# Boeing Alert Service Bulletin 737-53A1293: Revision 3

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- Document: [Boeing Alert Service Bulletin 737-53A1293](https://openairdocs.org/service-documents/boeing/737-53a1293.md)
- Title as filed: U.S. DOT/FAA - SB-737-53A1293-03
- Pages: 148
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Commercial 
Airplanes
737
Service Bulletin
ALERT
Number: 737-53A1293
Original Issue: August 13, 2008
Revision 3: January 23, 2015
ATA System: 5331
SUBJECT: FUSELAGE - Skin - Stringer S-1 and Stringer S-2R, Station 400 to Station 460
Inspection, Repair and Modification
Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15
CFR 300-774). An export license may be required before it is used for development, production or use by foreign
persons from specific countries. The controller of this data has the individual responsibility to abide by all export
laws.
9E991ECCN:
BOEING PROPRIETARY, CONFIDENTIAL AND/OR TRADE SECRET
Copyright © 2008 Boeing.
Unpublished Work. All Rights Reserved.
Treatment of this document and its content is governed by contract with Boeing. Rights to use this document
are licensed on a per aircraft basis and such rights may not be transferable. For more information, contact The
Boeing Company.
Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner,
BBJ, DC-8, DC-9, DC-10, KC-10, KC-46, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8, Poseidon and
Boeing liveries are all trademarks owned by The Boeing Company; and no trademark license is granted in
connection with this document unless provided in writing by Boeing.
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Table of Contents
Revision Transmittal Sheet ............................................ 5
Summary ...................................................... 9
1. PLANNING INFORMATION ........................................ 1 5
A. Effectivity ............................................... 1 5
1. Airplanes ............................................ 1 5
2. Spares Affected ........................................ 2 3
B. Concurrent Requirements ...................................... 2 3
C. Reason ................................................ 2 3
D. Description .............................................. 2 4
E. Compliance .............................................. 2 7
F. Approval ............................................... 5 2
G. Manpower .............................................. 5 3
H. Weight and Balance Changes .................................... 5 5
I. Electrical Load Data ......................................... 5 6
J. References .............................................. 5 6
1. Existing Data: ......................................... 5 6
2. Data Supplied with this Service Bulletin: ........................... 5 6
3. Installation Drawings Used in the Preparation of this Service Bulletin: ........... 5 7
K. Publications Affected ........................................ 5 7
L. Interchangeability and Intermixability of Parts ........................... 5 7
M. Software Accomplishment Summary ................................ 5 7
2. MATERIAL INFORMATION ........................................ 5 9
A. Material - Price and Availability ................................... 5 9
B. Industry Support Information .................................... 5 9
C. Parts Necessary for Each Airplane ................................. 5 9
1. Kits/Parts ............................................ 5 9
2. Parts and Materials Supplied by the Operator ........................ 5 9
3. Parts Modified and Reidentified ................................ 6 3
4. Parts Removed and Not Replaced .............................. 6 3
D. Parts Necessary to Change Spares ................................. 6 3
E. Special Tooling - Price and Availability ............................... 6 3
F. Special Tooling Necessary to do this Service Bulletin ....................... 6 3
3. ACCOMPLISHMENT INSTRUCTIONS .................................. 6 5
A. GENERAL INFORMATION ..................................... 6 5
B. WORK INSTRUCTIONS ....................................... 6 6
FIGURE 1: THIS FIGURE DELETED AT REVISION 1 [Group 1] ..................... 7 6
FIGURE 2: EXTERNAL FUSELAGE SKIN CHEM-MILL STEP INSPECTION - STRINGERS S-1 AND S-2R,
STA 400 - STA 460 [Group 1] ................................. 7 7
FIGURE 3: THIS FIGURE DELETED AT REVISION 1 [Group 2] ..................... 7 9
FIGURE 4: EXTERNAL FUSELAGE SKIN CHEM-MILL STEP INSPECTION - STRINGERS S-1 AND S-2R,
STA 400 - STA 460 [Group 2] ................................. 8 0
FIGURE 5: FUSELAGE SKIN - CRACK REMOVAL [Group 1] ...................... 8 2
FIGURE 6: 737-300,737-400 SERIES AIRPLANE - REPAIR DOUBLER FABRICATION AND INSTALLATION
[Group 1] ............................................ 8 5
FIGURE 7: EXTERNAL FUSELAGE SKIN CHEM-MILL STEP INSPECTION AFTER REPAIR - STRINGERS
S-1 AND S-2R, STA 400 - STA 460 [Group 1] ........................ 9 5
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FIGURE 8: 737-500 SERIES AIRPLANES - REPAIR DOUBLER FABRICATION AND INSTALLATION
[Group 1] ............................................ 9 7
FIGURE 9: EXTERNAL FUSELAGE SKIN CHEM-MILL STEP INSPECTION AFTER REPAIR - STRINGERS
S-1 AND S-2R, STA 400 - STA 460 [Group 2] ........................ 1 0 8
FIGURE 10: FUSELAGE SKIN - CRACK REMOVAL [Group 2] ..................... 1 1 0
FIGURE 11: REPAIR DOUBLER FABRICATION AND INSTALLATION [Group 2] ........... 1 1 3
FIGURE 12: POST REPAIR - CRITICAL FASTENER ROW INSPECTION [Group 2] .......... 1 1 9
FIGURE 13: PREVENTIVE MODIFICATION - INSPECTION, FABRICATION AND INSTALLATION [Group
1 ]  ................................................ 1 2 1
FIGURE 14: PREVENTIVE MODIFICATION ON EXISTING REPAIR - INSPECTION, FABRICATION AND
INSTALLATION [Group 1] .................................. 1 3 3
FIGURE 15: EXTERNAL FUSELAGE CHEM-MILL STEP POST REPAIR OR POST PREVENTIVE
MODIFICATION INSPECTION - STRINGERS S-1 AND S-2R, STA 400 - STA 460 [Group 1]
................................................. 1 4 5
FIGURE 16: POST REPAIR OR POST PREVENTIVE MODIFICATION - CRITICAL FASTENER ROW
INSPECTION - STA 400 - STA 460 [Group 1] ........................ 1 4 7
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Commercial 
Airplanes
737
Service Bulletin
ALERT
Revision Transmittal SheetNumber: 737-53A1293Original Issue: August 13, 2008
Revision 3: January 23, 2015
ATA System: 5331
SUBJECT: FUSELAGE - Skin - Stringer S-1 and Stringer S-2R, Station 400 to Station 460
Inspection, Repair and Modification
This revision includes all pages of the service bulletin.
COMPLIANCE INFORMATION RELATED TO THIS REVISION
Federal Aviation Administration (FAA) Airworthiness Directive AD 2008-09-13 and AD 2012-12-04 are related
to this service bulletin. AD 2012-12-04 supersedes AD 2008-19-03. The effective date of AD 2012-12-04 is July
23, 2012.
The Federal Aviation Administration (FAA) will possibly release an additional Airworthiness Directive related to
this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service
bulletin mandatory.
More work is necessary on Group 1 airplanes inspected or changed in accordance with Revision 2 of this service
bulletin. For Group 1 airplanes, the inspection threshold has been lowered and a preventive modification is
