TM 1-1520-265-23
Change 2 4-41
4.16.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-16.
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.
NOTE
Either probe identified in paragraph 4.16.3.1 may be used depending primarily on the
ease of accessibility and user friendliness. If the probes are changed, steps
4.16.3.5b.(1), (2), and (3) shall be repeated each time a change is made.
4.16.3.7 Marking and Recording of Inspection Results. Mark and record inspection results as
required by paragraph 1.3.
4.16.4 Backup Method. None required.
4.16.5 System Securing. The tail pylon, if opened, requires securing in accordance with the
applicable technical manuals listed in Table 1-1.
4.17 TAIL ROTOR PYLON ATTACHING HARDWARE (PT).
4.17.1 Description (Figure 4-1, Index No. 17). This procedure is primarily for use on tapered pins,
attachment bolts, barrel-nuts, washers, retainers, pylon hinge bolts, washers, and nuts used on the
tail rotor pylon.
4.17.2 Defects. This inspection is used to detect cracks found anywhere on the parts described
above. No cracks are allowed.
4.17.3 Primary Method. Fluorescent Penetrant.
4.17.3.1 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.
4.17.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance
and the tail pylon removed in accordance with the applicable technical manuals listed in Table 1-1.
4.17.3.3 Access. Not applicable.
4.17.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.
4.17.3.5 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluorescent
Penetrant Method, paragraph 1.4.7 and Table 1-5. Inspect area of concern. See Figure 4-17.
4.17.3.6 Marking and Recording of Inspection Results. Mark and record inspection results as
required by paragraph 1.3.
4.17.4 Backup Method. None required.
