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.)
Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-13.
a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal lift-
Inspect the part.
Any signal similar to the notches in the test block is cause for rejection.
Either probe identified in paragraph 220.127.116.11 may be used depending primarily on the ease of accessibility and user
friendliness. If the probes are changed, steps 18.104.22.168 b. (1), (2), and (3) shall be repeated each time a change is
Marking and Recording of Inspection Results. Mark and record the inspection results as required by
Backup Method. None required.
System Securing. The main rotor damper, if removed, requires installation in accordance with the applicable
technical manuals listed in Table 1-1.
MAIN ROTOR DAMPER TRUNNION (ET).
Description (Figure 2-1. Index No. 14). The main rotor damper trunnion provides the attachment point for the
main rotor damper to the main rotor pitch housing.
Defects. This inspection is used to verify crack indications found visually on the main rotor damper trunnion. No
cracks are allowed.
Primary Method. Eddy Current.
NDI Equipment and Materials. (Refer to Appendix B.)
Eddy Current Inspection Unit
Probe, straight, shielded surface, 100 KHz-500 KHz
Probe, right angle, shielded surface, 100 KHz-500 KHz, 90 °
1/2 inch drop
Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)
Teflon Tape, refer to Table 1-8
Aircraft Marking Pencil, refer to Table 1-8