June 02, 1988

Revision 2: October 01, 2009 747-53A2303

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 1 of 79

Commercial

Airplane

Group 747

Service Bulletin

Number: 747-53A2303

Date: June 02, 1988

Revision 2: October 01, 2009

ATA System: 5310 5311

SUBJECT: FUSELAGE - Nose Section - Station 400 to 520 Stringer Lap Splice Inspection, Repair 

and Modification

BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET

Copyright © 1989 The Boeing Company

Unpublished Work - All Rights Reserved

Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable 

subject matter. Boeing also claims copyright in this document as a compilation and/or collective work.

This document includes proprietary information owned by The Boeing Company and/or one or more third 

parties. Treatment of the document and the information it contains is governed by contract with Boeing. For 

more information, contact The Boeing Company, P.O. Box 3707, Seattle, Washington 98124.

Boeing, 707, 717, 727, 737, 747, 757, 767, 777, BBJ, BOEING BUSINESS JET, DC-8, DC-9, DC-10, MD-10, 

MD-11, MD-80, MD-90, the Boeing logo and the Boeing livery are among the trademarks owned by Boeing or 

its subsidiaries. No intellectual property license (express or implied) is granted in connection with this document 

or otherwise.
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BLANK PAGE
 Table of Contents

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

Table of Contents

Revision Transmittal Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1. PLANNING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

A. Effectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1. Airplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

E. Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

2. Data supplied with this Service Bulletin: . . . . . . . . . . . . . . . . . . . . . . . . . 36

3. Installation Drawings Used in the Preparation of this Service Bulletin: . . . . . . . . . . 36

4. Process Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . 36

2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

A. Material - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

C. Parts Necessary For Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

1. Kits/Parts: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

2. Parts and Materials Supplied by the Operator: . . . . . . . . . . . . . . . . . . . . . . 40

3. Parts Modified and Reidentified: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

4. Parts Removed and Not Replaced: . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . 40

3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

FIGURE 1: THIS FIGURE IS DELETED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

FIGURE 2: INITIAL INSPECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

FIGURE 3: INTERNAL ACCESS AND RESTORATION. . . . . . . . . . . . . . . . . . . . . . . . . 54

FIGURE 4: THIS FIGURE IS DELETED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

FIGURE 5: TOP ROW PROTRUDING HEAD FASTENER MODIFICATION INSPECTION . . . . . . 57

FIGURE 6: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND REPAIR DOUBLER INSTALLED

BY SERVICE BULLETIN 747-53A2321 - INSPECTION . . . . . . . . . . . . . . . . . 64

FIGURE 7: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND SKIN REPLACEMENT

MODIFICATION BY SERVICE BULLETIN 747-53A2321 - INSPECTION . . . . . . . . 66

FIGURE 8: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND REPAIR DOUBLER INSTALLED
 Table of Contents

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

BY SERVICE BULLETIN 747-53A2321 - ALTERNATIVE INSPECTION . . . . . . . . . 68

FIGURE 9: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND SKIN REPLACEMENT

MODIFICATION BY SERVICE BULLETIN 747-53A2321 - ALTERNATIVE INSPECTION 70

APPENDIX A: DISCREPANT STRUCTURE REPORT . . . . . . . . . . . . . . . . . . . . . . . . . 72

APPENDIX B: ALTERNATIVE LAP SPLICE TRIM INSTRUCTIONS . . . . . . . . . . . . . . . . . . 75

APPENDIX C: EXTENSION OF THE 141U2100 MODIFICATION DOUBLERS WHEN AN SRM REPAIR

IS PRESENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
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Commercial

Airplanes 747

Service Bulletin

Number: 747-53A2303 Revision Transmittal Sheet

Original Issue: June 02, 1988

Revision 2: October 01, 2009

ATA System: 5310 5311

SUBJECT: FUSELAGE - Nose Section - Station 400 to 520 Stringer Lap Splice Inspection, Repair 

and Modification

This Revision includes all pages of the service bulletin.

COMPLIANCE INFORMATION RELATED TO THIS REVISION

More work is necessary on airplanes on which the Flight Safety inspections are being accomplished. The repeat 

inspection interval has been reduced from 5,000 flight-cycles to 3,000 flight-cycles since the last Flight Safety 

inspection was accomplished, or within 1,000 flight-cycles after the date on Revision 2, whichever occurs later.

More work is also necessary on airplanes modified as shown in the initial release and/or Revision 1 of this 

service bulletin. Airplanes that have accomplished a protruding head fastener modification or a modification as 

given in certain Structural Repair Manual (SRM) repairs will be required to accomplish the doubler modification 

as given in Paragraph 1.E., Compliance. In addition, airplanes that have had a structural modification 

accomplished as given in the SRM or other Boeing service bulletins will be required to accomplish post 

modification inspections as given in Paragraph 1.E., Compliance.

REASON FOR REVISION

This revision is sent to update inspection requirements and to update the post modification inspection 

requirements for airplanes that have accomplished a modification as shown in the initial release and/or Revision 

1 of this service bulletin. This revision is also sent to remove the optional top row protruding head fastener 

modification, as well as modifications per certain SRM repairs.

Changes to this service bulletin include:

– Airworthiness Directive (AD) 90-21-17 supersedes AD 89-05-03.

– Specific repair figures in SRM 53-30-03 are referenced as an acceptable modification.

– Compliance information is added to Paragraph 1.E., Compliance. Existing compliance information to 

accomplish the Flight Safety Inspection Program, the Economics Based Inspection Program and the 

modification has been moved from the logic diagrams in Figure 1 to Tables 1 and 2 of Paragraph 1.E., 

Compliance. Compliance information for the repeat post modification inspections is included in Table 3 of 

Paragraph 1.E., Compliance. New compliance information for the inspection and modification of airplanes 

with certain SRM repairs or the optional top row protruding head fastener modification that was shown in 

the original release and Revision 1 of this service bulletin is added to Tables 4 and 5.

– The 747 Non-Destructive Test manual, Boeing service bulletins, a Service Related Problem, a Boeing 

Document, an AD and SRM references are added to Paragraph 1.J., References.

– Primer and Sealant are added to the Parts and Materials Supplied by the Operator.

– Paragraph 3.B., Work Instructions have been extensively rewritten.
 

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BOEING SERVICE BULLETIN 747-53A2303

– Figure 1 is deleted. The information previously in the logic diagrams has been moved to the tables in 

Paragraph 1.E., Compliance.

– The NDT procedures referenced in Figure 2 have been changed.

– Figure 4 is deleted to remove the top row protruding head fastener modification.

– Figure 5 is added to inspect the top row protruding head fastener modification accomplished by previous 

releases of this service bulletin for cracks.

– Figure 6 is added to provide inspections for airplanes with doublers installed by this service bulletin and 

doublers installed by service bulletin 747-53A2321 for cracks.

– Figure 7 is added to provide inspections for airplanes with doublers installed by this service bulletin and the 

skin replacement modification by service bulletin 747-53A2321 for cracks.

– Figure 8 is added to provide alternative inspections to the Figure 6 inspections for cracks.

– Figure 9 is added to provide alternative inspections to the Figure 7 inspections for cracks.

– Appendix B is added to provide alternative lap splice trim instructions.

– Appendix C is added to show how the Drawing 141U2100 modification doublers should be changed when 

an SRM repair is present in the modification area.

Paragraph 1.A., Effectivity, shows changes of airplane operators. Each operator should examine the Effectivity 

paragraph for changes.

Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity, to show the location 

of important changes.

Pages with no vertical lines have no important changes.

REVISION HISTORY

Original Issue: June 02, 1988

Revision 1: March 29, 1990

Revision 2: October 1, 2009
Original Issue: June 02, 1988

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Commercial

Airplanes 747

Service Bulletin

Number: 747-53A2303 Summary

Original Issue: June 02, 1988

Revision 2: October 01, 2009

ATA System: 5310 5311

SUBJECT: FUSELAGE - Nose Section - Station 400 to 520 Stringer Lap Splice Inspection, Repair 

and Modification

CONCURRENT REQUIREMENTS

None.

BACKGROUND

Based on a structural review of the 747 airplane, incorporation of a modification per Revision 2 of this service 

bulletin is recommended on aging airplanes.

Accomplishment of the intent of this service bulletin will ensure the structural integrity of the fuselage skin lap 

splice along stringer 6 left and stringer 6 right from Station (STA) 400 to 520 throughout the operational life of 

the airplane.

One operator reported fuselage skin cracks of 0.16 inch long at 10 rivet locations in the upper fastener row of 

the left stringer 6 skin lap splice between STA 400 and 420 on one airplane. This airplane had accumulated 

29,439 flight hours and 22,248 reduced pressure cycles (approximately 19,000 equivalent full pressure cycles). 

Investigation revealed the cracks were initiated in the fastener countersinks and were propagated by cabin 

pressurization cyclic loading.

A structural reassessment of the 747 airplane was made under the requirements of Federal Aviation 

Administration (FAA) Advisory Circular 91-56, in accordance with Federal Aviation Regulation (FAR) 25.571 as 

amended in 1978, to ensure the safe operation of 747 airplanes throughout their operational life. As a result of 

this reassessment, the stringer lap splice, left and right sides, between STA 400 and 520 have been determined 

to be structurally significant and critical to the structural integrity of the airplane.

Skin cracks not detected prior to reaching critical crack length may result in in-flight depressurization of the 

airplane and the inability to withstand current regulatory fail-safe loads.

Therefore, a flight safety inspection program is defined in this bulletin which will continue throughout the 

operational life of the airplane.

This service bulletin is the subject of Federal Aviation Administration (FAA) Airworthiness Directives (AD) 

90-21-17 and 90-06-06. AD 90-21-17 supersedes AD 89-05-03.

Boeing Service Related Problem (SRP) 747OP-SRP-53-0292 is related to this service bulletin.
 

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BOEING SERVICE BULLETIN 747-53A2303

ACTION (PRR 82284R)

As recommended by the 747 Aging Fleet Structures Working Group, accomplish a modification per the 

accomplishment instructions at or before the accumulation of 23,000 flight-cycles. Airplanes on which a 

protruding head fastener modification or a modification as given in certain SRM repairs are required to 

accomplish the external doubler modification given in this service bulletin at the time given in Paragraph 1.E., 

Compliance, Table 5.

This bulletin details a flight safety inspection program, an economics based inspection program, structural 

modifications to improve the resistance to cracking along the affected skin lap splice, and an after-modification 

inspection program.

The flight safety inspection program is defined as follows:

On unmodified airplanes initiate a detailed and High Frequency Eddy Current (HFEC) inspection at the time 

given in Paragraph 1.E., Compliance, Table 1. If a crack is not indicated, reinspect as given in Paragraph 1.E., 

Compliance, Table 1. As an alternative, install a modification which will consist of the installation of an external 

doubler. If cracks are indicated during the initial inspection, modify the skin lap splice per the accomplishment 

instructions of this service bulletin before further flight. On any area left unmodified, repeat the initial inspection 

as given in Paragraph 1.E., Compliance, Table 1.

At modified areas initiate the post modification internal and external inspections at the time given in Paragraph 

1.E., Compliance, Table 3. If no cracks are found, repeat these inspections as given in Paragraph 1.E., 

Compliance, Table 3. If cracks are found, repair per 747 Structural Repair Manual or contact Boeing. If the 

Service Bulletin 747-53-2272 Zone 2 modification has previously been accomplished, the after modification 

inspections per this service bulletin may be performed using external methods only, and with a repeat interval 

as given in Paragraph 1.E., Compliance, Table 3.

The Economic Based Inspection Program has a lower initial threshold than the Flight Safety Inspection 

Program. The repeat inspection interval, inspection methods, and options are the same for both inspection 

programs.

EFFECTIVITY

747-100, 747-100B, 747-200B, 747-200C, 747-200F, 747-300, 747SR and 747SP series airplanes. Refer to 

Paragraph 1.A.1., Airplanes for the list of affected airplanes.

COMPLIANCE

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

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

bulletin mandatory.

Federal Aviation Administration (FAA) Airworthiness Directives 90-21-17 and 90-06-06 are related to this 

service bulletin.

Refer to Paragraph 1.E., Compliance.

INDUSTRY SUPPORT INFORMATION

Boeing warranty remedies are not available for the inspection, and/or repair procedures given in this service 

bulletin.
 

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BOEING SERVICE BULLETIN 747-53A2303

MANPOWER

Refer to Paragraph 1.G., Manpower.

MATERIAL INFORMATION

Boeing Supplied Kits/Parts. Refer to Paragraph 2.A., Material - Price and Availability.
 

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BOEING SERVICE BULLETIN 747-53A2303

STA

520

STA

400

STA

400

STA

520

UPPER SKIN PANEL

INSPECT FOR

CRACKS IN TOP ROW

3 ROW SPLICE SHOWN

4 ROW SPLICE SIMILAR

STRINGER NO.6

LEFT SIDE SHOWN

RIGHT SIDE SIMILAR

LOWER SKIN

PANEL

AND ACCOMPLISH A

STRUCTURAL MODIFICATION

J76126
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Commercial

Airplanes 747

Service Bulletin

Number: 747-53A2303

Original Issue: June 02, 1988

Revision 2: October 01, 2009

ATA System: 5310 5311

SUBJECT: FUSELAGE - Nose Section - Station 400 to 520 Stringer Lap Splice Inspection, Repair 

and Modification

1. PLANNING INFORMATION

A. Effectivity

1. Airplanes

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

Number, and Serial Number data.

This service bulletin is for the airplanes shown below. Refer to PRR 82284R for data about this 

change.

Airplane models:

GROUP CONFIGURATION DESCRIPTION

1 - 747-100, -200B and -200F airplanes, line 

number 1 through 200 with standard upper deck 

configuration of one right side crew entry door.

2 - 747-100 and -200B airplanes, line number 1 

through 200 with right and left side upper deck 

crew entry doors.

3 - 747-100, -100B, -200B, -200C, -200F, 747SP 

and 747SR airplanes, line number 201 through 

628 with standard upper deck configuration of 

one right side crew entry door.

4 - 747-100, -100B, -200B, -200C, -200F, 747SP 

and 747SR airplanes, line number 201 through 

628 with right and left side upper deck crew 

entry doors.

