TM 1-1520-265-23
3.3.3.7 Marking and Recording of Inspection Results. Mark and record inspection results as required by paragraph 1.3.
3.3.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.
3.3.5 System Securing. The intermediate gearbox, if removed, requires installation in accordance with the applicable
technical manuals listed in Table 1-1.
3.4 TAIL ROTOR DRIVE SHAFT (ET).
3.4.1 Description (Figure 3-1. Index No. 4). The tail rotor is driven by a series of seven shafts. The shafts run from the
tail take off flange on the rear of the main transmission to the intermediate gearbox. The tail rotor drive shaft then runs
from the intermediate gearbox to the tail gearbox.
3.4.2 Defects. This inspection is used to verify crack indications found visually on the tail rotor drive shaft. No cracks
are allowed.
3.4.3 Primary Method. Eddy Current.
3.4.3.1 NDI Equipment and Materials. (Refer to Appendix B.)
a.
Eddy Current Inspection Unit
b.
Probe, straight, shielded surface, 100 KHz-500 KHz
c.
Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop
d.
Cable Assembly
e.
Reference Block, three-notched aluminum (0.008, 0.020, 0.040 EDM notches)
f.
Teflon Tape, refer to Table 1-8
g.
Aircraft Marking Pencil, refer to Table 1-8
3.4.3.2 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 shall be removed in accordance with the
applicable technical manuals listed in Table 1-1.
3.4.3.3 Access. Accessibility of the tail rotor drive shaft varies considerably. Refer to Figure 1-4 and Table 1-2 to locate
applicable access provisions.
3.4.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
paragraph 1.4.4.
3-8
