PART 4 - ULTRASONIC
FUSE PIN 69B90909 INSPECTION AT THE FORWARD END OF THE NACELLE UPPER LINK
1. Purpose
A. Use this procedure to do an ultrasonic inspection of fuse pins 69B90909 installed on the forward side
of the upper link. 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: TBD
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) Transducer - It is necessary to use a zero degree longitudinal wave transducer with a crystal
diameter not larger than 0.125 inch (3.2 mm). A case diameter not larger than 0.20 inch (5.1 mm)
is necessary for good sensitivity. A 10 MHz transducer is recommended but other frequencies can
be used if the instrument can be calibrated as shown in Paragraph 4. These transducers were
used to prepare this procedure:
(a) 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.
(b) 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).
(c) 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.
NOTE: Transducers of frequencies between 5 MHz and 12 MHz can be used if they can be
calibrated with the instrument as specified in Paragraph 4.
(3) Reference Standard - Make Reference Standard NDT4109 as specified in Figure 2.
(4) Transducer Guides NDT4109-G1, NDT4109-G2, NDT4108/9-G3 & NDT4108/9-G4. See Figure 3.
(5) Couplant - All ultrasonic couplants that will not cause damage to the airplane structure can be
used. Commercial grease or oil can be used if the sensitivity of Paragraph 4. are satisfactory.
747
NONDESTRUCTIVE TEST MANUAL
PART 4 54-30-08
Page 1
Nov 15/2015D6-7170
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
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