5 - 747-200 and -300 airplanes, line number 201 

through 628 with a 208 inch Stretched Upper 

Deck (SUD) configuration, including airplanes 

modified to SUD per Master Change 42360-( )
 

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BOEING SERVICE BULLETIN 747-53A2303

747-100 747-100B 747-200B 747-200C

747-200F 747-300 747SP 747SR

IDENTIFICATION BY CUSTOMER, CUSTOMER CODE, GROUP AND VARIABLE NUMBER

AAR AIRCRAFT SALES & LEASING (AFD)

4 RB681–RB682 RB691

AERO CONTROLS (AEO)

2 RA722–RA723

AEROLINEAS ARGENTINAS (ARG)

3 RD122–RD127

AEROSUR (REO)

5 RS235

AFRICA UNITED HOLDING CO. (UHD)

3 RB010

4 RD513

AFX (AXL)

3 RD201

AGES AIRCRAFT SALES & LEASING (AGJ)

1 RB004

AIR ATLANTA ICELANDIC (AID)

3 RD414 RR204

4 RD141–RD142 RD144 RD647–RD648 RD771

5 RS211 RS233 RS237

AIR CANADA (ACN)

4 RA749–RA750 RD531

AIR CHINA (BEJ)

3 RD782

AIR FRANCE (AFA)

3 RR306

4 RD655 RD657–RD658

AIR GULF FALCON (GFG)

1 RA535 RA537

AIR INDIA (AIN)

4 RA729 RA731

AIR UNIVERSAL (UVL)

4 RD649

AMERICAN AIRLINES (AAL)

3 RA266
 

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BOEING SERVICE BULLETIN 747-53A2303

ARKIA ISRAELI AIRLINES (ARK)

1 RA253

3 RR332

ATLAS AIR (TLS)

3 RD361–RD366 RD691–RD692

4 RD641 RD646 RD753–RD754 RJ333

RR301

AVIATION EXPOSURE MANAGEMENT (EXU)

4 RD131–RD132 RD143

BANC OF AMERICA LEASING (SBC)

1 RD001–RD002

BOEING (TBC)

4 RR222–RR223

BOEING AIRCRAFT HOLDING CO. (BHC)

3 RD181 RJ132

4 RB693 RD451–RD454

BOEING WICHITA MOD CENTER (WMC)

4 RD455

C.A.L. CARGO AIR LINES (CRG)

4 RJ331–RJ332

C.I.T. LEASING CORPORATION (TCI)

3 RB011 RD047

CAPITAL ASSET MANAGEMENT (CPG)

3 RD053

CARGAIR (CGL)

3 RD203

CARGO B AIRLINES (CBO)

3 RR561

CATHAY PACIFIC AIRWAYS (CAT)

3 RD581

4 RD358

CORSAIR (COR)

5 RS239–RS240

DUBAI AIR WING (DAW)

3 RD622

EL AL ISRAEL AIRLINES (ELA)

4 RR225–RR226
 

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BOEING SERVICE BULLETIN 747-53A2303

ELITE AIRLINES S.A. (ETE)

4 RB696

EUROPEAN AVIATION AIR CHARTER (EUL)

4 RD135–RD138

EVERGREEN INTERNATIONAL A/L (EVR)

1 RA028 RA631 RA633

3 RB604 RB607 RD004 RD041–RD043

RJ131 RJ133

4 RD772–RD773

EVERGREEN TRADE INC. (EVG)

1 RA371

3 RD056–RD057 RD241 RD243 RD254–RD255

RD257

EXPORT RESTRICTED AIRPLANES (YWV)

1 RA101–RA103 RA112 RA161–RA163

3 RG141–RG142 RG171

4 RB711 RD681–RD682 RG101–RG104 RR001–RR004

FINOVA (GRB)

1 RA651

GA TELESIS, LLC (GTG)

4 RB692 RB697

GE (GEC)

1 RA016

GECAS (GEF)

1 RA007 RA013 RA027

GENERIC CUSTOMER/SUPPLIER (XXX)

3 RR202–RR203

4 RD104 RD592

5 RD382

GLOBAL AIR LEASING (GAO)

3 RG164

GLOBAL PEACE INITIATIVE (GPI)

3 RG174

GRACE CATHEDRAL INC. (GCI)

4 RG193

HORTA (HOB)

3 RG163

INTERNATIONAL AIR LEASES (IAL)

3 RB006
 

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BOEING SERVICE BULLETIN 747-53A2303

IRAQI AIRWAYS (IRQ)

3 RG095 RG172 RJ301–RJ303

JAL INTERNATIONAL (JAL)

5 RS251–RS252 RS254

JET AERO HOLDINGS (JHD)

3 RG122

JOHNSON SPACE CENTER (ZBR)

1 RA908

3 RB601 RG091

JUMBO JET LEASING (JJL)

1 RA526 RA532–RA534 RA539

KABO AIR (KAB)

1 RA560

2 RA305

3 RB008 RD121

4 RA316

KALITTA AIR (KAC)

1 RA401–RA402 RA524 RA635 RA913

3 RA546 RA548 RB605 RD052

RD054 RD083 RD224–RD225 RD571

RD621 RD623 RR262 RR265

RR361–RR362

4 RD221 RR261 RR501

KUWAIT AIRWAYS (KUW)

3 RD202 RD204

L-3 COMMUNICATIONS (LCS)

4 RD352

LOGISTIC AIR, INC. (LGA)

1 RA015 RA217 RA910

4 RB722–RB723

MK AIRLINES (MKA)

3 RD055 RD441 RD781 RR022–RR023

RR264 RR336

4 RR224 RR421 RR504

NEA HOLDINGS, INC. (NEA)

1 RB001

3 RD045–RD046

NIPPON CARGO AIRLINES (NCA)

4 RR552–RR553
 

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BOEING SERVICE BULLETIN 747-53A2303

NORTHWEST AIRLINES (NWA)

3 RD242 RD251–RD253 RD258–RD259 RR341–RR342

RR344–RR345

4 RR005 RR503

OMAN ROYAL FLIGHT (RFO)

3 RG161

ORIENT THAI AIRLINES (OTH)

1 RA540

3 RA528 RA543–RA544

4 RD222 RD516

5 RS253 RS292 RS712

PAKISTAN INT'L AIRLINES (PIA)

4 RD701–RD702

5 RS301

PHUKET AIRLINES (PHK)

4 RD421–RD424

5 RD381 RD605 RS238 RS241

RS711

POLAR AIR CARGO (PAO)

4 RD752

PRATT & WHITNEY ENGINE SERVICE (PWE)

3 RG213

4 RG222

PRONAIR (TXI)

4 RR221

QANTAS (QAN)

5 RS273

ROYAL AIR MAROC (RAM)

3 RD671

SATAIR (SAI)

5 RD606

SAUDI ARABIAN AIRLINES (SVA)

3 RB741–RB746 RB748 RH121

5 RS311–RS315

SAUDI ROYAL FLIGHT (SRF)

3 RH101 RH122

5 RS699

SKYLEASE I DBA TRADEWINDS AIRLINES (TWN)

3 RD461

4 RA726
 

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BOEING SERVICE BULLETIN 747-53A2303

SOUTH AFRICAN AIRWAYS (SAA)

5 RS212 RS232 RS236

SOUTHERN AIR (SOF)

3 RD411–RD412 RD583 RR302–RR305

4 RB695 RD272 RD642–RD643 RD751

RR551

5 RD383 RD601–RD602 RD607 RS721

STAR AIRLINES (SRQ)

4 RD426

SUO1 (UO1)

3 RB013–RB016

TESIS AVIATION ENTERPRISE (TEV)

3 RA784

TRANSAERO AIRLINES (TRX)

3 RD226 RD471–RD475

4 RD356

5 RS271

TRANSATLANTIC INTL AIRLINES (TIB)

3 RG173

UPS (UPS)

1 RA026 RA029 RA033 RA902

RA912 RA915–RA916

3 RD051 RD058–RD059

4 RD593

VIRGIN ATLANTIC AIRWAYS (VAA)

4 RD357

WHIRLPOOL FINANCIAL CORP. (ZZW)

1 RB005

WINGS WORLD WIDE (WWW)

4 RG221

WORLDWIDE AIRCRAFT HOLDING CO. (WAH)

3 RG008

YEMENIA (YEM)

3 RG162

YONA (IOP)

3 RG009

4 RG191
 

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IDENTIFICATION BY VARIABLE NUMBER

Variable Group

RA001–RA007 1

RA009 1

RA011–RA020 1

RA022–RA034 1

RA101–RA110 1

RA112–RA115 1

RA161–RA164 1

RA201 1

RA203 1

RA216–RA217 1

RA245 2

RA251–RA259 1

RA261–RA266 3

RA301–RA308 2

RA309 1

RA310 2

RA311 1

RA312 2

RA313–RA318 4

RA351–RA360 1

RA369–RA373 1

RA401–RA414 1

RA415–RA418 3

RA501–RA502 1

RA521–RA527 1

RA528 3

RA532–RA535 1

RA537–RA540 1

RA541–RA548 3

RA551–RA552 1

RA559–RA561 1

RA581–RA582 1

RA585 1

RA601–RA602 1

RA631–RA635 1

RA651–RA652 1

RA671–RA675 2
 

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RA677 2

RA701–RA702 1

RA722–RA724 2

RA725–RA726 4

RA728–RA731 4

RA741–RA743 2

RA744–RA745 4

RA749–RA750 4

RA761–RA762 1

RA781–RA782 1

RA783–RA784 3

RA901–RA916 1

RB001–RB005 1

RB006–RB016 3

RB041–RB044 1

RB071–RB075 1

RB101–RB102 1

RB601–RB602 3

RB604–RB607 3

RB681–RB697 4

RB711 4

RB721–RB723 4

RB741–RB748 3

RD001–RD002 1

RD003–RD004 3

RD021–RD022 3

RD041–RD059 3

RD071–RD072 3

RD081–RD083 3

RD091 3

RD101–RD102 3

RD103–RD104 4

RD121–RD127 3

RD131–RD144 4

RD171–RD172 3

RD181–RD183 3

RD201–RD204 3

RD221–RD222 4

RD223–RD226 3

Variable Group
 

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RD241–RD243 3

RD251–RD259 3

RD271–RD272 4

RD351–RD358 4

RD361–RD366 3

RD381–RD383 5

RD411–RD414 3

RD421–RD426 4

RD431–RD435 3

RD441–RD442 3

RD451–RD456 4

RD461 3

RD471–RD475 3

RD513–RD519 4

RD531–RD533 4

RD551 3

RD561 4

RD571 3

RD581–RD583 3

RD592–RD593 4

RD601–RD607 5

RD621–RD623 3

RD641–RD649 4

RD651–RD655 4

RD657–RD658 4

RD661 4

RD671 3

RD681–RD682 4

RD691–RD692 3

RD701–RD702 4

RD721–RD722 5

RD741–RD742 3

RD751–RD754 4

RD761 4

RD771–RD773 4

RD781–RD782 3

RE001 4

RG001–RG009 3

RG091 3

Variable Group
 

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RG095 3

RG101–RG104 4

RG121–RG126 3

RG141–RG142 3

RG161–RG164 3

RG171–RG174 3

RG191–RG193 4

RG211–RG213 3

RG221–RG222 4

RH101 3

RH111–RH112 4

RH121–RH122 3

RJ131–RJ133 3

RJ151–RJ152 3

RJ301–RJ303 3

RJ331–RJ333 4

RR001–RR005 4

RR021–RR023 3

RR031 3

RR201 1

RR202–RR204 3

RR221–RR226 4

RR261 4

RR262–RR265 3

RR301 4

RR302–RR306 3

RR331–RR332 3

RR336 3

RR341–RR345 3

RR361–RR362 3

RR421–RR422 4

RR501 4

RR503–RR504 4

RR521 3

RR531 3

RR551–RR553 4

RR561 3

RS211–RS212 5

RS221–RS222 5

Variable Group
 

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BOEING SERVICE BULLETIN 747-53A2303

2. Spares Affected

None.

B. Concurrent Requirements

None.

C. Reason

As a result of the Federal Aviation Administration (FAA) Sponsored Aging Fleet Conference, a 747 

Structures Working Group with Airline and Boeing members and FAA observers was formed to review 

structural service bulletin modifications and recommend selected service bulletins for incorporation on 

aging airplanes. These service bulletin modifications have been recommended for incorporation on 

aging 747 airplanes.

Accomplishment of the inspection programs and modifications described in this service bulletin will 

ensure the structural integrity of the fuselage skin lap splice along the left and right stringer 6 from 

Station (STA) 400 to 520 throughout the operational life of the airplane.

One operator reported fuselage skin cracks of 0.16 inch long at 10 rivet locations in the upper fastener 

row of the left stringer 6 skin lap splice between STA 400 and 420 on one airplane. This airplane had 

accumulated 29,439 flight hours and 22,248 reduce pressure cycles (approximately 19,000 equivalent 

full pressure cycles). Investigation revealed the cracks were initiated in the fastener countersinks and 

were propagated by cabin pressurization cyclic loading.

A structural reassessment of the 747 airplane was made under the requirements of FAA Advisory 

Circular 91-56, in accordance with Federal Aviation Regulation (FAR) 25.571 as amended in 1978, to 

ensure the safe operation of 747 airplanes throughout their operational life. As a result of this 

reassessment, the stringer lap splice, left and right sides, between STA 400 and 520 have been 

determined to be structurally significant and critical to the structural integrity of the airplane. Skin 

cracks not detected prior to reaching critical crack length many result in in-flight depressurization of 

the airplane and the inability to withstand current regulatory fail-safe loads.

RS231–RS241 5

RS251–RS254 5

RS271–RS273 5

RS291–RS292 5

RS301 5

RS311–RS315 5

RS699 5

RS701–RS702 5

RS711–RS712 5

RS721 5

Variable Group
 

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BOEING SERVICE BULLETIN 747-53A2303

The modifications contained in this service bulletin do not alter the skin lap splices structural 

environment such that a flight safety inspection is no longer required. Therefore, a flight safety 

inspection program is defined in this bulletin which will continue throughout the operational life of the 

airplane.

This service bulletin is the subject of Federal Aviation Administration (FAA) Airworthiness Directive 

(AD) 90-21-17. AD 90-21-17 supersedes AD 89-05-03.

Boeing Service Related Problem (SRP) 747OP-SRP-53-0292 is related to this service bulletin.

Revision 1 is issued to recommend modification per this service bulletin for incorporation on aging 747 

airplanes. The incorporation threshold for this service bulletin is shown in the Description and 

Accomplishment Instructions. In addition, this revision is also issued to formalize and update Telex 

Alert Service Bulletin 747-53A2303, to add an economics based initial inspection program, provides 

complete details on the external doubler modification, and adds reference to Federal Aviation 

Administration Airworthiness Directive AD-89-05-03, Amendment 39-6146.

