December 21, 1989

Revision 3: April 16, 2009 747-53-2307

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 1 of 68

Commercial

Airplane

Group 747

Service Bulletin

Number: 747-53-2307

Date: December 21, 1989

Revision 3: April 16, 2009

ATA System: 5310 5331

SUBJECT: FUSELAGE - Skin - Upper Body Longitudinal Lap Joint (Stringers 23 and Above) 

Inspection and Repair

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Unpublished Work - All Rights Reserved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, 

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 Table of Contents

December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

Table of Contents

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

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

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

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

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

2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

E. Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2. Data supplied with this Service Bulletin: . . . . . . . . . . . . . . . . . . . . . . . . . 23

3. Installation Drawings Used in the Preparation of this Service Bulletin: . . . . . . . . . . 23

K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . 23

2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

A. Material - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

C. Parts Necessary For Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

1. Kits/Parts: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

2. Parts and Materials Supplied by the Operator: . . . . . . . . . . . . . . . . . . . . . . 26

3. Parts Modified and Reidentified: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

4. Parts Removed and Not Replaced: . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . 26

3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

FIGURE 1: EXTERNAL LAP JOINT INSPECTION LOGIC DIAGRAM . . . . . . . . . . . . . . . . . 32

FIGURE 2: EXTERNAL LAP JOINT CORROSION INSPECTION . . . . . . . . . . . . . . . . . . . 38

FIGURE 3: FLIGHT DECK LAP JOINT INTERNAL ACCESS . . . . . . . . . . . . . . . . . . . . . . 48

FIGURE 4: UPPER DECK LAP JOINT INTERNAL ACCESS . . . . . . . . . . . . . . . . . . . . . . 52

FIGURE 5: MAIN DECK LAP JOINT INTERNAL ACCESS . . . . . . . . . . . . . . . . . . . . . . . 54

FIGURE 6: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.090 INCHES OR

LESS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

FIGURE 7: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.071 INCHES OR

LESS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
 Table of Contents

December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

BLANK PAGE
Original Issue: December 21, 1989

Revision 3: April 16, 2009 747-53-2307

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Commercial

Airplanes 747

Service Bulletin

Number: 747-53-2307 Revision Transmittal Sheet

Original Issue: December 21, 1989

Revision 3: April 16, 2009

ATA System: 5310 5331

SUBJECT: FUSELAGE - Skin - Upper Body Longitudinal Lap Joint (Stringers 23 and Above) 

Inspection and Repair

This revision includes all pages of the service bulletin.

COMPLIANCE INFORMATION RELATED TO THIS REVISION

More work is necessary on airplanes changed as shown in Revision 2, Revision 1 or the original issue of this 

service bulletin. On lap joints where the upper (overlapping) skin thickness at the upper row of fasteners is 0.071 

inches or less will be required to accomplish a structural modification as given Boeing Service Bulletin 747-

53A2463. In addition, for airplanes with the optional protruding head fastener modification installed, the repeat 

inspection interval has been reduced from 3,000 flight-cycles to 1,000 flight-cycles.

REASON FOR REVISION

This revision is sent to add references to 747-53A2463 for a structural modification and post modification 

inspections for lap joint locations where the upper (overlapping) skin thickness at the upper row of fasteners is 

0.071 inches or less. In addition, this revision is sent to change the repeat inspection interval from 3,000 flightcycles to 1,000 flight-cycles, for airplanes with the optional protruding head fastener modification installed.

Changes to this service bulletin include:

— Service Related Problem references are added to the summary section, Paragraph 1.C., Reason and 

Paragraph 1.J., References.

— Industry Support Information is added to the Summary sections and Paragraph 2.B.

— Paragraph 1.D., Description - Details to contact Boeing for structural modification information are added.

— New compliance information given in Boeing Service Bulletin 747-53A2463 Revision 1 is referred to in 

Paragraph 1.E., Compliance.

— Paragraph 1.H., Weight and Balance Changes - A statement regarding the structural modification is added.

— Paragraph 3.A., General Information - Dimensions, tolerances and substitutions notes are added.

— Paragraph 3.B., Work Instructions - Instructions to inspect repairs are added. References to modifications 

as given in Service Bulletin 747-53A2463 are added.

— Notes are added throughout the service bulletin to inform operators that they should not use SRM 

53-30-03, Figure 18 or 27 for a lap joint repair as these repairs do not have adequate coverage of the lap 

joint area.

— Figure 1 and Figure 2 - Instructions to accomplish the structural modification as given in Boeing Service 

Bulletin 747-53A2463 are added. Figure 2 has been changed to be consistent with the logic diagrams in 

Figure 1.

— Figure 3 - A station number in the illustration is corrected for the flight engineer’s section.

— Added references to FAA AD 94-12-09, Amendment 39-8937.
 

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BOEING SERVICE BULLETIN 747-53-2307

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: December 21, 1989

Revision 1: August 27, 1992

Revision 2: October 14, 1993

Revision 3: April 16, 2009
Original Issue: December 21, 1989

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Commercial

Airplanes 747

Service Bulletin

Number: 747-53-2307 Summary

Original Issue: December 21, 1989

Revision 3: April 16, 2009

ATA System: 5310 5331

SUBJECT: FUSELAGE - Skin - Upper Body Longitudinal Lap Joint (Stringers 23 and Above) 

Inspection and Repair

CONCURRENT REQUIREMENTS

None.

BACKGROUND

Based on a structural review of the 747 airplane, accomplishment of the inspection program and incorporation 

of a select portion of the lap joint modification per this service bulletin is recommended on aging airplanes.

This inspection will detect corrosion and fatigue cracks in upper body skin longitudinal lap joints caused by 

disbonding of the cold bond at the joint. Continued operation of an airplane that has corrosion or fatigue cracking 

in lap joints could lead to separation of the skin at the lap joint causing rapid decompression of the airplane. 

Several operators have reported corrosion, and associated bulging of skin at upper body lap joints on airplanes 

with 26,733 to 70,000 flight-hours. One operator reported cracking and corrosion of the lap joint at Stringer 12 

from Station 1515 to 1735 and Stringer 4L at Station 1710 on an airplane with 35,134 flight-hours. One other 

operator reported corrosion and cracking at the lap joint at Stringer 4R, Station 1500 on an airplane with 49,024 

flight-hours. Another operator reported a one inch crack at Stringer 0, Station 738 suspected to have been 

caused by corrosion from disbonding at the cold bonded lap joint. There have been numerous additional 

instances of corrosion reported at the Stringer 23 lap joint. 

This bulletin supersedes that portion of Service Bulletin 747-53-2157 which addresses the upper body skin 

longitudinal lap joints. 

Airplanes previously inspected per Service Bulletin 747-53-2157 require additional inspection of lap joint areas 

as described herein. 

Any lap joint areas repaired per Service Bulletin 747-53-2157 do not require further repair but an After 

Modification Inspection is necessary at intervals given by Revision 1 of this bulletin. 

This bulletin does not supersede Service Bulletin 747-53-2253 or Service Bulletin 747-53A2303 which address 

the upper body skin longitudinal lap joints at Stringer 6 in Section 41. 
 

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BOEING SERVICE BULLETIN 747-53-2307

Subsequent to previous releases of this service bulletin a review of all bulletins which recommend repeat 

inspections was performed to determine if the inspections were appropriate on aging airplanes. This review 

indicated that lap joints where the upper (overlapping) skin thickness is less than or equal to 0.071 inches should 

be modified at the times given in Service Bulletin 747-53A2463 on aging 747 airplanes, line numbers 1 through 

200.

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

This item is identified in Boeing Structural Item Interim Advisory (SIIA) 747-71. 

Federal Aviation Administration (FAA) Airworthiness Directives 90-15-06, Amendment 39-6653 and 94-12-09, 

Amendment 39-8937 are related to this service bulletin. 

ACTION

As recommended by the 747 Structures Working Group, accomplish the inspection program per this service 

bulletin. In addition, do the selected portion of the lap joint modification that addresses lap joints fastened with 

deep countersink rivets. Incorporation thresholds for the inspection and modification are shown in the 

Description and Accomplishment Instructions

Do a detailed external visual inspection of the upper body longitudinal lap joints at Stringers 23 and above from 

Station 140 to 2360 (except Stringer 6 from Station 340 to 520) within 1,000 flight-cycles after receipt of the 

original release of this bulletin, or before 15,000 flight-cycles have accumulated, whichever comes later. 

Visually inspect all lap joints for evidence of corrosion or cracking and make any necessary repair prior to further 

flight as given in the Accomplishment Instructions. Repeat these visual inspections at intervals not to exceed 

1,000 flight-cycles for the lap joints in Sections 41, 42, and 46. Repeat the visual inspections at 2,000 flight-cycle 

intervals for the lap joints in Section 44. 

As an alternative to repeat inspections of Sections 41, 42, and 46 at 1,000 flight-cycle intervals, do an external 

high frequency eddy current (HFEC) inspection of selected lap joints together with the above initial visual 

inspection. Repeat the visual inspections at 2,000 flight-cycle intervals and the HFEC inspections in Section 41 

and 42 at 4,000 flight-cycle intervals and the HFEC inspections in Section 46 at 6,000 flight-cycle intervals. 

For airplanes with more than 15,000 flight-cycles, within 1000 flight cycles after receipt of this service bulletin, 

do a external HFEC inspection of selected lap joints together with the visual inspections. Repeat the visual 

inspections at 2000 flight-cycle intervals and the HFEC inspections at 4,000 flight-cycle intervals in Section 41 

and 42 and at 6,000 flight-cycle intervals in Section 46.

On aircraft with a main deck side cargo door, extended intervals for inspection are not permitted on selected 46-

section skin lap areas at Stringers 4-Left and 12-Left. Refer to the Accomplishment Instructions. 

On all the lap joints where the upper (overlapping) skin thickness is 0.071 inches or less, a structural 

modification is required at the time given in Service Bulletin 747-53A2463.

If the operator’s plan is to continue with this service bulletin, rather than per the instructions in Service Bulletin 

747-53A2463, based on the age of the airplane, refer to the Accomplishment Instructions for the Full or Optional 

Modification procedure. 

Do an After Modification Inspection of lap joint areas after the Full or Optional Modification. Refer to the 

Accomplishment Instructions for procedure and intervals for inspection. 

Corrosion inhibiting compound (BMS 3-23) is recommended to be applied internally to lap joint areas after Full 

or Optional Modification as given in the Accomplishment Instructions. 
 

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BOEING SERVICE BULLETIN 747-53-2307

EFFECTIVITY

747-100, 200B and -200F 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 90-15-06 and 94-12-09 are related to this 

service bulletin.

Boeing recommends a detailed visual inspection for all airplanes with less than 15,000 flight cycles within 1,000 

flight cycles after receipt of this service bulletin. Repeat detailed visual inspections at 1,000 flight cycle intervals 

on non-terminated lap joints in Sections 41, 42, and 46 and 2,000 flight cycles intervals for Section 44. This 

group of airplanes can elect to do the inspection for older airplanes per Method II to extend the inspection 

intervals.

Airplanes with 15,000 or more flight cycles must do a detailed visual inspection and a High Frequency Eddy 

Current (HFEC) inspection within 1,000 flight cycles after receipt of this service bulletin. Repeat detailed visual 

inspections at 2,000 flight cycle intervals on non-terminated lap joints in Sections 41, 42, 44 and 46. Repeat 

HFEC inspections at 4,000 flight cycle intervals on non-terminated lap joints in Sections 41, 42 and 6,000 flight 

cycle intervals for Section 46. Section 44 does not require a HFEC inspection.

Refer to Service Bulletin 747-53A2463 for new compliance information.

INDUSTRY SUPPORT INFORMATION

Boeing warranty remedies are not available for the configuration changes, inspections, and/or repair procedures 

given in this service bulletin.

MANPOWER

MATERIAL INFORMATION

Boeing Supplied Kits *

* Kit is necessary only on airplanes with a main deck side cargo door. 

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

Task Total Task Hours Elapsed Hours

External Visual Inspection 152 38

External HFEC Inspection 56 14

Internal Visual with LFEC Inspection 

(Main Deck Side Cargo Door Only)

8 8

Full or Optional Modification Refer to Paragraph 1.G., Manpower
 

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BOEING SERVICE BULLETIN 747-53-2307

S-14

S-6

S-0

S-23

S-19

(TYPICAL)

LAP JOINT

SECTION 46

S-4

S-12

1480

STA

2360

STA

41

42

44

LEFT SIDE OPPOSITE

RIGHT SIDE SHOWN

OF SKIN, AND MISSING OR DISTRESSED FASTENERS.

