3. Prepare for the Inspection
A. Access the upper link through the access panels located on the upper half of the strut. See Figure 1.
B. Remove the fuse pin secondary and primary retention caps to get access to the inspection surfaces of
the fuse pins. See Figure 1.
C. Remove all paint and sealant from the ends of the fuse pin and clean fully. Use a non-abrasive scraper
to remove the paint. The part number is etched on the end of the fuse pin and can cause the surface to
be rough. If necessary, lightly sand this area by approved methods to permit the transducer to fully
touch the part.
NOTE: Make sure that the part number is not removed when you sand the fuse pin.
D. Identify the part number of the pin to be examined.
4. Instrument Calibration
NOTE: A transducer guide is used during this inspection because of the small transducer size.
A. Find the part number of the fuse pin to be examined in Table 1 and use Table 1 to see what transducer
guide to use.
B. Connect the transducer to the instrument and do the initial adjustments of the instrument.
NOTE: Do not use reject unless the instrument has certified linear reject. Do not use more than 10%
reject.
C. Set the instrument frequency to 10 MHz. See Paragraph 2.A.(1).
D. Put the transducer into the transducer guide so that the bottom of the transducer is equal with the
bottom of the hole. Tighten the setscrew lightly. See Figure 4.
E. Put couplant on the reference standard at position A and then put the transducer at position A. See
Figure 4.
F. Adjust the instrument controls to get the first two back surface signals at 40% and 80% of full screen
width. The instrument's screen range is now calibrated. See Figure 4.
G. Put couplant on the reference standard. Put the transducer on the reference standard above the
reference notch at position C. See Figure 5.
H. Move the transducer guide above the reference notch to get a maximum signal from the reference
notch. The signal from the notch will be close to 20% full screen width.
I. Adjust the instrument gain controls to get the notch signal at 80% full screen height. Turn the
transducer in the guide hole to make sure the notch signal is at a maximum amplitude and adjust the
setscrew so that it is tight. Move the transducer guide above the reference notch one more time to
make sure the signal is at a maximum height of 80%. See Figure 5.
J. Put the transducer at position B or D. Make sure the back surface signal is at 87% full screen width at
position B, or at 95% full screen width at position D. See Figure 5.
K. Increase the gain 6 dB.
L. Examine all noise signals to make sure the signal-to-noise ratio is larger than 3:1. If the signal-to-noise
ratio is less than 3:1, try a different transducer or a higher frequency transducer.
NOTE: Make sure the initial pulse is not greater than 10% of full screen width. If necessary, adjust the
instrument controls or use a different transducer.
747
NONDESTRUCTIVE TEST MANUAL
PART 4 54-30-08
Page 2
Nov 15/2015D6-7170
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
EFFECTIVITY
ALL
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