TM 1-1520-265-23
Change 2
3-13
NOTE
Either probe identified in paragraph 3.5.3.1 may be used depending primarily on the
ease of accessibility and user friendliness. If the probes are changed, steps 3.5.3.5b.
(1), (2), and (3) shall be repeated each time a change is made.
3.5.3.7 Marking and Recording of Inspection Results. Mark and record inspection results as
required by paragraph 1.3.
3.5.4 Backup Method. None required.
3.5.5 System Securing. The tail rotor drive shaft supports, if removed, require installation in
accordance wit the applicable technical manuals listed in Table 1-1.
3.6 TAIL ROTOR DRIVE SHAFT COUPLING (PT).
3.6.1 Description (Figure 3-1, Index No. 6). The tail rotor drive shaft couplings are multiple disc,
flexible couplings which are used to carry torque and allow for minor misalignment of the tail drive
shaft components. Also, the couplings allow the drive shaft to remain in alignment as the airframe
flexes in flight.
3.6.2 Defects. This inspection is used to verify crack indications found visually on the tail rotor
drive shaft coupling. No cracks are allowed.
3.6.3 Primary Method. Fluorescent Penetrant.
3.6.3.1 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.
3.6.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance.
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. If required, the tail
rotor drive shaft coupling shall be removed in accordance with the applicable technical manuals
listed in Table 1-1.
3.6.3.3 Access. Not applicable.
WARNING
Maintenance Platforms/Workstands
Use only appropriate platforms, workstands, or other approved locally procured
stands and restraint equipment when working above 10 feet on helicopters in a
nontactical environment. Otherwise, personnel injury could result from accidental
falls.
3.6.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.
3.6.3.5 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 3-6.