ACCOMPLISH A STRUCTURAL MODIFICATION ON ALL LAP JOINTS

WHERE THE UPPER (OVERLAPPING) SKIN THICKNESS IS 0.071

INCHES OR LESS AS GIVEN IN SERVICE BULLEIN 747-53A2463.

INSPECT LAP JOINTS FOR CORROSION, CRACKS OR PILLOWING

140

STA

520

STA

1000

STA

SECTIONS

1370319
Original Issue: December 21, 1989

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Commercial

Airplanes 747

Service Bulletin

Number: 747-53-2307

Original Issue: December 21, 1989

Revision 3: April 16, 2009

ATA System: 5310 5331

SUBJECT: FUSELAGE - Skin - Upper Body Longitudinal Lap Joint (Stringers 23 and Above) 

Inspection and Repair

1. PLANNING INFORMATION

A. Effectivity

1. Airplanes

This service bulletin is for the airplanes shown below.

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

Number, and Serial Number data. 

Airplane models:

747-100 747-200B 747-200F

IDENTIFICATION BY CUSTOMER, CUSTOMER CODE, GROUP AND VARIABLE NUMBER

AERO CONTROLS (AEO)

1 RA722–RA723

AGES AIRCRAFT SALES & LEASING (AGJ)

1 RB004

AIR GULF FALCON (GFG)

1 RA535 RA537

GROUP CONFIGURATION DESCRIPTION

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

numbers 1 through 200, with different skin 

thickness than airplanes in Group 3.

2 - 747-200F series airplane, line number 168.

3 - 747-100 series airplanes, line numbers 2 though 

161, with different skin thickness than airplanes 

in Group 1.
 

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BOEING SERVICE BULLETIN 747-53-2307

ALBARAKA (AAB)

1 RB102

ARKIA ISRAELI AIRLINES (ARK)

1 RA253

BANC OF AMERICA LEASING (SBC)

1 RA106 RD001–RD002

EVERGREEN A/C SALES & LEASING (EVG)

1 RA371

EVERGREEN INTERNATIONAL A/L (EVR)

3 RA028 RA631 RA633

EXPORT RESTRICTED AIRPLANES (YWV)

3 RA101–RA103 RA112 RA161–RA163

FINOVA (GRB)

1 RA651

GE (GEC)

1 RA016

GECAS (GEF)

1 RA007 RA013 RA027

JOHNSON SPACE CENTER (ZBR)

1 RA908

JUMBO JET LEASING (JJL)

1 RA526 RA532–RA534 RA539

KABO AIR (KAB)

1 RA305 RA560

KALITTA AIR (KAC)

3 RA401–RA402 RA524 RA635 RA913

LOGISTIC AIR, INC. (LGA)

1 RA217

3 RA015 RA910

NEA HOLDINGS, INC. (NEA)

1 RB001

ORIENT THAI AIRLINES (OTH)

1 RA540

UPS (UPS)

3 RA026 RA029 RA033 RA902

RA912 RA915–RA916
 

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BOEING SERVICE BULLETIN 747-53-2307

WHIRLPOOL FINANCIAL CORP. (ZZW)

1 RB005

IDENTIFICATION BY VARIABLE NUMBER

Variable Group

RA001 1

RA002 3

RA003–RA005 1

RA006 3

RA007–RA010 1

RA011 3

RA012–RA014 1

RA015 3

RA016–RA025 1

RA026 3

RA027 1

RA028–RA030 3

RA031–RA032 1

RA033 3

RA034 1

RA101–RA103 3

RA104–RA110 1

RA111–RA112 3

RA113–RA115 1

RA161–RA163 3

RA164 1

RA201–RA203 1

RA216–RA217 1

RA245–RA246 1

RA251–RA259 1

RA301–RA312 1

RA351–RA360 1

RA369–RA373 1

RA401–RA405 3

RA406–RA414 1

RA501–RA502 1

RA521–RA523 1

RA524 3

RA525–RA527 1

RA532–RA540 1
 

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BOEING SERVICE BULLETIN 747-53-2307

2. Spares Affected

None.

B. Concurrent Requirements

None.

C. Reason

As a result of the 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 inspections and recommend selected service bulletins for incorporation on aging 

airplanes. This inspection program and a select portion of the lap joint modification that addresses 

lap joints fastened with deep countersink rivets have been recommended for accomplishment on 

aging 747 airplanes.

RA551–RA552 1

RA559–RA561 1

RA581–RA582 1

RA585 1

RA601–RA602 1

RA631–RA635 3

RA651–RA652 1

RA671–RA677 1

RA701–RA702 1

RA721–RA724 1

RA741–RA743 1

RA761–RA762 1

RA781–RA782 1

RA901–RA902 3

RA903–RA909 1

RA910–RA916 3

RB001–RB005 1

RB041 3

RB042 1

RB043 3

RB044 1

RB071–RB075 1

RB101–RB102 1

RD001–RD002 1

RR201 2

Variable Group
 

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BOEING SERVICE BULLETIN 747-53-2307

This inspection will detect corrosion or cracking in upper body skin longitudinal lap joints caused by 

disbonding of the cold bond at the lap joint. Continued operation of an airplane that has corrosion or 

cracking in lap joints could lead to separation of the skin at the lap joint causing rapid decompression 

of the airplane. 

Several operators have reported corrosion, and associated bulging of skin at upper body lap joints on 

airplanes with 26,733 to 70,000 flight-hours. 

One operator reported corrosion of one to three lap joint rivets and bulging of the skin at Stringer 12 

near Station 1694 on an airplane with 34,827 flight-hours. This operator also reported cracked and 

corroded fuselage skin with separation at the lap joint at Stringer 12 L and R at six locations each side 

from Station 1515 to 1735 and Stringer 4L at Station 1710 on the same airplane with 35,134 flighthours. 

One other operator reported a corrosion bulge resulting in a skin lap crack at Stringer 4R, Station 1500 

on an airplane with 49,024 flight-hours and 13,594 flight-cycles. 

Another operator reported a one inch skin crack starting from the lap joint at Stringer 0 near Station 

738 on an airplane with 49,800 flight-hours which was suspected to have been caused by corrosion 

from disbonding at the cold bonded lap joint (Ref. SIIA 747-71). This operator also reported two 

airplanes with skin corrosion of lap joint at Stringer 4L. On one airplane, with 35,985 flight-hours, this 

corrosion was found at four locations between Stations 1482 and 1676. On the other airplane, 

corrosion was found near Stations 1510 and 1615 on an airplane with 36,461 flight-hours. 

Also, an operator has reported skin corrosion in the lap joint at Stringer 23R near Station 1400 on an 

airplane with 26,733 flight-hours and skin corrosion with bulging skin involving the lap joint at Stringer 

23L between Station 1720 and 1820 on another airplane. 

There have been numerous additional instances of corrosion reported at the Stringer 23 lap joint. 

This bulletin supersedes that portion of Service Bulletin 747-53-2157 which addresses the upper body 

skin longitudinal lap joints. 

Airplanes previously inspected per Service Bulletin 747-53-2157 require additional inspection of lap 

joint areas as described herein. 

Any lap joint areas repaired per Service Bulletin 747-53-2157 do not require further repair, but an After 

Modification Inspection is made necessary by Revision 1 of this bulletin. Refer to the Accomplishment 

Instructions of this bulletin for procedure and the time interval for inspection. 

This bulletin does not supersede Service Bulletin 747-53-2253 or Service Bulletin 747-53A2303 which 

address the upper body skin longitudinal lap joints at Stringer 6 in Section 41. 

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

This item is identified in Boeing Structural Item Interim Advisory (SIIA) 747-71. 

Federal Aviation Administration (FAA) Airworthiness Directives 90-15-06, Amendment 39-6653 and 

94-12-09, Amendment 39-8937 are related to this service bulletin.
 

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As a result of the 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 inspections and recommend selected service bulletins for incorporation on aging 

airplanes. Based on a structural review of the 747 airplane, the Structures Working Group has 

determined that a select portion of the lap joint modification per this service bulletin, at or before the 

indicated threshold, should be accomplished to support the continued structural integrity of aging 747 

airplanes.

Subsequent to previous releases of this service bulletin a review of all bulletins which recommend 

repeat inspections was performed to determine if the inspections were appropriate on aging airplanes. 

This review indicated that lap joints where the upper (overlapping) skin thickness is less than or equal 

to 0.071 inches should be modified at the times given in Service Bulletin 747-53A2463 on aging 747 

airplanes, line numbers 1 through 200.

Revision 1 was sent to make these changes:

1. Add an After Modification Inspection that is necessary after Full or Optional Modification. 

2. Add instructions to change the terminating action for lap joints fastened with deep countersink 

fasteners at these locations:

a. Stringer 12 from STA 520 - 740 (Line Number 59 - 200 only).

b. Stringer 12 from STA 740 - 1000.

c. Stringer 19 from STA 520 - 740.

In these lap joints, the upper (overlapping) skin panel has a doubler hot bonded to the skin. 

The countersink depth of the rivet is greater than the basic skin gage. While this is not a 

problem for a skin panel with the hot bond intact, disbonding will result in a knife edge 

condition in the skin layer. This condition makes these lap joints more susceptible to fatigue 

cracking. Several operators have reported cracks at these lap joints. 

3. Add an Optional Modification for lap joints with outer skin panel thickness of 0.090 inches or less 

that do not have either cracks or corrosion. 

4. Add instruction to make necessary the HFEC inspection in Sections 41, 42, and 46 on airplanes 

with 15,000 or more flight-cycles. For these areas, the repeat HFEC inspection is necessary at 

4,000 flight-cycle intervals in Section 41 and 42 and at 6,000 flight-cycle intervals in Section 46. 

5. Add instruction to allow a minimum of 1.5 diameter edge margin for the skin lap joints at the top 

row of fastener holes on the inner skin panel for lap joints changed by the Full or Optional 

modification. 

6. Add instruction to permit the top row of fastener holes to be oversized by 1/64 inch diameter 

before HFEC inspection to decrease incorrect crack indication. 

7. Add instruction to recommend that corrosion inhibiting compound BMS 3-23 be applied internally 

to lap joints after terminating action (Full Modification). 

8. Add inspection, terminating action, and oversize fastener kit for airplanes with a main deck side 

cargo door to Figure 6.
 

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9. Add reference to Aging Airplane Corrosion Prevention and Control Program D6-36022. 

10. Add Figure 6 to show outer skin panel thickness at skin lap joints of 0.090 inches or less. 

11. Add reference to Federal Aviation Administration (FAA) Airworthiness Directive 90-15-06, 

Amendment 39-6653. 

12. Remove references to protruding head fasteners from the Accomplishment Instructions and from 

Flagnote 3 of Figure 1. The type of fasteners necessary are given by the Structural Repair 

Manual.

13. Remove the lap joint shown in Figure 2 in Section 44 at stringer 23 from Body Station 1000 to 

1241. There is not a lap joint at this location. 

14. Change Flagnote 1 of Figure 2 to show that airplanes not listed in Flagnote 1 have fay-sealed lap 

joints at stringer 4 in Body Section 44.

15. Instruction to contact Boeing for jacking instructions is added. 

Revision 2 was sent to make the following changes:

1. Add a chart in Figure 2 to assist the operator to plan the initial inspection. The chart uses station 

and stringer locations to identify the areas of inspection. The chart also defines the alternative 

inspection to extend the repeat inspection threshold for airplanes with less than 15,000 flight 

cycles. In addition, the chart defines the only inspection recommended for airplanes with 15,000 

flight cycles or more.

2. Change to the illustrations showing the lap joint locations for Section 41. These illustrations have 

had the reference to Str 6 removed from the detail because service bulletins 747-53-2253 and 

747-53A2303 show inspections and repair at Str 6. The station callout for Str 0 is changed to 

reflect the correct starting point for the inspections. The tables showing the lap joint locations 

have also been revised to remove Str 6 information and to correct the starting point for Str 0.

3. Add a Compliance statement to the Summary information and to Section I, D in the service 

bulletin.

4. Remove redundant information in Figure 1 logic diagram for Inspection Method II.

5. Change the flight cycle threshold in Flag note 5 of Figure 1. The change brings the statement in 

accord with the 747 Aging Fleet Structures Working Group recommendation and the flight cycle 

threshold in the first paragraph of the Description.

Revision 3 is sent to add a structural modification and post modification inspections for lap joint 

locations where the upper (overlapping) skin thickness at the upper row of fasteners is 0.071 inches 

or less. In addition, this revision is sent to change the repeat inspection interval from 3,000 flightcycles to 1,000 flight-cycles, for airplanes with the optional protruding head fastener modification 

installed.

Changes to this service bulletin include:

— Service Related Problem references are added to the summary section, Paragraph 1.C., Reason 

and Paragraph 1.J., References.

— Industry Support Information is added to the Summary sections and Paragraph 2.B.
 

