PART 4 - ULTRASONIC
FUSE PIN 69B89612, 65B90394 AND 65B94182 INSPECTION AT THE AFT END OF THE NACELLE
DIAGONAL BRACE
1. Purpose
A. Use this procedure to examine fuse pins 69B89612, 65B90394 and 65B94182 for cracks. These fuse
pins are installed on the aft end of the diagonal brace (see Figure 1). Cracks have been found to occur
circumferentially on the inside diameter of the fuse pin. The minimum crack size that can be
satisfactorily found with this procedure is 0.085 inch deep by 0.25 inch long (2.2 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. Use this procedure to do the ultrasonic inspections on the inboard
and outboard fuse pins of struts 1 thru 4. 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) 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 0.192 inch (4.9
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 specified 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: KB
Aerotech.
(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:
Nortec (Staveley, 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 NDT4115. See Figure 2.
(4) Transducer Guide NDT4115G. 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 requirements of Paragraph 4. are
satisfactory.
747
NONDESTRUCTIVE TEST MANUAL
PART 4 54-30-07
Page 1
Nov 15/2015D6-7170
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
EFFECTIVITY
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