Revision 2 is sent to update inspection requirements and to update the post modification inspection 

requirements for airplanes that have accomplished a modification as shown in the initial release and/

or Revision 1 of this service bulletin. This revision is also sent to remove the optional top row 

protruding head fastener modification, as well as modifications per certain SRM repairs.

Changes to this service bulletin include:

– Airworthiness Directive (AD) 90-21-17 supersedes AD 89-05-03.

– Specific repair figures in SRM 53-30-03 are referenced as an acceptable modification.

– Compliance information is added to Paragraph 1.E., Compliance. Existing compliance 

information to accomplish the Flight Safety Inspection Program, the Economics Based Inspection 

Program and the modification has been moved from the logic diagrams in Figure 1 to Tables 1 

and 2 of Paragraph 1.E., Compliance. Compliance information for the repeat post modification 

inspections is included in Table 3 of Paragraph 1.E., Compliance. New compliance information 

for the inspection and modification of airplanes with certain SRM repairs or the optional top row 

protruding head fastener modification that was shown in the original release and Revision 1 of 

this service bulletin is added to Tables 4 and 5.

– The 747 Non-Destructive Test manual, Boeing service bulletins, a Service Related Problem, a 

Boeing Document, an AD and SRM references are added to Paragraph 1.J., References.

– Primer and Sealant are added to the Parts and Materials Supplied by the Operator.

– Paragraph 3.B., Work Instructions have been extensively rewritten.

– Figure 1 is deleted. The information previously in the logic diagrams has been moved to the 

tables in Paragraph 1.E., Compliance.

– The NDT procedures referenced in Figure 2 have been changed.

– Figure 4 is deleted to remove the top row protruding head fastener modification.

– Figure 5 is added to inspect the top row protruding head fastener modification accomplished by 

previous releases of this service bulletin for cracks.

– Figure 6 is added to provide inspections for airplanes with doublers installed by this service 

bulletin and doublers installed by service bulletin 747-53A2321 for cracks.

– Figure 7 is added to provide inspections for airplanes with doublers installed by this service 

bulletin and the skin replacement modification by service bulletin 747-53A2321 for cracks.

– Figure 8 is added to provide alternative inspections to the Figure 6 inspections for cracks.

– Figure 9 is added to provide alternative inspections to the Figure 7 inspections for cracks.

– Appendix B is added to provide alternative lap splice trim instructions.

– Appendix C is added to show how the Drawing 141U2100 modification doublers should be 

changed when an SRM repair is present in the modification area.
 

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D. Description

As recommended by the 747 Aging Fleet Structures Working Group, accomplish a modification per 

the accomplishment instructions at or before the accumulation of 23,000 flight-cycles. Airplanes on 

which a protruding head fastener modification or a modification as given in certain SRM repairs are 

required to accomplish the external doubler modification given in this service bulletin at the time given 

in Paragraph 1.E., Compliance, Table 5.

This service bulletin defines a flight safety inspection program and an economics based inspection 

program to detect cracking of the skin lap splice along the left and right stringer 6 between STA 400 

to 520. Modifications are also described that will improve the resistance to this cracking. An aftermodification inspection program is also defined. The flight safety and economics based inspection 

programs differ in inspection thresholds and basic intent. The modifications described herein are 

alternatives to the repeated initial flight safety or economics based inspections, but incorporation does 

not eliminate the need for the flight safety after modification inspections.

NOTE:

1. Concurrent incorporation of Boeing service bulletin 747-53-2272 "FUSELAGE - Nose 

Section 41 Body Frame Structure Replacement and Reinforcement" Zone 2 

modification and Boeing service bulletin 747-53-2253, "FUSELAGE - Nose Section - 

Station 340 to 400 Stinger 6 Inspection and Modification", is recommended because of 

similar access and inspection requirements.

2. For Group 1 and Group 2 airplanes to be modified per this service bulletin revision 1 or 

later should, concurrent with any of the modification described herein delaminate 

stringer 6 skin lap splice, remove adhesive and replace with fay surface sealant in 

accordance with 747 Structural Repair Manual Subject 53-30-03 Figure 10. Group 2 

airplanes are not required to delaminate the left stringer 6 skin lap splice where the skin 

lap splice contains four rows of fasteners.

3. Initial inspection thresholds shall be determined from the total number of pressurized 

flights that obtain a 2.0 psi pressure differential or greater.

4. On group 5 airplanes which have been modified to the Stretched Upper Deck (SUD), 

280 inch extension per MC 42360-( ), the above initial inspection thresholds are 

measured from the time of the SUD modification, when the body skin panel in this area 

were replaced.

5. Airplanes that have previously been modified per Structural Repair Manual 53-30-03 

Figure 10 along the left and right stringer from STA 400 to 520 prior to the initial release 

of this service bulletin, without accomplishing the initial flight safety inspection program 

of this bulletin, are to be inspected at the thresholds specified in the flight safety 

inspection program, but a different inspection procedure is defined herein.

6. On Group 1 and 2 airplanes, the instructions for the structural modification will be based 

on the condition of the individual airplane modified. Operators will need to make a 

contract with Boeing to get instructions as given in Paragraph 1.E., Compliance.

Flight Safety Inspection Program:
 

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The flight safety inspection program is the minimum inspection program necessary to ensure the 

structural integrity of the affected skin lap splice throughout the operation life of the airplane. The intent 

of this inspection program is to detect cracks between STA 400 to 520 on the left and right stringer 6 

of the fuselage skin lap splice prior to their reaching critical crack length. Since the program is 

concerned only with safety, without economic consideration any cracking found may be extensive and 

potentially costly to repair.

For airplanes on which the full modification per this bulletin has not been previously accomplished, 

initiate a detailed and eddy current inspection at the time given in Paragraph 1.E., Compliance, Table 

1.

If no cracks are indicated, reinspect at the time given in Paragraph 1.E., Compliance. As an 

alternative, install the external doubler modification over the skin lap splice as given in this service 

bulletin.

At all unmodified areas of the skin lap splice, repeat the initial inspections at the time given in 

Paragraph 1.E., Compliance, Table 1.

For any lap splice which requires repair per the 747 SRM for cracking per this bulletin Revision 2 or 

later, the lap splice should have incorporated the modification specified per this service bulletin at the 

time given in Paragraph 1.E., Compliance.

After modification, internal and external eddy current inspections are required on modified areas of the 

skin lap splice at the times given in Paragraph 1.E., Compliance, Table 3. As an alternative, the post 

modification inspections required per this service bulletin may be performed using external methods 

only, but with a reduced repeat interval as given in Paragraph 1.E., Compliance, Table 3.

The flight safety addendum is a summary of the required inspection. Refer to Appendix A.

Economics Based Inspection Program - Operator’s Option:

The economics based inspection program applies only to those affected airplanes on which a 

modification has not been accomplished. On these airplanes, at the operator’s option, this inspection 

program may be implemented in lieu of the initial flight safety inspection until a modification is 

accomplished. After modification inspections are in accordance with the "Flight Safety Inspection 

Program". The intent of this optional program is to give guidance to enable the operator to initiate 

inspection and modification prior to extensive skin lap splice cracking which may result in more costly 

repairs.

For applicable airplanes, initiate detailed and eddy current inspections as given in Paragraph 1.E., 

Compliance, Table 1. The repeat inspection interval, inspection methods, and options are the same 

for both inspection programs.

Modification:

As recommended by the 747 Aging Fleet Structures Working Group, modification should be 

accomplished at or before the accumulation of 23,000 flight-cycles.

The modification consists of installing the specified external doubler modification to the skin lap splice. 

This modification improves the fuselage skin lap splice resistance to cracking between STA 400 to 

520 along the left and right stringer 6. However, this modification does not alter the skin lap splice’s 

structural environment such that a flight safety inspection is no longer required. Start to do the postmodification inspections at the time given in Paragraph 1.E., Compliance, Table 3.
 

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BOEING SERVICE BULLETIN 747-53A2303

This service bulletin is the subject of Federal Aviation Administration (FAA) Airworthiness Directives 

(AD) 90-21-17 and 90-06-06.

This service bulletin is listed in Boeing Document D6-35999.

PLEASE REPORT YOUR PLANNED ACTION AND INSPECTION RESULTS TO BOEING 

CUSTOMER SUPPORT AS SOON AS EACH INSPECTION IS COMPLETE.

THESE REPORTS WILL ASSIST BOEING IN COMPILING DATA RELATIVE TO FLEET SERVICE 

EXPERIENCE AND PROVIDE FOR THE MOST COST EFFECTIVE MEANS OF RESOLVING THE 

REPORTED PROBLEM.

NOTE: Contact Boeing for instructions if any damaged areas exceed the specified limits. To expedite

Boeing response, be specific when defining and locating damage. Circumstances leading to

the damage and any secondary effects, when known, should be included in the

communication and followed by sketches and photographs when appropriate. In addition,

where corrosion is involved, length, width, and greatest depth of clean-up are required.

CONTACT: BOEING COMMERCIAL AIRPLANES

 ATTENTION: MANAGER, AIRLINE SUPPORT

Revision 2 - More work is necessary on airplanes on which the Flight Safety inspections are being 

accomplished. The repeat inspection interval has been reduced from 5,000 flight-cycles to 3,000 

flight-cycles since the last Flight Safety inspection was accomplished, or within 1,000 flight-cycles 

after the date on Revision 2, whichever occurs later. More work is also necessary on airplanes 

modified as shown in the initial release and/or Revision 1 of this service bulletin. Airplanes that have 

accomplished a protruding head fastener modification or a modification as given in certain Structural 

Repair Manual (SRM) repairs will be required to accomplish the doubler modification as given in 

Paragraph 1.E., Compliance. In addition, airplanes that have had a structural modification 

accomplished as given in the SRM or other Boeing service bulletins will be required to accomplish post 

modification inspections as given in Paragraph 1.E., Compliance.

E. Compliance

The Federal Aviation Administration (FAA) will possibly release another Airworthiness Directive 

related to this service bulletin. The Airworthiness Directive will make the compliance tasks and times 

given in this service bulletin mandatory.

Federal Aviation Administration (FAA) Airworthiness Directives 90-21-17 and 90-06-06 are related to 

this service bulletin.
 

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BOEING SERVICE BULLETIN 747-53A2303

Boeing recommends operators do the inspections and modifications shown in this service bulletin at 

the following intervals:

Table 1: Flight Safety and Economics Based Inspection Programs

Condition Action

Compliance Time (Whichever 

Occurs Later)

Repeat Interval 

(Not to Exceed)

Airplanes with 16,000 total 

flight-cycles or more as of 

March 31, 1989 that have 

not had the modification 

shown in any version of 

this service bulletin done. 

(a) (d) (e) (f) (g) (i)

Inspect the skin lap splice 

between STA 400 and 

520 for cracks at 

unmodified areas as 

given in Paragraph 3.B., 

PART 1.

Within 100 flight-cycles after 

March 31, 1989, unless previously 

accomplished within the last 4,900 

flight-cycles before March 31, 

1989. (i)

-

Airplanes with between 

12,000 and 16,000 total 

flight-cycles as of March 

31, 1989, that have not 

had the modification 

shown in any version of 

this service bulletin done. 

(a) (d) (e) (f) (g) (i)

Inspect the skin lap splice 

between STA 400 and 

520 for cracks at 

unmodified areas as 

given in Paragraph 3.B., 

PART 1.

Before 16,100 total flight-cycles or 

within 1,000 flight-cycles after 

March 31, 1989, whichever occurs 

first, unless previously 

accomplished within the last 4,000 

flight-cycles before March 31, 

1989. (a) (i)

-

Airplanes with 12,000 total 

flight-cycles or less as of 

March 31, 1989 that have 

not had the modification 

shown in any version of 

this service bulletin done. 

(a) (d) (e) (f) (g) (i)

Inspect the skin lap splice 

between STA 400 and 

520 for cracks at 

unmodified areas as 

given in Paragraph 3.B., 

PART 1.

Before 13,000 total flight-cycles, 

unless previously accomplished 

within the last 5,000 flight-cycles 

before March 31, 1989. (a) (d) (i)

-

Airplanes that have had 

the modification shown in 

the initial release or 

Revision 1 or Revision 2 of 

this service bulletin done.

Refer to Table 3: Post 

Modifications 

Inspections.

Refer to Table 3: Post 

Modifications Inspections

Refer to Table 3: 

Post 

Modifications 

Inspections

Crack(s) found. Install a repair as given in 

Paragraph 3.B., PART 2. 

(b) (e)

Before further flight. (h)

As an alternative, do the 

modification as given in 

Paragraph 3.B., PART 3. 

(b) (c)

No crack(s) found. (j) Repeat inspections as 

given in Paragraph 3.B., 

PART 1.

Within 3,000 

flight-cycles 

after the last 

inspection.

Within 1,000 

flight-cycles 

after the date on 

Revision 2 of 

this service 

bulletin.

3,000 flightcycles (b)

As an alternative, do the 

modification as given in 

Paragraph 3.B., PART 3. 

(b) (c)

(a) On Group 5 airplanes that have been modified by Boeing to the Stretched Upper Deck (SUD) 

configuration, the initial inspection thresholds should be calculated from the time that the SUD modification 

was accomplished, when the skin panel in this area was replaced.
 

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(b) Accomplishment of the modification given in Table 2 terminates the requirement for repeat inspections 

given in this table.

(c) After accomplishment of the modification, do the post modification inspections as given in Table 3.

(d) For the economics based inspection program, start to do the inspections at or before 8,000 total flightcycles.

(e) Local repairs accomplished on the lap splice must be removed and the structural modification as given in 

Paragraph 3.B., PART 3 must be installed before the accumulation of 23,000 total flight-cycles or within 30 

months after repair installation, whichever occurs earlier. Refer to Table 2.

(f) For airplanes that have had the Service Bulletin 747-53A2321 modification installed, refer to Table 3 for 

post-modification inspections.

NOTE:FAA AD 2006-24-02 mandates the Service Bulletin 747-53A2321 modification for airplanes line 

number 1 through 200 at 20,000 total flight-cycles. The Service Bulletin 747-53A2321 modification was 

optional for all other affected airplanes.

