Commercial

Airplanes 747

Service Bulletin

ALERT

Number: 747-71A2329

Original Issue: September 27, 2013

ATA System: 7121

SUBJECT: POWER PLANT - Engine Mounts - Forward Engine Mount Barrel Nut Inspection and

Replacement

Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15

CFR 300-774). An export license may be required before it is used for development, production or use by foreign

persons from specific countries. The controller of this data has the individual responsibility to abide by all export

laws.

ECCN: 9E991

BOEING PROPRIETARY, CONFIDENTIAL AND/OR TRADE SECRET

Copyright © 2013 Boeing.

Unpublished Work. All Rights Reserved.

Treatment of this document and its content is governed by contract with Boeing. Rights to use this document

are licensed on a per aircraft basis and such rights may not be transferable. For more information, contact The

Boeing Company.

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BBJ, DC-8, DC-9, DC-10, KC-10, KC-46, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8, Poseidon and

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ALERT ALERT

BLANK PAGE
Table of Contents

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1. PLANNING INFORMATION ........................................ 9

A. Effectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1. Airplanes ............................................. 9

2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

E. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2. Data Supplied with this Service Bulletin: . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3. Installation Drawings Used in the Preparation of this Service Bulletin: . . . . . . . . . . . 15

K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

M. Software Accomplishment Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

A. Material - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

C. Parts Necessary for Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

1. Kits/Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2. Parts and Materials Supplied by the Operator . . . . . . . . . . . . . . . . . . . . . . . . 17

3. Parts Modified and Reidentified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4. Parts Removed and Not Replaced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

E. Special Tooling - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . 18

3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

FIGURE 1: FORWARD ENGINE MOUNT BARREL NUT ULTRASONIC (UT) INSPECTION . . . . . 23

FIGURE 2: FORWARD ENGINE MOUNT BOLT AND BARREL NUT REPLACEMENT . . . . . . . . 26

APPENDIX A: INSPECTION RESULTS REPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

APPENDIX B: ULTRASONIC (UT) INSPECTION PROCEDURE . . . . . . . . . . . . . . . . . . . . . . 34

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BLANK PAGE
Commercial

Airplanes 747

Service Bulletin

ALERT

Summary Number: 747-71A2329

Original Issue: September 27, 2013

ATA System: 7121

SUBJECT: POWER PLANT - Engine Mounts - Forward Engine Mount Barrel Nut Inspection and

Replacement

THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH

1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OWNER.

CONCURRENT REQUIREMENTS

None.

BACKGROUND

Accomplishment of this service bulletin will make sure the barrel nuts on the forward engine mount do not have

a crack. A crack on both sides of the barrel nut will cause complete failure of the barrel nut. Complete failure of

two or more barrel nuts on the same engine reduces the load capacity of the forward engine mount and could

result in separation of an engine from the airplane. Separation of an inboard engine under power could result

in loss of control of the airplane.

An operator reported that while replacing the No.2 engine, the Non Destructive Test (NDT) inspection of the

barrel nuts on the forward engine mount revealed cracks on 2 out of 4 barrel nuts. The operator also discovered

1 cracked barrel nut on the No. 1 engine. This is the first reported occurrence on the 747-8. Also, The Boeing

Company did a NDT inspection of barrel nuts on a flight test airplane. There were 2 barrel nuts where a crack

had initiated on the No. 2 engine. These barrel nuts are located at the forward end of the strut box and are used

to fasten the forward engine mount to the strut. A barrel nut with a crack on one side will still be able to carry

ultimate load. A crack on both sides of the barrel nut will cause complete failure of the barrel nut. Boeing has

not received any reports of a barrel nut with a crack on both sides.

This service bulletin gives instructions to inspect the barrel nuts on the forward engine mount and replace barrel

nuts that have a crack. This will prevent the complete failure of barrel nuts that could result in the separation of

an engine from the airplane. This service bulletin also has operators report the results of barrel nut inspections

to Boeing, as well as sending any cracked parts to Boeing. The inspection reports will be used in the root cause

investigation of this issue.

Boeing will issue a service bulletin for terminating action of this issue after completion of the root cause

investigation.

Boeing Fleet Team Digest (FTD) 747 FTD 71-13001 is related to this service bulletin.

Boeing Service Related Problem (SRP) 747-8-SRP-71-0060 is related to this service bulletin.

Export Controlled ECCN: 9E991 - BOEING

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This table is provided to operators for planning purposes only. Refer to the applicable sections for more

information.

Planning Data Affected Reference

Spares Affected No Paragraph 1.A.2., Spares Affected

Paragraph 1.E., Compliance and Paragraph

1.F., Approval

AD Related Yes

Weight and Balance Change No Paragraph 1.H., Weight and Balance Changes

Electrical Load Changed No Paragraph 1.I., Electrical Load Data

Publications Affected No Paragraph 1.K., Publications Affected

Airplane Flight Operations Affected (Flight Crew No Paragraph 1.K., Publications Affected

Operations Manual and/or FAA Approved Airplane Flight Manual)

Kits/Parts Required No Paragraph 2.C.1., Kits/Parts

Paragraph 2.C.2., Parts and Materials Supplied

by the Operator

Operator Supplied Parts/Material Yes

Paragraph 2.F., Special Tooling Necessary to

do this Service Bulletin

Special Tooling Required No

ACTION

1. Do ultrasonic (UT) inspection of the barrel nuts on the forward engine mount for cracked barrel nuts

or removal and dye penetrant inspection of existing bolt and barrel nuts and installation of new or

serviceable bolt and barrel nuts on the forward engine mount.

Condition 1: No Crack Found During UT Inspection

a. Send inspection results report and any cracked bolts and barrel nuts to Boeing.

b. Repeat ultrasonic (UT) inspection of the barrel nuts on the forward engine mount for cracked barrel

nuts or removal and dye penetrant inspection of existing bolt and barrel nuts and installation of

new or serviceable bolt and barrel nuts on the forward engine mount.