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— Paragraph 1.D., Description - Details to contact Boeing for structural modification information are 

added.

— New compliance information given in Boeing Service Bulletin 747-53A2463 Revision 1 is referred 

to in Paragraph 1.E., Compliance.

— Paragraph 1.H., Weight and Balance Changes - A statement regarding the structural modification 

is added.

— Paragraph 3.A., General Information - Dimensions, tolerances and substitutions notes are 

added.

— Paragraph 3.B., Work Instructions - Instructions to inspect repairs are added. References to 

modifications as given in Service Bulletin 747-53A2463 are added.

— Notes are added throughout the service bulletin to inform operators that they should not use SRM 

53-30-03, Figure 18 or 27 for a lap joint repair as these repairs do not have adequate coverage 

of the lap joint area.

— Figure 1 and Figure 2 - Instructions to accomplish the structural modification as given in Boeing 

Service Bulletin 747-53A2463 are added. Figure 2 has been changed to be consistent with the 

logic diagrams in Figure 1.

— Figure 3 - A station number in the illustration is corrected for the flight engineer’s section.

— Added references to FAA AD 94-12-09, Amendment 39-8937.

D. Description

Subsequent to previous releases of this service bulletin a review of all bulletins which recommend 

repeat inspections was performed to determine if the inspections were appropriate on aging airplanes. 

This review indicated that lap joints where the upper (overlapping) skin thickness is less than or equal 

to 0.071 inches should be modified at the times given in Service Bulletin 747-53A2463 on aging 747 

airplanes, line numbers 1 through 200. Refer to Service Bulletin 747-53A2463 to determine whether 

to continue with the instructions in this service bulletin or with the instructions in Service Bulletin 747-

53A2463.

Based on a structural review of the 747 airplane, it is recommended that the inspection program be 

accomplished per this service bulletin. A select portion of the lap joint modification that addresses lap 

joints fastened with deep countersink rivets per the Accomplishment Instructions should be 

accomplished prior to, or upon accumulation of 20,000 flight cycles or within 1000 flight cycles after 

receipt of Revision 1 of this service bulletin, whichever is later.

Within 1,000 flight-cycles after receipt of this bulletin, a detailed external visual inspection is done at 

the upper body longitudinal lap joints at Stringers 23 and above from Station 140 to 2360 (except 

Stringer 6 from Station 340 to 520). A visual inspection is done at all lap joints for evidence of corrosion 

or cracking and any necessary repair is done as given in the Accomplishment Instructions prior to 

further flight. These visual inspections are repeated at intervals not to exceed 1,000 flight-cycles for 

the lap joints in Sections 41 (Station 140 - 520), 42 (Station 520 - 1000), and 46 (Station 1480 - 2360). 

Visual inspections are repeated at 2,000 flight-cycle intervals for the lap joints in Section 44 (Station 

1000 - 1480). 

As an alternative to repeat inspections of Sections 41, 42, and 46 at 1,000 flight-cycle intervals, 

external high frequency eddy current (HFEC) inspection can be done at selected lap joints together 

with the above initial visual inspection. The visual inspection is repeated at 2,000 flight-cycle intervals 

and the HFEC inspection in Section 41 and 42 at 4,000 flight-cycle intervals and the HFEC inspection 

in Section 46 at 6,000 flight-cycle intervals. 
 

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For airplanes with 15,000 flight-cycles or more, within 1000 flight cycles after receipt of this service 

bulletin, do an external HFEC inspection of selected lap joints together with the visual inspections. 

Repeat the visual inspections at 2000 flight cycle intervals and the HFEC inspections at 4,000 flightcycle intervals in Section 41 and 42 and at 6,000 flight-cycle intervals in Section 46.

On aircraft with a main deck side cargo door, extended intervals for inspection are not permitted on 

selected 46-section skin lap areas at Stringers 4-Left and 12-Left. Refer to the Accomplishment 

Instructions. 

In lieu of continued reinspections, terminating action can be done by a Full Modification or by an 

Optional Modification. The Full Modification is accomplished when an uncorroded lap joint area is 

separated between adjacent circumferential splices, adhesive removed, protective finish and faying 

surface sealant is applied, and joint is refastened per 747 Structural Repair Manual Subject 53-30-03. 

Terminating action in a corroded or cracked lap joint area may be accomplished when the area is 

repaired per 747 Structural Repair Manual Subject 53-30-03. For the Full Modification in Section 42 

only, repair of deep countersink fasteners at selected lap joints is made necessary by Revision 1 as 

given in the Accomplishment Instructions.

An Optional Modification is permitted at selected lap joint areas with outer skin panel thickness of 

0.090 inches or less that do not have either cracks or corrosion. For the Optional Modification, the 

countersunk fasteners are replaced in only the top row of the lap joint with 1/16 inch diameter oversize 

protruding head fasteners. Corrosion inhibiting compound (BMS 3-23) must be applied internally to 

lap joints after Optional Modification. An open hole HFEC inspection is necessary before fastener 

installation. This Optional Modification is not permitted at the lap joints with deep countersink fasteners 

located in Section 42. 

It is recommended that this service bulletin be accomplished concurrently with service bulletins 747-

53A2265, 747-53-2272, 747-53A2279, 747-53-2305, and 747-53A2463 due to common access. 

Airplanes modified per the initial release of this service bulletin do require more work. As a result of 

Rev 1, an after modification inspection will be required.

NOTE: For lap joints with an upper (overlapping) skin thickness equal to or less than 0.071 inches

blend out damage that is less than 10% of the original thickness. Repair damage greater than

10% of the original thickness per SRM 53-30-03 Fig. 19. If the damaged area is more than

the specified limits in SRM 53-30-03 Fig. 19, contact Boeing for repair instructions.

SEND TO:

BOEING COMMERCIAL AIRPLANE GROUP ATTENTION: 

MANAGER, AIRLINE SUPPORT

To define the repair for each lap joint, the structural condition of the adjacent skin, the location 

of the damage, the dimensions of the damage, and existing local repairs must be known. 

Because of these reasons, it is likely that unique repair drawings will be needed to define the 

terminating action for each airplane by Service Bulletin 747-53A2463.

Federal Aviation Administration (FAA) Airworthiness Directives 90-15-16, Amendment 39-6653 and 

94-12-09, Amendment 39-8937 are related to this service bulletin.

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

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Revision 3 - More work is necessary on airplanes changed as shown in Revision 2, Revision 1 or the 

original issue of this service bulletin. On lap joints where the upper (overlapping) skin thickness at the 

upper row of fasteners is 0.071 inches or less will be required to accomplish a structural modification 

as given Boeing Service Bulletin 747-53A2463. In addition, for airplanes with the optional protruding 

head fastener modification installed, the repeat inspection interval has been reduced from 3,000 flightcycles to 1,000 flight-cycles.

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 90-15-06 and 94-12-09 are related to 

this service bulletin.

Boeing recommends a detailed visual inspection for all airplanes with less than 15,000 flight cycles 

within 1,000 flight cycles after receipt of this service bulletin. Repeat detailed visual inspections at 

1,000 flight cycle intervals on non-terminated lap joints in Sections 41, 42, and 46 and 2,000 flight 

cycles intervals for Section 44. This group of airplanes can elect to do the inspection for older airplanes 

per Method II to extend the inspection intervals.

Airplanes with 15,000 or more flight cycles must do a detailed visual inspection and a High Frequency 

Eddy Current (HFEC) inspection within 1,000 flight cycles after receipt of this service bulletin. Repeat 

detailed visual inspections at 2,000 flight cycle intervals on non-terminated lap joints in Sections 41, 

42, 44 and 46. Repeat HFEC inspections at 4,000 flight cycle intervals on non-terminated lap joints in 

Sections 41, 42 and 6,000 flight cycle intervals for Section 46. Section 44 does not require a HFEC 

inspection.

Longitudinal lap joints where the upper (overlapping) skin thickness at the upper row of fasteners is 

less than or equal to 0.071 inches will require accomplishment of a structural modification or a second 

modification, and post modification inspections at the times given in SB 747-53A2463 Revision 1 

"FUSELAGE - Skin - Longitudinal Lap Joints Inspection and Repair", Paragraph 1.E., Compliance, 

Table 3.

SB 747-53A2463 Revision 1 includes instructions for accomplishing the structural modification.

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.
 

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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, repair, 

and modification procedures of this service bulletin as an AMOC to the corresponding requirements 

of paragraph A., B., and F. of AD 90-15-06. 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 H. of the AD. All 

provisions of AD 90-15-06 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 applicable inspection, 

repair, and modification procedures of this service bulletin as an AMOC to the corresponding 

requirements of paragraphs (a), (b), (c), (e), (f) and (g) of AD 94-12-09. 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 (i) of the AD. All provisions of AD 94-12-09 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.

Task Number of Persons Task Hours Elapsed Hours

Visual Inspection of Lap 

Joints

4 152 38

Eddy Current Inspection of 

Lap Joints

4 56 14

TOTAL FOR EACH AIRPLANE 208 52

(a) Crew size, man hour and elapsed time shown does not include time for lap joint repair or 

access to accomplish such repair since it is dependent on the extent of repairs required. It is 

assumed that operators will not perform terminating action on all lap joint areas at one time. 

Therefore, crew size, man hours and elapsed time should be based on operator's experience 

and on the length and location of the lap joint for which terminating action is accomplished. 

Accomplishment of terminating action is estimated to be 96 man hours for each 200 inch length 

of uncracked and uncorroded lap joint. 
 

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The following breakdown of manpower requirements is suggested as a guide to assist operators in 

planning and accomplishing this modification on airplanes with Main Deck Side Cargo Door (MDSCD) 

Modification. This estimate is for direct labor performed by an experienced crew. It does not include 

setup, planning, familiarization, cure time, part fabrication, tool acquisition, or lost time. Factor this 

estimate as necessary based on your own experience. 

H. Weight and Balance Changes

Installation of lap joint repairs and modifications as outlined in Boeing Service Bulletin 747-53A2463 

"Fuselage - Skin - Longitudinal Lap Joints Inspection and Repair" will affect the weight and balance of 

the airplane. Determination of these changes is necessary, once the configuration of the lap joint 

repairs and modifications are defined.

I. Electrical Load Data

Not applicable.

J. References

1. Existing Data:

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

b. 747 Maintenance Manual (AMM) Subject 25-11-01, 25-11-02, 25-11-03, 25-11-05, 25-14-

01, 25-19-00, 25-21-01, 25-21-02, 25-21-04, 25-21-12, 25-22-01, 25-22-03, 25-22-06, 25-

23-01, 25-23-04, 25-23-05, 25-24-00, 25-24-05, 25-24-11, 25-24-12, 25-24-19, 25-25-01, 

25-25-03, 25-25-04, 25-26-02, 25-26-03, 25-26-06, 25-27-00, 25-28-01, 25-28-15, 25-28-

23, 25-31-04, 25-40-01, 25-40-03, 25-59-01, 25-68-02, 31-00-00, 34-11-00, 35-00-00, 35-

21-00, 52-11-01, 52-13-01, 52-51-01, 53-21-01, 53-21-02 

c. 747 Structural Repair Manual (SRM) Subject 51-10-01, 53-30-03 

d. 747 Nondestructive Test (NDT) Manual D6-7170, Part 6, Subjects 51-00-00, 53-30-00, 53-

30-02, 53-30-03, 53-30-05, 53-30-09, and 53-30-19

e. 747 Structural Item Interim Advisory (SIIA) 747-71 

f. Boeing Service Bulletins 747-53-2157, "Body Longitudinal Skin Lap Joints, Tear Strap/Skin 

Lap Splices, Window Forgings, Skin Panel Doublers, And Selected Skin Panel Corrosion 

Inspection"; 747-53-2253, "Fuselage - Nose Section - Station 340 to 400 Stringer 6 Skin 

Inspection and Modification"; 747-53A2265, "Fuselage - Nose Section 41 - Body Frame 

Structure Inspections and Crack Repairs"; 747-53A2279, "Fuselage - Skin - Upper Body 

Skin Bonded Tear Strap Inspection and Modification"; 747-53A2303, "Fuselage - Nose 

Section - Station 400 to 520 Stringer 6 Skin Lap Splice Inspection Repair and Modification" 

747-53A2463 "Fuselage - Skin - Longitudinal Lap Joints Inspection and Repair"

Task Number of Persons Task Hours Elapsed Hours

Internal Visual Inspection 

and Low Frequency Eddy 

Current Inspection 

(MDSCD Mod)

188
 

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g. FAA Airworthiness Directive (AD) 90-15-06, Amendment 39-6653 and 94-12-09, 

Amendment 39-8937.

h. Boeing Document D6-36022, "Aging Airplane Corrosion Prevention and 

Control Program, Model 747.