(g) For Groups 1 and 2 airplanes (line number 1 - 200) that have had the skin lap joint cold bond 

delamination repair given in 747-100/200/300 SRM 53-30-03 Figure 10 accomplished, and have also had 1/

16 inch diameter oversize protruding head fasteners installed in the upper row, treat this configuration as a 

modification and refer to Table 3 for Post-modification inspections.

(h) After accomplishment of the repair, until the structural modification given in Paragraph 3.B, PART 3 is 

done, any additional requirements given in the applicable SRM must be followed, including repeat 

inspections of blind fasteners.

(i) March 31, 1989 is the effective date of FAA AD 89-05-03, which was superseded by FAA AD 90-21-17.

(j) This applies to unmodified sections of the lap splice outside the repair area.

Table 2: Modification

Condition Action Compliance Time

All airplanes where no previous 

modifications or repairs have been 

installed in the affected area.

Accomplish the structural 

modification as given in 

Paragraph 3.b., PART 3. (a)

Before 23,000 total flight-cycles 

or within 4 years after April 17, 

1990 (the effective date of FAA 

AD 90-06-06), whichever 

occurs later.

Airplanes that have not had the 

structural modification 

accomplished, but that have had 

lap joint repairs accomplished. 

Remove any existing repairs 

and accomplish the structural 

modification as given in 

Paragraph 3.b., PART 3. (a) (b)

Before 23,000 total flight-cycles 

or within 30 months after repair 

installation, whichever occurs 

earlier.

(a) After accomplishment of the modification, do the post modification inspections as given in Table 3.

(b) Until the structural modification given in Paragraph 3.B, PART 3 is accomplished, any additional 

requirements as given in the SRM must be followed, including repeat inspections for blind fastener 

repairs.

Table 1: Flight Safety and Economics Based Inspection Programs

Condition Action

Compliance Time (Whichever 

Occurs Later)

Repeat Interval 

(Not to Exceed)
 

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BOEING SERVICE BULLETIN 747-53A2303

Table 3: Post Modification Inspections

Condition Action

Compliance Time

(Whichever Occurs Later)

Repeat Interval 

(Not to Exceed)

Airplanes modified 

with the Service 

Bulletin 747-

53A2321 repair 

doubler installation 

and the Drawing 

141U2100 doubler 

installation. (b) (c)

Accomplish an 

internal and 

external HFEC 

inspection for 

cracks as given in 

Paragraph 3.B., 

PART 4. (a)

Within 10,000 

flight-cycles after 

the modification 

was installed. (f)

Within 1,000 flight cycles after 

the date on Revision 2 of this 

service bulletin or 5,000 flight 

cycles after the last detailed 

and High Frequency Eddy 

Current inspection of the skin 

lap splice as given in a 

previous version of this service 

bulletin, whichever occurs first. 

-

Airplanes that have 

had the structural 

modification as 

given in Drawing 

141U2100 

accomplished. (b) 

(c) (e)

Accomplish an 

internal and 

external HFEC 

inspection for 

cracks as given in 

Paragraph 3.B., 

PART 4. (a)

Within 10,000 

flight-cycles after 

the modification 

was installed.

Within 1,000 flight cycles after 

the date on Revision 2 of this 

service bulletin or 5,000 flight 

cycles after the last detailed 

and High Frequency Eddy 

Current inspection of the skin 

lap splice as given in a 

previous version of this service 

bulletin, whichever occurs first. 

-

Airplanes that have 

had a structural 

modification as 

given in 747 SRM 

53-30-03 Figure 

19, 25, 28, or 34 

accomplished for 

the full length of the 

lap joint. (b) (d)

Accomplish an 

internal and 

external HFEC 

inspection for 

cracks as given in 

Paragraph 3.B., 

PART 4. (a)

Within 10,000 

flight-cycles after 

the modification 

was installed.

Within 1,000 flight cycles after 

the date on Revision 2 of this 

service bulletin or 5,000 flight 

cycles after the last detailed 

and High Frequency Eddy 

Current inspection of the skin 

lap splice as given in a 

previous version of this service 

bulletin, whichever occurs first. 

-

Airplanes that have 

had a protruding 

head fastener 

modification or any 

SRM modification 

other than 747-100/

200/300 SRM 

53-30-03 Figure 

19, 25, 28, or 34 for 

the full length of the 

lap splice. (c)

Refer to Table 4 

and Table 5 for 

inspections and 

modification.

Refer to Table 4 and Table 5 for inspections and 

modification.

Refer to Table 4 

and Table 5 for 

inspections and 

modification.

No crack(s) found. Repeat 

inspection as 

given in 

Paragraph 3.B., 

PART 4. (a)

Within 3,000 

flight-cycles after 

the last postmodification 

inspection.

Within 1,000 flight-cycles after 

the date on Revision 2 of this 

service bulletin.

3,000 flightcycles (a)

Crack(s) found Contact Boeing 

for repair 

instructions and 

do the repair.

Repair before further flight. -
 

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BOEING SERVICE BULLETIN 747-53A2303

(a) As an alternative, do inspections for cracks as shown in Figure 8 or Figure 9. The repeat inspection 

interval is 800 flight-cycles.

(b) If the lower skin panel was replaced as given in Boeing Service Bulletin 747-53A2321, but the external 

doubler was not installed, this inspection is not applicable. Contact Boeing for inspection instructions or do 

inspections in accordance with Table 1.

(c) On Group 1 and 2 airplanes, more work may be required on airplanes that were delivered with cold 

bonded lap splices. Contact Boeing for further information and/or instructions regarding this issue as given in 

Table 5. Boeing Service Bulletins 747-53A2463, 747-53-2253, 747-53A2267, and 747-53-2307 are also 

related to this issue.

(d) In areas of the crew entry door, the 747 SRM repair/modification should not extend forward of STA 425. 

If it extends forward of STA 425, contact Boeing for inspection instructions.

(e) Includes doubler configurations modified as given in Appendix C.

(f) Compliance time since installation of the Drawing 141U2100 modification.

Table 4: Inspections of Certain Configurations

Condition Action

Compliance Time

(Whichever Occurs Later)

Repeat Interval 

(Not to Exceed)

In areas where a 747 SRM 

external doubler repair was 

installed as a modification, 

except as given in 747 SRM 

53-30-03 Figure 19, 25, 28, 

or 34 for the full length of the 

lap joint. (a)

Accomplish an internal 

HFEC inspection for 

cracks as given in 

Paragraph 3.B., PART 

5.

Within 10,000 

flight-cycles after 

the structural 

modification was 

installed.

Within 500 flightcycles after the 

date on Revision 

2 of this service 

bulletin.

-

In areas where a protruding 

head fastener modification 

was installed as given in the 

initial release or Revision 1 

of this service bulletin.

Accomplish an external 

HFEC inspection for 

cracks as given in 

Paragraph 3.B., PART 

5.

Within 10,000 

flight-cycles after 

the structural 

modification was 

installed.

Within 500 flightcycles after the 

date on Revision 

2 of this service 

bulletin.

-

Crack(s) found Install a repair as given 

in Paragraph 3.B., 

PART 2. (b) (d)

Before further flight. (c)

As an alternative, 

accomplish the 

modification as given 

in Paragraph 3.B., 

PART 3. (b)

Affected areas where no 

crack(s) were found.

Repeat inspection as 

given in Paragraph 

3.B., PART 5.

Within 500 flight-cycles after the 

last inspection.

500 flight-cycles 

(b)

(a) In areas of the crew entry door, the 747 SRM repair/modification should not extend forward of STA 425. 

If it extends forward of STA 425, contact Boeing for inspection instructions.

Table 3: Post Modification Inspections

Condition Action

Compliance Time

(Whichever Occurs Later)

Repeat Interval 

(Not to Exceed)
 

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BOEING SERVICE BULLETIN 747-53A2303

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.

(b) Accomplishment of the modification given in Table 5 is required and terminates the requirement for 

repeat inspections given in this table.

(c) After accomplishment of the repair, until the structural modification given in Paragraph 3.B, PART 3 is 

done, any additional requirements given in the applicable SRM must be followed, including repeat 

inspections of blind fasteners.

(d) Local repairs accomplished on the lap splice must be removed and the structural modification must be 

installed within 30 months of the repair as given in Paragraph 3.B., Part 3.

Table 5: Modification of Certain Configurations

Condition Action

Compliance Time

(Whichever Occurs Later)

Airplanes that have accomplished 

a protruding head fastener 

modification and/or a SRM 53-30-

03 repair or modification that is 

not per Figure 19, 25, 28, or 34 for 

the full length of the lap splice. (b)

Accomplish the 

Structural Modification 

as given in Paragraph 

3.B., PART 3.

Within 14,000 flightcycles after the first 

modification was 

installed. (a)

Within 3,000 flightcycles after the date on 

Revision 2 of this 

service bulletin. (a)

(a) After the modification doubler installation, refer to Table 3 for Post Modification inspections. The post 

modification inspection thresholds are measured from the time of the modification doubler installation.

(b) On Group 1 and 2 airplanes, the instructions for the structural modification will be based on the condition 

of the lap splices on the individual airplane to be modified. Operators will need to make a contract with 

Boeing to get instructions for the structural modification. It is suggested that operators contact Boeing with 

requests for structural modification data at least one year before the data will be needed to make the 

modification. The airplane is not to be operated without this modification after the compliance time given in 

this table.

Table 4: Inspections of Certain Configurations

Condition Action

Compliance Time

(Whichever Occurs Later)

Repeat Interval 

(Not to Exceed)
 

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BOEING SERVICE BULLETIN 747-53A2303

This service bulletin has been approved by the FAA. In addition, the Manager of the FAA Seattle 

Aircraft Certification Office (ACO) approves the accomplishment of the applicable inspection and 

repair procedures of this service bulletin and the structural modification (and associated postmodification inspection) procedures specified in paragraph 1.E., Compliance of this service bulletin as 

an AMOC to the corresponding requirements of paragraphs A., B., C., D., and E. of AD 90-21-17. This 

AMOC only applies to the areas inspected as given in this service bulletin. When this service bulletin 

specifies contacting Boeing for repair instructions, the repair instructions must be approved by the 

FAA in accordance with paragraph G. of the AD. All provisions of AD 90-21-17 that are not specifically 

referenced in this paragraph remain fully applicable and must be complied with.

The Manager of the FAA Seattle ACO also approves the accomplishment of the structural modification 

procedures specified in Tables 2 and 5 of paragraph 1.E., Compliance of this service bulletin as an 

AMOC to the corresponding requirements of paragraph (A) of AD 90-06-06. This AMOC only applies 

to the areas modified as given in this service bulletin. When this service bulletin specifies contacting 

Boeing for repair instructions, the repair instructions must be approved by the FAA in accordance with 

paragraph C. of the AD. All provisions of AD 90-06-06 that are not specifically referenced in this 

paragraph remain fully applicable and must be complied with.

G. Manpower

The table below shows an estimate of the task hours necessary to do this service bulletin for each 

airplane. 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

— Time to inspect the work

— Time to cure the materials

— Time to make the parts

— Time to find the tools.

TABLE 1: Initial Inspection (Modification Not Accomplished) (Paragraph 3.B., PART 1)

Task

Number of Persons Task Hours Elapsed Hours

Left Right Left Right Left Right

Initial Flight Safety Inspection

All Groups 1 1 2 2 2 2

Economics Based Inspection.

All Groups 1 1 1 1 1 1

TABLE 2: Structural Modification (Paragraph 3.B., PART 3)

Task

Number of Persons Task Hours Elapsed Hours

Left Right Left Right Left Right

Access

All Groups 2 2 10 14 5 7

Open Hole Inspection

All Groups 113333

Fastener Modification

Group 1 Airplanes 2 2 12 10 6 5
 

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BOEING SERVICE BULLETIN 747-53A2303

Group 2 Airplanes 2 2 10 10 5 5

Group 3 Airplanes 2 2 12 10 6 5

Group 4 Airplanes 2 2 10 10 5 5

Group 5 Airplanes 2 2 12 12 6 5

External Doubler Modification

Group 1 Airplanes 2 2 330 330 165 165

Group 2 Airplanes 2 2 310 330 155 165

Group 3 Airplanes 2 2 340 310 170 155

Group 4 Airplanes 2 2 310 310 155 155

Group 5 Airplanes 2 2 340 340 170 170

SRM Modification 

All Groups (a) (a) (a)

Restoration 

All Groups 2 2 10 14 5 7

TOTAL FOR EACH AIRPLANE (b) (b)

(a) Crew size, Man Hours, Elapsed Time is dependant on the extent of the cracking. Estimates must be 

made by the operator on a case by case bases.

(a) Total Man Hours and Elapsed Time is the sum of the Access, Open Hole Inspection, Restoration and the 

individual modification to be accomplished.

TABLE 3: Post Modification Inspections (Paragraph 3.B., PART 4) and Inspection of Certain 

Configurations (Paragraph 3.B., PART 5.)

Task

Number of Persons Task Hours Elapsed Hours

Left Right Left Right Left Right

Top Row Protruding Head 

Fastener Modification 

Inspection (a)

2 2 16 16 8 8

Doubler Inspection (a) 2 2 31 31 15.5 15.5

Doubler and Skin 

Modification Inspection 

(a)

2 2 31 31 15.5 15.5

Doubler Alternative 

Inspection (a)

2 2 38 38 19 19

Doubler and Skin 

Modification Alternative 

Inspection (a)

2 2 30.5 30.5 15.25 15.25

TABLE 2: Structural Modification (Paragraph 3.B., PART 3)

Task

Number of Persons Task Hours Elapsed Hours

Left Right Left Right Left Right
 

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BOEING SERVICE BULLETIN 747-53A2303

NOTE: Additional time will be required for repairs if cracks are found.

H. Weight and Balance Changes

I. Electrical Load Data

Not applicable.

J. References

1. Existing Data:

a. Engineering Change Memo PRR 82284R

SRM Modification 

Inspection (a)

(b) (b) (b)

(a) Operators will not be required to accomplish all of the post modification inspections. The required 

inspection will be determined on the airplanes configuration at the stringer 6 skin lap splice, left and right 

sides.

(b) Crew size, Man Hours, Elapsed Time is dependant on the extent of the repair. Estimates must be made 

by the operator on a case by case bases.