Condition 2: Any Crack Found On Any Barrel Nut During UT Inspection

a. Do removal and dye penetrant inspection of existing bolt and barrel nuts and installation of new

or serviceable bolt and barrel nuts on the forward engine mount.

b. Send inspection results report and any cracked bolts and barrel nuts to Boeing.

c. Repeat ultrasonic (UT) inspection of the barrel nuts on the forward engine mount for cracked barrel

nuts or removal and dye penetrant inspection of existing bolt and barrel nuts and installation of

new or serviceable bolt and barrel nuts on the forward engine mount.

Condition 3: Barrel nuts replaced in accordance with removal and dye penetrant inspection of existing

bolt and barrel nuts and installation of new or serviceable bolt and barrel nuts on the forward engine

mount.

Export Controlled ECCN: 9E991 - BOEING

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BOEING SERVICE BULLETIN 747-71A2329

ALERT ALERT
a. Send inspection results report and any cracked bolts and barrel nuts to Boeing.

b. Repeat ultrasonic (UT) inspection of the barrel nuts on the forward engine mount for cracked barrel

nuts or removal and dye penetrant inspection of existing bolt and barrel nuts and installation of

new or serviceable bolt and barrel nuts on the forward engine mount.

EFFECTIVITY

All 747-8/-8F Airplane(s). Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplane(s).

COMPLIANCE

The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service

bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin

mandatory.

Refer to Paragraph 1.E., Compliance.

INDUSTRY SUPPORT INFORMATION

At the time of release of this service bulletin, warranty remedies have not been determined. A subsequent

revision or Information Notice will address the warranty remedies available, if any.

MANPOWER

Engines Total Task Hours Elapsed Hours

PART 1: ULTRASONIC (UT) INSPECTION OF BARREL 6.00 6.00

NUTS ON FORWARD ENGINE MOUNT

PART 2: REMOVAL AND DYE PENETRANT INSPECTION 16.40 6.80

OF EXISTING BOLT AND BARREL NUTS AND INSTALLATION OF NEW OR SERVICEABLE BOLT AND BARREL

NUTS ON FORWARD ENGINE MOUNT

PART 3: SEND APPENDIX A INSPECTION RESULTS RE- (a) (a)

PORT AND ANY CRACKED BOLTS AND BARREL NUTS

(a) No manpower estimate was calculated for this task.

Refer to Paragraph 1.G., Manpower.

MATERIAL INFORMATION

Operator Supplied Parts/Materials.

Refer to Paragraph 2.A., Material - Price and Availability.

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ALERT ALERT
Commercial

Airplanes 747

Service Bulletin

ALERT

Number: 747-71A2329

Original Issue: September 27, 2013

ATA System: 7121

SUBJECT: POWER PLANT - Engine Mounts - Forward Engine Mount Barrel Nut Inspection and

Replacement

THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH

1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OWNER.

1. PLANNING INFORMATION

A. Effectivity

1. Airplanes

Refer to Service Bulletin Index D6-30300 Part 3 for Airplane Variable Number, Line Number, and

Serial Number data.

This service bulletin is for the airplane(s) shown below.

NOTE: This service bulletin is for the airplanes shown in the effectivity list below. The effectivity

list includes all affected airplanes scheduled to be delivered before SEP 22, 2014. In

addition, at least one airplane scheduled to be delivered after SEP 22, 2014 is affected

by this service bulletin and is in Group(s) 1 as described in the Group Configuration table.

Affected airplanes will be added to the service bulletin's MyBoeingFleet.com (MBF) "get

effectivity" result when they are added to the MBF Fleet Profile Page.

GROUP CONFIGURATION DESCRIPTION

1 - All 747-8/-8F airplanes.

Airplane Models:

747-8, 747-8F

Variable Number Group

RC001 - RC008 1

RC022 - RC036 1

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Variable Number Group

RC066 1

RC501 - RC509 1

RC511 1

RC521 - RC528 1

RC541 1

RC546 - RC549 1

RC551 - RC563 1

RC571 - RC572 1

RC574 - RC582 1

RC601 - RC605 1

RC641 - RC642 1

RC671 - RC672 1

2. Spares Affected

None.

B. Concurrent Requirements

None.

C. Reason

Accomplishment of this service bulletin will make sure the barrel nuts on the forward engine mount do

not have a crack. A crack on both sides of the barrel nut will cause complete failure of the barrel nut.

Complete failure of two or more barrel nuts on the same engine reduces the load capacity of the forward

engine mount and could result in separation of an engine from the airplane. Separation of an inboard

engine under power could result in loss of control of the airplane.

An operator reported that while replacing the No.2 engine, the Non Destructive Test (NDT) inspection

of the barrel nuts on the forward engine mount revealed cracks on 2 out of 4 barrel nuts. The operator

also discovered 1 cracked barrel nut on the No. 1 engine. This is the first reported occurrence on the

747-8. Also, The Boeing Company did a NDT inspection of barrel nuts on a flight test airplane. There

were 2 barrel nuts where a crack had initiated on the No. 2 engine. These barrel nuts are located at

the forward end of the strut box and are used to fasten the forward engine mount to the strut. A barrel

nut with a crack on one side will still be able to carry ultimate load. A crack on both sides of the barrel

nut will cause complete failure of the barrel nut. Boeing has not received any reports of a barrel nut

with a crack on both sides.

This service bulletin gives instructions to inspect the barrel nuts on the forward engine mount and

replace barrel nuts that have a crack. This will prevent the complete failure of barrel nuts that could

result in the separation of an engine from the airplane. This service bulletin also has operators report

the results of barrel nut inspections to Boeing, as well as sending any cracked parts to Boeing. The

inspection reports will be used in the root cause investigation of this issue.

Export Controlled ECCN: 9E991 - BOEING

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ALERT ALERT
Boeing will issue a service bulletin for terminating action of this issue after completion of the root cause

investigation.

Boeing Fleet Team Digest (FTD) 747 FTD 71-13001 is related to this service bulletin.

Boeing Service Related Problem (SRP) 747-8-SRP-71-0060 is related to this service bulletin.

D. Description

1. Do ultrasonic (UT) inspection of the barrel nuts on the forward engine mount for cracked barrel

nuts or removal and dye penetrant inspection of existing bolt and barrel nuts and installation of

new or serviceable bolt and barrel nuts on the forward engine mount.