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

Program, Model 747".

2. Data supplied with this Service Bulletin:

a. Drawings:

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

None.

K. Publications Affected

L. Interchangeability and Intermixability of Parts

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

Drawing Number Title Sheet DCN ADCN

015U0566 Replacement Fastener Instl -

Lap Splice Rework,

Sta. 1656 to Sta. 2002

Str 4L and Str 12L - Top Kit

P/L (a) A -

1 (a) - -

2 (a) - -

(a) Drawings sent with Revision 1 of this service bulletin.

Publication Chapter-Section

747 Corrosion Prevention Manual 53-30-47 
 

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BLANK PAGE
 

December 21, 1989

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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.

Date: August 27, 1992

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

acknowledgment. The prices (and ROLT) are subject to acceptance within 180 days from the date 

shown above. After 180 days, 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 configuration changes, inspection, and/or repair 

procedures given in this service bulletin.

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.

Kit Number Name

ROLT 

(Weeks) Unit Price

015U0566-1 Replacement Fastener Instl-Lap 

Splice Rework, Sta 1656 to Sta 

2002, S-4L and S-12L, Top Kit

42 $5927.00
 

December 21, 1989

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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.

2. Parts and Materials Supplied by the Operator:

None.

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.

015U0566- Replacement Fastener Instl. - Lap Splice Rework, Sta 1656 to Sta 2002 Str 4L to Str 

12L - Top Kit

New Part Number

QTY

-1 Name Notes

 015U0566 - Top Kit (a) (b) (c) (d)

(a) This kit is for airplanes with Main Deck Side Cargo Door Modification only. This kit contains 

fasteners to accomplish the full modification from Sta 1656 to Sta 2002 at Str 4L and Str 12L only. 

(b) See sheet PL of drawing 015U0566, supplied with this service bulletin, for kit contents.

(c) This kit has more parts than necessary for installation. Discard or save parts not used.

(d) If grip length shown is not available at Boeing, fasteners supplied in kits may be one grip length 

longer than indicated. Also, if any fasteners part numbers listed are not available or have been 

superseded, substitute fasteners may be supplied in kits. Boeing Document D-590 and Boeing 

Drawing 012W6100 are used to determine the part numbers used as substitutes.
 

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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. The following paragraphs outline the general accomplishment instructions. The 

suggested sequence of operations and detailed accomplishment instructions are 

indicated by circle notes on the figures. 

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

3. Figure 1 contains the Logic Diagram presentations of the following general 

accomplishment instructions. 

4. Lap joints on cargo door are not required to be inspected or modified on aircraft with 

Main Deck Side Cargo Door.

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

inspection program per this service bulletin. In addition, do the selected portion of the 

lap joint modification that addresses lap joints fastened with deep countersink rivets. 

Incorporation thresholds for the inspection and modification are shown in the Description 

and Accomplishment Instructions

6. To accomplish the Full or Optional Modification on lap joints where the upper 

(overlapping) skin panel thickness is 0.090 inches or less, a HFEC inspection on some 

fastener holes is required. Figure 6 identifies the locations where the upper 

(overlapping) skin panel thickness is 0.090 inches or less. Lap joints where the upper 

(overlapping) skin panel thickness is 0.071 inches or less require an after modification 

inspection. Figure 7 identifies the locations where the upper (overlapping) skin panel 

thickness is 0.071 inches or less. 

7. In some areas of the lap joints, a doubler is bonded to the upper (overlapping) skin 

panel. The skin panel thicknesses used in Figure 6 and Figure 7 do not include doublers. 

The thickness dimension used in Figure 6 and Figure 7 are for skin panels only. The 

modifications and after modification inspections are based on skin panel thickness only. 

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

definition of the acronyms.

9. 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 SRM, Chapter 51
 

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BOEING SERVICE BULLETIN 747-53-2307

— Torque limits to tighten nuts and bolts are given in 747 SRM, Chapter 51.

10. 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.

11. 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.

B. WORK INSTRUCTIONS

1. For all lap joints affected by this bulletin as identified by Figure 2, perform inspection of the lap 

splices using Method I or II as outlined in the logic diagrams of Figure 1.

Method I: Visual Inspection only (Do not use for airplanes with more than 15,000 flight cycles) 

Within 1,000 flight-cycles after receipt of the original release of this bulletin, do a detailed visual 

inspection of the affected lap joints per Figure 2, circle notes 1 and 3. Repair any corrosion 

beyond limits or cracking as specified in Figure 2, circle note 3. Repeat the detailed visual 

inspection at intervals not to exceed 1,000 flight-cycles for the nonterminated lap joints in 

Sections 41, 42, and 46. Repeat the detailed visual inspection at intervals not to exceed 2,000 

flight-cycles in Section 44.

Method II: Visual and Eddy Current Inspection (Required for airplanes with 15,000 or more flight 

cycles, optional for airplanes with less than 15,000 flight cycles)

Within 1,000 flight-cycles after receipt of the original release of this bulletin, do a detailed visual 

inspection of the affected lap joints per Figure 2, circle notes 1 and 3. At the same time do an 

external high frequency eddy current (HFEC) inspection of selected lap joints as indicated in 

Figure 2, circle notes 2 and 3. Repair any corrosion beyond limits or cracking as specified in 

Figure 2, circle note 3. Repeat the detailed visual inspections at intervals not to exceed 2,000 

flight-cycles in Sections 41, 42, 44, and 46. Repeat the HFEC inspections at intervals not to 

exceed 4,000 flight-cycles for the nonterminated lap joints in Sections 41 and 42 and intervals 

not to exceed 6,000 flight-cycles for the nonterminated lap joints in Section 46. Eddy Current 

inspections are not required for lap joints in Section 44. 

On aircraft with a main deck side cargo door, do an internal low frequency eddy current (LFEC) 

inspection per 747 Non Destructive Test Manual D6-7170, Part 6, Subject 53-30-09 on selected 

46-section skin lap areas at Stringer 4-left and 12-left together with the above initial visual 

inspections.

2. In lieu of continued reinspections, modification of lap joint areas shown in Figure 2 is 

accomplished as follows:
 

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BOEING SERVICE BULLETIN 747-53-2307

NOTE:

1. At laps where the upper (overlapping) skin thickness is 0.071 inch or less, Boeing 

recommends that operators accomplish the structural modification as given in 

Boeing Service Bulletin 747-53A2463, "Fuselage - Skin - Longitudinal Lap Joints 

Inspection and Repair". Refer to the compliance table in Paragraph 1.E. of Service 

Bulletin 747-53A2463 to determine whether to continue with the instructions in this 

service bulletin or to accomplish the modification given in Service Bulletin 747-

53A2463.

2. The optional modification should not be accomplished at lap joint locations where 

the upper (overlapping) skin thickness at the upper row of fasteners is 0.071 inches 

or less.

3. Do not use 747-100/200/300 SRM 53-30-03 Figure 18 or 27 when accomplishing 

a lap joint repair. 747-100/200/300 SRM 53-30-03 Figure 19 should be used for lap 

joint repairs.

4. Figure 7 shows the locations of all lap joints where the upper (overlapping) skin 

thickness at the upper row of fasteners is less than or equal to 0.071 inches.

a. Full modification in an uncorroded lap joint is accomplished when the lap joint is separated 

along an entire skin panel between adjacent circumferential splices, adhesive is removed, 

faying surface sealant is applied and the joint is refastened per 747 Structural Repair 

Manual Subject 53-30-03 Figure 9 or Figure 10 as applicable. This does not apply to deep 

countersink fastener locations. See following procedure for deep countersink fastener 

modification. 

b. Full modification in the area of deep countersink rivets, Str 12, Sta 520 to Sta 1000 and Str 

19, Sta 520 to Sta 740, must be accomplished by the following method. Separate the lap 

joint between adjacent circumferential splices and remove adhesive to inspect for corrosion 

or cracks. Do a HFEC open hole inspection of all fastener locations per 747 Non Destructive 

Test Manual D6-7170 Part 6, Subject 53-30-00 Figure 1,3 or 4. At rivet locations, drill to 

oversize dimension of 0.284-0.296. Apply fay surface sealant to the lap joint to fill the 

remaining countersink void, and install 9/32 protruding head fasteners in all three fastener 

rows in lap joint. All bolt locations in lap joint area are to be reworked per 747 Structural 

Repair Manual Subject 53-30-03, Fig. 10.

c. Full modification in a corroded lap joint is accomplished when a permanent repair of 

corroded lap joint area is conducted per 747 Structural Repair Manual Subject 53-30-03 

concurrently with full modification of the remaining part of the lap joint per step 3.a. If the 

amount of material removed exceeds 10 percent, trim the affected area and repair per SRM. 

At the same time inspect the body frame in the corroded area and repair any frame cracking 

per Structural Repair Manual Subject 51-40-03.

NOTE: Do not use 747-100/200/300 SRM 53-30-03 Figure 18 or 27 when accomplishing

a lap joint repair. 747-100/200/300 SRM 53-30-03 Figure 19 should be used for lap

joint repairs.
 

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BOEING SERVICE BULLETIN 747-53-2307

d. Modification in a lap joint that is both corrosion and crack free is accomplished by either the 

full modification per step 3.a. or an optional modification. The optional modification consists 

of replacing existing countersunk fasteners, in areas where the upper (overlapping) skin 

panel thickness is 0.090 or less, with 1/16 inch oversized protruding head fasteners in the 

lap joint upper fastener row without disturbing the rest of the lap joint.

e. Full modification of the lap joints around the Main Deck Side Cargo Door (MDSCD) 

modification can be accomplished by the following method. Remove the straps and doublers 

at Str 4, Sta 1660 to Sta 2000. Remove doublers from Str 12, Sta 1741 to Sta 1780, Sta 

1920 to Sta 1961. Full modification of the lap joints forward of Sta 1741 and aft of Sta 1961 

can be accomplished. After full modification of Str 4 and Str 12 in this area, reinstall straps 

and doublers using the special kit of oversize fasteners. Refer to drawing 015U0566, PL, Sh 

1 and Sh 2.

For both Full and Optional Modifications on lap joints where the upper (overlapping) skin panel 

thickness is 0.090 inches or less, a HFEC inspection of some fastener holes is required. Do an 

open hole HFEC inspection in the upper fastener row of lap joint per 747 Non Destructive Test 

Manual D6-7170 Part 6, 53-30-00 Figure 1, 3 or 4 for countersunk holes or 51-00-00 Figure 1 or 

11 for non countersunk holes to verify holes are crack free. For both full and optional 

modifications it is acceptable to oversize holes in upper fastener row by 1/64 inch to decrease 

incorrect crack indication. After inspection, enlarge holes again by 3/64 inch to permit installation 

of 1/4 inch protruding head fasteners. See Figure 6 for upper (overlapping) skin panels 0.090 

thickness or less. The HFEC inspection is not required on lap joints where the upper 

(overlapping) skin panel thickness is greater than 0.090 inches. 

Conduct both an internal and external detailed visual inspection for cracking and corrosion of the 

lap joint prior to the modification. Apply corrosion prevention compound BMS 3-23, at time of 

modification, to the lap joint externally under the wing to body fairing and internally at all lap joint 

areas. 

NOTE:

1. When accomplishing terminating action on a specific lap joint length, contact 

Boeing for jacking requirements (specify lap joint being reworked, details of 

airplane configuration including weight and CG, and any other work being 

performed concurrently on the airplane). Lap joint must be opened completely 

between circumferential splices. No partial lap joint rework is allowed.

2. To accomplish terminating action with either the full or optional modification, the 

standard 2 dia. edge margin requirement is changed to 1.5 dia minimum at the top 

row of fasteners on the inner skin panel of all lap joints.

3. Apply corrosion inhibiting compound (BMS 3-23 or equivalent) internally to all lap 

joint areas after terminating action is accomplished. Affected lap joints for which 

inspection or terminating action has been accomplished by previous release of this 

service bulletin do not require additional work for application of corrosion inhibiting 

compound. Application of corrosion inhibiting compound is mandatory for airplanes 

repaired by the optional modification. 

3. Restore airplane to normal configuration.

4. After modification reinspect as follows:
 

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BOEING SERVICE BULLETIN 747-53-2307

a. External HFEC inspection for skin cracks at the upper fastener row of the lap joint (0.071 

and less upper (overlapping) skin thicknesses only) per 747 NDT, Part 6, 53-30-19 

(preferred) or 747 NDT, Part 6, 51-00-00 Figure 4. See Figure 7 for areas of the lap joints 

that require reinspection.

— at 10,000 flight cycles after full modification per Revision 1 or later revision;

— at 7000 flight cycles after optional modification;

— at 5000 flight cycles for Sec. 42 deep countersink fastener locations reworked per the 

original release of this service bulletin;

Repeat at 1,000 flight cycle intervals (applicable to all modification methods).