required to mitigate Widespread Fatigue Damage (WFD) concerns at the ATC antenna location. Post preventive
modification inspections are required.
No more work is necessary on Group 2 airplanes inspected or changed in accordance with Revision 2 of this
service bulletin.
No airplanes have been added or removed from the effectivity of this service bulletin.
REASON FOR REVISION
This revision is sent to revise inspection thresholds and provide structural modification requirements to address
WFD requirements at the ATC antenna location for Group 1 airplanes, to provide post modification inspection
for Group 1 airplanes and provide an Alternative Method of Compliance (AMOC) for Supplemental Structural
Inspection Document (SSID) items F-39A, F-39B, F-39E and F-39F. For Group 1 and Group 2 airplanes, the
Ultrasonic Phase Array (UTPA) inspection option NDI procedure number has been revised.
These sections were changed:
1. Summary, Background, reference to 737-SRP-53-0406 added and reference to 737-SRP-53-0334
deleted.
2. Summary, Action, reference to preventive modification for Group 1 airplanes added.
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3. Summary, Compliance, reference to AD 2012-12-04 added.
4. Summary illustration, revised.
5. 1.C., Reason, reference to 737-SRP-53-0406 added and reference to 737-SRP-53-0334 deleted.
6. 1.D., Description, reference to preventive modification for Group 1 airplanes added.
7. 1.E., Compliance, Tables 1, 2, 3 and 4 revised to add preventive modification and follow-on inspection
thresholds.
8. 1.E., Compliance, Table 7 added to reference alternate SSID inspection requirements.
9. 1.F., Approval, revised to add requirements for AD 2012-12-04 and reference to an AMOC for AD
2008-09-13.
10. 1.G., Manpower, Table 3 added for preventive modification, preventive modification on existing repair
and post repair or post preventive modification skin panel inspection - Group 1 airplanes.
11. 1.J., References, 737-SRP-53-0406, AD 2008-09-13, AD 2012-12-04 added and reference to
737-SRP-53-0334 deleted.
12. 2.C., Parts Necessary for Each Airplane, Table 3 added for preventive modification and Table 4 added
for preventive modification on an existing repair.
13. 3.B., Work Instructions, reference to preventive modification added, compliance threshold revised and
reference to Figures 13, 14, 15 and 16 added.
14. Figure 2, UTPA inspection procedure revised.
15. Figure 4, UTPA inspection procedure revised.
16. Figure 5, revised illustrations and step table.
17. Figure 6, revised illustrations, step table and fastener table.
18. Figure 7, UTPA inspection procedure revised.
19. Figure 8, revised illustrations and step table.
20. Figure 9, UTPA inspection procedure revised.
21. Figure 10, revised illustrations and step table.
22. Figure 11, revised illustrations and step table.
23. Figure 13, new figure added to do a preventive modification.
24. Figure 14, new figure added to do a preventive modification on an existing repair.
25. Figure 15, new figure added to do a post repair skin inspection.
26. Figure 16, new figure added to do a post modification critical fastener row inspection.
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Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity and format changes,
to show the location of all content changes.
Pages with no vertical lines have no changes.
REVISION HISTORY
August 13, 2008Original Issue:
July 07, 2010Revision 1:
August 10, 2011Revision 2:
January 23, 2015Revision 3:
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Commercial 
Airplanes
737
Service Bulletin
ALERT
SummaryNumber: 737-53A1293Original Issue: August 13, 2008
Revision 3: January 23, 2015
ATA System: 5331
SUBJECT: FUSELAGE - Skin - Stringer S-1 and Stringer S-2R, Station 400 to Station 460
Inspection, Repair and Modification
THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH
1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OWNER.
CONCURRENT REQUIREMENTS
None.
BACKGROUND
Accomplishment of the inspections in this service bulletin will make sure that fuselage skin cracks at stringers
S-1 and S-2R, between Body Stations STA 400 and STA 460 are found and repaired. An Air Traffic Control
(ATC) antenna was installed at this location at delivery on the affected airplanes. All airplanes listed in this
service bulletin require inspection even if the ATC antenna has been removed. This action is necessary to find
and repair fatigue cracks of the skin panels at the chem-mill steps. Continued operation with undetected skin
cracks could cause unscheduled down time for repairs or possibly a decompression of the airplane.
Boeing has received several reports from multiple operators regarding fuselage skin cracks adjacent to the ATC
antenna.
A total of 60 cracks have been found on Group 1 airplanes (10 inch tear strap bays) at both S-1 and S-2R. The
affected airplanes had accumulated between 40,080 and 67,032 total flight cycles.
A total of 3 cracks have been found on Group 2 airplanes (20 inch tear strap bays) at S-1 only but similar cracking
is possible at S-2R. The affected airplanes had accumulated between 43,565 and 44,700 total flight cycles.
Analysis by Boeing indicates that the cracks are caused by fatigue due to high tension stresses and local bending
at the edge of the chem-mill pockets of the bonded skin. The cracks initiate at the inner surface of the skin and
typically originate at multiple sites along the chem-mill step. Multiple site originations can result in several adjacent
partial-thickness cracks. These adjacent partial-thickness cracks can be subsequently linked together before
propagating through the full-thickness of the skin.
Additional follow-on analysis to address Widespread Fatigue Damage (WFD) requirements has determined a
reduced inspection threshold and a preventive modification is required on Group 1 airplanes that have reached
a specified threshold.
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Accomplishment of the work given in this service bulletin will make sure that cracks in the fuselage skin at
stringers S-1 and S-2R, between STA 400 and STA 460 are detected and repaired.
Boeing Service Related Problem (SRP) 737-SRP-53-0406 is related to this service bulletin.
Multi-Operator Message (MOM) MOM-MOM-09-0807-01B (R1) is related to this service bulletin.
On Group 1 airplanes the skin pockets adjacent to the ATC Antenna have been determined to be structure that
is susceptible to Widespread Fatigue Damage (WFD).
This table is provided to operators for planning purposes only. Refer to the applicable sections for more
information.
ReferenceAffectedPlanning Data
Paragraph 1.A.2., Spares AffectedNoSpares Affected
Paragraph 1.E., Compliance and Paragraph
1.F., Approval
YesAD Related
Paragraph 1.H., Weight and Balance ChangesYesWeight and Balance Change
Paragraph 1.I., Electrical Load DataNoElectrical Load Changed
Paragraph 1.K., Publications AffectedNoPublications Affected
Paragraph 1.K., Publications AffectedNoAirplane Flight Operations Affected (Flight Crew
Operations Manual and/or FAA Approved Air-
plane Flight Manual)
Paragraph 2.C.1., Kits/PartsNoKits/Parts Required
Paragraph 2.C.2., Parts and Materials Supplied
by the Operator
YesOperator Supplied Parts/Material
Paragraph 2.F., Special Tooling Necessary to