Condition 1: No Crack Found During UT Inspection

a. Send inspection results report and any cracked bolts and barrel nuts to Boeing.

b. Repeat ultrasonic (UT) inspection of the barrel nuts on the forward engine mount for cracked

barrel nuts or removal and dye penetrant inspection of existing bolt and barrel nuts and

installation of new or serviceable bolt and barrel nuts on the forward engine mount.

Condition 2: Any Crack Found On Any Barrel Nut During UT Inspection

a. Do removal and dye penetrant inspection of existing bolt and barrel nuts and installation of

new or serviceable bolt and barrel nuts on the forward engine mount.

b. Send inspection results report and any cracked bolts and barrel nuts to Boeing.

c. Repeat ultrasonic (UT) inspection of the barrel nuts on the forward engine mount for cracked

barrel nuts or removal and dye penetrant inspection of existing bolt and barrel nuts and

installation of new or serviceable bolt and barrel nuts on the forward engine mount.

Condition 3: Barrel nuts replaced in accordance with removal and dye penetrant inspection of

existing bolt and barrel nuts and installation of new or serviceable bolt and barrel nuts on the

forward engine mount.

a. Send inspection results report and any cracked bolts and barrel nuts to Boeing.

b. Repeat ultrasonic (UT) inspection of the barrel nuts on the forward engine mount for cracked

barrel nuts or removal and dye penetrant inspection of existing bolt and barrel nuts and

installation of new or serviceable bolt and barrel nuts on the forward engine mount.

The work in this service bulletin is done in the maintenance zone(s) given below.

Affected Maintenance Zones

Model Zone

747-8, 747-8F 412, 422, 432, 442

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ALERT ALERT
E. Compliance

The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to

this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this

service bulletin mandatory.

When more than one OPTION is given for a CONDITION, do only one of the OPTION numbers. When

more than one ACTION is given for a CONDITION number or an OPTION number, do all of the ACTION

numbers for that CONDITION number or OPTION number.

The Conditions, Actions and Compliance times shown apply to each engine independently.

Do the required actions in accordance with Paragraph 3. Accomplishment Instructions.

The following abbreviations are used in the compliance tables:

1. PART 1: UT INSPECTION refers to PART 1: ULTRASONIC (UT) INSPECTION OF BARREL

NUTS ON FORWARD ENGINE MOUNT.

2. PART 2: DYE PENETRANT INSPECTION refers to PART 2: REMOVAL AND DYE PENETRANT

INSPECTION OF EXISTING BOLT AND BARREL NUTS AND INSTALLATION OF NEW OR

SERVICEABLE BOLT AND BARREL NUTS ON FORWARD ENGINE MOUNT.

3. PART 3: SEND REPORT AND ANY CRACKED PARTS refers to PART 3: SEND APPENDIX A

INSPECTION RESULTS REPORT AND ANY CRACKED BOLTS AND BARREL NUTS.

Table 1: Inspection of the Barrel Nuts on the Forward Engine Mount

Repeat Interval (Not

to Exceed)

Compliance Time (Whichever occurs

later)

Condition Action

200 flight

cycles (a)

Within 30

days after

the original

issue date

of this service bulletin.

Within 200 flight cycles from

the date of issuance of the

original certificate of airworthiness or the original export certificate of airworthiness.

Do PART 1: UT INSPECTION

or

PART 2: DYE PENETRANT INSPECTION. (b)

All Airplanes

Within 10 days after accom- - -

plishment of PART 1: UT

INSPECTION.

ACTION 1:

Do PART 3: SEND REPORT AND

ANY CRACKED PARTS.

CONDITION 1: NO

CRACK FOUND

DURING UT INSPECTION

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ALERT ALERT
Table 1: Inspection of the Barrel Nuts on the Forward Engine Mount

Repeat Interval (Not

to Exceed)

Compliance Time (Whichever occurs

later)

Condition Action

CONDITION 2: ACTION 1: Before further flight. - -

ANY CRACK

FOUND ON ANY

BARREL NUT

DURING UT INSPECTION

Do PART 2: DYE PENETRANT INSPECTION. (b)

Within 10 days after accom- - -

plishment of installation of

bolts and barrel nuts in accordance with PART 2:

DYE PENETRANT INSPECTION.

ACTION 2:

Do PART 3: SEND REPORT AND

ANY CRACKED PARTS.

Within 10 days after accom- - -

plishment of installation of

bolts and barrel nuts in accordance with PART 2:

DYE PENETRANT INSPECTION.

ACTION 1:

Do PART 3: SEND REPORT AND

ANY CRACKED PARTS.

CONDITION 3:

BARREL NUTS

AND BOLTS REPLACED IN ACCORDANCE WITH

PART 2: DYE

PENETRANT INSPECTION

(a) No terminating action is given.

(b) Whenever PART 2: DYE PENETRANT INSPECTION is done, all bolts and barrel nuts on that engine

mount must be removed and replaced with new or serviceable parts.

F. Approval

This service bulletin was examined by the Federal Aviation Administration (FAA). The changes specified

in this service bulletin comply with the applicable regulations and are FAA approved, as well as European

Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/JAA approved

airplanes listed in the service bulletin effectivity. This service bulletin and its approval were based on

the airplane in its original Boeing delivery configuration or as modified by other approved Boeing

changes.

If an airplane has a non-Boeing modification or repair that affects a component or system also affected

by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval

before incorporating this service bulletin.

G. Manpower

The table below shows an estimate of the task hours necessary to do this inspection and installation

for each engine. This estimate is for direct labor only, done by an experienced crew. Adjust the estimate

with operator task hour data if necessary. The estimate does not include lost time. These are some

examples of lost time:

• Time to adjust to the workplace

• Time to schedule the work

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BOEING SERVICE BULLETIN 747-71A2329

ALERT ALERT
• Time to inspect the work

• Time to cure the materials

• Time to make the parts

• Time to find the tools.