Post-modification inspections per this service bulletin at lap joints with upper (overlapping) 

skin thickness of 0.071 inch or less at the upper fastener row can be terminated after the 

structural modification given in Service Bulletin 747-53A2463 has been done. Postmodification inspection data for lap joints with upper (overlapping) skin thickness of 0.071 

inch or less at the upper fastener row will be included with the structural modification data 

given as part of the Service Bulletin 747-53A2463 requirements.

b. Detailed visual inspection for corrosion per Boeing Document D6-36022.

External at 5 year intervals

Internal at 8 year intervals with application of corrosion inhibiting compound.

c. If any corrosion or cracks are found, repair per 747 Structural Repair Manual Subject 

53-30-03, notify Boeing of the details of the discrepancy and continue inspection per steps 

4.a. and 4.b. above.

NOTE: Do not use 747-100/200/300 SRM 53-30-03 Figure 18 or 27 when accomplishing

a lap joint repair. 747-100/200/300 SRM 53-30-03 Figure 19 should be used for lap

joint repairs.

5. Inspect repairs as given in 747-100/200/300 SRM 53-30-03 or as given in the 747 Repair 

Assessment Guidelines document D6-36181. For any external doubler repairs greater than 40 

inches in length (in the horizontal direction) do internal surface HFEC inspections every 3,000 

flight-cycles.
 FIGURE 1: EXTERNAL LAP JOINT INSPECTION LOGIC DIAGRAM

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BOEING SERVICE BULLETIN 747-53-2307

FIGURE 1: EXTERNAL LAP JOINT INSPECTION LOGIC DIAGRAM

INSPECTION METHOD I: VISUAL ONLY

(DO NOT USE FOR AIRPLANES WITH

15,000 OR MORE FLIGHT-CYCLES)

WITHIN 1,000 FLIGHT CYCLES

AFTER RECEIPT OF THIS BULLETIN

PERFORM THE FOLLOWING

CONDUCT A DETAILED EXTERNAL VISUAL

INSPECTION TO DETERMINE IF CORROSION

OR CRACKING EXISTS AT COLD-BONDED

LONGITUDINAL BODY SKIN LAP JOINTS AT S-23

AND ABOVE FROM STATION 140 TO 2360

(REF FIGURE 2)

AREAS OF CRACKS

OR CORROSION

NO CRACKS

OR CORROSION

CONDUCT HFEC INSPECTION FOR

CRACKS AT UPPER FASTENER ROW

OF LAP JOINT OVER COMPLETE

LENGTH OF LAP JOINT AS

INDICATED IN FIGURE 2

CONDUCT TERMINATING

ACTION ON AFFECTED

LAP JOINTS

DO POST

MODIFICATION

INSPECTION

(SKIN GAGE

0.071 OR LESS)

REPEAT VISUAL INSPECTION

OF ALL NONTERMINATED LAP

JOINTS IN SECTIONS 41,42

AND 46 AT 1,000 FLIGHTCYCLE INTERVALS AND SECTION 44 AT 2,000 FLIGHTCYCLE INTERVALS

CORROSION BUT

NO CRACKS

CRACKS

DETERMINE AMOUNT OF MATERIAL

LOSS PER LFEC INSPECTION

METHOD IN 747 NDT D6-7170,

PART 6, 51-00-00, FIGURE 5

OR FIGURE 12

CONTINUED ON NEXT PAGE

1 5

2

3

A B C D

1370326

(SHEET 1 OF 6)
 FIGURE 1: EXTERNAL LAP JOINT INSPECTION LOGIC DIAGRAM

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BOEING SERVICE BULLETIN 747-53-2307

AT 5,000 FLIGHT-CYCLES FOR

DEEP COUNTERSINK RIVETS

REWORKED PER ORIGINAL RELEASE

DO POST MODIFICATION

INSPECTION (SKIN GAGE

0.071 OR LESS)

CONDUCT TERMINATING ACTION

ON REMAINDER OF LAP JOINT

BETWEEN CIRCUMFERENTIAL

SPLICES WITHIN 15 MONTHS

DO POST MODIFICATION

INSPECTION (SKIN GAGE

0.071 OR LESS)

AT 7,000 FLIGHT-CYCLES 

AFTER OPTIONAL 

MODIFICATION

AT 10,000 FLIGHT-CYCLES

AFTER FULL MODIFICATION

EXTERNAL HFEC INSPECTIONS FOR 

CRACKS AT THE UPPER FASTENER

ROW OF THE LAP JOINT PER THE 

747 NDT MANUAL

MATERIAL LOSS

LESS THAN 10%

MATERIAL LOSS

GREATER THAN 10%

CONDUCT TERMINATING ACTION ON

30 MONTHS

CORRODED LAP JOINT BETWEEN

CIRCUMFERENTIAL SPLICES WITHIN

CORRODED JOINTS BETWEEN

INTERVALS

REPEAT INSPECTION OF

CIRCUMFERENTIAL SPLICES

AT 500 FLIGHT-CYCLE

FLIGHT

CORROSION PER SRM

53-30-03 PRIOR TO

FURTHER PRESSURIZED

REPAIR ALL CRACKS OR

THEN WITHIN 1,000 FLIGHT-CYCLES 

FROM LAST EXTERNAL HFEC INSPECTION

A B C D

CONTINUED FROM PREVIOUS PAGE

4

3

3

6

1370333

(SHEET 2 OF 6)
 FIGURE 1: EXTERNAL LAP JOINT INSPECTION LOGIC DIAGRAM

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BOEING SERVICE BULLETIN 747-53-2307

INSPECTION METHOD II:

VISUAL AND EDDY CURRENT INSPECTION

(REQUIRED FOR AIRPLANES WITH 15,000 OR MORE FLIGHT-CYCLES)

WITHIN 1,000 FLIGHT-CYCLES AFTER RECEIPT OF THIS

BULLETIN PERFORM THE FOLLOWING

CONDUCT A DETAILED EXTERNAL VISUAL INSPECTION TO DETERMINE

IF CORROSION OR CRACKING EXISTS AT COLD-BONDED LONGITUDINAL BODY

SKIN LAP JOINTS AT S-23 AND ABOVE FROM STATION 140 TO 2360

(REF FIGURE 2)

CONDUCT AN EXTERNAL HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTION

OF SELECTED LAP JOINTS IN SECTIONS 41, 42 AND 46 FOR SKIN CRACKING

AS INDICATED IN FIGURE 2

NO CRACKS

OR CORROSION

CONDUCT TERMINATING

ACTION ON AFFECTED

LAP JOINTS

DO POST

MODIFICATION

INSPECTION

(SKIN GAGE

0.071 OR LESS)

REPEAT VISUAL INSPECTION

OF ALL NONTERMINATED LAP

JOINTS IN SECTIONS 41,42,

44 AND 46 AT 2,000 FLIGHT

CYCLE INTERVALS; REPEAT

HFEC INSPECTIONS AT

4,000 FLIGHT-CYCLES FOR

SECTIONS 41 AND 42, 6,000

FLIGHT-CYCLES FOR SECTION

46

CORROSION BUT CRACKS

NO CRACKS

DETERMINE AMOUNT OF MATERIAL

LOSS PER LFEC INSPECTION

METHOD IN 747 NDT D6-7170,

PART 6, 51-00-00, FIGURE 5

OR FIGURE 12

1 5

2

3

A

CONTINUED ON NEXT PAGE

B C D

1370334

(SHEET 3 OF 6)
 FIGURE 1: EXTERNAL LAP JOINT INSPECTION LOGIC DIAGRAM

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BOEING SERVICE BULLETIN 747-53-2307

The instruction numbers shown below agree with the numbers shown inside the flag symbols in FIGURE 1.

1. A "CYCLE" IS A FLIGHT CYCLE WITH CABIN PRESSURE DIFFERENTIAL GREATER THAN 2.0 PSID.

DO POST MODIFICATION

INSPECTION (SKIN GAGE

0.071 OR LESS)

DO POST MODIFICATION

INSPECTION (SKIN GAGE

0.071 OR LESS)

AT 10,000 FLIGHT-CYCLES

AFTER FULL MODIFICATION

AT 5,000 FLIGHT-CYCLES FOR

DEEP COUNTERSINK RIVETS

REWORKED PE RORIGINAL RELEASE

AT 7,000 FLIGHT-CYCLES 

AFTER OPTIONAL 

MODIFICATION

EXTERNAL HFEC INSPECTIONS FOR 

CRACKS AT THE UPPER FASTENER

ROW OF THE LAP JOINT PER THE 

747 NDT MANUAL

THEN WITHIN 1,000 FLIGHT-CYCLES 

FROM LAST EXTERNAL HFEC INSPECTION

MATERIAL LOSS

LESS THAN 10%

REPEAT INSPECTION OF

CORRODED JOINTS BETWEEN

CIRCUMFERENTIAL SPLICES

AT 500 FLIGHT-CYCLE

INTERVALS

CONDUCT TERMINATING ACTION ON

CORRODED LAP JOINT BETWEEN

CIRCUMFERENTIAL SPLICES WITHIN

30 MONTHS

MATERIAL LOSS

GREATER THAN 10%

REPAIR ALL CRACKS OR

CORROSION PER SRM

53-30-03 PRIOR TO

FURTHER PRESSURIZED

FLIGHT

CONDUCT TERMINATING ACTION

ON REMAINDER OF LAP JOINT

BETWEEN CIRCUMFERENTIAL

SPLICES WITHIN 15 MONTHS

4

3

3

6

A

CONTINUED FROM PREVIOUS PMAGE

B C D

1370338

(SHEET 4 OF 6)
 FIGURE 1: EXTERNAL LAP JOINT INSPECTION LOGIC DIAGRAM

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BOEING SERVICE BULLETIN 747-53-2307

2. EXTERNALLY, EVIDENCE OF CORROSION INCLUDES SKIN PILLOWING OR BULGES BETWEEN 

FASTENERS; WHITE POWDER PROTRUDING FROM LAP JOINT; LOOSE, MISSING OR 

DISTRESSED FASTENER HEADS; SKIN CRACKS; OR CORROSION THROUGH THE SKIN AS 

SHOWN IN NOTES 1 AND 2. SKIN PILLOWING IN EXCESS OF 0.010 INCH IS CONSIDERED 

EVIDENCE OF CORROSION. AS AN ALTERNATIVE TO MEASURING PILLOWING OF SKIN AND 

VISUAL INSPECTION FOR DISTRESSED FASTENERS, EDDY CURRENT INSPECTION PER 747 NON 

DESTRUCTIVE TEST MANUAL D6 7170, PART 6, 51-00-00, FIGURE 5 MAY BE USED TO MEASURE 

THE EXTENT OF MATERIAL LOSS IN THE LAP JOINT.

NOTE:

1. Distressed fasteners are evidenced by cracking of the fastener head, dishing of fastener 

head or excessive countersink depth. Refer to the ’Distressed Fastener Examples’ illustration 

at the end of this Figure.

2. Measuring of pillowing is accomplished by using a suitable straight edge and thickness gage. 

Minimum length of straight edge should be 4.50 inches. Refer to the ’Pillowing Example’ 

illustration at the end of this Figure.

3. TERMINATING ACTION HAS A CHOICE OF PROCEDURES.

FULL MODIFICATION:

FULL MODIFICATION CONSISTS OF OPENING THE LAP JOINT BETWEEN CIRCUMFERENTIAL 

SPLICES, REMOVING ADHESIVE, REPAIRING ALL CRACKS AND CORROSION, AND 

REASSEMBLING LAP JOINT PER SRM SUBJECT 53-30-03 FIG 9 AND 10. FULL MODIFICATION FOR 

DEEP COUNTERSINK FASTENER LOCATIONS AT STR 12 STA 520 - 1000 AND STR 19 STA 520 - 740 

CONSISTS OF OPENING THE LAP JOINT BETWEEN CIRCUMFERENTIAL SPLICES, REMOVING 

ADHESIVE, REPAIRING ALL CRACKS AND CORROSION, AND REASSEMBLING THE LAP JOINT 

WITH 9/32 INCH PROTRUDING HEAD FASTENERS IN ALL FASTENER LOCATIONS. THIS IS THE 

ONLY ACCEPTABLE MOD FOR DEEP COUNTERSINK FASTENERS AND GIVES THE OPERATOR 

FULL MOD STATUS ON POST MOD INSPECTION SCHEDULE.

