TM 1-1520-264-23
2.28 TAIL ROTOR HUB (ET).
2.28.1
Description (Figure 2-1. Index No. 28). The tail rotor hub has a stainless steel strap pack that passes
through the hub to provide for attachment of the tail rotor blades.
2.28.2
Defects. Defects can occur anywhere on the surface of the tail rotor hub. No cracks are allowed.
2.28.3
Primary Method. Eddy Current.
2.28.3.1
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 titanium (0.008, 0.020, and 0.040 EDM notches)
f.
Teflon Tape, refer to Table 1-8
g.
Aircraft Marking Pencil, refer to Table 1-8
2.28.3.2
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 hub shall be removed in accordance with the applicable
technical manuals listed in Table 1-1.
2.28.3.3
Access. Not applicable.
Maintenance Platforms/Workstands
Use only appropriate platforms, workstands, or other approved locally procured
stands and restraint equipment when working above 10 feet on helicopter in a
nontactical environment. Otherwise, personnel injury could result from accidental
falls.
2.28.3.4
Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
paragraph 1.4.4.
2.28.3.5
NDI Equipment Settings.
a.
Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19 ”.
Frequency F1
- 200 KHz
F2
- off
HdB
- 57.0
VdB
- 69.0
Rot
- 30°
Probe drive
- mid
2-65