PART 1: ULTRASONIC (UT) INSPECTION OF BARREL NUTS ON FORWARD ENGINE MOUNT

Task Number of Persons Task Hours Elapsed Hours

Open Access 1 1.00 1.00

FIGURE 1 1 4.00 4.00

Close Access 1 1.00 1.00

TOTAL FOR EACH ENGINE 6.00 6.00

PART 2: REMOVAL AND DYE PENETRANT INSPECTION OF EXISTING BOLT AND BARREL

NUTS AND INSTALLATION OF NEW OR SERVICEABLE BOLT AND BARREL NUTS ON

FORWARD ENGINE MOUNT

Task Number of Persons Task Hours Elapsed Hours

Open Access 3 4.20 1.40

FIGURE 2 2 8.00 4.00

Close Access 3 4.20 1.40

TOTAL FOR EACH ENGINE 16.40 6.80

PART 3: SEND APPENDIX A INSPECTION RESULTS REPORT AND ANY CRACKED BOLTS

AND BARREL NUTS

Task Number of Persons Task Hours Elapsed Hours

Send Report and - - -

Parts

TOTAL FOR EACH ENGINE (a) (a)

(a) No manpower estimate was calculated for this task.

H. Weight and Balance Changes

None.

I. Electrical Load Data

Not changed.

J. References

1. Existing Data:

a. Boeing Service Related Problem (SRP) 747-8-SRP-71-0060

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ALERT ALERT
b. Service Bulletin Index D6-30300

c. Standard Overhaul Practices Manual (SOPM) 20-50-01

d. Standard Wiring Practices Manual (SWPM) 20-10-11, 20-10-12, 20-10-19

e. 747 Fleet Team Digest (FTD) 71-13001

f. 747-8 Aircraft Maintenance Manual (AMM) 54-62-04, 71-00-00, 71-11-04, 71-21-03

2. Data Supplied with this Service Bulletin:

None.

3. Installation Drawings Used in the Preparation of this Service Bulletin:

Drawing Number Title

310U8010 ENGINE MOUNT TO STRUT MODULE - GENX-2B

The table above lists applicable drawings used to prepare this service bulletin. The drawings are

not necessary to make the specified changes, and are not supplied with this service bulletin. The

drawings may not be applicable to all airplane configurations or operators.

K. Publications Affected

1. Publications:

None.

2. Damage Tolerance Based Structural Inspections:

Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue

Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the

Maintenance Program. This service bulletin does not affect FCS, therefore DTIs are not necessary.

L. Interchangeability and Intermixability of Parts

Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.

M. Software Accomplishment Summary

Not affected.

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ALERT ALERT
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ALERT ALERT

BLANK PAGE
2. MATERIAL INFORMATION

A. Material - Price and Availability

The operator can supply the parts and materials shown in Paragraph 2.C., Parts Necessary for Each

Airplane. As an alternative, operators can purchase the parts from Boeing Spares. The Boeing price

data shown below is given for planning purposes. Supply data can be given if requested. The parts

are subject to the terms and conditions of the Boeing standard purchase order acknowledgment. Prices

are in United States Dollars. Terms: Net 30 days

Reference this service bulletin and submit your purchase order by one of these methods:

1. Order on-line via ATA Spec 2000 or The Boeing PART Page

2. Fax to (206) 662-7145

REFER TO THE BOEING PART PAGE ON MYBOEINGFLEET.COM OR CONTACT FIRST RESPONDER

AT FR@BOEING.COM FOR THE LATEST REORDER LEAD TIME (ROLT) AND PRICE INFORMATION

Unit Price as of

the original issue

date of this Service Bulletin (US

Dollars)

ROLT as of the

original issue

date of this Service Bulletin (Calendar Days)

Part Number Name Date QTY

SL4081C14SP1 BARREL NUT 10/11/2013 144 76 $383.00

12/23/2013 856

BACB30US14-31M BOLT 10/11/13 16 146 $98.00

03/14/2014 184

B. Industry Support Information

At the time of release of this service bulletin, warranty remedies have not been determined. A subsequent

revision or Information Notice will address the warranty remedies available, if any.

C. Parts Necessary for Each Airplane

1. Kits/Parts

None.

2. Parts and Materials Supplied by the Operator

The following parts or materials are necessary to do the change in this service bulletin. Parts and

materials in the manuals given in Paragraph 1.J., References, can also be necessary. Examine

operator part and material supply to make sure all necessary parts and materials are available.

Part Number / QTY Name Notes

Specification

SL4081C14SP1 4 (a) BARREL NUT (b)

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ALERT ALERT
Part Number / QTY Name Notes

Specification

BACB30US14-31M 4 (a) BOLT (c)

2 MARKING LACQUER (d)

ounces

-

(a) Quantity of 4 required for each engine. Quantity may vary based on inspection results.

(b) Shur-Lock Company (97393), 2541 White Road Irvine, California 92614

(c) LISI Aerospace North America (727622), 2600 Skypark Drive Torrance, CA 90505

(d) F-925, Skydrol Resistant Torque Seal, Organic Products Company, PO Box 560625,

Dallas, TX 75356-0625 (MSDS41617)

3. Parts Modified and Reidentified

None.

4. Parts Removed and Not Replaced

None.

D. Parts Necessary to Change Spares

None.

E. Special Tooling - Price and Availability

None.

F. Special Tooling Necessary to do this Service Bulletin

No special tools or equipment are necessary to do the change in this service bulletin. But, maintenance

and overhaul tools in the manuals given in Paragraph 1.J., References, can be necessary. Examine

operator tool supply to make sure all necessary tools are available.

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BOEING SERVICE BULLETIN 747-71A2329

ALERT ALERT
3. ACCOMPLISHMENT INSTRUCTIONS

A. GENERAL INFORMATION

CAUTION: KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL

PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED MATERIAL,

METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES CAN CAUSE

DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE SPARKS OR

OTHER ELECTRICAL DAMAGE.

NOTE: 1. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for

definition of the acronyms.

2. Obey all of the warnings and cautions given in the specified manual sections.

3. Unless shown differently, these dimensions and tolerances are used:

– Linear dimensions are in inches

– Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus

or minus 0.03 inch

– Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch

– Angular tolerance is plus or minus 2 degrees

– Hole dimensions for standard solid rivets and fasteners are in Structural Repair

Manual (SRM) Chapter 51

– Torque Values:

— Values for structural fasteners are given in 747 Structural Repair Manual,

Chapter 51.

— Values for airframe maintenance tasks are included in Chapter 20 of 747

Airplane Maintenance Manual (AMM).

— Values for electrical maintenance tasks are included in Chapter 20 of

Standard Wiring Practices Manual (SWPM).

