(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-
a. Place probe on part in the inspection locations and null. Adjust phase as required to obtain horizontal lift-off.
b. 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 made.