Applicability

Change in Weight (Pounds)

Change in Moment 

(Pound-Inches)

Left Side Right Side Left Side Right Side

Protruding Head Fastener Modification (c)

All Groups +0.1 +0.1 +50 +50

External Doubler Modification

Group 1 Airplanes +19 +19 +8740 +8740

Group 2 Airplanes +20 +19 +10120 +8740

Group 3 Airplanes +22 +20 +10120 +9660

Group 4 Airplanes +20 +21 +10120 +9660

Group 5 Airplanes +23 +23 +10580 +10580

Structural Repair Manual Modification

All Groups (a) (a)

Total (b) (b)

(a) Changes in weight and moment is not given due to the variability of the Structural 

Repair Manual modifications

(b) Total weight and moment change is the sum of the weights or the sum of the 

moments for the modifications made to an individual airplane’s left and right side.

(c) The protruding head fastener modification is deleted in Revision 2.

TABLE 3: Post Modification Inspections (Paragraph 3.B., PART 4) and Inspection of Certain 

Configurations (Paragraph 3.B., PART 5.)

Task

Number of Persons Task Hours Elapsed Hours

Left Right Left Right Left Right
 

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BOEING SERVICE BULLETIN 747-53A2303

b. Engineering Change Memo MC 42360-( )

c. Service Related Problem (SRP) 747OP-SRP-53-0292

d. 747 Maintenance Manual (AMM) Subject 25-21-04, 25-22-03, 25-23-01, 25-24-00, 

25-24-11, 25-24-12, 25-24-19, 25-25-01, 25-25-04, 25-26-02, 25-26-03, 25-26-06, 

25-28-15, 25-28-23, 25-40-03, 52-51-01, 52-51-00, 52-13-01.

e. 747 Structural Repair Manual (SRM) Subject 51-10-02.

f. 747 Structural Repair Manual (SRM) Subject 53-30-03

g. 747 Nondestructive Test (NDT) Manual, Part 6, Subject 51-00-00, 53-30-00, 53-30-03, 

53-30-05, 53-30-10, 53-30-15, 53-30-19

h. Boeing Service Bulletin 747-53-2253 "FUSELAGE - Nose Section - Station 340 to 400 

Stinger 6 Inspection and Modification"

i. Boeing Service Bulletin 747-53-2272 "FUSELAGE - Nose Section 41 Body Frame Structure 

Replacement and Reinforcement"

j. Boeing Service Bulletin 747-53A2321, "FUSELAGE - Skin - Upper Body Skin Inspection 

and Repair at Longitudinal Rows of Fasteners at Stringers Along Flat Side in Section 41"

k. Boeing Service Letter 747-SL-53-44, dated 31 May, 1988

l. FAA Airworthiness Directive 89-05-03, 90-21-17, 90-06-06

m. Boeing Document D6-35999, "Aging Airplane Service Bulletin Structural Modification 

Program, Model 747"

n. Boeing Document D6-36181, "Repair Assessment Guidelines - Model 747"

o. Supplement Structural Inspection Document (SSID) D6-35022 Item F-25

p. Boeing Parts Standards Document D-590

q. Boeing Drawing 012W6100 
 

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BOEING SERVICE BULLETIN 747-53A2303

2. Data supplied with this Service Bulletin:

a. Drawings:

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

None.

4. Process Data:

Boeing Process specifications referred to on the drawings are not given in this service bulletin 

since these procedures are frequently used as standard shop practices.

K. Publications Affected

1. Publications

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 affects FCS and new DTI requirements for the 

structure affected are contained in Paragraph 1.E., Compliance of this service bulletin.

L. Interchangeability and Intermixability of Parts

Refer to Paragraph 2.C., Parts Necessary For Each Airplane, for interchangeability and intermixability 

information.

Drawing Number Title Sheet DCN ADCN

141U2100 Doubler Installation - Exterior 

Stringer 6 Station 400 to 520, 

Repair

PL (a) - -

1 (a) - -

2 (a) - -

3 (a) - -

4 (a) - -

5 (a) - -

(a) Transmitted with Revision 1.

Publication Chapter-Section

747 Structural Repair Manual 53-30
 

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BOEING SERVICE BULLETIN 747-53A2303

2. MATERIAL INFORMATION

A. Material - Price and Availability

Boeing can supply the kits shown in Paragraph 2.C., Parts Necessary For Each Airplane as shown 

below. If there is a limit to the quantity (QTY) of available kits, a supply sequence is given by Spares. 

More kits become available as shown in the Reorder Lead Time (ROLT). ROLT is calculated from the 

date Boeing gets the purchase order.

The kits are subject to the terms and conditions of the Boeing standard purchase order 

acknowledgment. After the Unit Price date, new price and ROLT data is applicable. Prices are in 

United States dollars. Terms: Net 30 days.

Reference this service bulletin and submit your purchase order by one of the methods that follow: 

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

2. Fax to (206) 662-7145

3. Spares Customer Support - MC 36-65

Boeing Spares Department

P.O. Box 3707

Seattle, Washington 98124-2207 USA

B. Industry Support Information

Boeing warranty remedies are not available for the inspection, and/or repair procedures given in this 

service bulletin.

Kit Number Name Date QTY

ROLT 

(Weeks)

Unit Price thru

Mar 29/90

141U2100-1 Doubler Kit 06/22/90 4 22 $319.00

141U2100-3 Doubler Kit 06/22/90 4 22 $515.00

141U2100-4 Doubler Kit 06/22/90 3 22 $515.00

141U2100-5 Doubler Kit 06/22/90 3 22 $325.00

141U2100-6 Doubler Kit 06/22/90 4 22 $325.00

141U2100-7 Doubler Kit 06/22/90 3 22 $318.00

141U2100-8 Doubler Kit 06/22/90 4 22 $516.00
 

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BOEING SERVICE BULLETIN 747-53A2303

C. Parts Necessary For Each Airplane

1. Kits/Parts:

To get the kits/parts shown below, refer to Paragraph 2.A., Material - Price and Availability.

NOTE: One top kit and the items shown in Paragraph 2.C.2., Parts and Materials Supplied by

the Operator, are necessary for each airplane.

Kit 141U2100

New Part 

Number

QTY

-8 -7 -6 -5 -4 -3 -1 Name Notes

141U2100-1 . . . . . . - External Doubler, Group 3, 

Left Side

141U2100-3 . . . . . - . External Doubler, Groups 

2 and 4, Left Side

141U2100-4 . . . . - . . External Doubler, Groups 

3 and 4, Right Side

141U2100-5 . . . - . . . External Doubler, Group 5, 

Left Side

141U2100-6 . . - . . . . External Doubler, Group 5, 

Right Side

141U2100-7 . - . . . . . External Doubler, Group 1, 

Left Side

141U2100-8 - . . . . . . External Doubler, Group 5, 

Right Side

141U2100-11 . 1 . . . . 1 Doubler

141U2100-13 . 1 . . . . 1 Doubler

141U2100-15 . . . . . 1 . Doubler

141U2100-16 1 . . . 1 . . Doubler

141U2100-17 . . . . . 1 . Doubler

141U2100-18 1 . . . 1 . . Doubler

141U2100-19 . . . . 1 . Doubler

141U2100-20 . . . . 1 . . Doubler

141U2100-22 1 . . . . . . Doubler

141U2100-23 . . . 1 . . . Doubler

141U2100-24 . . 1 . . . . Doubler

141U2100-25 . . . 1 . . . Doubler

141U2100-26 . . 1 . . . . Doubler

BACR15CE5D5 614 764 664 664 557 557 705 Rivet

BACR15CE5D6 6 10 10 10 6 6 10 Rivet

BACR15CE5D7 27 . . 27 27 . Rivet

BACR15CE6D8 2 . . . 2 2 4 Rivet

BACR15CE6D10 3 . . . 5 5 . Rivet
 

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BACR15DS7D6 . 2 2 2 . . 2 Rivet

BACR15DS7D7 8 14 16 16 8 8 16 Rivet

BACR15DS7D8 22 28 28 28 22 22 31 Rivet

BACR15DS7D9 29 35 30 30 29 29 31 Rivet

BACR15DS7D10 7 . . . 7 7 . Rivet

BACR15BB5D5 59 115 117 117 59 59 117 Rivet

BACR15BB5D6 98 . . . 65 65 . Rivet

BACR15BB5D7 3 . . . 3 3 . Rivet

BACR15BB6D7 185 257 257 257 185 185 257 Rivet

BACR15BB6D8 25 14 14 14 25 25 10 Rivet

BACR15BB6D9 12 . . . 12 12 . Rivet

BACR15BB6D10 2 . . . . . . Rivet

BACR15BB8D7 94 188 39 39 . . . Rivet

BACR15BB8D8 99 151 23 23 47 47 23 Rivet

BACR15BB8D9 66 28 25 25 66 66 25 Rivet

BACR15BB8D10 35 . 14 14 35 35 . Rivet

BACR15BB8D11 9 . . . 6 6 . Rivet

BACR15ET7D7 6 8 288 288 149 149 288 Rivet

BACR15ET7D8 10 23 148 148 83 83 148 Rivet

BACR15ET7D9 18 6 9 9 28 28 4 Rivet

BACR15ET7D10 53 . . . 58 58 . Rivet

BACR15ET7D11 26 . . . 26 26 . Rivet

BACR15MY6K5Y 3 . . . 3 3 . Rivet

BACR15MY6K7Y 39 . . . 39 39 . Rivet

BACR15MY6K8Y 5 . . . 2 2 . Rivet

BACR15MY6K9Y . . . . 3 3 . Rivet

BACR15NW6K6Y 2 . . . 2 2 . Rivet

BACC30R6 49 . . . 49 49 . Collar

Kit 141U2100

New Part 

Number

QTY

-8 -7 -6 -5 -4 -3 -1 Name Notes
 

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2. Parts and Materials Supplied by the Operator:

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.

Part Number / 

Specification QTY Name Notes

BMS 5-95 32 oz. Sealant (a)

BMS 10-11, Type I 8 oz. Primer (a)

- As Required Modification Parts (b)

(a) See the Qualified Products List at the end of the Boeing Material Specification 

(BMS) for supplier data.

(b) Refer to 747-100/200/300 SRM 53-30-03 Figures 19, 25, 28 or 34 for the 

materials required to accomplish the lap joint modification.
 

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BOEING SERVICE BULLETIN 747-53A2303

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. 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 are given in 747 Structural Repair 

Manual, Chapter 51

— Torque limits to tighten nuts and bolts are given in 747 Structural Repair Manual, 

Chapter 51.

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

4. As recommended by the 747 Aging Fleet Structures Working Group, accomplish the 

modification per this service bulletin prior to, or upon the accumulation of 23,000 flightcycles

5. Adequate lighting must be used for this inspection. The eddy current inspections may be 

conducted without removal of the paint, provided the paint does not interfere (see NonDestructive Test (NDT) Manual D6-7170) with the inspections. Paint must be removed 

using an approved chemical stripper in any situation where the inspector determines 

that the paint is interfering with proper functioning of the inspection equipment or where 

the fastener heads are not clearly visible.

6. Inspection is not required at Station (STA) 400 to 416 at those locations where there is 

an upper deck door cutout. Right side on all Group 1, 2, 3 and 4 airplanes. Left side on 

all Group 2 and 4 airplanes.

7. Refer to Paragraph 1.E., Compliance for thresholds and repeat inspection intervals.

8. For approved fastener and process material substitutions, refer to 747 SRM, Chapter 

51, Alternate fasteners are given in 747 SRM Chapter 51 and Boeing Drawing 

012W6100.

9. If the length of any fastener specified in this service bulletin does not meet the 

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.
 

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10. A Detailed Inspection 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.

11. These work instructions refer to procedures included on 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 "as given 

in" are included in the instruction, the procedure in the Boeing document must be used.

12. Refer to Appendix A for the Flight Safety Addendum for this service bulletin.

13. Refer to Appendix B for alternate skin trim instructions.

14. Refer to Appendix C for instructions to extend the 141U2100 modification doublers if 

previous SRM repairs are present.

B. WORK INSTRUCTIONS

PART 1 - FLIGHT SAFETY INSPECTION PROGRAM

1. Initial inspection on airplanes on which the modification given in PART 3 or in any previous 

version of this service bulletin has not been accomplished: 

a. At the time specified in Paragraph 1.E., Compliance, inspect the skin lap splice at Stringer 

6, from STA 400 to STA 520, on the left and right side of the airplane, for cracks as given in 

Figure 2.

NOTE: The optional Economics Based Inspection Program may be initiated at an earlier

time than the Flight Safety Inspection Program, as given in Paragraph 1.E.,

Compliance. Other than the initial inspection threshold, all other compliance

requirements for the Economics Based Inspection Program are the same as the

Flight Safety Inspection Program.

b. If no cracks are found, repeat the inspections given in Figure 2 at the times specified in 

Paragraph 1.E., Compliance.

As an alternative, accomplish the modification in PART 3 to terminate the Flight Safety or 

Economics Based inspection program.

c. If a crack is found, accomplish the modification in PART 3.

As a time-limited alternative, accomplish a repair as given in PART 2. Continue to do 

inspections in unrepaired areas as given in Figure 2. Continue to do inspections in repaired 

areas as given in Paragraph 1.E., Compliance, Table 1 and the related footnotes.

Send Boeing a report of any discrepancies that are found.

PART 2 - REPAIR

1. Gain access as necessary for removal of the top row of fasteners along the left and right stringer 

6 lap splice as given in Figure 3.
 

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BOEING SERVICE BULLETIN 747-53A2303

NOTE:

1. This repair may be installed temporarily instead of the modification in PART 3, but 

it does not terminate the inspections that are necessary as given in PART 1.

2. In all locations where cracks are trimmed, use care to make sure that adjacent 

internal tear straps, door cutout internal bear straps, and other internal structure are 

not cut or otherwise damaged.

3. For any skin lap splice repair installed as given in previous revisions of this service 

bulletin, the lap splice must incorporate the modification specified in PART 3 of 

Revision 2 at the time specified in Paragraph 1.E., Compliance, Table 2 or Table 4.

4. If skin cracks are found in the area of the 0.025 inch thick bonded internal doubler 

at STA 425 to STA 457, adjacent to the upper deck door cutout, the repair should 

be based on the total thickness of the cracked or trimmed out skin and doubler. The 

skin trim out should not extend forward of STA 425 for this condition.

5. If cracks extend forward of STA 425 at the door cutout, contact Boeing for repair 

instructions.

2. Repair cracks as given in 747-100/200/300 SRM 53-30-03 Figures 17, 20, 23, 26, 29, or 32. 

Contact Boeing if the inner skin panel is to be trimmed.