— Values for engine maintenance tasks are included in Chapter 70 of 747

Airplane Maintenance Manual (AMM).

— Non-standard torque values for maintenance tasks are included in the

applicable installation step.

4. Use the approved fastener, process and material substitutions in accordance with

SRM Chapter 51.

5. Refer to the SWPM 20-10-11 and SWPM 20-10-12 for the wire installation procedures,

and SWPM 20-10-19 for the wire separation requirements, as accepted procedures.

6. The necessary conditions for selection of clamp type and size are included in SWPM

20-10-12. If any wire bundle support clamp specified in this service bulletin does not

make a correct fit on the wire bundle, refer to SWPM 20-10-12 as an accepted

procedure to select a clamp that fits correctly.

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ALERT ALERT
7. If the length of any fastener specified in this service bulletin does not meet installation

standards given in SRM Chapter 51, then a fastener of the same specification, or

an approved substitute, with a length which meets the installation standards given

in SRM Chapter 51 may be used. In addition, washers may be installed for fastener

grip length in accordance with SRM Chapter 51. Refer to SOPM 20-50-01 for alternate

full threaded fasteners (screws) needed for installation in this service bulletin.

8. A Detailed Inspection (DET) is defined as: An intensive examination of a specific

item, installation, or assembly to detect damage, failure, or irregularity. Available

lighting is normally supplemented with a direct source of good lighting at an intensity

deemed appropriate. Inspection aids such as mirrors, magnifying lenses, etc. may

be necessary. Surface cleaning and elaborate procedures may be required.

9. These work instructions refer to procedures included in other Boeing documents.

When the words "refer to" are used and the operator has an accepted alternative

procedure, the accepted alternative procedure can be used. When the words "in

accordance with" are included in the instruction, the procedure in the Boeing document

must be used.

10. Refer to APPENDIX A for Inspection Results Report instructions.

11. Refer to APPENDIX B for Ultrasonic (UT) Inspection procedure.

12. The instructions in Paragraph 3.B., Work Instructions and the figures can include

operation of tools or test equipment. Boeing Engineering Tool Drawings, the Illustrated

Tool and Equipment Manual, and the Special Tool and Ground Handling Drawing

Index contain data on versions of the tools or test equipment that you can use. It is

permitted to use replaced tools. It is not permitted to use superseded tools.

13. If it is necessary to remove more parts for access, you can remove those parts. If

you can get access without removing identified parts, it is not necessary to remove

all of the identified parts. Jacking and shoring limitations must be observed.

14. Where the work instructions include installation of a kept part, a new or serviceable

part with the same part number can be installed as an alternative to the kept part.

15. If shading is used, shaded areas in Figures are to separate the non-critical and

non-authoritative information from the critical and authoritative information.

16. When more than one OPTION is given for a CONDITION, do only one of the OPTION

numbers. When more than one ACTION is given for a CONDITION number or an

OPTION number, do all of the ACTION numbers for that CONDITION number or

OPTION number.

17. The compliance times for the actions in Paragraph 3.B., WORK INSTRUCTIONS

are in Paragraph 1.E., Compliance.

18. The CONDITIONS, ACTIONS and OPTIONS shown apply to each engine

independently.

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ALERT ALERT
19. Some steps in the Work Instructions are identified as Required for Compliance (RC).

If this service bulletin is mandated by an Airworthiness Directive (AD), then the steps

identified as RC must be done to comply with the AD. Alternative procedures for

steps not identified with RC can be used if the RC steps can still be done as specified,

and the airplane can be put back in a serviceable condition. An Alternative Method

of Compliance (AMOC) is not necessary for deviations to steps that are not identified

as RC.

B. WORK INSTRUCTIONS

1. Do PART 1: ULTRASONIC (UT) INSPECTION OF BARREL NUTS ON FORWARD ENGINE

MOUNT for cracked barrel nuts or PART 2: REMOVAL AND DYE PENETRANT INSPECTION

OF EXISTING BOLT AND BARREL NUTS AND INSTALLATION OF NEW OR SERVICEABLE

BOLT AND BARREL NUTS ON FORWARD ENGINE MOUNT.

CONDITION 1: NO CRACK FOUND DURING UT INSPECTION

a. ACTION 1: Do PART 3: SEND APPENDIX A INSPECTION RESULTS REPORT AND ANY

CRACKED BOLTS AND BARREL NUTS.

CONDITION 2: ANY CRACK FOUND ON ANY BARREL NUT DURING UT INSPECTION

a. ACTION 1: Do PART 2: REMOVAL AND DYE PENETRANT INSPECTION OF EXISTING

BOLT AND BARREL NUTS AND INSTALLATION OF NEW OR SERVICEABLE BOLT AND

BARREL NUTS ON FORWARD ENGINE MOUNT.

b. ACTION 2: Do PART 3: SEND APPENDIX A INSPECTION RESULTS REPORT AND ANY

CRACKED BOLTS AND BARREL NUTS.

CONDITION 3: BARREL NUTS REPLACED IN ACCORDANCE WITH PART 2: REMOVAL AND

DYE PENETRANT INSPECTION OF EXISTING BOLT AND BARREL NUTS AND INSTALLATION

OF NEW OR SERVICEABLE BOLT AND BARREL NUTS ON FORWARD ENGINE MOUNT

a. ACTION 1: Do PART 3: SEND APPENDIX A INSPECTION RESULTS REPORT AND ANY

CRACKED BOLTS AND BARREL NUTS.

2. Put the airplane back to a serviceable condition.

PART 1: ULTRASONIC (UT) INSPECTION OF BARREL NUTS ON FORWARD ENGINE MOUNT

1. Open fan cowl. Refer to 747-8 AMM 71-11-04 as an accepted procedure.

2. Prepare APPENDIX A Inspection Results Report.

3. RC - Do UT inspection of forward engine mount barrel nuts in accordance with FIGURE 1.

4. Close fan cowl. Refer to 747-8 AMM 71-11-04 as an accepted procedure.

PART 2: REMOVAL AND DYE PENETRANT INSPECTION OF EXISTING BOLT AND BARREL

NUTS AND INSTALLATION OF NEW OR SERVICEABLE BOLT AND BARREL NUTS ON FORWARD

ENGINE MOUNT

1. Remove fan cowl. Refer to 747-8 AMM 71-11-04 as an accepted procedure.

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BOEING SERVICE BULLETIN 747-71A2329

ALERT ALERT
2. Remove the No. 2 Forward Fairing. Refer to 747-8 AMM 54-62-04 as an accepted procedure.

