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h. Slide the probe to the inboard ½ inch void and note the dot position.
The dot should fall to the bottom center of the screen well within the
alarm box causing the alarm to activate with a steady tone.
i. Press the ALARM key and select HORN VOL. The alarm sound
volume may be adjusted to operator preference.
j. Press the RUN key and place the probe on the good area near the
k. Press the NULL key. The dot should move to the top center of the
screen. As the probe is moved outboard of the mast, note the
average position of the dot. It may be necessary to re-null to allow
for the progressively thinner skin towards the outboard areas.
l. Although the Bondmaster is programmed to automatically set test
parameters, the specific requirements of this inspection require that
the preceeding be used as a starting point.
18.104.22.168 Inspection Procedure. Refer to Bond Test method, paragraph 1.4.6.
a. Using the aircraft marking pencil, trace out a pattern of concentric
circles beginning ½ inch from the mast and spaced ½ inch apart so
that the last circle is 12 ½ to 13 inches from the mast. Make the
marks only dark enough to be visible at close distance. If an attach-
ment or other feature intersects the circle, merely stop and restart on
the other side of the obstruction.
b. Place the probe on the underside of the base-plate as close to the
mast as possible.
c. Scan around the mast. Actual inspection can be carried out by doing
one half the base-plate at a time. Move the center of the probe out to
each progressively larger concentric circle. Use the circle as a guide
to insure complete coverage by keeping the probe centered on the
d. Mark all areas that cause the alarm to sound with a steady tone.