(2) It is possible that a surface condition has caused the signal. Look at the inner diameter of the fuse
pin at the approximate location where the ultrasonic indication occurs. Try to finger-dampen the
ultrasonic signal. Put a small quantity of couplant on your finger and rub the inner diameter of the
fuse pin at the location where the ultrasonic signal occurred. The signal will move up and down a
large amount if a surface condition has caused the ultrasonic signal. If the ultrasonic signal can
not be dampened, reject the fuse pin.
C. Make a record of all ultrasonic signals that are less than 40% full screen height so you can refer to
these records when you do this inspection again.
D. To make sure that the ultrasonic signals are not caused by sound transfer into the fuse pin attach
fitting, do one of the steps that follow:
(1) Lift the engine to remove the load from the fuse pin. Refer to Service Bulletin 747-54A2153 to
remove the weight of the engine and pylon from the fuse pin.
(2) Remove the pin from the airplane. Do a magnetic particle inspection as specified in Service
Bulletin 747-54A2153.
E. To make sure there are cracks when you get ultrasonic indications with the fuse pin installed, do an
eddy current inspection as specified in Part 6, 51-00-00, Procedure 13. It will be necessary to first
remove all cadmium and corrosion from the inner diameter of the fuse pin. Refer to Service Bulletin
747-54A2153 for instructions on how to refinish the fuse pins after the inspection is done. To make sure
there are cracks when you get ultrasonic indications with the fuse pin removed from the airplane, do a
magnetic particle inspection as specified in Service Bulletin 747-54A2153.
Table 1: Screen Location of Internal Reflections and Back Surface Signals
ENGINE
CONFIGURATION/
PART NUMBER
STRUT
*[1]
FUSE PIN BACK SURFACE SIGNAL
INTERNAL
REFLECTION
POSITION RANGE
%FSW
*[2]
TRANSDUCER
GUIDE/HOLE
POSITION
METAL DISTANCE POSITION
IN. MM %FSW
*[2]
JT9D-70
65B94182-8 I/B 2.440 62.0 98% ---- NDT4123P
---- O/B NO INSPECTION REQUIRED ----
JT9D-XXX (EXCEPT
-70)
69B90410-3,
-4, -600
I/B 2.937 74.6 59% 25% - 35% NDT4120G1/C
65B90341-3,
-4, -600
O/B 3.819 97.0 76% 30% - 40% NDT4120G1/C
CF6
65B94182-3 I/B 2.937 74.6 59% 20% - 30% NDT4120G1/C
69B89612-3 I/B 2.937 74.6 59% 20% - 30% NDT4120G1/C
---- O/B NO INSPECTION REQUIRED -----
RB211
69B89612-3 I/B 2.937 74.6 59% 25% - 35% NDT4120G1/C
69B89612-5 O/B 3.885 98.7 78% 25% - 35% NDT4120G1/C
747
NONDESTRUCTIVE TEST MANUAL
PART 4 54-30-10
Page 5
Nov 15/2015D6-7170
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
EFFECTIVITY
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