3. Install the forward bootstrap tool assembly. Refer to 747-8 AMM 71-00-00 as an accepted procedure.

4. RC - Apply the load to the forward engine mount. Refer to 747-8 AMM 71-00-00 as an accepted

procedure.

NOTE: Apply the load to the forward engine mount to remove the tension load from the forward

engine mount bolts.

5. Prepare APPENDIX A Inspection Results Report.

6. RC - Replace barrel nuts and do dye penetrant inspection in accordance with FIGURE 2.

7. Remove the load to the forward engine mount. Refer to 747-8 AMM 71-00-00 as an accepted

procedure.

8. Remove the forward bootstrap tool assembly. Refer to 747-8 AMM 71-00-00 as an accepted

procedure.

9. Install the No. 2 Forward Fairing. Refer to 747-8 AMM 54-62-04 as an accepted procedure.

10. Install fan cowl. Refer to 747-8 AMM 71-11-04 as an accepted procedure.

PART 3: SEND APPENDIX A INSPECTION RESULTS REPORT AND ANY CRACKED BOLTS AND

BARREL NUTS

1. RC - Send Appendix A Inspection Results Report and any cracked bolts and barrel nuts to The

Boeing Company. Refer to APPENDIX A for instructions.

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ALERT ALERT
FIGURE 1: FORWARD ENGINE MOUNT BARREL NUT ULTRASONIC (UT) INSPECTION

(SHEET 1 OF 3)

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ALERT ALERT
FIGURE 1: FORWARD ENGINE MOUNT BARREL NUT ULTRASONIC (UT) INSPECTION

(SHEET 2 OF 3)

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BOEING SERVICE BULLETIN 747-71A2329

ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY

numbers shown below are the number of parts necessary for each engine.

Step Task Name Identification Qty More Data

Identify location of the barrel nut so that

the location can by recorded in APPENDIX A.

1 Identify BARREL NUT SL4081C14SP1 4

Do UT Inspection of barrel nuts for any

crack in accordance with APPENDIX B.

2 Inspect BARREL NUT SL4081C14SP1 4

Record the location and UT inspection

results in APPENDIX A.

3 Record BARREL NUT SL4081C14SP1 4

FIGURE 1: FORWARD ENGINE MOUNT BARREL NUT ULTRASONIC (UT) INSPECTION

(SHEET 3 OF 3)

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ALERT ALERT
FIGURE 2: FORWARD ENGINE MOUNT BOLT AND BARREL NUT REPLACEMENT

(SHEET 1 OF 4)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY

numbers shown below are the number of parts necessary for each engine.

FIGURE 2: FORWARD ENGINE MOUNT BOLT AND BARREL NUT REPLACEMENT

(SHEET 2 OF 4)

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ALERT ALERT
Step Task Name Identification Qty More Data

Identify and mark the location and orientation of the barrel nut so that the location and orientation can by recorded in

APPENDIX A.

1 Identify BARREL NUT SL4081C14SP1 4

If torque stripe is present, do a DET of

the torque stripe for evidence of fastener

rotation so that the results can be

recorded in APPENDIX A. Evidence of

fastener rotation is if the edges of the

torque stripe are not aligned across the

fastener and the structure.

2 Inspect BOLT BACB30US14-31M 4

Refer to 747-8 AMM 71-00-00 as an accepted procedure.Remove BOLT BACB30US14-31M 4

Refer to 747-8 AMM 71-00-00 as an accepted procedure.Remove / WASHER BACW10BP14ACU 4

Keep

Refer to 747-8 AMM 71-00-00 as an accepted procedure.Remove BARREL NUT SL4081C14SP1 4

Refer to 747-8 AMM 71-00-00 as an accepted procedure.Remove / RETAINER SLR4124C14 4

Keep

(a) Do a dye penetrant inspection for any

crack in accordance with 747-8 AMM

71-21-03.

3 Inspect BOLT BACB30US14-31M 4

(a) (b) Do a dye penetrant inspection for

any crack in accordance with 747-8

AMM 71-21-03.

Inspect BARREL NUT SL4081C14SP1 4

(a) Record the location, orientation, if

torque stripe is aligned and dye penetrant or UT inspection results in APPENDIX A.

4 Record BARREL NUT SL4081C14SP1 4

FIGURE 2: FORWARD ENGINE MOUNT BOLT AND BARREL NUT REPLACEMENT

(SHEET 3 OF 4)

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BOEING SERVICE BULLETIN 747-71A2329

ALERT ALERT
Step Task Name Identification Qty More Data

(c) Refer to 747-8 AMM 71-00-00 as an

accepted procedure.

Install BOLT BACB30US14-31M 4

(New)

5

Refer to 747-8 AMM 71-00-00 as an accepted procedure.Install WASHER BACW10BP14ACU 4

(Kept)

(c) Refer to 747-8 AMM 71-00-00 as an

accepted procedure.

Install BARREL NUT SL4081C14SP1 4

(New)

Refer to 747-8 AMM 71-00-00 as an accepted procedure.Install RETAINER SLR4124C14 4

(Kept)

Apply a torque stripe to bolt head and

forward engine mount. Refer to Paragraph 2.C.2., Parts and Materials Supplied by the Operator for acceptable

material.

MARKING LAC- - 4

QUER

Apply

(a) The dye penetrant inspection of the removed bolts and barrel nuts may be performed at a later time if new

bolts and barrel nuts are installed. Dye penetrant inspection must be performed in time to comply with

CONDITION 2, ACTION 2, or CONDITION 3, ACTION 1 of Paragraph 1.E., Compliance.

(b) No dye penetrant inspection is required for any barrel nut that was shown to be cracked during UT inspection. All other barrel nuts must be dye penetrant inspected.

(c) A serviceable part may be installed in place of a new part if the part has been dye penetrant inspected

since it was last removed from service and no crack was found.

