PART 4 - ULTRASONIC
NACELLE MIDSPAR STRUT TO WING ATTACHMENT FUSE PIN
1. Purpose
A. To detect cracks in the steel fuse pins at the midspar strut to wing attachment fittings. The cracks
originate in the radii of the shear out plane inner surface and extend circumferentially around the pin
(see Figure 7).
NOTE: Refer to Part 6, 54-40-04 for an alternative high frequency eddy current procedure for this
inspection.
NOTE: Internal ultrasonic reflections interfere with inspection of fuse pin P/N 69B89611 at the (c)-(d)
location, therefore, the alternative eddy current inspection is recommended.
B. Service Bulletin Reference: 747-54-2063
2. Equipment
A. Instrument -- Any ultrasonic instrument capable of operating between 4 and 6 MHz, which will satisfy
the requirements of this procedure, may be used. The procedure was developed using the following
instruments:
(1) USL 38; Krautkramer
(2) NDT-131; Nortec
NOTE: In general, tuned frequency instruments give better signal presentation for this
inspection.
B. Transducer -- 5 MHz longitudinal wave transducer 0.25 inch (0.64 cm) diameter element and outside
case diameter of 0.35 - 0.45 inch (0.9 - 1.1 cm) is required. The procedure was developed using
Krautkramer-Branson Aerotech transducer part numbers:
(1) Gamma Series, MSW-QC, 224-590.
(2) Gamma Series, IPS, 5 MHz, 224-340.
(3) Alpha Transducers, P/N LI2818 and P/N 124-340.
NOTE: Refer to Figure 5 for acceptable transducer response pattern.
C. Reference Standard -- Fabricate or purchase reference standard No. 409, per Figure 1.
D. Transducer Scanning Guide -- Fabricate per Figure 2.
E. Reference Block -- One inch thick steel block.
F. Couplant -- Use grease or equivalent as ultrasonic couplant between transducer and fuse pin head.
3. Prepare for the Inspection
A. Remove panels necessary to gain access to fuse pin head.
B. Remove dirt or paint from transducer contact location on fuse pin head.
C. Apply couplant to transducer contact surface.
4. Instrument Calibration
A. Switch on instrument, connect transducer, and carry out preliminary procedures required by
manufacturer.
747
NONDESTRUCTIVE TEST MANUAL
PART 4 54-30-03
Page 1
Nov 15/2015D6-7170
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
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