SPLIT CONES (PT).
3.12.1 Description (Figure 3-1, Index No. 12). The tail rotor gearbox split cones provide support
to the inner retention plate attached to the output shaft of the tail rotor gearbox.
3.12.2 Defects. Defects may occur anywhere on the surface of the tail rotor gearbox inner/outer
split cones. All areas where rework has been performed shall be inspected for cracks. No cracks
are allowed.
3.12.3 Primary Method. Fluorescent Penetrant.
3.12.3.1 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--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) rinse
or wipe: or drying until there is no visible solvent residue left on parts..
3.12.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance
and the tail rotor gearbox inner/outer split cones removed in accordance with the applicable
technical manuals listed in Table 1-1.