do this Service Bulletin
NoSpecial Tooling Required
ACTION
1. Get external access to the area around the ATC antenna at stringers S-1 and S-2R, between STA 400
and STA 460.
2. Do external Detailed Inspection (DI) for any crack in the fuselage skin along the chem-mill steps at
stringers S-1 and S-2R, between STA 400 and STA 460.
3. Do external Non Destructive Inspections (NDI) for any crack in the fuselage skin along the chem-mill
steps at stringers S-1 and S-2R, between STA 400 and STA 460. The NDI's that can be used are
Medium Frequency Eddy Current (MFEC), Magneto Optical Imaging (MOI), C-Scan or Ultrasonic
Phased Array (UTPA).
4. If no crack is found:
a. Do repeat external DI and NDI for any crack in the fuselage skin along the chem-mill steps at
stringers S-1 and S-2R, between STA 400 and STA 460 at intervals in accordance with Paragraph
1.E., Compliance.
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b. Group 1:
Do the preventive modification in accordance with Paragraph 1.E., Compliance.
(1) Do repeat external DI and NDI for any crack in the fuselage skin along the chem-mill steps
(not covered by the preventive modification) between STA 400 and STA 460 at intervals in
accordance with Paragraph 1.E., Compliance.
(2) Do post-modification damage tolerance inspections (DTI) of the fuselage skin at the critical
fastener row common to the preventive modification in accordance with this service bulletin.
5. Group 1:
If any of the following is found as a result of the external DI and NDI, contact Boeing for repair
instructions, do the repair and do repeat external DI and NDI of the fuselage skin chem-mill steps (not
covered by a repair) for any crack in accordance with Paragraph 1.E., Compliance.
a. Group 1, Configuration 1:
(1) Any crack found before 33,000 total flight cycles.
(2) Any crack found in four or more tear strap bays.
(3) Any crack found longer than 5 inches.
(4) Any crack found not contained within the skin cut-out.
b. Group 1, Configuration 2-5:
(1) Any crack found before 35,000 total flight cycles.
(2) Any crack found in four or more tear strap bays.
(3) Any crack found longer than 5 inches.
(4) Any crack found not contained within the skin cut-out.
The repair must be removed and replaced with the preventive modification before the compliance time
in accordance with Paragraph 1.E., Compliance. After the accomplishment of the preventive modification:
a. Do repeat external DI and NDI for any crack in the fuselage skin along the chem-mill steps (not
covered by the preventive modification) between STA 400 and STA 460 at intervals in accordance
with Paragraph 1.E., Compliance.
b. Do post-modification damage tolerance inspections (DTI) of the fuselage skin at the critical fastener
row common to the preventive modification accomplished in accordance with this service bulletin.
If all of the following are found as a result of the external DI and NDI, do the repair or preventive
modification in accordance with this service bulletin.
a. Group 1, Configuration 1:
(1) Any crack found at or after 33,000 total flight cycles.
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(2) Any crack found in three or less tear strap bays.
(3) Any crack found 5 inches or shorter.
(4) Any crack found contained within the skin cut-out.
b. Group 1, Configuration 2-5:
(1) Any crack found at or after 35,000 total flight cycles.
(2) Any crack found in three or less tear strap bays.
(3) Any crack found 5 inches or shorter.
(4) Any crack found contained within the skin cut-out.
Do repeat external DI and NDI for any crack in the fuselage skin along the chem-mill steps at S-1 and
S-2R (not covered by the repair or preventive modification), between STA 400 and STA 460 at intervals
in accordance with Paragraph 1.E., Compliance. If the repair is accomplished, it must be removed and
replaced with the preventive modification before the compliance time in accordance with Paragraph
1.E., Compliance. After the accomplishment of the preventive modification:
a. Do repeat external DI and NDI for any crack in the fuselage skin along the chem-mill steps at S-1
and S-2R (not covered by the preventive modification), between STA 400 and STA 460 at intervals
in accordance with Paragraph 1.E., Compliance.
b. Do post repair or post preventive modification damage tolerance inspections (DTI) of the fuselage
skin at the critical fastener row common to the repair or preventive modification accomplished in
accordance with this service bulletin.
6. Group 2:
If any of the following is found as a result of the external DI and NDI, contact Boeing for repair
instructions, do the repair and do repeat external DI and NDI of the fuselage skin chem-mill steps (not
covered by a repair) for any crack in accordance with Paragraph 1.E., Compliance.
a. Any crack found before 33,000 total flight cycles.
b. Any crack found between STA 400 and STA 420.
c. Any crack found between STA 440 and STA 460.
d. Any crack found longer than 12.5 inches.
e. Any crack found not contained within the skin cut-out.
If all of the following is found as a result of the external DI and NDI, do the repair in accordance with
this service bulletin.
a. Any crack found at or after 33,000 total flight cycles.
b. Any crack found between STA 420 and STA 440.
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c. Any crack found 12.5 inches or shorter.
d. Any crack found contained within the skin cut-out.
After the accomplishment of the repair:
a. Do repeat external DI and NDI for any crack in the fuselage skin along the chem-mill steps at S-1
and S-2R (not covered by the repair), between STA 400 and STA 460 at intervals in accordance
with Paragraph 1.E., Compliance.
b. Do post repair damage tolerance inspections (DTI) of the fuselage skin at the critical fastener row
common to the repair accomplished in accordance with this service bulletin.
EFFECTIVITY
737-300/-400/-500 Airplanes. Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplanes.
COMPLIANCE
Federal Aviation Administration (FAA) Airworthiness Directive AD 2008-09-13 and AD 2012-12-04 are related
to this service bulletin. The effective date of AD 2012-12-04 is July 23, 2012.
The Federal Aviation Administration (FAA) will possibly release an additional Airworthiness Directive related to
this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service
bulletin mandatory.
Refer to Paragraph 1.E., Compliance.
INDUSTRY SUPPORT INFORMATION
Boeing warranty remedies are not available for the inspection and repair procedures given in this service bulletin.
MANPOWER
Refer to Paragraph 1.G., Manpower.
MATERIAL INFORMATION
Operator Supplied Parts/Materials.
Refer to Paragraph 2.A., Material - Price and Availability.
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BOEING SERVICE BULLETIN 737-53A1293
ALERT  ALERT
STA
460
000000000000  STA
400
000
DO DETAILED INSPECTION AND DO MFEC INSPECTION
OR MOI INSPECTION OR C-SCAN OR ULTRASONIC
PHASE ARRAY INSPECTION FOR CRACKS IN THE
FUSELAGE SKIN ALONG THE CHEM-MILL STEPS
GROUP 1: INSTALL THE PREVENTIVE MODIFICATION
TYPICAL CRACKS
- S-1
STA  STA  STA  STA  STA  STA  STA
460  450  440  430  420  410  00t
ATC ANTENNA
WD  INSPECTION AREA
10 INCH TEAR STRAP BAY CONFIGURATION SHOWN  1579184
20 INCH TEAR STRAP BAY CONFIGURATION SIMILAR
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### Page 15