3. Install equipment that was removed for access as given in Figure 3.

4. Put the airplane back to a serviceable condition. Continue to do inspections in unrepaired areas 

as given in Paragraph 1.E., Compliance. Do the modification given in PART 3 at the time given 

in Paragraph 1.E., Compliance.

PART 3 - MODIFICATION

1. Gain access as necessary for removal of the fasteners along the left and right stringer 6 lap splice 

as given in Figure 3.
 

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BOEING SERVICE BULLETIN 747-53A2303

NOTE:

1. These modification options may be used as an alternative to the inspections given 

in PART 1.

2. It is recommended that the scribe line inspections given in Boeing Service Bulletin 

747-53A2563, "Fuselage - Skin - Inspections of the Fuselage Skin and Butt Joint 

Splice Straps for Scribe Lines" be done in the affected area prior to doubler 

installation. If the scribe line inspections are not done prior to doubler installation, 

it may be necessary to remove the doublers to accomplish the scribe line 

inspections. 

3. On Group 1 and 2 airplanes to be modified as given in Revision 1 of this service 

bulletin or later, at the same time as the modification given in this service bulletin is 

installed, delaminate the stringer 6 lap splice, remove the adhesive, and replace 

with faying surface sealant as given in 747-100/200/300 SRM 53-30-03 Figure 10. 

On Group 2 airplanes it is not necessary to delaminate the left side stringer 6 lap 

splice where the splice contains four rows of fasteners.

4. In all locations where cracks are trimmed, use care to make sure that adjacent 

internal tear straps, door cutout internal bear straps, and other internal structure are 

not cut or otherwise damaged.

5. If skin cracks are found in the area of the 0.025 inch thick bonded internal doubler 

at STA 425 to STA 457, adjacent to the upper deck door cutout, the modification 

should be based on the total thickness of the cracked or trimmed out skin and 

doubler. The skin trim out should not extend forward of STA 425 for this condition.

6. If cracks extend forward of STA 425 at the door cutout, contact Boeing for repair 

instructions.

7. The protruding head fastener modification has been removed from this service 

bulletin as part of Revision 2.

2. If cracks were not found during the PART 1 or PART 5 inspections, do the steps that follow:

a. Remove any SRM repair that exists between STA 400 and STA 520 in the area of the 

modification. Contact Boeing if the inner skin was trimmed, since the modification per 

Drawing 141U2100 may not be applicable.

b. Remove the lap joint fasteners and do open hole HFEC inspections at the top and bottom 

rows of lap joint fastener holes as given in 747 NDT, Part 6, 51-00-00 Figure 1, 11, or 16.

c. If cracks are found, go to Step 3.

d. If no cracks are found, do the external doubler modification as given in Drawing 141U2100 

Sheets 1 - 5.
 

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BOEING SERVICE BULLETIN 747-53A2303

NOTE:

1. Protruding head fasteners may be oversized up to 0.250 inch in diameter 

common to the existing lap joint and frame flanges. 1.7D edge margin must 

be maintained in the frame flanges and 4D spacing must be maintained in the 

skin. If fastener holes common to the upper row of the existing lap joint exceed 

these limitations, refer to Appendix B for alternate trim instructions.

2. In the area of removed SRM doublers or trim outs, locally extend the profile of 

the lower doubler to act as a filler for the upper skin trim. Additionally, extend 

the Drawing 141U2100 doublers above and below the removed SRM repair 

such that the perimeter row of fasteners is installed in new fastener holes. 

Refer to Appendix C for additional instructions. Install BACR15BB5D( ) rivets 

in the new fastener holes.

e. Finish the modification area as necessary to match adjacent structure.

3. If cracks were found during the PART 1 or PART 5 inspections, or during the open-hole HFEC 

inspection done prior to the modification, do the steps that follow:

a. Remove any SRM repair that exists between STA 400 and STA 520 in the area of the 

modification. Contact Boeing if the inner skin was trimmed, other than as given in Appendix 

B, since the modification per Drawing 141U2100 may not be applicable.

b. Trim out all cracks as given in 747-100/200/300 SRM 53-30-03 Figures 17, 20, 23, 26, 29, 

or 32, or as given in Appendix B. Contact Boeing for instructions if cracks were found in the 

inner skin at the bottom row of fastener holes in the lap joint.

c. Do the external doubler modification as given in Drawing 141U2100 Sheets 1 - 5.

NOTE:

1. Protruding head fasteners may be oversized up to 0.250 inch in diameter 

common to the existing lap joint and frame flanges. 1.7D edge margin must 

be maintained in the frame flanges and 4D spacing must be maintained in the 

skin. If fastener holes common to the upper row of the existing lap joint exceed 

these limitations, refer to Appendix B for alternate trim instructions.

2. In the area of removed SRM doublers or trim outs, locally extend the profile of 

the lower doubler to act as a filler for the upper skin trim. Additionally, extend 

the Drawing 141U2100 doublers above and below the removed SRM repair 

such that the perimeter row of fasteners is installed in new fastener holes. 

Refer to Appendix C for additional instructions. Install BACR15BB5D( ) rivets 

in the new fastener holes.

d. Finish the modification area as necessary to match adjacent structure.

4. Install equipment that was removed for access as given in Figure 3.

5. Put the airplane back to a serviceable condition. Do post-modification inspections as given in 

PART 4 at the times given in Paragraph 1.E., Compliance, Table 3.
 

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BOEING SERVICE BULLETIN 747-53A2303

PART 4 - POST-MODIFICATION INSPECTIONS

1. At the times given in Paragraph 1.E., Compliance, Table 3:

NOTE: For all Group 1 and 2 airplanes that have been modified as given in this revision or

previous revisions of this service bulletin, contact Boeing for additional instructions as

given in Paragraph 1.E., Compliance, Table 5. More work may be necessary on

airplanes that were delivered with cold bonded lap splices.

a. If the doubler installation as given in Service Bulletin 747-53A2321 has been installed and 

a doubler has also been installed as given in this service bulletin, do a detailed inspection 

and internal and external HFEC inspections of the skin in the area of the modification as 

given in Figure 6.

NOTE: As an alternative for airplanes on which the Service Bulletin 747-53-2272 Zone 2

modification has been previously accomplished, it is acceptable to do only external

inspections as given in Figure 8. However, the alternative inspection given in

Figure 8 has a shorter repeat inspection interval, as given in Paragraph 1.E.,

Compliance, Table 3. 

b. If the modification given on Drawing 141U2100 (including doubler configurations modified 

as given in Appendix C), or as given in 747-100/200/300 SRM 53-30-03 Figure 19, 25, 28, 

or 34 has been accomplished for the full length of the lap joint, do a detailed inspection and 

internal and external HFEC inspections of the skin in the area of the modification as given 

in Figure 7. 

NOTE: As an alternative for airplanes on which the Service Bulletin 747-53-2272 Zone 2

modification has been previously accomplished, it is acceptable to do only external

inspections as given in Figure 9. However, the alternative inspection given in

Figure 9 has a shorter repeat inspection interval, as given in Paragraph 1.E.,

Compliance, Table 4. 

2. If no cracks are found, do the inspections again at the time specified in Paragraph 1.E., 

Compliance, Table 3.

3. If cracks are found, repair before further flight. Contact Boeing for repair instructions.

4. Report any discrepancies using the reporting system described in the Flight Safety Addendum 

given in Appendix A of this service bulletin. 

5. Put the airplane back to a serviceable condition.

PART 5 - INSPECTION AND MODIFICATION OF CERTAIN CONFIGURATIONS

1. At the times given in Paragraph 1.E., Compliance, Table 4:

a. In areas where the top row protruding head fastener modification has been accomplished 

as given in the original release or Revision 1 of this service bulletin, do an external HFEC 

inspection of the skin around the fasteners in the upper row of the lap joint for cracks as 

given in Figure 5. 
 

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BOEING SERVICE BULLETIN 747-53A2303

b. If a modification as given in 747-100/200/300 SRM 53-30-03 has been accomplished as 

given in the original release or Revision 1 of this service bulletin, do an internal HFEC 

inspection for cracks as given in the applicable SRM figures, except at compliance times 

and intervals given in Paragraph 1.E., Compliance, Table 4.

2. If cracks are found, do one of the following:

a. Install a modification as given in PART 3. or

b. Install a repair as given in PART 2.

NOTE: The full external doubler modification given in PART 3 must be installed at the time

specified in Paragraph 1.E., Compliance, Table 5.

3. If no cracks are found, do one of the following:

a. Install a modification as given in PART 3. or

b. Repeat the inspections as given in Paragraph 1.E., Compliance, Table 4.

NOTE: The full external doubler modification given in PART 3 must be installed at the time

specified in Paragraph 1.E., Compliance, Table 5.
 FIGURE 1: THIS FIGURE IS DELETED

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

FIGURE 1: THIS FIGURE IS DELETED

THIS FIGURE IS DELETED.

D38438

(SHEET 1 OF 1)
 FIGURE 2: INITIAL INSPECTIONS

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BOEING SERVICE BULLETIN 747-53A2303

FIGURE 2: INITIAL INSPECTIONS

STA

520

STA

400

STRINGER NO.6

4 ROW SPLICE LEFT SIDE GROUPS 3 AND 5;

RIGHT SIDE GROUP 5 (OPPOSITE) SEE A

SEE B 3 ROW SPLICE LEFT SIDE GROUP 1

LOWER SKIN PANEL

UPPER SKIN PANEL

STA

520

STA

400

J76130

(SHEET 1 OF 5)
 FIGURE 2: INITIAL INSPECTIONS

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BOEING SERVICE BULLETIN 747-53A2303

A

B

1

1 UPPER SKIN

PANEL

UPPER SKIN

PANEL

LOWER SKIN

PANEL

LOWER SKIN

PANEL

STRINGER 6

STRINGER 6

STA

400

STA

400

FWD

UP

FWD

UP

(4-ROW SPLICE)

LEFT SIDE GROUPS 3 AND 5

RIGHT SIDE GROUP 5 (OPPOSITE)

(3-ROW SPLICE)

LEFT SIDE GROUP 1

INDICATES AREA

TO BE INSPECTED

J76135

(SHEET 2 OF 5)
 FIGURE 2: INITIAL INSPECTIONS

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BOEING SERVICE BULLETIN 747-53A2303

STA

520

STA

400

STRINGER NO.6

STA

520

STA

400

UPPER SKIN PANEL

DOOR CUTOUT

LOWER SKIN

PANEL

SEE C

RIGHT SIDE SHOWN

4-ROW SPLICE RIGHT SIDE GROUPS 3 AND 4;

LEFT SIDE GROUPS 2 AND 4 (OPPOSITE)

SEE D 3-ROW SPLICE RIGHT SIDE

GROUPS 1 AND 2

J76147

(SHEET 3 OF 5)
 FIGURE 2: INITIAL INSPECTIONS

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BOEING SERVICE BULLETIN 747-53A2303

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

UP

FWD

UP

FWD

STA

417

STA

417

DOOR CUTOUT

DOOR CUTOUT

STRINGER 6

STRINGER 6

UPPER SKIN PANEL

UPPER SKIN PANEL

LOWER SKIN

PANEL

LOWER SKIN

PANEL

INDICATES AREA

TO BE INSPECTED

D

C

1

1

(4-ROW SPLICE)

RIGHT SIDE OF GROUPS 3 AND 4

LEFT SIDE GROUPS 2 AND 4 OPPOSITE

(3-ROW SPLICE)

RIGHT SIDE OF GROUPS 1 AND 2

J76479

(SHEET 4 OF 5)
 FIGURE 2: INITIAL INSPECTIONS

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BOEING SERVICE BULLETIN 747-53A2303

NOTE: If protruding head fasteners are in the top row of the lap splice, contact Boeing for inspection

instructions.

1. Using a high frequency eddy current method per 747 NDT, 53-30-02 or 747 NDT, 53-30-06 externally 

inspect the skin at the top row of lap splice between body stations 400 and 520. Also perform a detailed 

inspection of the skin lap splice for cracking concurrent with the eddy current inspection.

(SHEET 5 OF 5)
 FIGURE 3: INTERNAL ACCESS AND RESTORATION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

FIGURE 3: INTERNAL ACCESS AND RESTORATION

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 airplane.

FLIGHT COMPARTMENT

AFT PARTITION FLIGHT COMPARTMENT DOOR

E11 RACK ENCLOSURE

PARTITION

RIGHT CREW DOOR

LEFT CREW DOOR

FORWARD LEFT

PARTITION

LOWER CLOSURE PANEL

PSU PANEL

STOWAGE BIN

UPPER CLOSURE PANEL

CENTER LIGHTED REVEAL

1

TYPICAL UPPER DECK CONFIGURATION

WITH LEFT AND RIGHT CREW DOOR

(OTHER UPPER DECK CONFIGURATIONS SIMILAR)

2

J76482

(SHEET 1 OF 2)
 FIGURE 3: INTERNAL ACCESS AND RESTORATION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

1. Remove and salvage equipment and furnishings as required to gain access to Body Station 400 to 520 

frames. See the following maintenance manual subjects for removal procedures:

2. Install all items which are removed in the preceding step per the applicable maintenance manual subject 

or operators comparable procedure.

Equipment Maintenance Manual Subject

Insulation 747-100/200/300 AMM 25-21-04

Ceiling Panels 747-100/200/300 AMM 25-22-03

Passenger Service Units 747-100/200/300 AMM 25-23-01

Forward Closets 747-100/200/300 AMM 25-24-00

Forward Right Partition 747-100/200/300 AMM 25-24-11

Forward Left Partition 747-100/200/300 AMM 25-24-12

Crew Rest Area 747-100/200/300 AMM 25-24-19

Passenger Seats 747-100/200/300 AMM 25-25-01

Wall Mounted Attendant Seat 747-100/200/300 AMM 25-25-04

Stairway Forward Right partition 747-100/200/300 AMM 25-26-02

Stairway Aft Right partition 747-100/200/300 AMM 25-26-03

Stairway Forward Left partition 747-100/200/300 AMM 25-26-06

Sidewall Stowage Units 747-100/200/300 AMM 25-28-15

Overhead Stowage Units 747-100/200/300 AMM 25-28-23

Lavatories 747-100/200/300 AMM 25-40-03

Flight Compartment Door 747-100/200/300 AMM 52-51-01/52-51-00

Crew Entry Door 747-100/200/300 AMM 52-13-01

Insulation 747-100/200/300 AMM 25-21-04

Ceiling Panels 747-100/200/300 AMM 25-22-03

Passenger Service Units 747-100/200/300 AMM 25-23-01

Forward Closets 747-100/200/300 AMM 25-24-00

Forward Right Partition 747-100/200/300 AMM 25-24-11

Forward Left Partition 747-100/200/300 AMM 25-24-12

Crew Rest Area 747-100/200/300 AMM 25-24-19

Passenger Seats 747-100/200/300 AMM 25-25-01

Wall Mounted Attendant Seat 747-100/200/300 AMM 25-25-04

Stairway Forward Right partition 747-100/200/300 AMM 25-26-02

Stairway Aft Right partition 747-100/200/300 AMM 25-26-03

Stairway Forward Left partition 747-100/200/300 AMM 25-26-06

Sidewall Stowage Units 747-100/200/300 AMM 25-28-15

Overhead Stowage Units 747-100/200/300 AMM 25-28-23

Lavatories 747-100/200/300 AMM 25-40-03

Flight Compartment Door 747-100/200/300 AMM 52-51-01/52-51-00

Crew Entry Door 747-100/200/300 AMM 52-13-01

(SHEET 2 OF 2)
 FIGURE 4: THIS FIGURE IS DELETED

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

FIGURE 4: THIS FIGURE IS DELETED

THIS FIGURE IS DELETED.