OPTIONAL MODIFICATION:

OPTIONAL MODIFICATION CONSISTS OF REMOVING THE UPPER ROW OF FASTENERS AT A 

CORROSION FREE LAP JOINT, HFEC OPEN HOLE INSPECT FOR CRACKS IN REMOVED 

FASTENER LOCATIONS, AND INSTALLING 1/4 INCH PROTRUDING HEAD FASTENERS. THE 

OPTIONAL MODIFICATION IS NOT APPLICABLE TO DEEP COUNTERSINK FASTENER LOCATIONS.

NOTE:

1. Longitudinal lap joints where the upper (overlapping) skin thickness at the upper row of 

fasteners is less than or equal to 0.071 inches will require accomplishment of a structural 

modification or a second modification, and post modification inspections at the times given in 

SB 747-53A2463 Revision 1 "FUSELAGE - Skin - Longitudinal Lap Joints Inspection and 

Repair", Paragraph 1.E., Compliance.

2. The optional modification should not be accomplished at lap joint locations where the upper 

(overlapping) skin thickness at the upper row of fasteners is 0.071 inches or less.

3. Figure 7 shows the locations of all lap joints where the upper (overlapping) skin thickness at 

the upper row of fasteners is less than or equal to 0.071 inches.

(SHEET 5 OF 6)
 FIGURE 1: EXTERNAL LAP JOINT INSPECTION LOGIC DIAGRAM

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BOEING SERVICE BULLETIN 747-53-2307

4. IN ADDITION, THERE MUST BE NO EVIDENCE OF MISSING FASTENER HEADS, SKIN CRACKS, OR 

CORROSION COMPLETELY THROUGH THE SKIN AND FOR SECTION 46, THE TEAR STRAPS MUST 

HAVE BEEN REWORKED BY TEMPORARY REPAIR OR TERMINATING ACTION PER SERVICE 

BULLETIN 747-53A2279 IN AREA ADJACENT TO CORROSION. CORRECT AS REQUIRED TO MEET 

THESE CONDITIONS. 

5. AS RECOMMENDED BY THE 747 AGING FLEET STRUCTURES WORKING GROUP, ACCOMPLISH 

THE INSPECTION PROGRAM AND A SELECT PORTION OF THE LAP JOINT MODIFICATION THAT 

ADDRESSES LAP JOINTS FASTENED WITH DEEP COUNTERSINK RIVETS PER THIS SERVICE 

BULLETIN PRIOR TO, OR UPON THE ACCUMULATION OF 20,000 FLIGHT CYCLES OR WITHIN 1000 

FLIGHT CYCLES AFTER RECEIPT OF REVISION 1 OF THIS SERVICE BULLETIN, WHICHEVER IS 

LATER.

6. DO NOT USE 747 STRUCTURAL REPAIR MANUAL SUBJECT 53-30-03 FIGURE 18 OR 27 WHEN 

ACCOMPLISHING A LAP JOINT REPAIR.

DISTRESSED FASTENER EXAMPLES

DISHING OF FASTENER HEAD

EXCESSIVE

COUNTERSUNK DEPTH

CRACKS AT

FASTENER SHANK

1370348

PILLOWING EXAMPLES

INBD

4.50

MIN

INNER SKIN AT JOINT

STRAIGHT EDGE

OUTER SKIN

AT JOINT

SKIN PILLOWING

DIMENSION

(PILLOWING SHOWN

EXAGGERATED FOR

CLARITY)

1370351

(SHEET 6 OF 6)
 FIGURE 2: EXTERNAL LAP JOINT CORROSION INSPECTION

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BOEING SERVICE BULLETIN 747-53-2307

FIGURE 2: EXTERNAL LAP JOINT CORROSION INSPECTION

ENTRY DOOR

NO. 1

A

A

INDICATES AREA OF VISUAL AND HIGH FREQUENCY

EDDY CURRENT (HFEC) INSPECTIONS.

SECTION 41

LEFT SIDE

S-19

S-23

S-14

S-0

STA

520

STA

287

STA

260

STA

220

STA

180

STA

140

STA

340

STA

400

1 2 3

1 2

1370356

(SHEET 1 OF 10)
 FIGURE 2: EXTERNAL LAP JOINT CORROSION INSPECTION

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BOEING SERVICE BULLETIN 747-53-2307

UP

INBD

TYPICAL LAP JOINT

SECTION 41 STRINGER TYPICAL

SECTION 42, 44 AND 46

STRINGER TYPICAL

INNER SKIN

OUTER SKIN

SECTION A-A

1 3

2

1370362

(SHEET 2 OF 10)
 FIGURE 2: EXTERNAL LAP JOINT CORROSION INSPECTION

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BOEING SERVICE BULLETIN 747-53-2307

ENTRY DOOR

NO. 1

A

A

INDICATES AREA OF VISUAL AND HIGH FREQUENCY

EDDY CURRENT (HFEC) INSPECTIONS.

SECTION 41

LEFT SIDE

CREW DOOR

S-19

S-23

S-14

S-0

STA

520

STA

287

STA

260

STA

220

STA

180

STA

140

STA

340

STA

400

1 2 3

1 2

1370395

(SHEET 3 OF 10)
 FIGURE 2: EXTERNAL LAP JOINT CORROSION INSPECTION

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BOEING SERVICE BULLETIN 747-53-2307

S-23

S-19

S-12

S-6

S-0

S-23

S-19

S-12

S-6

S-0

WING BODY FAIRINGS ENTRY DOOR NO. 2

FORWARD

CARGO

DOOR

RIGHT SIDE

SECTION 42

LEFT SIDE

SECTION 42

STA

520

STA

941

STA

1000

STA

520

STA

1000

STA

741

WING BODY FAIRINGS

ENTRY DOOR NO. 2

A

A

INDICATES AREA OF VISUAL AND HIGH

FREQUENCY EDDY CURRENT (HFEC)

INSPECTIONS.

1 2 3

1 2

1370402

(SHEET 4 OF 10)
 FIGURE 2: EXTERNAL LAP JOINT CORROSION INSPECTION

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BOEING SERVICE BULLETIN 747-53-2307

S-23

S-19

S-12

S-4

ENTRY DOOR NO. 3

S-23

S-19

S-12

S-4

BL-0

STA

1000

STA

1241

STA

1480

ENTRY DOOR NO. 3

A

A

SECTION 44

APPLICABLE TO RA001-RA014, RA102, RA103 AND RA201 ONLY.

AIRPLANES NOT LISTED HAVE FAY-SEALED LAP JOINTS AND DO

NOT REQUIRE INSPECTION IN THESE AREAS.

INDICATES AREA OF VISUAL INSPECTION ONLY.

1

1

1

1 2

FWD

1

1370444

(SHEET 5 OF 10)
 FIGURE 2: EXTERNAL LAP JOINT CORROSION INSPECTION

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BOEING SERVICE BULLETIN 747-53-2307

A

A

SECTION 46

AFT

CARGO

DOOR

STA

1961.1

STA

1480

STA

1741.1

ENTRY DOOR NO. 4

S-23

S-19

S-12

S-4

S-4

S-12

S-19

S-23

ENTRY DOOR NO. 4

WING/BODY

FAIRINGS

WING/BODY

FAIRINGS

SEE FIGURE 6 FOR

AIRPLANES WITH

MAIN DECK SIDE

CARGO DOOR.

INDICATES AREA OF VISUAL AND HIGH FREQUENCY EDDY CURRENT (HFEC)

INSPECTIONS.

1 2 3

1 2

1370885

(SHEET 6 OF 10)
 FIGURE 2: EXTERNAL LAP JOINT CORROSION INSPECTION

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BOEING SERVICE BULLETIN 747-53-2307

A

A

SECTION 46

INDICATES AREA OF VISUAL AND HIGH FREQUENCY EDDY CURRENT (HFEC)

INSPECTIONS.

S-23

S-19

S-12

S-4

S-4

S-12

S-19

S-23

BL-0

ENTRY DOOR NO. 5

ENTRY DOOR NO. 5 STA

1961.1

STA

2181.1

STA

2360

BULK

CARGO

DOOR

1 2

1 2 3

1370886

(SHEET 7 OF 10)
 FIGURE 2: EXTERNAL LAP JOINT CORROSION INSPECTION

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BOEING SERVICE BULLETIN 747-53-2307

INITIAL PLANNING REFERENCE CHART

AREA OF INITIAL INSPECTION - VISUAL ONLY

1000 F/C THRESHOLD - REPEAT 1000 F/C INTERVALS

STR BODY STATION AREA

0 Sta 287 to Sta 941

4 L & R Sta 1480 to Sta 2360

6 L & R Sta 520 to Sta 1000

12 L & R Sta 520 to Sta 1000 - Sta 1480 to Sta 2360

14 L & R Sta 140 to Sta 520

19 L & R Sta 140 to Sta 1000 - Sta 1480 to Sta 2360

23 L & R Sta 140 to Sta 1000 - Sta 1480 to Sta 2360

AREA OF INITIAL INSPECTION - VISUAL ONLY

1000 F/C THRESHOLD - REPEAT 2000 F/C INTERVALS HFEC 

STR BODY STATION AREA

4 L & R Sta 1000 to Sta 1480 See F/N 1

12 L & R Sta 1000 to Sta 1480

19 L & R Sta 1000 to Sta 1480

23 L & R Sta 1000 to Sta 1480

AREA OF INITIAL INSPECTION - VISUAL AND HFEC

1000 F/C THRESHOLD - REPEAT 2000 F/C INTERVALS VISUAL AND 

4000 F/C INTERVALS HFEC

STR BODY STATION AREA

0 Sta 287 to Sta 941

6 L & R Sta 520 to Sta 1000

12 L & R Sta 520 to Sta 1000

14 L & R Sta 140 to Sta 520

19 L & R Sta 140 to Sta 1000

23 L & R Sta 140 to Sta 1000

AREA OF INITIAL INSPECTION - VISUAL AND HFEC

1000 F/C THRESHOLD - REPEAT 2000 F/C INTERVALS VISUAL AND 

6000 F/C INTERVALS HFEC

STR BODY STATION AREA

4 L & R Sta 1480 to Sta 2360

12 L & R Sta 1480 to Sta 2360

19 L & R Sta 1480 to Sta 2360

23 L & R Sta 1480 to Sta 2360

(SHEET 8 OF 10)
 FIGURE 2: EXTERNAL LAP JOINT CORROSION INSPECTION

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BOEING SERVICE BULLETIN 747-53-2307

The instruction numbers shown below agree with the numbers shown inside the circle symbols in FIGURE 2.

1. Perform an external detailed inspection to determine if corrosion or cracking exists at cold bonded 

longitudinal body skin lap joints. If evidence of corrosion or cracking is detected during the visual inspection, 

conduct a high frequency eddy current (HFEC) inspection (Ref. 747 Non-Destructive Test Manual D6-

7170, Part 6, Subject 53-30-02, 53-30-03, 53-30-05) for cracks in the skin at the upper row of fasteners in 

the lap joint over the entire length of the corroded or cracked skin panel.

NOTE:

1. In lieu of visual inspection, non destructive test method for corrosion detection per 747 NonDestructive Manual D6-7170, Part 6, Subject 51-00-00, Figure 5 or Figure 12 may be used.

2. Externally, evidence of corrosion includes skin pillowing or bulges between fasteners; white 

powder protruding from the lap joint; loose, missing or distressed fastener heads; skin cracks; 

or corrosion through the skin. 

3. Skin pillowing in excess of 0.010 inch is considered evidence of corrosion. As an alternative 

to measuring pillowing of skin and visual inspection for distressed fasteners, eddy current 

inspect (Ref. 747 Boeing Non-Destructive Test Manual D6-7170, Part 6, Subject 51-00-00, 

Figure 5 or Figure 12) to measure the extent of material loss in the lap joint. 

2. Perform a high frequency eddy current (HFEC) inspection (Ref. 747 Non-Destructive Manual D6-7170, 

Part 6, Subject 53-30-02, 53-30-03, 53-30-05) to determine if cracking exists in the outer skin of the lap 

splice at the upper fastener row (leftmost row at the Stringer 0 lap joint). Repair any cracking found per 747 

Structural Repair Manual Subject 53-30-03 prior to further pressurized flight.

3. Perform the following applicable actions: 

NOTE:

1. Longitudinal lap joints where the upper (overlapping) skin thickness at the upper row of 

fasteners is less than or equal to 0.071 inches will require accomplishment of a structural 

modification or a second modification, and post modification inspections at the times given in 

SB 747-53A2463 Revision 1 "FUSELAGE - Skin - Longitudinal Lap Joints Inspection and 

Repair", Paragraph 1.E., Compliance.

2. Do not use 747 Structural Repair Manual Subject 53-30-03 Figures 18 and 27 when 

accomplishing a lap joint repair.

3. Figure 7 shows the locations of all lap joints where the upper (overlapping) skin thickness at 

the upper row of fasteners is less than or equal to 0.071 inches.