Commercial 
Airplanes
737
Service Bulletin
ALERT
Number: 737-53A1293
Original Issue: August 13, 2008
Revision 3: January 23, 2015
ATA System: 5331
SUBJECT: FUSELAGE - Skin - Stringer S-1 and Stringer S-2R, Station 400 to Station 460
Inspection, Repair and Modification
THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH
1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OWNER.
1.    PLANNING INFORMATION
A. Effectivity
1. Airplanes
Refer to Service Bulletin Index Document D6-19567 Part 3 for Airplane Variable Number, Line
Number, and Serial Number data.
This service bulletin is for the airplanes shown below.
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DESCRIPTIONCONFIGURATIONGROUP
737 - 300/-400/-500 Airplanes, line numbers 1001 thru 2552, which
had an ATC antenna installed at STA 430 at delivery, with 10 inch
tear strap bays.
-1
Airplanes not inspected in accordance with the original issue of this
service bulletin.
1
Airplanes inspected in accordance with the original issue of this
service bulletin and the last inspection was a Detailed Inspection
procedure.
2
Airplanes inspected in accordance with the original issue of this
service bulletin and the last inspection was a MFEC or MOI or C-Scan
Non-Destructive Inspection procedure.
3
Airplanes inspected in accordance with Boeing
Multi-Operator-Message MOM-MOM-09-0807-01B (R1), dated
15-Dec-2009 and the last inspection was a Detailed Inspection
procedure.
4
Airplanes inspected in accordance with Boeing
Multi-Operator-Message MOM-MOM-09-0807-01B (R1), dated
15-Dec-2009 and the last inspection was a MFEC or MOI or C-Scan
Non-Destructive Inspection procedure.
5
737 - 300/-400/-500 Airplanes, line numbers 2553 thru 3132, all of
which had an ATC antenna installed at STA 430 at delivery, with 20
inch tear strap bays.
-2
Airplane Models:
737-300, 737-400, 737-500
GroupVariable Number
1PJ301 - PJ302
1PJ551
2PJ552 - PJ561
2PJ601 - PJ615
2PJ811
2PJ816 - PJ817
1PM389 - PM399
1PM401 - PM417
1PM541 - PM542
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GroupVariable Number
2PM543 - PM550
1PM551 - PM564
1PP048 - PP054
1PP140 - PP160
1PP198 - PP199
1PP221
1PP508 - PP517
2PP518 - PP520
1PP805 - PP808
1PP874 - PP875
2PP876 - PP877
1PP910 - PP930
1PP951 - PP952
1PP966 - PP967
1PP984 - PP990
1PP993
1PQ013 - PQ016
1PQ038 - PQ041
1PQ069 - PQ085
1PQ101 - PQ199
1PQ201 - PQ202
1PQ230
1PQ237
1PQ251 - PQ267
1PQ281 - PQ296
2PQ297 - PQ299
1PQ301 - PQ307
1PQ331 - PQ332
1PQ341 - PQ344
2PQ345 - PQ348
1PQ361 - PQ369
2PQ370 - PQ373
2PQ391 - PQ395
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GroupVariable Number
1PQ401 - PQ407
2PQ408 - PQ410
1PQ411 - PQ413
2PQ414 - PQ418
1PQ421
2PQ431 - PQ438
2PQ447 - PQ448
2PQ451
2PQ454
1PQ471 - PQ472
2PQ473 - PQ475
1PQ481
1PQ486 - PQ487
1PQ491 - PQ493
1PQ771
2PQ772
1PQ791 - PQ793
1PQ801 - PQ805
1PQ931 - PQ932
2PQ933 - PQ935
2PQ951
2PQ971 - PQ997
2PR001 - PR017
2PR021 - PR034
2PR041 - PR045
2PR061 - PR072
2PR077 - PR082
2PR091 - PR092
2PR096
2PR101
2PR121 - PR122
2PR131 - PR132
2PR141 - PR143
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GroupVariable Number
2PR161 - PR172
2PR181
1PS601 - PS616
2PS617 - PS630
1PS631
1PS636 - PS638
1PS641 - PS644
1PS651 - PS657
1PS666 - PS669
1PS691 - PS692
1PS701 - PS703
2PS704 - PS706
1PS751 - PS762
2PS763 - PS799
2PS811
2PS836 - PS837
2PS841 - PS846
2PS851 - PS852
2PS856
2PS861 - PS863
2PS866 - PS868
2PS871 - PS874
2PS896 - PS897
2PS901 - PS941
2PS956 - PS957
2PS961 - PS963
2PS971 - PS978
1PT001 - PT011
2PT012 - PT015
1PT021 - PT028
2PT029 - PT031
1PT041 - PT063
2PT064
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GroupVariable Number
1PT101 - PT105
1PT121 - PT125
2PT126 - PT138
1PT146 - PT148
1PT161 - PT170
1PT181 - PT187
2PT188
1PT211 - PT220
1PT295
1PT301 - PT306
2PT307 - PT309
1PT331 - PT360
1PT381 - PT399
1PT401 - PT438
1PT501 - PT512
2PT513 - PT517
1PT561 - PT565
1PT581 - PT584
2PT585 - PT586
1PT611 - PT621
1PT641 - PT642
2PT643 - PT644
1PT651 - PT655
2PT656
1PT671 - PT672
2PT681 - PT685
1PT701 - PT703
2PT716 - PT717
2PT721 - PT725
2PT801 - PT834
2PT851 - PT854
2PT871 - PT886
2PT901 - PT930
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GroupVariable Number
2PT971 - PT973
2PT981 - PT985
2PT996
1PU001 - PU025
2PU301
2PU311 - PU313
1PV021 - PV055
1PV201 - PV203
2PV204 - PV209
2PV226 - PV229
1PV231 - PV237
1PV271 - PV272
1PV281 - PV283
2PV284 - PV287
2PV296
2PV301 - PV302
2PV351
2PV356 - PV357
1PW027 - PW054
1PW061 - PW068
1PW072
2PW086 - PW088
1PW091 - PW094
1PW101 - PW102
1PW106
1PW111 - PW120
1PW156 - PW157
1PW161 - PW167
2PW168 - PW171
1PW201 - PW244
2PW245 - PW252
1PW261
2PW262 - PW264
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GroupVariable Number
1PW265 - PW268
2PW271 - PW276
1PW278
1PW281
2PW282 - PW292
1PW293
1PW296
1PW301 - PW327
2PW401 - PW408
2PW411 - PW418
2PW421 - PW424
2PW431 - PW435
2PW441 - PW450
1PW461 - PW467
1PW501 - PW502
1PW504
1PW511 - PW520
2PW521 - PW522
2PW524 - PW525
1PW526
2PW527 - PW530
1PW531 - PW546
2PW547 - PW550
1PW556 - PW557
1PW561 - PW564
1PW571 - PW576
1PW591 - PW596
1PW611 - PW620
2PW621 - PW622
1PW631 - PW634
2PW635 - PW637
1PW661 - PW662
1PW681 - PW683
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GroupVariable Number
1PW701 - PW702
1PW711 - PW717
1PW741 - PW742
1PW761
1PW771
2PW831
2PW851 - PW856
2. Spares Affected
None.
B. Concurrent Requirements
None.
C. Reason
Accomplishment of the inspections in this service bulletin will make sure that fuselage skin cracks at
stringers S-1 and S-2R, between Body Stations STA 400 and STA 460 are found and repaired. An Air
Traffic Control (ATC) antenna was installed at this location at delivery on the affected airplanes. All
airplanes listed in this service bulletin require inspection even if the ATC antenna has been removed.
This action is necessary to find and repair fatigue cracks of the skin panels at the chem-mill steps.
Continued operation with undetected skin cracks could cause unscheduled down time for repairs or
possibly a decompression of the airplane.
Boeing has received several reports from multiple operators regarding fuselage skin cracks adjacent
to the ATC antenna.
A total of 60 cracks have been found on Group 1 airplanes (10 inch tear strap bays) at both S-1 and
S-2R. The affected airplanes had accumulated between 40,080 and 67,032 total flight cycles.
A total of 3 cracks have been found on Group 2 airplanes (20 inch tear strap bays) at S-1 only but
similar cracking is possible at S-2R. The affected airplanes had accumulated between 43,565 and
44,700 total flight cycles.
Analysis by Boeing indicates that the cracks are caused by fatigue due to high tension stresses and
local bending at the edge of the chem-mill pockets of the bonded skin. The cracks initiate at the inner
surface of the skin and typically originate at multiple sites along the chem-mill step. Multiple site
originations can result in several adjacent partial-thickness cracks. These adjacent partial-thickness
cracks can be subsequently linked together before propagating through the full-thickness of the skin.
Additional follow-on analysis to address Widespread Fatigue Damage (WFD) requirements has
determined a reduced inspection threshold and a preventive modification is required on Group 1
airplanes that have reached a specified threshold.
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Accomplishment of the work given in this service bulletin will make sure that cracks in the fuselage
skin at stringers S-1 and S-2R, between STA 400 and STA 460 are detected and repaired.
Boeing Service Related Problem (SRP) 737-SRP-53-0406 is related to this service bulletin.
Multi-Operator Message (MOM) MOM-MOM-09-0807-01B (R1) is related to this service bulletin.
On Group 1 airplanes the skin pockets adjacent to the ATC Antenna have been determined to be
structure that is susceptible to Widespread Fatigue Damage (WFD).
Revision 1 was sent to add more inspection areas, Ultrasonic Phased Array (UTPA) inspection
procedure, post repair inspection and change compliance. The option to use a Detailed Inspection (DI)
only has been removed. This revision requires that a Non Destructive Inspection (NDI) and a DI be
accomplished.
For Group 1 only, remove airplanes from the effectivity and add a repair.
Revision 2 is sent to revise the Group 1 repair figures and add the Group 2 repair instructions and post
repair inspection.
Revision 3 is sent to revise inspection thresholds and provide structural modification requirements to
