TM 1-1520-253-23
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
6.6.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-6.
a. Place probe on part in the inspection locations 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 6.6.3.1 may be used depending primarily on the ease of
accessibility and user friendliness. If the probes are changed, steps 6.6.3.5 b. (1), (2), and (3)
shall be repeated each time a change is made.
6.6.3.7 Marking and Recording of Inspection Results. Mark and record as required by paragraph 1.3.
6.6.4
Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.
6.6.5 System Securing. The bellcranks and supports, if removed, require installation in accordance with the applicable
technical manual listed in Table 1-1.
6.7.1 Description (Figure 6-1. Index No.7). The first and second stage controls consist of bellcranks and linkages which
mix inputs from the thrust, pitch, roll, and yaw closet control motions into two motions which are transmitted directly to
the forward and aft controls.
6.7.2 Defects. Inspect for damage after removal of bent or sheared rigging pin. Pay particular attention to rigging pin
holes and lugs. No cracks are allowed.
6.7.3 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
