TM 1-1520-253-23
6.9.1 Description (Figure 6-1. Index No. 9). This inspection procedure can be used on all of the above parts, especially
after: (1) bearings, bushings, or sleeves have been removed; and (2) bearings, bushings, or sleeves have been installed.
6.9.2 Defects. Inspect to verify cracks found visually. Particular attention shall be directed to the bore and lug areas.
No cracks are allowed.
6.9.3 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. Reference Block, three-notched magnesium (0.008, 0.020, and 0.040 EDM notches)
g. Teflon Tape, refer to Table 1-8
h. Aircraft Marking Pencil, refer to Table 1-8
6.9.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the identified part
removed as required in accordance with the applicable technical manuals listed in Table 1-1.
6.9.3.3 Access. Not applicable.
6.9.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
6.9.3.5 NDI Equipment Settings.
ll
a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e .
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%
b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on applicable test block as follows:
(1) Null probe on test block.
(2) Adjust phase as required to obtain horizontal lift-off.
(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when
probe is passed over 0.040 inch notch in test block. (Refer to standard instrument display shown in Figure
6.9.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-9.
