PART 4 - ULTRASONIC
HORIZONTAL STABILIZER CENTER SECTION LUG
1. Purpose
A. This procedure is an ultrasonic shear wave inspection to detect cracks initiating from the aluminum
alloy horizontal stabilizer center section lug bore. Refer to Figure 4.
2. Equipment
A. Any ultrasonic inspection equipment that is capable of operating in the frequency range between 4.0
MHz and 6.0 MHz and satisfies the performance requirements of this procedure is acceptable. The
following equipment was used during the development of this procedure:
(1) Instrument -- USL 38, Krautkramer/Branson Corp.
(2) Transducer -- 5 MHz, longitudinal wave, 0.25-inch (0.64 cm) diameter element in a 0.375-inch
(0.95 cm) diameter by 0.75-inch (1.90 cm) long cylindrical case with an end mounted connector.
(a) Automation P/N 57A3103
(3) Reference Standard -- Refer to Figure 1.
(4) Transducer Positioner -- Refer to Figure 2.
(5) Couplant -- An ultrasonic couplant compatible with the structure being inspected.
3. Prepare for the Inspection
A. Gain access through service access door 315AL. Refer to Figure 4.
B. Identify the inspection area and wipe the inspection surface clean. Refer to Figure 4, Flagnote 1.
4. Instrument Calibration
A. Connect the transducer and set the instrument frequency at 5 MHz.
B. Make a preliminary sweep time adjustment.
(1) Put the transducer on the side of the reference standard and set the eighth back reflection at 80
percent of full screen width.
C. Put a small amount of couplant in the transducer positioner receptacle hole. Firmly set the transducer
in the hole.
D. Put the transducer positioner on the reference standard so that the ultrasonic beam is directed at the
notch. Refer to Figure 3, Flagnote 1. Set the instrument response signal from the notch at 80 percent
of full screen width. Refer to Figure 3.
NOTE: Turn the transducer in the positioner to obtain a maximum response from the notch.
E. Adjust the instrument sensitivity to obtain a response signal of 90 percent of full screen height.
F. Scan the transducer toward and away from the notch and note the notch response signal movement.
5. Inspection Procedure
NOTE: The horizontal stabilizer center section lugs are each made from two 0.875-inch (2.22 cm) lug
halves sandwiched together at LBL 43.5 and RBL 43.5. Inspection of both lug halves is required at
each location. Refer to Figure 4.
A. Calibrate the instrument. Refer to Paragraph 4.
747
NONDESTRUCTIVE TEST MANUAL
PART 4 55-50-01
Page 1
Nov 15/2015D6-7170
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
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