D38438

(SHEET 1 OF 1)
 FIGURE 5: TOP ROW PROTRUDING HEAD FASTENER MODIFICATION INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

FIGURE 5: TOP ROW PROTRUDING HEAD FASTENER MODIFICATION INSPECTION

S-6

400

STA

LEFT SIDE SHOWN

400

STA

(3 ROW SPLICE)

LEFT SIDE OF GROUP 1, GROUP 3 AND GROUP 5 AIRPLANES

STRINGER 6

PANEL

LOWER SKIN

UPPER SKIN PANEL

520

STA

FWD

UP

1

INDICATES AREA

TO BE INSPECTED

J81666

(SHEET 1 OF 7)
 FIGURE 5: TOP ROW PROTRUDING HEAD FASTENER MODIFICATION INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

UPPER SKIN PANEL

STA

400

LOWER SKIN

PANEL

STRINGER 6

S-6 LEFT SIDE SHOWN

STA

400

STA

520

(4 ROW SPLICE)

LEFT SIDE OF GROUP 1, GROUP 3 AND GROUP 5 AIRPLANES

1

FWD

UP

INDICATES AREA

TO BE INSPECTED

J82065

(SHEET 2 OF 7)
 FIGURE 5: TOP ROW PROTRUDING HEAD FASTENER MODIFICATION INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

LEFT SIDE SHOWN

S-6

STA

400

STA

520

(3 ROW SPLICE)

LEFT SIDE OF GROUP 1, GROUP 2, GROUP 4 AND GROUP 5 AIRPLANES

FWD

UP

STA

417

DOOR CUTOUT

STRINGER 6

UPPER

SKIN

PANEL

LOWER SKIN

PANEL

INDICATES AREA

TO BE INSPECTED

1

J82031

(SHEET 3 OF 7)
 FIGURE 5: TOP ROW PROTRUDING HEAD FASTENER MODIFICATION INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

LEFT SIDE SHOWN

S-6

STA

400

STA

520

FWD

UP

STA

417

UPPER

SKIN

PANEL

INDICATES AREA

TO BE INSPECTED

1

(4-ROW SPLICE)

LEFT SIDE OF GROUP 2, GROUP 4 AND GROUP 5 AIRPLANES

DOOR CUTOUT

STRINGER 6

LOWER SKIN

PANEL

J82051

(SHEET 4 OF 7)
 FIGURE 5: TOP ROW PROTRUDING HEAD FASTENER MODIFICATION INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

RIGHT SIDE SHOWN

S-6

STA

400

STA

520

STA

417

DOOR CUTOUT

STRINGER 6

UPPER

SKIN

PANEL

LOWER SKIN

PANEL

INDICATES AREA

TO BE INSPECTED

1

(3-ROW SPLICE)

RIGHT SIDE OF ALL GROUP AIRPLANES

UP

FWD

J81673

(SHEET 5 OF 7)
 FIGURE 5: TOP ROW PROTRUDING HEAD FASTENER MODIFICATION INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

RIGHT SIDE SHOWN

S-6

STA

400

STA

520

STA

417

UPPER

SKIN

PANEL

INDICATES AREA

TO BE INSPECTED

1

(4-ROW SPLICE)

RIGHT SIDE OF ALL GROUP AIRPLANES

DOOR CUTOUT

STRINGER 6 LOWER SKIN

PANEL

UP

FWD

J81684

(SHEET 6 OF 7)
 FIGURE 5: TOP ROW PROTRUDING HEAD FASTENER MODIFICATION INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

The step number shown below agrees with the number shown in the circle symbols in the figure.

1. Do a High Frequency Eddy Current (HFEC) Inspection, as given in 747 NDT, Part 6, 53-30-19, on the upper 

skin 360 degrees around the fastener heads, along the top row of fasteners at the stringer 6 lap splice from 

outside the airplane, left and right sides, for cracks.

(SHEET 7 OF 7)
 FIGURE 6: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND REPAIR DOUBLER INSTALLED 

BY SERVICE BULLETIN 747-53A2321 - INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

FIGURE 6: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND REPAIR DOUBLER INSTALLED 

BY SERVICE BULLETIN 747-53A2321 - INSPECTION

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

STA

400

(3 ROW SPLICE)

LEFT SIDE OF GROUP 1, GROUP 3 AND GROUP 5 AIRPLANES

(RIGHT SIDE AND OTHER GROUPS SIMILAR)

STRINGER 6

PANEL

LOWER SKIN

UPPER SKIN

PANEL

LOWER DOUBLER

UPPER DOUBLER

INDICATES AREA TO

BE INSPECTED

STA

520

STA

400

STRINGER

NO.6

LEFT SIDE SHOWN

(RIGHT SIDE SIMILAR)

FWD

UP

1

2

3 4

J83748

(SHEET 1 OF 2)
 FIGURE 6: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND REPAIR DOUBLER INSTALLED 

BY SERVICE BULLETIN 747-53A2321 - INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

NOTE: The three-row lap splice configuration is shown. The four-row lap splice configuration is similar.

1. Do a High Frequency Eddy Current (HFEC) Inspection as given in 747 NDT, Part 6, 51-00-00 Figure 4 or 

747 NDT, Part 6, 53-30-19 of the skin 360 degrees around the fastener tails, along the top row of fasteners, 

from inside the airplane, left and right sides, for cracks. Inspections are not necessary at tear strap 

locations.

2. Do a HFEC Inspection as given in 747 NDT, Part 6, 51-00-00 Figure 4 or 747 NDT, Part 6, 53-30-19 of the 

doubler (or tripler which is not shown in the drawings) 360 degrees around the fastener head, along the 

indicated row of fasteners from outside the airplane, left and right sides, for cracks. In areas common to 

the tripler installed between STA 421 - 461 (near the upper deck door cutout), inspect the tripler instead of 

the doubler.

3. Do a detailed inspection of the modification area for cracks from inside the airplane, left and right sides.

4. Do a detailed inspection of the modification area for cracks from outside the airplane, left and right sides.

(SHEET 2 OF 2)
 FIGURE 7: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND SKIN REPLACEMENT MODIFICATION BY SERVICE BULLETIN 747-53A2321 - INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

FIGURE 7: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND SKIN REPLACEMENT 

MODIFICATION BY SERVICE BULLETIN 747-53A2321 - INSPECTION

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

STA

400

(3 ROW SPLICE)

LEFT SIDE OF GROUP 1, GROUP 3 AND GROUP 5 AIRPLANES

(RIGHT SIDE AND OTHER GROUPS SIMILAR)

STRINGER 6

PANEL

LOWER SKIN

UPPER SKIN

PANEL

LOWER DOUBLER

UPPER DOUBLER

INDICATES AREA TO

BE INSPECTED

STA

520

STA

400

STRINGER

NO.6

LEFT SIDE SHOWN

(RIGHT SIDE SIMILAR)

FWD

UP

1

2

3 4

1

J83750

(SHEET 1 OF 2)
 FIGURE 7: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND SKIN REPLACEMENT MODIFICATION BY SERVICE BULLETIN 747-53A2321 - INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

NOTE: The three-row lap splice configuration is shown. The four-row lap splice configuration is similar.

1. Do a High Frequency Eddy Current (HFEC) inspection as given in 747 NDT, Part 6, 51-00-00 Figure 4 or 

747 NDT, Part 6, 53-30-19 of the doubler, 360 degrees around the fastener tails, along the top row of 

fasteners from inside the airplane, left and right sides, for cracks. Inspections are not necessary at tear 

strap locations.

2. Do a HFEC inspection as given in 747 NDT, Part 6, 51-00-00 Figure 4 or 747 NDT, Part 6, 53-30-19 of the 

doubler (or tripler which is not shown in the drawings), 360 degrees around the fastener heads, along the 

indicated row of fasteners from outside the airplane, left and right sides, for cracks. In areas common to 

the tripler installed between STA 421 - 461 (near the upper deck door cutout), inspect the tripler instead of 

the doubler.

3. Do a detailed inspection of the modification area for cracks from inside the airplane, left and right sides.

4. Do a detailed inspection of the modification area for cracks from outside the airplane, left and right sides.

(SHEET 2 OF 2)
 FIGURE 8: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND REPAIR DOUBLER INSTALLED 

BY SERVICE BULLETIN 747-53A2321 - ALTERNATIVE INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

FIGURE 8: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND REPAIR DOUBLER INSTALLED 

BY SERVICE BULLETIN 747-53A2321 - ALTERNATIVE INSPECTION

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

(3 ROW SPLICE)

LEFT SIDE OF GROUP 1, GROUP 3 AND GROUP 5 AIRPLANES

(RIGHT SIDE AND OTHER GROUPS SIMILAR)

STA

400

STRINGER 6

PANEL

LOWER SKIN

UPPER SKIN

PANEL

LOWER DOUBLER

UPPER DOUBLER

INDICATES AREA TO

BE INSPECTED

STA

520

STA

400

STRINGER

NO.6

LEFT SIDE SHOWN

(RIGHT SIDE SIMILAR)

FWD

UP

1

2

3

J83749

(SHEET 1 OF 2)
 FIGURE 8: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND REPAIR DOUBLER INSTALLED 

BY SERVICE BULLETIN 747-53A2321 - ALTERNATIVE INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

NOTE:

1. The alternative inspection shown in this figure is no longer a satisfactory alternative for the Figure 

6 inspections if cracks and/or damage is found from previous inspection as shown in this figure.

2. The three-row lap splice configuration is shown. The four-row lap splice configuration is similar.

1. Do a Low Frequency Eddy Current Inspection as given in 747 Non Destructive Test manual, Part 6, Subject 

53-30-10 of the skin under the doubler, 360 degrees around the heads of the horizontal top and bottom 

rows of fasteners for cracks from outside the airplane, left and right sides.

2. Do a High Frequency Eddy Current Inspection as given in 747 NDT, Part 6, 51-00-00 Figure 4 or 747 NDT, 

Part 6, 53-30-19 of the doubler, 360 degrees around the heads of the horizontal row of indicated fasteners 

for cracks from outside the airplane, left and right sides. In areas common to the tripler installed between 

STA 421 - 461 (near the upper deck door cutout), inspect the tripler instead of the doubler.

3. Do a detailed inspection of the modification area for cracks from outside the airplane, left and right sides.

(SHEET 2 OF 2)
 FIGURE 9: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND SKIN REPLACEMENT MODIFICATION BY SERVICE BULLETIN 747-53A2321 - ALTERNATIVE INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

FIGURE 9: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND SKIN REPLACEMENT 

MODIFICATION BY SERVICE BULLETIN 747-53A2321 - ALTERNATIVE INSPECTION

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

(3 ROW SPLICE)

LEFT SIDE OF GROUP 1, GROUP 3 AND GROUP 5 AIRPLANES

(RIGHT SIDE AND OTHER GROUPS SIMILAR)

STA

400

STRINGER 6

PANEL

LOWER SKIN

UPPER SKIN

PANEL

LOWER DOUBLER

UPPER DOUBLER

INDICATES AREA TO

BE INSPECTED

STA

520

STA

400

STRINGER

NO.6

LEFT SIDE SHOWN

(RIGHT SIDE SIMILAR)

FWD

UP

1

2

3

1

J83751

(SHEET 1 OF 2)
 FIGURE 9: DOUBLER INSTALLED BY THIS SERVICE BULLETIN AND SKIN REPLACEMENT MODIFICATION BY SERVICE BULLETIN 747-53A2321 - ALTERNATIVE INSPECTION

June 02, 1988

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BOEING SERVICE BULLETIN 747-53A2303

NOTE:

1. The alternative inspection shown in this figure is no longer a satisfactory alternative for the Figure 

7 inspections if cracks and/or damage is found from previous inspection as shown in this figure.

2. The three-row lap splice configuration is shown. The four-row lap splice configuration is similar.

1. Do a Low Frequency Eddy Current Inspection as given in 747 Non Destructive Test manual, Part 6, Subject 

53-30-10 of the skin under the doubler, 360 degrees around the heads of the horizontal top row of fasteners 

for cracks from outside the airplane, left and right sides.

2. Do a High Frequency Eddy Current Inspection as given in 747 NDT, Part 6, 51-00-00 Figure 4 or 747 NDT, 

Part 6, 53-30-19 of the doubler, 360 degrees around the heads of the horizontal row of indicated fasteners 

for cracks from outside the airplane, left and right sides. In areas common to the tripler installed between 

STA 421 - 461 (near the upper deck door cutout), inspect the tripler instead of the doubler.

3. Do a detailed inspection of the Modification Area for cracks from outside the airplane, left and right sides.

(SHEET 2 OF 2)
 APPENDIX A: DISCREPANT STRUCTURE REPORT

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BOEING SERVICE BULLETIN 747-53A2303

APPENDIX A: DISCREPANT STRUCTURE REPORT

ADDENDUM

FLIGHT SAFETY SECTION

INSPECTION TO ENSURE STRUCTURAL INTEGRITY OF AIRFRAME

A structural reassessment of the 747 airplane has been conducted under the requirements of Federal Aviation 

Administration (FAA) Advisory Circular 91-56, in accordance with Federal Aviation Regulation (FAR) 2.571, as 

amended in 1978, to ensure the safe operation of 747 airplanes throughout their operational life.