A. For lap joint areas with cracking or corrosion completely through the skin, repair per 747 Structural 

Repair Manual Subject 53-30-03 prior to further pressurized flight.

B. For missing or distressed fasteners, replace fastener per 747 Structural Repair Manual Subject 53-

30-03, Figure 9 or 10, prior to next pressurized flight, except at deep countersink fastener locations. 

C. For lap joint areas with skin bulging or pillowing in excess of 0.010 inch, repair per 747 Structural 

Repair Manual Subject 53-30-03 unless the following three conditions have been met:

(SHEET 9 OF 10)
 FIGURE 2: EXTERNAL LAP JOINT CORROSION INSPECTION

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BOEING SERVICE BULLETIN 747-53-2307

1. Inspection per 747 Non-Destructive Test Manual D6-7170, Part 6, Subject 51-00-00, Figure 5 or 

Figure 12 indicates that material loss does not exceed 10 percent. 

2. No evidence of skin cracks or corrosion completely through the skin is found. 

3. For Section 46, tear straps have been reworked by temporary repair or terminating action per 

Service Bulletin 747-53A2279 in adjacent area. 

NOTE: Adjacent area refers to the area bounded by the 3 stringer bays above and below the

applicable lap joint and the closest tear strap forward and aft of the corroded area.

Where corrosion is within 5 inches of a frame, the next distant tear strap from and not

the tear strap closest to that frame determines that boundary. 

D. For lap joint areas where measured material loss does not exceed 10 percent, reinspect per this 

service bulletin at 500 flight-cycles as specified in the procedure (Method I or II) being used. 

Terminating action must be performed on corroded lap joint (from forward circumferential splice to aft 

circumferential splice) within 30 months of being found. 

E. For lap joint areas where material loss is greater than 10 percent, repair per 747 Structural Repair 

Manual Subject 53-30-03 prior to next pressurized flight. 

F. For any lap splice which is required to be repaired per 747 Structural Repair Manual Subject 53-30-

03, terminating action must be performed on the remaining unrepaired length of the skin panel (from 

forward circumferential splice to aft circumferential splice of repaired skin panel) within 15 months of 

the repair. If existing repairs are found during the initial visual inspection of this bulletin, terminating 

action must be accomplished on the remaining unrepaired length of the skin panel within 15 months 

of being found.

NOTE: Terminating action may still require further actions as given in Service Bulletin 747-53A2463.

G. Inspect repairs as given in 747-100/200/300 SRM 53-30-03 or as given in the 747 Repair Assessment 

Guidelines document D6-36181. For any external doubler repairs greater than 40 inches in length (in 

the horizontal direction) do internal surface HFEC inspections every 3,000 flight-cycles.

(SHEET 10 OF 10)
 FIGURE 3: FLIGHT DECK LAP JOINT INTERNAL ACCESS

December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

FIGURE 3: FLIGHT DECK LAP JOINT INTERNAL ACCESS

FLIGHT

ENGINEER'S

STATION

STA

394

STA

STA

STA

STA

332

260

340

520

LAVATORY

AREA

PILOTS'

STATION

OBSERVERS'

STATION

STOWAGE

AREA

UPPER DECK

TYPICAL FLIGHT DECK INSTALLATION

ALL AFFECTED CONFIGURATIONS SIMILAR

P5, P7, P12,

(AND P126)

OVERHEAD PANELS

1

2

3 5

UP

FWD

1370852

(SHEET 1 OF 4)
 FIGURE 3: FLIGHT DECK LAP JOINT INTERNAL ACCESS

December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

FWD

UP

6

330

300

STA

STA

1370856

(SHEET 2 OF 4)
 FIGURE 3: FLIGHT DECK LAP JOINT INTERNAL ACCESS

December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

The instruction numbers shown below agree with the numbers shown inside the circle symbols in Figure 3.

1. Remove the flight engineer's seat per 747 Maintenance Manual Subject 25-11-02 or operator's comparable 

procedure. Remove the observer's seat per 747 Maintenance Manual Subject 25-11-03 or operator's 

comparable procedure. Remove the crew seat per 747 Maintenance Manual Subject 25-11- 05 or 

operator's comparable procedure. 

UP

FWD

6

390

STA

300

STA

1370859

(SHEET 3 OF 4)
 FIGURE 3: FLIGHT DECK LAP JOINT INTERNAL ACCESS

December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

2. Remove the pilot's seats per 747 Maintenance Manual Subject 25-11-01, or operator's comparable 

procedure. 

3. Remove the pilots' overhead panel P5 and circuit breaker panels P7, P12 (and P126 if installed). Reference 

747 Maintenance Manual Subject 31-00-00.

4. Not shown - Cover pedestal, panels, racks, and all wire bundle connectors with plastic sheets to help 

prevent contamination or damage of equipment. 

5. Remove and salvage disconnect panels behind the pilots' overhead panel P5 and circuit breaker panels 

P7 and P12. Disconnect wire bundles as required to enable disconnect panels to be moved clear of 

modification area for dripshield removal. 

NOTE: Prior to disconnecting any wire bundles from disconnect panels, removing any wire bundles from

wire bundle clamps or disconnecting any separate ground wires, ensure that all wire bundles and

separate wires are identified and suitably marked for reinstallation. 

6. Remove and salvage the overhead sidewall linings, moldings, dripshields, and insulation in flight deck area 

per 747 Maintenance Manual Subject 25-14-01 or operator's comparable procedure. 

7. Not shown - Loosen and deflect any installed pitot static tubing as required in modification areas per 747 

Maintenance Manual Subject 34-11-00 or operator's comparable procedure. 

8. Not shown - Loosen and deflect, or remove any oxygen tubing in modification areas, as required per 747 

Maintenance Manual Subject 35-00-00 or operator's comparable procedure. 

9. Not shown - Remove crew escape hatch per 747 Maintenance Manual Subject 53-21-01 or operator's 

comparable procedure.

(SHEET 4 OF 4)
 FIGURE 4: UPPER DECK LAP JOINT INTERNAL ACCESS

December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

FIGURE 4: UPPER DECK LAP JOINT INTERNAL ACCESS

The instruction numbers shown below agree with the numbers shown inside the circle symbols in FIGURE 4.

1

AFT PARTITION

FLIGHT COMPARTMENT

FLIGHT COMPARTMENT DOOR

E11 RACK ENCLOSURE

PARTITION

RIGHT CREW DOOR

LEFT CREW DOOR

(IF INSTALLED)

FLOOR MOUNTED

ESCAPE SLIDE

(TYPICAL)

FORWARD LEFT

PARTITION

CENTER LIGHTED REVEAL

UPPER CLOSURE PANEL

TYPICAL UPPER DECK CONFIGURATION

WITH LEFT AND RIGHT CREW DOOR

(OTHER UPPER DECK CONFIGURATIONS SIMILAR)

WINDOW REVEAL

PSU PANEL

LOWER CLOSURE PANEL

STOWAGE BIN

1370861

(SHEET 1 OF 2)
 FIGURE 4: UPPER DECK LAP JOINT INTERNAL ACCESS

December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

1. Remove and salvage equipment and furnishings as required to gain access to STA 420 through STA 520 

lap joints. Refer to the following maintenance manual subjects for removal procedure.

2. Not shown - Install all items which are removed in the preceding step per the applicable maintenance 

manual subject or operator's comparable procedure.

Equipment Maintenance 

Manual Subject

Window Reveal 25-21-02

Sidewall and Ceiling Insulation 25-21-04 

Ceiling Panels 25-22-03

Passenger Service Units 25-23-01

Forward Closets 25-24-00 

Forward Right Partition 25-24-11

Forward Left Partition 25-24-12

Crew Rest Area 25-24-19

Passenger Seats 25-25-01

Wall Mounted Attendant Seat 25-25-04 

Stairway Forward Right Partition 25-26-02

Stair Aft Right Partition 25-26-03

Stairway Forward Left Partition 25-26-06 

Sidewall Stowage Units 25-28-15

Overhead Stowage Bins 25-28-23

Lavatories 25-40-03 

Floor Mounted Escape Slide 25-68-02

Crew Entry Door 52-13-01 

Flight Compartment Door 52-51-01 

(SHEET 2 OF 2)
 FIGURE 5: MAIN DECK LAP JOINT INTERNAL ACCESS

December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

FIGURE 5: MAIN DECK LAP JOINT INTERNAL ACCESS

The instruction numbers shown below agree with the numbers shown inside the circle symbols in FIGURE 5.

CAUTION: TO PREVENT DAMAGE TO FLOOR PANELS, IT IS RECOMMENDED THAT A 1/2 INCH THICK,

1 FOOT SQUARE PLYWOOD BEARING PAD BE USED UNDER EACH LEG OF LADDERS,

CEILING

ATTENDANT SERVICE

PANEL

PANEL

DOOR ONE

MAIN ENTRY

SERVICE UNIT

PASSENGER

PANEL

ATTENDANT

LINING PANEL

SIDEWALL

STOWAGE BIN

OVERHEAD

(OTHER MAIN DECK CONFIGURATIONS SIMILAR)

TYPICAL MAIN DECK CONFIGURATION

1

1370864

(SHEET 1 OF 2)
 FIGURE 5: MAIN DECK LAP JOINT INTERNAL ACCESS

December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

STANDS OR SCAFFOLDS. ADDITIONALLY, IT IS ALSO RECOMMENDED THAT ONLY ONE

PERSON BE ALLOWED TO USE EACH LADDER, STAND OR SCAFFOLD.

1. Remove and salvage equipment and furnishings as required to gain access to STA 140 through STA 2360 

lap joints. Refer to the following maintenance manual subjects for removal procedure. 

2. Not shown - Install all items which are removed in the preceding step per the applicable maintenance 

manual subject or operator's comparable procedure. 

Equipment Maintenance 

Manual Subject

Sidewall Lining Panels 25-21-01/-02 

Sidewall and Ceiling Insulation 25-21-04 

Sidewall Dado Panels 25-21-12 

Ceiling Panels 25-22-01/-03 

Entryway Ceiling Panels 25-22-06 

Passenger Service Units 25-23-01 

Attendant Service Unit 25-23-04 

Forward Closets 25-24-00 

Partitions 25-24-05 

Passenger Seats 25-25-01

Track Mounted Attendant Seats 25-25-03

Wall Mounted Attendant Seats 25-25-04 

Floor Covering 25-27-00 

Insulation Blankets 25-28-01 

Overhead Stowage Bins 25-28-23

Sidewall Galleys 25-31-04

Sidewall Lavatories 25-40-01 

Cargo Lining Panels 25-59-01 

Attendant Panel 25-23-05 

Oxygen Tubing 35-21-00 

Main Entry Door No. 1 52-11-01 

Floor Panels 53-21-02 

(SHEET 2 OF 2)
 FIGURE 6: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.090 INCHES OR 

LESS

Original Issue: December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

FIGURE 6: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.090 INCHES OR 

LESS

STA

2360

STA

1961.1

STA

1480

STA

1000

STA

520

SEE DETAIL I (PASS)

SEE DETAIL V (R6001)

SEE DETAIL II

NOTE: SEE DETAIL VII FOR A/P'S WITH MAIN DECK

SIDE CARGO DOOR MODIFICATION

SEE DETAIL III (PASS)

SEE DETAIL VI (R6001)

SEE DETAIL IV

1370872

(SHEET 1 OF 7)
 FIGURE 6: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.090 INCHES OR 

LESS

Original Issue: December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

LEFT SIDE SHOWN, RIGHT SIDE OPPOSITE

STA 899

R6001

STA 774

ALL EXCEPT

R6001

STA 796.5

ALL EXCEPT

R6001

STA 755

R6001 SEC 42

S-12

S-23

S-19

S-6

S-0

S-19

S-23

S-14

S-0

RIGHT SIDE OPPOSITE (EXCEPT CREW DOOR)

LEFT SIDE SHOWN

DETAIL II

DETAIL I

STA

520

1000

STA

941

STA

941

1

STA

287

STA

520

STA

1

2

1370868

(SHEET 2 OF 7)
 FIGURE 6: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.090 INCHES OR 

LESS

Original Issue: December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

LEFT SIDE SHOWN, RIGHT SIDE OPPOSITE

STA

SEC 46 1716

FWD

SEC 46

AFT

S-23

S-19

S-12

S-4

S-23

S-19

S-12

S-4

DETAIL IV

LEFT SIDE SHOWN, RIGHT SIDE OPPOSITE

ALL EXCEPT R6001 SEE DETAIL VI

DETAIL III

STA

1961

2360

STA

1

1

1741

STA

STA

1638

1572

STA

STA

STA

1480

1961

1484

STA

1

1370874

(SHEET 3 OF 7)
 FIGURE 6: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.090 INCHES OR 

LESS

Original Issue: December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

1485

STA

1961

STA

STA

1480

STA

1538

STA

STA 1642

1642

STA

1737

STA

1741

SEC 46

FWD

R6001

LEFT SIDE SHOWN, RIGHT SIDE OPPOSITE

SEC 41

R6001

STA

1572

S-12

S-4

S-19

S-23

S-0

S-14

S-19

S-23

STA

520

STA

287

1

DETAIL VI

LEFT SIDE SHOWN

RIGHT SIDE OPPOSITE (EXCEPT CREW DOOR)

DETAIL V

1

1370879

(SHEET 4 OF 7)
 FIGURE 6: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.090 INCHES OR 

LESS

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BOEING SERVICE BULLETIN 747-53-2307

STA

1480

STA

1572

STA

1700

STA

1735

STA

1960 STA

2000

STA

1965

S-4

S-12

S-19

S-23

STA

1638

STA

1716

STA

1485

6

3

4 5

1

4 5

DETAIL VII

1370880

(SHEET 5 OF 7)
 FIGURE 6: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.090 INCHES OR 

LESS

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BOEING SERVICE BULLETIN 747-53-2307

Station locations shown in table represent areas of lap joints where the upper (overlapping) skin thickness at 

the upper row of fasteners is 0.090 or less. Airplanes are presented in three groups to separate the passenger 

configuration from the freighter configuration and distinct lap joint inspection and terminating action 

requirements. Airplanes with the Main Deck Side Cargo Door (MDSCD) modification will find lap joint 

information for that area in Detail VII.

