Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:
Null probe on test block.
Adjust phase as required to obtain horizontal lift-off.
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
188.8.131.52 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-2.
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 are cause for rejection.
Either probe identified in paragraph 184.108.40.206 may be used depending primarily on the ease of
accessibility and user friendliness. If the probes are changed, steps 220.127.116.11 b. (1), (2), and (3)
shall be repeated each time a change is made.
18.104.22.168 Marking and Recording of Inspection Results. Mark and record inspection results as required by paragraph 1.3.
3.2.4 Backup Method. None required.
3.2.5 System Securing. The main transmission, if removed, requires installation in accordance with the applicable
technical manuals listed in Table 1-1.
3.3 INTERMEDIATE GEARBOX (ET).
3.3.1 Description (Figure 3-1. Index No.3). The intermediate gearbox is mounted at the base of the pylon. The
intermediate gearbox carries main transmission torque to the tail gearbox.
3.3.2 Defects. This inspection is used to verify crack indications found visually on the intermediate gearbox. All areas
where rework has been performed shall be inspected for cracks. No cracks are allowed.
3.3.3 Primary Method. Eddy Current.
22.214.171.124 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, 900 1/2 inch drop
Reference Block, three-notched aluminum (0.008, 0.020, 0.040 EDM notches)
Teflon Tape, refer to Table 1-8
Aircraft Marking Pencil, refer to Table 1-8