PART 4 - ULTRASONIC
FUSE PIN 69B90906 INSPECTION AT THE AFT END OF THE NACELLE DIAGONAL BRACE
1. Purpose
A. Use this procedure to do an ultrasonic inspection of fuse pins 69B90906 installed on the aft end of the
diagonal brace. This inspection is done to find fatigue cracks that start from corrosion pits and occur
circumferentially on the inside diameter of the fuse pin. The minimum crack size that can be
satisfactorily found with this procedure is 0.040 inch deep by 0.25 inch long (1 mm x 6.4 mm). Two
inspections are necessary to do on each fuse pin; one inspection from the inboard end and one
inspection from the outboard end. See Figure 1.
B. Service Bulletin Reference: 747-54A2153
2. Equipment
NOTE: Refer to Part 1, 51-01-00 for data about the equipment manufacturers.
A. All ultrasonic equipment that can do the calibration instructions of this procedure can be used.
(1) Instrument - It is necessary to use an ultrasonic instrument that can operate at 10 MHz.
Broadband instruments can be used if they can do the calibration instructions of this procedure.
These instruments were used to prepare this procedure:
(a) Epoch 2002 - Panametrics
(b) Sonic-136 - Staveley Instruments, Inc.
(c) USD 10 - Krautkramer Branson
(d) USN 50 - Krautkramer Branson
(2) Transducers - Two transducers of different case diameters are used for this procedure. Refer to
Table 1 to find out what transducer(s) you must use. It is necessary to use transducers with a
zero degree longitudinal wave and a crystal diameter not larger than 0.125 inch (3.2 mm). A 10
MHz transducer is recommended but other frequencies can be used if the instrument can be
calibrated as specified in Paragraph 4. These transducers were used to prepare this procedure:
(a) Transducers with a case diameter of 0.190 - 0.192 inches (4.83 - 4.88 mm):
1) A 10 MHz, 0.125 inch diameter (3.2 mm), 0 degree transducer. Case dimensions:
0.190 inch diameter (4.8 mm) by 0.60 inch long (15 mm). Part number: 389-002-190.
Manufacturer: Krautkramer Branson.
2) A 10 MHz, 0.125 inch diameter (3.2 mm), 0 degree transducer. Case dimensions:
0.192 inch diameter (4.9 mm) by 0.60 inch long (15 mm). Part number: SUC 175.
Manufacturer: Search Unit Systems (Division of NDT Product Engineering).
3) A 10 MHz, 0.125 inch diameter (3.2 mm), 0 degree transducer. Case dimensions:
0.190 inch diameter (4.8 mm) by 1.00 inch long (25.4 mm). Part number: Y-M-1/8-10.
Manufacturer: Staveley Instruments Inc.
(b) Transducers with a case diameter of 0.138 - 0.140 inches (3.50 - 3.56 mm):
1) A 10 MHz, 0.110 inch diameter (2.79 mm), 0 degree transducer. Case dimensions:
0.140 inch diameter (3.56 mm) by 0.60 inch long (15 mm). Part number: SUC 175-1/
MD. Manufacturer: Search Unit Systems (Division of NDT Products Engineering).
2) A 10 MHz, 0.125 inch diameter (3.2 mm), 0 degree transducer. Case dimensions: 0.14
inch diameter (3.6 mm) by 0.6 inch long (15 mm). Part number: SPO-5322.
Manufacturer: Staveley Instruments Inc.
747
NONDESTRUCTIVE TEST MANUAL
PART 4 54-30-06
Page 1
Nov 15/2015D6-7170
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
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