(6) Scan 360° around head ensuring transducer contact by monitoring the internal reflection signals
identified by flagnotes 2 and 3 in Figure 4. Pay particular attention to all signals occurring
between 35 percent and 50 percent of horizontal time base (between 40 percent and 65 percent
for fuse pin P/N 69B89611).
(7) Note all signals occurring between 35 percent and 50 percent (between 40 percent and 65
percent for fuse pin P/N 69B89611) of screen width with an amplitude of 50 percent or more of full
screen height, at the recommended calibration setting. These signals represent potential cracks
and require further investigation.
B. Inspect fuse pin locations (c) and (d).
NOTE: Internal ultrasonic reflections interfere with inspection of fuse pin P/N 69B89611 at the (c)-(d)
location, therefore, the alternate eddy current inspection is recommended.
(1) Locate the inspection area (see Figure 7).
(2) Calibrate equipment for inspection of fuse pin locations (c) and (d) per Paragraph 4.D.
(3) Insert transducer scanning guide (Figure 2) in fuse pin head as shown in Figure 7.
(4) Obtain backwall signal as shown in Figure 5.
NOTE: Different pin lengths will change backwall signal position.
(5) Scan 360° around head ensuring transducer contact and sound transmission is maintained. Pay
particular attention to any signals between 60 percent and 75 percent of the horizontal time base.
NOTE: Disregard signals between 0 percent and 60 percent of time base which may appear.
These are spurious signals outside the inspection area.
(6) Note all signals occurring between 60 percent and 75 percent of screen width with a maximum
amplitude of 35 percent or more of full screen height, at the recommended calibration setting.
These signals represent potential cracks and require further investigation.
(7) Note significant loss in back reflection from calibration setting.
6. Inspection Results
A. Fuse pin inspection locations (a) and (b).
(1) Signals between 35 percent and 50 percent (between 40 percent and 65 percent for fuse pin P/N
69B89611) of the horizontal time base, which exceed 50 percent of screen height, are potential
cracks.
(2) Confirm cracks by pin internal visual inspection or by employing the alternate fuse pin eddy
current inspection, Part 6, 54-40-04.
B. Fuse pin inspection location (c) and (d).
(1) Signals between 60 percent and 75 percent of the horizontal time base, which exceeds 30
percent of full screen height, are potential cracks.
NOTE: Signals from 0 percent to 60 percent of time base are outside the inspection area and
should be ignored.
(2) A significant loss in back reflection may indicate a crack.
(3) Confirm cracks by pin internal visual inspection or by employing the alternate fuse pin eddy
current inspection, Part 6, 54-40-04.
747
NONDESTRUCTIVE TEST MANUAL
PART 4 54-30-03
Page 3
Nov 15/2015D6-7170
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
EFFECTIVITY
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