FIGURE 2: FORWARD ENGINE MOUNT BOLT AND BARREL NUT REPLACEMENT

(SHEET 4 OF 4)

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ALERT ALERT
APPENDIX A: INSPECTION RESULTS REPORT

(SHEET 1 OF 4)

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BOEING SERVICE BULLETIN 747-71A2329

ALERT ALERT
Service Bulletin 747-71A2329

Airplane Registry, Variable or Line Number:

Flight Hours: Flight Cycles: Date of Inspection:

Barrel Nut

Being Installed

(New /

Serviceable)

Location

of Crack

on Bolt or

Barrel Nut

(LEFT

SIDE /

RIGHT

SIDE /

BOTH

SIDES) (If

applicable)

Barrel Nut

Lot Number

Location

of Lot

Number

on Barrel

Nut (Forward Face

/ Aft Face)

Torque

Stripe

Aligned

(Yes / No)

Crack

Found (Y /

N) on

(BOLT /

BARREL

NUT /

BOTH)

Inspection

Method

Used (UT /

DYE PENETRANT)

Bolt and

Barrel Nut

Location

Engine

Number

1 A

B

C

D

2 A

B

C

D

3 A

B

C

D

4 A

B

C

D

REPORTING INSTRUCTIONS:

1. Record the airplane registry, variable or line number.

2. Refer to illustration above for bolt and barrel nut location and orientation.

APPENDIX A: INSPECTION RESULTS REPORT

(SHEET 2 OF 4)

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ALERT ALERT
3. Record which inspection method was used.

4. Report if any crack was found or if no crack was found for every barrel nut. Report if any crack was

found on any bolts that were dye penetrant inspected.

a. If no crack was found, mark "No".

b. If any crack was found, mark "Yes" and mark if the cracked part was the "Bolt", the "Barrel Nut"

or "Both".

NOTE: Step 5 through Step 9 are only required if PART 2: REMOVAL AND DYE PENETRANT

INSPECTION OF EXISTING BOLT AND BARREL NUTS AND INSTALLATION OF NEW OR

SERVICEABLE BOLT AND BARREL NUTS ON FORWARD ENGINE MOUNT was done.

5. Record inspection results of the torque stripe. If the torque stripe is aligned, mark "Yes". If the torque

stripe is not aligned, mark "No". If no torque stripe is present, mark "N/A".

6. Record which face of the barrel nut the lot number is on, the forward face or the aft face. Mark "Forward

Face" or "Aft Face"

7. Record the lot number of the barrel nut. The barrel nut has the lot number marked on either the forward

face or the aft face. The part number is marked on the opposite face from the lot number. If UT Inspection

was done, record if lot number was visible. (Lot Number Example: XX-XXX)

8. Report the location of any crack found for all cracked bolts and barrel nuts. Report which side of the

bolt or barrel nut was cracked. Report "Left Side, Right Side, or Both Sides".

9. Record if the barrel nut being installed in FIGURE 2 is a new barrel nut or a previously used barrel nut.

NOTE: This information may be used for the terminating action.

10. Send the inspection results report to Boeing through the Boeing Communication System (BCS).

11. Please provide any detailed explanation or comments about the cracked bolts or barrel nuts in the BCS

message to Boeing.

12. Send any cracked bolts or barrel nuts to:

Spares Distribution Center

Warranty and Overhaul Area, SSA 111

THE BOEING COMPANY

Attention: Chris Morrow/Constantine Kostakis

(425) 237-1425

Mail Code 04-AR

APPENDIX A: INSPECTION RESULTS REPORT

(SHEET 3 OF 4)

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ALERT ALERT
2201 S. 142nd St

PO BOX 3707 98124-2207 (This line is only required if shipped via U.S. Postal Service)

SEATAC WA 98168-3713

USA

APPENDIX A: INSPECTION RESULTS REPORT

(SHEET 4 OF 4)

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BOEING SERVICE BULLETIN 747-71A2329

ALERT ALERT
BARREL NUT ULTRASONIC (UT) INSPECTION

1. PURPOSE

a. Use this ultrasonic procedure to detect cracks in the four barrel nuts of the forward engine mount.

This procedure will detect a crack that completely severs one side of the barrel nut.

2. EQUIPMENT

a. Instrument

(1) Use an ultrasonic flaw detector.

(2) A GE USM Go was used to develop this procedure, alternate instruments can be used.

b. Transducer

(1) Use a transducer that:

(a) Operates at 10 MHz.

(b) Is cylindrical in shape.

(c) Has a case diameter of 0.31 inch (7.9 mm), or less.

(d) Has a top mount micro-dot connector.

(e) Has a minimum length of 0.50 inch (12.7 mm) and a maximum length of 1.0 inch (25

mm), not including the connector.

(f) Does not have a delay line.

(2) The transducer that follows was used to help prepare this procedure but, alternate transducers

can be used:

(a) Gamma, 10.0 MHz/.187" P/N 389-084-180; GE Inspection Technologies.

c. Transducer Extension Handle

(1) Two transducer extension handles are recommended to help get access to the inspection

area. It is difficult to reach the inspection areas without the extensions.

(a) A 2 inch long (51 mm) extension handle is recommended to help examine the right and

left barrel nuts on the forward side and the right barrel nut on the aft side of the forward

engine mount. The transducer extension handle that follows was used to help prepare

this procedure but, alternate handles can be used:

1) SPC-604FX-2; EC-NDT

APPENDIX B: ULTRASONIC (UT) INSPECTION PROCEDURE

(SHEET 1 OF 7)

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ALERT ALERT
(b) An 8 inch long (203 mm), flexible shaft, extension handle is recommended to help examine

the left barrel nut on the aft side of the forward engine mount. This extension handle is

used because the position of the de-icing duct on the left side of the engine restricts the

access to the barrel nut. The transducer extension handle that follows was used to help

prepare this procedure but, alternate handles can be used:

1) SPC-604FX-8; EC-NDT

d. Reference Standard

(1) Use an un-installed new or serviceable forward engine mount barrel nut for a reference

standard to calibrate the equipment.

(2) The barrel nuts are made from Inconel 718.

(3) The barrel nuts are 1.5 inches (38.1 mm) long.