The inspections specified in the tables in Paragraph 1.E., Compliance are recommended for the detection of 

cracks in the Body Station 400 to 520 skin lap splice at Stringer (S)-6L and S-6R prior to their reaching critical 

lengths. Failure to detect cracks prior to their reaching critical length may result in in-flight depressurization of 

the airplane and the inability to withstand current regulatory failsafe loads.

Any skin splice cracks should be repaired prior to further flight unless specifically approved by your cognizant 

regulatory agency.

Report any discrepancies to Boeing Customer Support Engineering using the reporting system described in this 

addendum.

Boeing requests that operators use the following Structural Significant Item (SSI) reporting system to report any 

discrepancies that are found in accomplishing a Flight Safety Inspection.

1. Upon recognition of a discrepancy, the following information should be sent to Boeing:

Heading: ATTENTION - SSI DISCREPANCY - SERVICE BULLETIN RELATED

– Service bulletin number

– Airplane serial number on which discrepancy was found

– Identification of structural item found damaged

– Flight cycles and hours on damaged item

– Location and description of damage including direction and size

– When discovered and inspection method used

Send a message through your Boeing Field Service Representative or directly to:

747 Customer Support Engineering

2. An operator’s follow up report containing all available pertinent data, relative to the structural discrepancy, 

shall be sent to Boeing within 10 working days. A summary of the information that should be reported is 

sown in the DISCRAPANT STRUCTURE REPORT form attached. Operators may use this form or any 

suitable alternative which contains the same information.

3. All data and reports dealing with the Flight Safety Inspection Program shall be submitted either through a 

Boeing Field Service Representative or directly to:

BOEING COMMERCIAL AIRPLANE GROUP

ATTENTION: MANAGER, AIRLINE SUPPORT

4. All reports will be reviewed immediately.
 APPENDIX A: DISCREPANT STRUCTURE REPORT

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BOEING SERVICE BULLETIN 747-53A2303

5. The Boeing Company will summarize the results of all reported significant data for distribution semiannually to operators and appropriate Airworthiness Authorities.

SCHEDULED MAINTENANCE WALK-AROUND

6.

5.

4.

3.

4A.

4B.

2. AIRCRAFT DATA

DISCREPANT STRUCTURE REPORT

1.

STATION

MODEL

REPORT DATA A.T.A. INDEX

NAME

IPC/DWG REF

COMPONENT FLIGHT CYCLES SINCE NEW 

COMPLETE THE FOLLOWING IF KNOWN AND DIFFERENT FROM SECTION 2:

S/N

REPAIR DATA PLANNED COMPLETED

ACTION

SB

MPD

STRUCTURAL SIGNIFICANT ITEM NO.

SERVICE BULLLETINS INCORPORATED IN AREA OF DISCREPANCY

INSPECTION DATA 

CORRESPONDING INSPECTION LEVELS

X 24291 ORIG. 3/84 (FRONT)

6A. WHEN DISCOVERED

OVERHAUL

UNSCHEDULED

SYMPTOM (FUEL/PRESS. LEAK . . . )

RELATED FLEET EXPERIENCE

ACCIDENT INVESTIGATION

SSID

SERIES 50

6B. INSPECTION LEVEL

GENERAL VISUAL

EXTERNAL SURVEILLANCE

DETAILED

SPECIAL

6C. DETECTION METHOD

INTERNAL SURVEILLANCE

VISUAL

MAG. VISUAL

DYE PENETRANT

ULTRASONIC

X-RAY

LOW FREQUENCY

EDDY CURRENT

HIGH FREQUENCY

EDDY CURRENT

BORESCOPE

MAGNETIC 

PARTICLE

TAP TEST

SOUND

SMELL

FEEL

FUEL LEAK

PRESS. LOSS

SIDE 1

AIRLINE/AGENCY MONTH DAY YEAR

REPORT NO.

MFG. SERIAL NO. FLIGHT HOURS

SERIES TAIL NO.

FLIGHT CYCLES

COMPONENT FLIGHT HOURS SINCE NEW

COMPONENT DATA (AS APPLICABLE AND AVAILABLE):

P/N

SRM REF

SINCE OVERHAUL

SINCE OVERHAUL

NO.

SERVICE BULLETIN 

OF SERVICE BULLETIN

APPLICABLE SECTION

INCORPORATION

DATE OF

CYCLES AT INCORPORATION

TOTAL FLIGHT HOURS AND

HOURS

HOURS

HOURS

FLIGHTS

FLIGHTS

FLIGHTS

AD

OTHER (E.G., SDR, MRR)

IPC SRM

SIIA

SERIES 50 NO.

(COMPLETE KNOWN INFO., CHECK APPROPRIATE ITEMS FOR DISCREPANT STRUCTURE):

CURRENT INSPECTION INTERVALS (FLIGHT)

SPECIAL/DIRECTED (AD, SB . . . )

REFERENCES ASSOCIATED WITH INSPECTION/REPAIR (SPECIFY NO., PAGE, FIGURE, ETC)

W76755
 APPENDIX A: DISCREPANT STRUCTURE REPORT

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BOEING SERVICE BULLETIN 747-53A2303

STRINGER

Attach sketch, photos and text as required to describe defect and specific location.

DISCREPANT STRUCTURE REPORT

X 2491 ORIG. 1/84 (BACK)

INSPECTED BY

ORIGINATED BY

REPAIRED BY

DATE

7. DISCREPANCY DESCRIPTION:

SIDE 2

associated discrepancies on the same airplane, related experience with this discrepancy on any airplane, and previous

modification(s) to the discrepant structure.

When applicable, give details of

7A. TYPE OF DISCREPANCY:

LEAK

DETACHED

DENTED

DELAMINATED

DEFORMED

CRACKED

CORRODED

BENT CONTAMINATED

BURNED

BUCKLED

BROKEN

CLOGGED WORN

STUCK

OUT-OF-TOLERANCE

MISSING

LOOSE

ADJUSTED

IMPROPERLY

WRINKLED

7B. SIZE OF DISCREPANCY: INCHES, OR CENTIMETERS

AREA

FINAL MEASUREMENT (IF DIFFERENT)

CRACK LENGTH INITIALLY DETECTED

DEPTH

DATE

DATE

X

7C. DISCREPANT PART:

FRAME/BULKHEAD

PRESSURE BULKHEAD

FRAME AROUND OPENING

WINDOW FORGING

KEEL BEAM

FLOOR

SPAR

RIB

FLAP TRACK

FAIRING

WING CENTER SECTION

WING DRY-BAY AREA/COMPT

LANDING GEAR BEAM

JOINT/SPLICE

LUG

WELD

BOND

OPEN HOLE

FASTENER HOLE

CUTOUT

NOTCH/GROOVE

DISCONTINUITY

BASIC MATERIAL

BUSHING

PIN

SKIN

PLATE/PANEL

CHORD

NO.

STRUT/BRACE

BEAM

LINK/ROD

LONGERON

FITTING

BRACKET/SLIP

STOP

FASTENER

ACCESS/LIGHTENING HOLE

7D. LOCATION OF DISCREPANT PART:

GENERAL LOCATION (E.G., BILGE, UNDER GALLEY)

WING STA NO.

BODY STA NO.

VERT STAB. STA

HORIZ STAB. STA

NOSE LANDING GEAR

MAIN LANDING GEAR

WING LANDING GEAR

BODY LANDING GEAR

DOOR ACCESS PANEL

RUDDER

ELEVATOR

AILERON

FLAP

SLAT

SPOILER

TAB (ALSO CHECK ABOVE)

INTERIOR

INBOARD

LEFT

FORWARD

UPPER

LEADING EDGE

MIDDLE

SPECIFIC LOCATION

EXTERIOR

OUTBOARD

RIGHT

AFT

LOWER

TRAILING EDGE

SIDE

NACELLE/PYLON

COMPARTMENT

W76756
 APPENDIX B: ALTERNATIVE LAP SPLICE TRIM INSTRUCTIONS

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BOEING SERVICE BULLETIN 747-53A2303

APPENDIX B: ALTERNATIVE LAP SPLICE TRIM INSTRUCTIONS

1. Alternate Trim Option 1: Local Lap Splice Trim

Refer to the trim instructions below and Detail A for a diagram of a typical local lap splice trim.

Locally trim out the upper and lower skin as shown in Detail A to remove any crack indications or discrepant 

fastener holes. When installing the 141U2100 Sheet 1 - 5 doublers, revise the profile of the lower external 

modification doubler to extend upwards into the trim area. Install 5/32 inch diameter BACR15BB( )D( ) 

rivets in the new fastener holes.

2. Alternate Trim Option 2: Full Lap Splice Trim in Areas With No Crew Entry Door

Refer to Detail B for a trim of the entire length of the affected lap joint, from STA 400 to STA 520, on 

airplanes without a crew entry door in the affected area.

In areas without a left or right side crew entry door, it is acceptable to trim off the entire upper skin panel 

lap joint from STA 400 to STA 520. If the upper skin panel is trimmed, additionally trim the upper fastener 

row of the lower skin panel from STA 400 to STA 520. Revise the profile of the lower external modification 

doubler to extend upwards into the trim area. Install 5/32 inch diameter BACR15BB( )D( ) rivets in the new 

fastener holes.

3. Alternate Trim Option 3: Lap Splice Trim in Areas With a Crew Entry Door

Refer to Detail C for a trim of the affected lap joint, from STA 425 to STA 520, on airplanes with a crew 

entry door in the affected area.

In areas with a left and/or right side crew entry door, it is acceptable to trim the upper skin panel lap joint 

from STA 425 to STA 520. If the upper skin panel is trimmed, additionally trim the upper fastener row of 

the lower skin panel from STA 425 to STA 520. Revise the profile of the lower external modification doubler 

to extend upwards into the trim area. Install 5/32 inch diameter BACR15BB( )D( ) rivets in the new fastener 

holes.

4. Trim Instructions:

A. Gain access to the area to be trimmed.

B. Remove the fasteners from the longitudinal lap splice as necessary.

C. Tape a stainless steel sheet to the fuselage skin below the damage to protect the fuselage skin.

CAUTION: USE CARE TO NOT GOUGE, SCRATCH, OR BUCKLE THE SKIN ADJACENT TO THE

REPAIR.

D. Carefully separate the bonded skins with nylon or hardwood wedges. Use a sufficient number of 

wedges to slowly and continuously move apart the skins to prevent buckling.

NOTE: To help separate the bonded skins, cold soak the joint with dry ice (solid carbon dioxide) for

approximately 30 minutes.

E. Carefully cut out the damaged area of the overlapped (or overlapping) skin. Use a sheet metal guard 

between the skins to prevent damage to the overlapping skin. Make a 0.50 inch radius at the internal 

and external corners of the cutout.
 APPENDIX B: ALTERNATIVE LAP SPLICE TRIM INSTRUCTIONS

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BOEING SERVICE BULLETIN 747-53A2303

F. Break all sharp edges of the original and repair parts 0.015 to 0.030 inch.

G. Remove all nicks, scratches, gouges, burrs and sharp edges from the skin panels.
 APPENDIX B: ALTERNATIVE LAP SPLICE TRIM INSTRUCTIONS

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BOEING SERVICE BULLETIN 747-53A2303

NOTE: The illustrations show a typical three row lap splice. For airplanes with a four row lap splice

in the affected area, trim out all four rows common to the upper skin panel. Trim out only the

upper row common to the lower skin panel.

LOWER SKIN

PANEL

UPPER SKIN 

PANEL

EDGE OF UPPER 

SKIN PANEL

EDGE OF LOWER 

SKIN PANEL

TRIM LINE

(LOWER SKIN)

TRIM LINE

(UPPER SKIN)

TRIM LINE

(UPPER SKIN)

LOWER SKIN

PANEL

UPPER SKIN 

PANEL

S-6

STA

520

STA

400

OVERSIZE HOLE

LOCATIONS

EDGE OF UPPER 

SKIN PANEL

EDGE OF LOWER 

SKIN PANEL

TRIM LINE

(LOWER SKIN)

TRIM LINE

(UPPER SKIN)

A

A

A

A

A

B

1419415
 APPENDIX B: ALTERNATIVE LAP SPLICE TRIM INSTRUCTIONS

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BOEING SERVICE BULLETIN 747-53A2303

LOWER SKIN

PANEL

TRIM LINE

(UPPER SKIN)

UPPER SKIN 

PANEL

TRIM LINE

(LOWER SKIN)

A-A

LOWER SKIN

PANEL

UPPER SKIN 

PANEL

A-A

BEFORE TRIM AFTER TRIM

LOWER SKIN

PANEL

UPPER SKIN 

PANEL

S-6

STA

425

STA

520

OVERSIZE HOLE

LOCATIONS

EDGE OF UPPER 

SKIN PANEL

EDGE OF LOWER 

SKIN PANEL

TRIM LINE

(LOWER SKIN)

TRIM LINE

(UPPER SKIN)

EDGE OF CREW

DOOR CUTOUT

TRIM LINE

(UPPER SKIN)

A-A

AFTER MODIFICATION

LOWER EXTERNAL

MODIFICATION

DOUBLER

UPPER SKIN 

PANEL

LOWER SKIN

PANEL

UPPER EXTERNAL

MODIFICATION

DOUBLER

S-6

STRINGER

A

A

INBD INBD INBD

C

1423332
 APPENDIX C: EXTENSION OF THE 141U2100 MODIFICATION DOUBLERS WHEN AN SRM REPAIR IS 

PRESENT

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BOEING SERVICE BULLETIN 747-53A2303

APPENDIX C: EXTENSION OF THE 141U2100 MODIFICATION DOUBLERS WHEN AN SRM REPAIR IS 

PRESENT

Extend the 141U2100 Modification doublers in the area of a typical 747-100/200/300 SRM 53-30-03 lap splice 

repair. The doublers should be extended a minimum of one fastener row beyond the SRM repair fastener holes 

as shown. Do not end the doubler on a stringer.

NOTE: The three-row lap splice configuration is shown. The four-row lap splice configuration is similar.

141U2100 UPPER DOUBLER

EDGE OF

LOWER SKIN

LOWER SKIN

UPPER SKIN

TYPICAL UPPER SKIN

TRIM LINE

141U2100 LOWER DOUBLER

(EXTENDED INTO TRIM AREA)

NEW FASTENER HOLES

EXISTING FASTENER HOLES

1574622