TM 1-1520-253-23
4.14.3.2
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 landing gear shall be removed in accordance with the
applicable technical manuals listed in Table 1-1.
4.14.3.3
Access. Not applicable.
4.14.3.4
Preparation of Part. The forward landing gear support structure shall be thoroughly, cleaned. Refer to
Preparation of Part or Area for NDI, paragraph 1.4.4.
4.14.3.5
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.)
4.14.3.6
Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-14.
a.
Place probe on part 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 4.14.3.1 may be used depending primarily on the
ease of accessibility and user friendliness. If the probes are changed, steps 4.14.3.5 b.
(1), (2), and (3) shall be repeated each time a change is made.
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