TM 1-1520-253-23
3.2.1 Description (Figure 3-1. Index No. 2). This inspection is applicable to the aluminum adapters on the forward
driveshaft ends of shafts 1 through 6, both ends of shaft number 7, the forward end of aft shaft number 8, both ends of
aft shaft number 9, and the engine driveshaft adapters.
3.2.2 Defects. Defects may occur anywhere on the surface of the aluminum driveshaft adapter assemblies. Particular
attention shall be given to areas around bolts. No cracks are allowed.
3.2.3 Primary Method. Eddy Current.
a.
Eddy Current Inspection Unit
b.
Probe, straight, shielded surface, 100 KHz-500 KHz
c.
Probe, right angle, shielded surface, 100 KHz-500 KHz, 901/2 inch drop
d.
Cable Assembly
e.
Reference Block, three-notched aluminum (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
3.2.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. 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 components shall be removed in accordance with the applicable
technical manuals listed in Table 1 -1.
3.2.3.3 Access. Access is through the cabin crown tunnel covers. See Figure 1-4 - CH-47: 8; MH-47:3.
3.2.3.4 Preparation of Part. The aluminum driveshaft adapters shall be thoroughly cleaned. Refer to Preparation of Part
or Area for NDI, paragraph 1.4.4.
3.2.3.5 NDI Equipment Settings.
lI
a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9e .
Frequency F1
- 200 KHz
F2
- off
HdB
- 57.0
VdB
- 69.0
Rot
- 56
Probe drive
- mid
LPF
- 100
HPF
-0
H Pos
- 80%
V Pos
-20%
