TM 1-1520-264-23
3.2
DRIVE SHAFTS (ET).
3.2.1
Description (Figure 3-1. Index No. 2). The drive shaft assembly links the helicopter drive system gearboxes
to the main transmission. The system consists of input drive shafts 1 and 2; tail rotor drive shafts 3, 4, 5, and 6; and a
titanium APU drive shaft 7. See Figure 3-2 for drive shaft locations.
3.2.2
Defects. This inspection is used to verify crack indications found visually on the drive shafts. No cracks are
allowed.
3.2.3
Primary Method. Eddy Current.
3.2.3.1
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, and 0.040 EDM notches) (use for 1 through 6)
f.
Reference Block, three-notched titanium (0.008, 0.020, and 0.040 EDM notches) (use for drive shaft 7)
g.
Teflon Tape, refer to Table 1-8
h.
Aircraft Marking Pencil, refer to Table 1-8
Exercise extreme caution when handling and inspecting the drive shaft
assemblies. The assembly may be rendered unserviceable by even slight dents
or scratches.
3.2.3.2
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 drive shaft shall be removed in accordance with the applicable
technical manuals listed in Table 1-1.
3.2.3.3
Access. Accessibility of the drive shafts varies considerably. Refer to Figure 1-4 and Table 1-2 to locate
applicable access provisions.
3.2.3.4
Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
paragraph 1.4.4.
3-4
