TM 1-1520-253-23
4.23.3.2
Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance in accordance
with the applicable technical manuals listed in Table 1-1.
4.23.3.3
Access. Not applicable.
4.23.3.4
Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
4.23.3.5
NDI Equipment Settings.
Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19eII.
a.
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 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 1-7.)
4.23.3.6
Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-23.
a.
Place probe on a good area in the inspection location and null. Adjust phase as required to obtain
horizontal lift-off.
b.
Inspect the part.
c.
Any signal similar to the notches in the test block is cause for rejection.
NOTE
Either probe identified in paragraph 4.23.3.1 may be used depending primarily on the
ease of accessibility and user friendliness. If the probes are changed, steps 4.23.3.5 b.
(1), (2), and (3) shall be repeated each time a change is made. 4.23.3.7 Marking and
Recording of Inspection Results. Mark and record as required by paragraph 1.3.
4.23.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.
4.23.5 System Securing. None required.
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