address WFD requirements at the ATC antenna location for Group 1 airplanes, to provide post
modification inspection for Group 1 airplanes and provide an Alternative Method of Compliance (AMOC)
for Supplemental Structural Inspection Document (SSID) items F-39A, F-39B, F-39E and F-39F. For
Group 1 and Group 2 airplanes, the Ultrasonic Phase Array (UTPA) inspection option NDI procedure
number has been revised.
D. Description
1. Get external access to the area around the ATC antenna at stringers S-1 and S-2R, between STA
400 and STA 460.
2. Do external Detailed Inspection (DI) for any crack in the fuselage skin along the chem-mill steps
at stringers S-1 and S-2R, between STA 400 and STA 460.
3. Do external Non Destructive Inspections (NDI) for any crack in the fuselage skin along the chem-mill
steps at stringers S-1 and S-2R, between STA 400 and STA 460. The NDI's that can be used are
Medium Frequency Eddy Current (MFEC), Magneto Optical Imaging (MOI), C-Scan or Ultrasonic
Phased Array (UTPA).
4. If no crack is found:
a. Do repeat external DI and NDI for any crack in the fuselage skin along the chem-mill steps
at stringers S-1 and S-2R, between STA 400 and STA 460 at intervals in accordance with
Paragraph 1.E., Compliance.
b. Group 1:
Do the preventive modification in accordance with Paragraph 1.E., Compliance.
(1) Do repeat external DI and NDI for any crack in the fuselage skin along the chem-mill
steps (not covered by the preventive modification) between STA 400 and STA 460 at
intervals in accordance with Paragraph 1.E., Compliance.
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(2) Do post-modification damage tolerance inspections (DTI) of the fuselage skin at the critical
fastener row common to the preventive modification in accordance with this service
bulletin.
5. Group 1:
If any of the following is found as a result of the external DI and NDI, contact Boeing for repair
instructions, do the repair and do repeat external DI and NDI of the fuselage skin chem-mill steps
(not covered by a repair) for any crack in accordance with Paragraph 1.E., Compliance.
a. Group 1, Configuration 1:
(1) Any crack found before 33,000 total flight cycles.
(2) Any crack found in four or more tear strap bays.
(3) Any crack found longer than 5 inches.
(4) Any crack found not contained within the skin cut-out.
b. Group 1, Configuration 2-5:
(1) Any crack found before 35,000 total flight cycles.
(2) Any crack found in four or more tear strap bays.
(3) Any crack found longer than 5 inches.
(4) Any crack found not contained within the skin cut-out.
The repair must be removed and replaced with the preventive modification before the compliance
time in accordance with Paragraph 1.E., Compliance. After the accomplishment of the preventive
modification:
a. Do repeat external DI and NDI for any crack in the fuselage skin along the chem-mill steps
(not covered by the preventive modification) between STA 400 and STA 460 at intervals in
accordance with Paragraph 1.E., Compliance.
b. Do post-modification damage tolerance inspections (DTI) of the fuselage skin at the critical
fastener row common to the preventive modification accomplished in accordance with this
service bulletin.
If all of the following are found as a result of the external DI and NDI, do the repair or preventive
modification in accordance with this service bulletin.
a. Group 1, Configuration 1:
(1) Any crack found at or after 33,000 total flight cycles.
(2) Any crack found in three or less tear strap bays.
(3) Any crack found 5 inches or shorter.
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(4) Any crack found contained within the skin cut-out.
b. Group 1, Configuration 2-5:
(1) Any crack found at or after 35,000 total flight cycles.
(2) Any crack found in three or less tear strap bays.
(3) Any crack found 5 inches or shorter.
(4) Any crack found contained within the skin cut-out.
Do repeat external DI and NDI for any crack in the fuselage skin along the chem-mill steps at S-1
and S-2R (not covered by the repair or preventive modification), between STA 400 and STA 460
at intervals in accordance with Paragraph 1.E., Compliance. If the repair is accomplished, it must
be removed and replaced with the preventive modification before the compliance time in accordance
with Paragraph 1.E., Compliance. After the accomplishment of the preventive modification:
a. Do repeat external DI and NDI for any crack in the fuselage skin along the chem-mill steps
at S-1 and S-2R (not covered by the preventive modification), between STA 400 and STA
460 at intervals in accordance with Paragraph 1.E., Compliance.
b. Do post repair or post preventive modification damage tolerance inspections (DTI) of the
fuselage skin at the critical fastener row common to the repair or preventive modification
accomplished in accordance with this service bulletin.
6. Group 2:
If any of the following is found as a result of the external DI and NDI, contact Boeing for repair
instructions, do the repair and do repeat external DI and NDI of the fuselage skin chem-mill steps
(not covered by a repair) for any crack in accordance with Paragraph 1.E., Compliance.
a. Any crack found before 33,000 total flight cycles.
b. Any crack found between STA 400 and STA 420.
c. Any crack found between STA 440 and STA 460.
d. Any crack found longer than 12.5 inches.
e. Any crack found not contained within the skin cut-out.
If all of the following is found as a result of the external DI and NDI, do the repair in accordance
with this service bulletin.
a. Any crack found at or after 33,000 total flight cycles.
b. Any crack found between STA 420 and STA 440.
c. Any crack found 12.5 inches or shorter.
d. Any crack found contained within the skin cut-out.
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After the accomplishment of the repair:
a. Do repeat external DI and NDI for any crack in the fuselage skin along the chem-mill steps
at S-1 and S-2R (not covered by the repair), between STA 400 and STA 460 at intervals in
accordance with Paragraph 1.E., Compliance.
b. Do post repair damage tolerance inspections (DTI) of the fuselage skin at the critical fastener
row common to the repair accomplished in accordance with this service bulletin.
Revision 1 - More work is necessary on airplanes inspected as shown in the original issue of this service
bulletin. Additional areas have been identified to be inspected for chem-mill step cracking, the Detailed
Inspection must be done with a Non Destructive Inspection method, and the compliance times shown
in Paragraph 1.E., Compliance have been reduced.
Revision 2 - No more work is necessary on the airplanes changed in accordance with Revision 1 of
this service bulletin.
Revision 3 - More work is necessary on Group 1 airplanes inspected or changed in accordance with
Revision 2 of this service bulletin. For Group 1 airplanes, the inspection threshold has been lowered
and a preventive modification is required to mitigate Widespread Fatigue Damage (WFD) concerns at
the ATC antenna location. Post preventive modification inspections are required.
No more work is necessary on Group 2 airplanes inspected or changed in accordance with Revision
2 of this service bulletin.
The work in this service bulletin is done in the maintenance zone(s) given below.
Affected Maintenance Zones
ZoneModel
107737-300, 737-400, 737-500
E. Compliance
Federal Aviation Administration (FAA) Airworthiness Directive AD 2008-09-13 and AD 2012-12-04 are
related to this service bulletin. The effective date of AD 2012-12-04 is July 23, 2012.
The Federal Aviation Administration (FAA) will possibly release an additional Airworthiness Directive
related to this service bulletin. The Airworthiness Directive will make the compliance tasks and times
given in this service bulletin mandatory.
NOTE: If any repair or modification in the Accomplishment Instructions, Paragraph 3.B., Work
Instructions, is not applicable, contact Boeing for repair or modification instructions and do
the repair or modification before further flight.
NOTE: The damage tolerance inspections specified in Table 4 and Table 6 below may be used in
support of compliance with 14 Code of Federal Regulations, Section 121.1109 or 129.109.
Do the required actions in accordance with Paragraph 3.B., Accomplishment Instructions.
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### Page 28