3. PREPARATION FOR INSPECTION

a. Identify and get access to the inspection area on the airplane. Refer to the service bulletin.

b. Remove all dirt and grease from the inspection area that the transducer will touch.

c. Select the reference standard that will be used to calibrate the equipment. See para. 2.d. to select

the reference standard.

4. INSTRUMENT CALIBRATION

a. Connect the transducer to the instrument.

b. Set the instrument frequency to 10 MHz, or a broadband setting that includes 10 MHz.

c. Set the initial pulse to 0% full screen width. See Appendix B Figure B1.

d. If the material velocity can be adjusted on the instrument, set the velocity to 0.224

inches/microsecond (5.69 mm/microsecond).

e. Set the display to show a 2 inch (51 mm) screen range.

f. Identify the inspection area.

g. Select the optional transducer extension recommended for the applicable location of the barrel

nut to be examined. See Para. 2.c. (Transducer Extension Handle).

h. Put couplant on the flat surface of an un-installed new or serviceable barrel nut.

i. Put the transducer on the center of the barrel nut. (see Appendix B Figure B1, detail I and Appendix

B Figure B2)

APPENDIX B: ULTRASONIC (UT) INSPECTION PROCEDURE

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NOTE: Make sure that the transducer fully touches the barrel nut and is not at the location of the

retainer.

j. If the velocity and screen range have been adjusted as specified above, the signal from the threaded

bore in the barrel nut will occur at approximately 18% Full Screen Width (FSW) (0.39 inch (10

mm)). Adjust the gain so the threaded bore signal on the display to 90% Full Screen Height (FSH).

See Appendix B Figure B1, Detail II.

k. If necessary, adjust the range and delay to cause the threaded bore signal to occur at approximately

18% FSW (0.39 inch (10 mm) on a 2 inch (51 mm) screen range). See Appendix B Figure B1,

Detail II.

l. Move the transducer until it is aligned with the edge of the barrel nut. See Appendix B Figure B1,

detail III and Appendix B Figure B2.

NOTE: Do not permit the transducer to overhang the edge of the barrel nut since the transducer

will be restricted by the barrel nut bore of the engine mount hanger fitting during the

inspection on the airplane.

m. The signal from the back surface of the barrel nut will occur at approximately 75% FSW (1.5 inches

(38.1 mm) on a 2 inch (51 mm) screen range with the correct velocity). See Appendix B Figure

B1, Detail IV.

n. Adjust the gain to get the back surface signal height to 100% FSH.

o. Add 6dB of gain.

p. Crack indications will occur between 25% and 50% FSW.

5. INSPECTION PROCEDURE

a. Identify and get access to the inspection area.

b. A total of 4 barrel nuts will be examined. (Two on the forward side of the forward engine mount

and two on the aft side).

(1) Examine the two forward barrel nuts as follows:

(a) Put the transducer on the forward side of a barrel nut in the center of the nut to get a

signal to occur from the threaded hole. Keep the transducer against the retainer to help

guide the transducer. See Appendix B Figure B2.

NOTE: The 2 inch long (51 mm) transducer extension handle is recommended to help

examine the barrel nuts on the forward side of the engine mount.

(b) Move the transducer away from the center to the outer edge of the barrel nut until it stops

at the edge of the bore in the hanger fitting. Examine on both sides of the threaded hole.

See Appendix B Figure B2.

(c) Identify all barrel nuts as cracked if:

APPENDIX B: ULTRASONIC (UT) INSPECTION PROCEDURE

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1) A signal occurs between 25% and 50% FSW.

NOTE: The back surface signal of the barrel nut will not occur when the transducer

is positioned in the area of the threaded hole because the hole will block

the sound from reaching the back surface. Multiple reflections from the

threaded hole can occur. Appendix B Figure B1, Detail II shows the first

threaded hole reflection at approximately 18% FSW and the second multiple

at approximately 36% FSW. The amplitude of the threaded hole signals will

rise and fall together.

(2) Examine the two aft barrel nuts as follows:

NOTE: The two inch long (51 mm) transducer extension handle is recommended to examine

the right, aft barrel nut and the eight inch long (203 mm) handle is recommended to

examine the left, aft barrel nut.

(a) Put the transducer on the aft side of the of a barrel nut in the center of the nut to get a

signal to occur from the threaded hole. Keep the transducer against the retainer to help

guide the transducer. See Appendix B Figure B2.

(b) Move the transducer away from the center to the outer edge of the barrel nut until it stops

at the edge of the bore in the hanger fitting. Examine on both sides of the threaded hole.

See Appendix B Figure B2.

(c) Identify all barrel nuts as cracked if:

1) A signal occurs between 25% and 50% FSW.

2) The back surface signal is not displayed on the screen at approximately 75% FSW

when the transducer on the barrel nut is adjacent to either side of the barrel nut bore

and the retainer as shown in Appendix B Figure B2.

NOTE: The back surface signal of the barrel nut will not occur when the transducer

is positioned in the area of the threaded hole because the hole will block

the sound from reaching the back surface. Multiple reflections from the

threaded hole can occur. Appendix B Figure B1, Detail II shows the first

threaded hole reflection at approximately 18% FSW and the second multiple

at approximately 36% FSW. The amplitude of the threaded hole signals will

rise and fall together.

6. INSPECTION RESULTS

a. If a signal occurs between 25% and 50% FSW, the barrel nut must be considered cracked even

if the back surface signal is shown on the instrument display.

b. If no back surface signal occurs and no signal occurs between 25% and 50% FSW then:

(1) Make sure that there is sufficient couplant on the barrel nut.

(2) Make sure that the transducer is in good contact with the surface of the barrel nut.

APPENDIX B: ULTRASONIC (UT) INSPECTION PROCEDURE

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(3) Make sure that the transducer is not on the retainer.

(4) Off angle cracks can prevent the back surface signal from occurring. Reject the barrel nut if

a back surface signal does not occur on the instrument display.

APPENDIX B: ULTRASONIC (UT) INSPECTION PROCEDURE

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APPENDIX B: ULTRASONIC (UT) INSPECTION PROCEDURE

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APPENDIX B: ULTRASONIC (UT) INSPECTION PROCEDURE

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ALERT ALERT