TM 1-1520-264-23
4.7.3.3 Access. Access to the aft portions of F.S. 530, all stringers aft of F.S. 530, and both forward and aft portions of
F.S. 547 is by removal of covers R/L 545. Access to all stringers forward of F.S..530 and the forward portion of the F.S.
530 frame is by entry into the tailboom at L/R 330 and crawling aft.
4.7.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,
paragraph 1.4.4.
4.7.3.5 NDI Equipment Settings.
a.
Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19ell.
Frequency F1
- 200 KHz
F2
- off
HdB
- 57.0
VdB
- 69.0
Rot
- 56°°
Probe drive - mid
LPF
- 100
HPF
-0
H Pos
- 80%
VPos
- 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. (See the standard instrument display shown in Figure 1-7.)
4.7.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-7.
a.
Place probe on a good area in the inspection location and n
ull. 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 4.7.3.1 may be used depending primarily on the ease of accessibility and
user friendliness. If the probes are changed, steps 4.7.3.5 b.(1), (2), and (3) shall be repeated each time a
change is made.
4.7.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph
1.3.
4.7.4
Backup Method. None required.
4.7.5
System Securing. Secure applicable access covers.
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