Group 1, Configuration 1:
Table 1: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Within 1,800
flight cycles
after the Revi-
sion 3 date of
this service
bulletin.
Before
33,000 total
flight cycles.
Option 1: Do an external Detailed In-
spection (DI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 1.
AND
Airplanes with less than
33,200 total flight cy-
cles at the Revision 3
date of this service bul-
letin and have not ac-
complished inspections
in accordance with the
original issue of this
service bulletin.
Do an external Non Destructive In-
spection (NDI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 1 using
one of the following procedures:
1. Medium Frequency Eddy Cur-
rent(MFEC)
or
2. Magneto Optical Imaging (MOI)
or
3. C-Scan
(a) (c)
OR
-Within 1,800
flight cycles
after the Revi-
sion 3 date of
this service
bulletin.
Before
33,000 total
flight cycles.
Option 2: Do an external Detailed In-
spection (DI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 1.
AND
Do an external Non Destructive In-
spection (NDI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 1 using
the Ultrasonic Phased Array (UTPA)
procedure.
(a)
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### Page 29

Group 1, Configuration 1:
Table 1: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Within 1,800
flight cycles
after the effec-
tive date of
AD 2012-12-
04.
Before
35,000 total
flight cycles.
Option 1: Do an external Detailed In-
spection (DI) of the fuselage skin
chem mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 1.
AND
Airplanes with more
than 33,199 total flight
cycles at the Revision
3 date of this service
bulletin and have not
accomplished inspec-
tions in accordance
with the original issue
of this service bulletin.
Do an external Non Destructive In-
spection (NDI) of the fuselage skin
chem mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 1 using
one of the following procedures:
1. Medium Frequency Eddy Current
(MFEC)
or
2. Magneto Optical Imaging (MOI)
or
3. C-Scan
(a) (c)
OR
-Within 1,800
flight cycles
after the effec-
tive date of
AD 2012-12-
04.
Before
35,000 total
flight cycles.
Option 2: Do an external Detailed In-
spection (DI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tion, Paragraph 3.B., PART 1.
AND
Do an external Non Destructive In-
spection (NDI) of the fuselage skin
chem mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 1 using
the Ultrasonic Phased Array (UTPA)
procedure.
(a)
1,800 flight cy-
cles. (b)
Within 1,800 flight cycles af-
ter the last NDI. (b)
Repeat external DI and NDI of the
fuselage skin chem-mill steps for any
crack in accordance with Accomplish-
ment Instructions, Paragraph 3.B.,
PART 1.
No crack found in the
fuselage skin AND Op-
tion 1 used.
OR
2,400 flight cy-
cles. (b)
Within 2,400 flight cycles af-
ter the last NDI. (b)
No crack found in the
fuselage skin AND Op-
tion 2 used.
(a) (c)
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### Page 30