SECTION 41

STR AREA GROUP AREA GROUP

Str 0 Sta. 287 to Sta. 520 1,2,3

Str 14 L Sta. 134.4 to Sta. 520 1,2 Sta. 134.4 to C2

C3 to Sta. 520

3

R Sta. 134.4 to Sta. 520 1,2 Sta. 134.4 to C2

C3 to Sta. 520

3

Str 19 L Sta. 134.4 to Sta. 400 1,2 Sta. 134.4 to C2

C3 to Sta. 400

3

R Sta. 134.4 to Sta. 400 1,2 Sta. 134.4 to C2

C3 to Sta.400

3

Str 23 L Sta. 134.4 to Sta. 400 1,2 Sta. 134.4 to C2

C3 to Sta. 400

3

R Sta. 134.4 to Sta. 400 1,2 Sta. 134.4 to C2

C3 to Sta. 400

3

SECTION 42

STR AREA GROUP AREA GROUP

Str 0 Sta. 520 to Sta. 941 1,2,3

Str 6 L Sta. 520 to Sta. 941 1,2,3

R Sta. 520 to Sta. 941 1,2,3

Str 12 L Sta. 520 to Sta. 1000 1,2,3

R Sta. 520 to Sta. 1000 1,2,3

Str 19 L Sta. 520 to Sta. 741.1 1,2,3

L Sta. 741.1 to Sta. 772 1,2 Sta. 741.1 to Sta. 899 3

R Sta. 520 to Sta. 741.1 1,2,3

R Sta. 741.1 to Sta. 772 1,2, Sta. 741.1 to Sta. 899 3

Str 23 L Sta. 520 to Sta. 796.5 1,2 Sta. 520 to Sta. 755 3

R Sta. 520 to Sta. 796.5 1,2 Sta. 520 to Sta. 755 3

SECTION 46

STR AREA GROUP AREA GROUP

Str 4 L Sta. 1572 to Sta. 2360 1,2,3

R Sta. 1572 to Sta. 2360 1,2,3

Str 12 L Sta. 1484 to Sta. 2360 1,2,3

R Sta. 1484 to Sta. 2360 1,2,3

(SHEET 6 OF 7)
 FIGURE 6: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.090 INCHES OR 

LESS

Original Issue: December 21, 1989

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BOEING SERVICE BULLETIN 747-53-2307

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

1. Illustrations show highlighted areas where the upper (overlapping) skin thickness is 0.090 or less. Where 

the upper (overlapping) skin thickness at upper fastener row tapers longitudinally and changes between 

body frames from more than 0.090 inches thickness to less than 0.090 inches thickness, the start of 

protruding head fasteners is indicated at a specific body frame, even though the skin may be thicker than 

0.090 at the start. Refer to Table I.

2. The skin configuration of the upper (overlapping) skin in this area is a doubler hot bonded to the skin. This 

area is fastened with deep countersink rivets. 

3. The skin panel joints at Str 4 between Sta 1741 and Sta 1961 and Str 12 between Sta 1741 and the forward 

side of the door, and between the aft side of the door and Sta 1961 are butt joints and require no inspection 

or modification.

4. These areas require inspection. Refer to 747 Non Destructive Test Manual D6-7170, Part 6, Subject 53-

30-09. 

5. The straps and doublers at Str 4, Sta 1700 to Sta 2000, and Str 12, Sta 1735 to forward side of door, and 

from the aft side of door to Sta 1965 need to be removed to accomplish full modification of the lap joints 

forward of Sta 1741 and aft of Sta 1961. Reinstallation of the straps and doublers will require a special kit 

of oversize fasteners. 

6. No inspection of this area is necessary. The MDSCD modification accomplished terminating action per this 

service bulletin in this area.

Str 19 L Sta. 1480 to Sta. 1638

Sta. 1741 to Sta. 2360

1,2 Sta. 1480 to Sta. 1538

Sta. 1642 to Sta.1737.6

Sta. 1741 to Sta. 2360

3

R Sta. 1480 to Sta. 1638

Sta. 1741 to Sta. 2360

1,2 Sta. 1480 to Sta. 1538

Sta. 1642 to Sta.1737.6

Sta. 1741 to Sta. 2360

3

Str 23 L Sta. 1480 to Sta 1716.5

Sta. 1741 to Sta. 2360

1,2 Sta. 1642 to Sta.2360 3

R Sta. 1480 to Sta 1716.5

Sta. 1741 to Sta. 2360

1,2 Sta. 1642 to Sta.2360 3

SECTION 46

STR AREA GROUP AREA GROUP

(SHEET 7 OF 7)
 FIGURE 7: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.071 INCHES OR 

LESS

Original Issue: December 21, 1989

Revision 3: April 16, 2009 747-53-2307

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BOEING SERVICE BULLETIN 747-53-2307

FIGURE 7: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.071 INCHES OR 

LESS

SEE DETAIL III (PASS) SEE DETAIL I (PASS)

SEE DETAIL V (R6001)

SEE DETAIL II

SEE DETAIL IV

STA

1480

STA

2360

STA

1961.1

STA

1000

STA

520

NOTE: SEE DETAIL VI FOR A/P'S WITH MAIN DECK

SIDE CARGO DOOR MODIFICATION

1370873

(SHEET 1 OF 6)
 FIGURE 7: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.071 INCHES OR 

LESS

Original Issue: December 21, 1989

Revision 3: April 16, 2009 747-53-2307

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BOEING SERVICE BULLETIN 747-53-2307

881

STA

S-12

S-23

S-19

S-6

S-0

S-19

S-23

S-14

S-0

RIGHT SIDE OPPOSITE (EXCEPT CREW DOOR)

LEFT SIDE SHOWN

DETAIL II

763

STA

STA

741

DETAIL I

STA

520

1000

STA

941

STA

941

1

STA

287

STA

520

STA

1

1370882

(SHEET 2 OF 6)
 FIGURE 7: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.071 INCHES OR 

LESS

Original Issue: December 21, 1989

Revision 3: April 16, 2009 747-53-2307

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BOEING SERVICE BULLETIN 747-53-2307

ALL

S-23

S-19

S-12

S-4

S-23

S-19

S-12

S-4

DETAIL IV

DETAIL III

STA

1961

STA

2181

2360

STA

1

1

1741

STA

STA

1622.5

STA

STA

1480

1961

STA

1572

STA

1738.2

STA

1741

STA

1489.5

STA

1737.8

PASS

ONLY

1370883

(SHEET 3 OF 6)
 FIGURE 7: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.071 INCHES OR 

LESS

Original Issue: December 21, 1989

Revision 3: April 16, 2009 747-53-2307

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 66 of 68

BOEING SERVICE BULLETIN 747-53-2307

1489.5

STA

1622.5

STA

STA

1780

STA

1700 1961

STA

STA

1480

STA

1735

STA

1920

STA

1572

S-12

S-4

S-19

S-23

S-0

S-14

S-19

S-23

STA

520

STA

287

1

DETAIL VI

DETAIL V

1

1370884

(SHEET 4 OF 6)
 FIGURE 7: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.071 INCHES OR 

LESS

Original Issue: December 21, 1989

Revision 3: April 16, 2009 747-53-2307

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 67 of 68

BOEING SERVICE BULLETIN 747-53-2307

This figure will assist the operator in identifying lap joint areas for the After Modification Inspection. All lap joints 

where the upper (overlapping) skin thickness at the upper row of fasteners is 0.071 or less must have the After 

Modification Inspection. Station locations shown in table represent areas of lap joints where the upper 

(overlapping) skin thickness at the upper row of fasteners is 0.071 or less. Airplanes are presented in three 

groups to separate the passenger configuration from the freighter configuration. 

SECTION 41

STR AREA GROUP AREA GROUP

Str 0 Sta. 287 to Sta. 520 1,2,3

Str 14 L Sta. 134.4 to Sta. 520 1,2 Sta. 134.4 to C2

C3 to Sta. 520

3

R Sta. 134.4 to Sta. 520 1,2 Sta. 134.4 to C2

C3 to Sta. 520

3

Str 19 L Sta. 134.4 to Sta. 400 1,2 Sta. 134.4 to C2

C3 to Sta. 400

3

R Sta. 134.4 to Sta. 400 1,2 Sta. 134.4 to C2

C3 to Sta. 400

3

Str 23 L Sta. 134.4 to Sta. 400 1,2 Sta. 134.4 to C2

C3 to Sta. 400

3

R Sta. 134.4 to Sta. 400 1,2 Sta. 134.4 to C2

C3 to Sta. 400

3

SECTION 42

STR AREA GROUP AREA GROUP

Str 0 Sta. 520 to STA. 941.1 1,2,3

Str 6 L Sta. 520 to STA. 941.1 1,2,3

R Sta. 520 to STA. 941.1 1,2,3

Str 12 L Sta. 520 to STA. 881.1 1,2,3

R Sta. 520 to STA. 881.1 1,2,3

Str 19 L Sta. 520 to Sta 763.07 1,2 Sta. 520 to Sta. 741.1 3

R Sta. 520 to Sta 763.07 1,2 Sta. 520 to Sta. 741.1 3

Str 23 L Sta. 520 to Sta. 741.1 1,2,3

R Sta. 520 to Sta. 741.1 1,2,3

SECTION 46

STR AREA GROUP AREA GROUP

Str 4 L Sta. 1572 to Sta. 1738.2

Sta. 1741.1 to Sta. 2360

1,2,3

R Sta. 1572 to Sta. 1738.2

Sta. 1741.1 to Sta. 2360

1,2,3

Str 12 L Sta. 1489.5 to Sta. 1737.8

Sta. 1741.1 to Sta. 2360

1,2,3

R Sta. 1489.5 to Sta. 1737.8

Sta. 1741.1 to Sta. 2360

1,2,3

(SHEET 5 OF 6)
 FIGURE 7: LOCATIONS OF LAP JOINT UPPER (OVERLAPPING) SKIN THICKNESS 0.071 INCHES OR 

LESS

Original Issue: December 21, 1989

Revision 3: April 16, 2009 747-53-2307

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 68 of 68

BOEING SERVICE BULLETIN 747-53-2307

The instruction number shown below agree with the number shown inside the circle symbol in the figure.

1. Illustrations show highlighted areas where the upper (overlapping) skin thickness is 0.071 or less. Where 

the upper (overlapping) skin thickness at upper fastener row tapers longitudinally and changes between 

body frames from more than 0.071 inches thickness to less than 0.071 inches thickness, the start of 

protruding head fasteners is indicated at a specific body frame, even though the skin may be thicker than 

0.071 at the start. Refer to Table I.

Str 19 L Sta. 1480 to Sta. 1622.5

Sta. 1741.1 to Sta. 2360

1,2 Sta. 1741.1 to Sta. 2360 3

R Sta. 1480 to Sta. 1622.5

Sta. 1741.1 to Sta. 2360

1,2 Sta. 1741.1 to Sta. 2360 3

Str 23 L Sta. 1961.1 to Sta.2360 1,2 Sta. 2181.1 to Sta. 2360 3

R Sta. 1961.1 to Sta.2360 1,2 Sta. 2181.1 to Sta. 2360 3

SECTION 46

STR AREA GROUP AREA GROUP

(SHEET 6 OF 6)