Group 1, Configuration 1:
Table 1: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Before further flight.Contact Boeing for repair instructions
in accordance with Accomplishment
Instructions, Paragraph 3.B., PART 1
and do the repair. (d)
Any crack found before
33,000 total flight cy-
cles.
OR
Any crack found in four
or more tear strap bays. AND (do Option 1 or Option 2)
1,800 flight cy-
cles. (b)
Within 1,800 flight cycles af-
ter the last NDI. (b)
Option 1: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a re-
pair) for any crack in accordance with
Accomplishment Instructions, Para-
graph 3.B., PART 3.
OR
Any crack found longer
than 5 inches.
OR
Any crack found not
contained within the
skin cut-out. AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair) for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 3 using one of
the following procedures:
1. MFEC
or
2. MOI
or
3. C-Scan
(a) (c)
OR
2,400 flight cy-
cles. (b)
Within 2,400 flight cycles af-
ter the last NDI. (b)
Option 2: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a re-
pair) for any crack in accordance with
Accomplishment Instructions, Para-
graph 3.B., PART 3.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair) for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 3 using UTPA
procedure.
(a)
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### Page 31

Group 1, Configuration 1:
Table 1: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Before further flight.Do the repair in accordance with Ac-
complishment Instructions, Paragraph
3.B., PART 2.
Any crack found at or
after 33,000 total flight
cycles.
(d)AND
ORAny crack found in
three or fewer tear
strap bays.
Do the preventive modification in ac-
cordance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 9.AND
(f)Any crack found 5 inch-
es or shorter.
AND AND (Do Option 1 or Option 2)
1,800 flight cy-
cles. (b)
Within 1,800 flight cycles af-
ter the last NDI. (b)
Option 1: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a re-
pair or preventive modification dou-
bler) for any crack in accordance with
Accomplishment Instructions, Para-
graph 3.B., PART 3.
Any crack found con-
tained within the skin
cut-out.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair or preventive modification
doubler) for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 3 using one of
the following procedures:
1. MFEC
or
2. MOI
or
3. C-Scan
(a) (c) (e) (f)
OR
2,400 flight cy-
cles. (b)
Within 2,400 flight cycles af-
ter the last NDI. (b)
Option 2: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a re-
pair or preventive modification) for any
crack in accordance with Accomplish-
ment Instructions, Paragraph 3.B.,
PART 3.
AND
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### Page 32

Group 1, Configuration 1:
Table 1: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair or preventive modification) for
any crack in accordance with Accom-
plishment Instructions, Paragraph
3.B., PART 3 using UTPA procedure.
(a) (e) (f)
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### Page 33

Group 1, Configuration 1:
Table 1: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Within 2,500
flight cycles
after the Revi-
sion 3 date of
this service
bulletin.
Before
45,000 total
flight cycles.
Do the preventive modification in ac-
cordance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 9.
(f)
All airplanes.
AND (do Option 1 or Option 2)
1,800 flight cy-
cles. (b)
Within 1,800 flight cycles af-
ter the last NDI. (b)
Option 1: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a
preventive modification) for any crack
in accordance with Accomplishment
Instructions, Paragraph 3.B., PART
3.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a preventive modification) for any
crack in accordance with Accomplish-
ment Instructions, Paragraph 3.B.,
PART 3 using the following procedure:
MFEC
(e) (f)
OR
2,400 flight cy-
cles. (b)
Within 2,400 flight cycles af-
ter the last NDI. (b)
Option 2: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a
preventive modification) for any crack
in accordance with Accomplishment
Instructions, Paragraph 3.B., PART
3.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a preventive modification) for any
crack in accordance with Accomplish-
ment Instructions, Paragraph 3.B.,
PART 3 using UTPA procedure.
(e) (f)
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### Page 34

Group 1, Configuration 1:
Table 1: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
(a) It is not necessary to inspect the chem-mill steps under an external repair doubler provided all of the following
apply:
1. The repair was installed in accordance with this service bulletin, or approved by the FAA, or approved
by a Boeing company authorized representative who was authorized by the FAA to make such findings.
2. The repair extends a minimum of three rows of fasteners on each side of the chem-mill step in the
circumferential direction.
Installation of an external repair that meets the requirements of items 1 and 2 above is terminating action for
repeat inspections under the repair area only.
(b) It is acceptable to change inspection procedures from Option 1 to Option 2 or from Option 2 to Option 1 if
you do as follows:
1. If the inspection procedure is being changed from Option 1 to Option 2, the first two Option 2 inspections
must be done within 1,800 flight cycle repeat intervals. Then Option 2 inspections that follow must
be done within 2,400 flight cycle repeat intervals.
2. If the inspection procedure is being changed from Option 2 to Option 1, the first Option 1 inspection
must be done within 2,400 flight cycles after the Option 2 inspection. Then Option 1 inspections that
follow must be done within 1,800 flight cycle repeat intervals.
(c) Magneto Optical Imaging (MOI) and C-Scan NDI inspection options cannot be used within 4 inches of an
existing repair or preventive modification doubler edge. Within 4 inches of an existing repair or preventive
modification doubler edge, the Medium Frequency Eddy Current (MFEC) or Ultrasonic Phased Array (UTPA)
NDI inspection options must be used.
(d) The repair must be removed and replaced by the preventive modification in accordance with Accomplishment
Instructions, Paragraph 3.B., PART 9 at the compliance time given in this table.
(e) It is not necessary to inspect the chem-mill steps under an external preventive modification doubler installed
in accordance with this service bulletin. Installation of the doubler is terminating action for repeat inspections
under the preventive modification doubler only.
(f) For airplanes with an existing skin repair accomplished in accordance with FIGURE 6 or FIGURE 8 of this
service bulletin that covers all eight chem-mill step inspection areas between STA 410 and STA 450 it is not
necessary to remove the existing repair. Installation of a skin repair meeting this requirement is terminating
action for the PART 9 - Preventive Modification and the repeat inspections under the repair doubler only.
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### Page 35

Group 1, Configuration 2, 4:
Table 2: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Within 900
flight cycles
after the effec-
tive date of
AD 2012-12-
04.
Before
35,000 total
flight cycles.
Option 1: Do an external Detailed In-
spection (DI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 1.
AND
Airplanes inspected in
accordance with the
original issue of this
service bulletin and the
last inspection was De-
tailed Inspection (DI)
procedure.
OR
Airplanes inspected in
accordance with Boeing
Multi-Operator Mes-
sage MOM-MOM-09-
0807-01B (R1) and the
last inspection was De-
tailed Inspection (DI)
procedure.
Do an external Non Destructive In-
spection (NDI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 1 using
one of the following procedures:
1. Medium Frequency Eddy Current
(MFEC)
or
2. Magneto Optical Imaging (MOI)
or
3. C-Scan
(a) (c)
OR
-Within 900
flight cycles
after the effec-
tive date of
AD 2012-12-
04.
Before
35,000 total
flight cycles.
Option 2: Do an external Detailed In-
spection (DI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 1.
AND
Do an external Non Destructive In-
spection (NDI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 1 using
the Ultrasonic Phased Array (UTPA)
procedure.
(a)
1,800 flight cy-
cles. (b)
Within 1,800 flight cycles af-
ter the last NDI. (b)
Repeat external DI and NDI of the
fuselage skin chem-mill steps for any
crack in accordance with Accomplish-
ment Instructions, Paragraph 3.B.,
PART 1.
No crack found in the
fuselage skin AND Op-
tion 1 used.
OR
2,400 flight cy-
cles. (b)
Within 2,400 flight cycles af-
ter the last NDI. (b)
No crack found in the
fuselage skin AND Op-
tion 2 used.
(a) (c)
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### Page 36

Group 1, Configuration 2, 4:
Table 2: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Before further flight.Contact Boeing for repair instructions
in accordance with Accomplishment
Instructions, Paragraph 3.B., PART 1
and do the repair.
Any crack found before
35,000 total flight cy-
cles.
OR
(d)Any crack found in four
or more tear strap bays.
OR AND (do Option 1 or Option 2)
1,800 flight cy-
cles. (b)
Within 1,800 flight cycles af-
ter the last NDI. (b)
Option 1: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a re-
pair) for any crack in accordance with
Accomplishment Instructions, Para-
graph 3.B., PART 3.
Any crack found longer
than 5 inches.
OR
Any crack found not
contained within the
skin cut-out.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair) for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 3 using one of
the following procedures:
1. MFEC
or
2. MOI
or
3. C-Scan
(a) (c)
OR
2,400 flight cy-
cles. (b)
Within 2,400 flight cycles af-
ter the last NDI. (b)
Option 2: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a re-
pair) for any crack in accordance with
Accomplishment Instructions, Para-
graph 3.B., PART 3.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair) for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 3 using UTPA
procedure.
(a)
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### Page 37

Group 1, Configuration 2, 4:
Table 2: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Before further flight.Do the repair in accordance with Ac-
complishment Instructions, Paragraph
3.B., PART 2.
Any crack found at or
after 35,000 total flight
cycles.
(d)AND
ORAny crack found in
three or fewer tear
strap bays.
Do the preventive modification in ac-
cordance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 9.AND
(f)Any crack found 5 inch-
es or shorter.
AND AND (Do Option 1 or Option 2)
1,800 flight cy-
cles. (b)
Within 1,800 flight cycles af-
ter the last NDI. (b)
Option 1: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a re-
pair or preventive modification dou-
bler) for any crack in accordance with
Accomplishment Instructions, Para-
graph 3.B., PART 3.
Any crack found con-
tained within the skin
cut-out.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair or preventive modification
doubler) for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 3 using one of
the following procedures:
1. MFEC
or
2. MOI
or
3. C-Scan
(a) (c) (e) (f)
OR
2,400 flight cy-
cles. (b)
Within 2,400 flight cycles af-
ter the last NDI. (b)
Option 2: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a re-
pair or preventive modification) for any
crack in accordance with Accomplish-
ment Instructions, Paragraph 3.B.,
PART 3.
AND
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### Page 38

Group 1, Configuration 2, 4:
Table 2: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair or preventive modification) for
any crack in accordance with Accom-
plishment Instructions, Paragraph
3.B., PART 3 using UTPA procedure.
(a) (e) (f)
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### Page 39

Group 1, Configuration 2, 4:
Table 2: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Within 2,500
flight cycles
after the Revi-
sion 3 date of
this service
bulletin.
Before
45,000 total
flight cycles.
Do the preventive modification in ac-
cordance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 9.
(f)
All airplanes.
AND (do Option 1 or Option 2)
1,800 flight cy-
cles. (b)
Within 1,800 flight cycles af-
ter the last NDI. (b)
Option 1: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a
preventive modification) for any crack
in accordance with Accomplishment
Instructions, Paragraph 3.B., PART
3.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a preventive modification) for any
crack in accordance with Accomplish-
ment Instructions, Paragraph 3.B.,
PART 3 using an MFEC procedure.
(e) (f)
OR
2,400 flight cy-
cles. (b)
Within 2,400 flight cycles af-
ter the last NDI. (b)
Option 2: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a
preventive modification) for any crack
in accordance with Accomplishment
Instructions, Paragraph 3.B., PART
3.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a preventive modification) for any
crack in accordance with Accomplish-
ment Instructions, Paragraph 3.B.,
PART 3 using UTPA procedure.
(e) (f)
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### Page 40

Group 1, Configuration 2, 4:
Table 2: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
(a) It is not necessary to inspect the chem-mill steps under an external repair doubler provided all of the following
apply:
1. The repair was installed in accordance with this service bulletin, or approved by the FAA, or approved
by a Boeing company authorized representative who was authorized by the FAA to make such findings.
2. The repair extends a minimum of three rows of fasteners on each side of the chem-mill step in the
circumferential direction.
Installation of an external repair that meets the requirements of items 1 and 2 above is terminating action for
repeat inspections under the repair area only.
(b) It is acceptable to change inspection procedures from Option 1 to Option 2 or from Option 2 to Option 1 if
you do as follows:
1. If the inspection procedure is being changed from Option 1 to Option 2, the first two Option 2 inspections
must be done within 1,800 flight cycle repeat intervals. Then Option 2 inspections that follow must
be done within 2,400 flight cycle repeat intervals.
2. If the inspection procedure is being changed from Option 2 to Option 1, the first Option 1 inspection
must be done within 2,400 flight cycles after the Option 2 inspection. Then Option 1 inspections that
follows must be done within 1,800 flight cycle repeat intervals.
(c) Magneto Optical Imaging (MOI) and C-Scan NDI inspection options cannot be used within 4 inches of an
existing repair or preventive modification doubler edge. Within 4 inches of an existing repair or preventive
modification doubler edge, the Medium Frequency Eddy Current (MFEC) or Ultrasonic Phased Array (UTPA)
NDI inspection options must be used.
(d) The repair must be removed and replaced by the preventive modification in accordance with Accomplishment
Instructions, Paragraph 3.B., PART 9 at the compliance time given in this table.
(e) It is not necessary to inspect the chem-mill steps under an external preventive modification doubler installed
in accordance with this service bulletin. Installation of the doubler is terminating action for repeat inspections
under the preventive modification doubler only.
(f) For airplanes with an existing skin repair accomplished in accordance with FIGURE 6 or FIGURE 8 of this
service bulletin that covers all eight chem-mill step inspection areas between STA 410 and STA 450 it is not
necessary to remove the existing repair. Installation of a skin repair meeting this requirement is terminating
action for the PART 9 - Preventive Modification and the repeat inspections under the repair doubler only.
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### Page 41

Group 1, Configuration 3, 5:
Table 3: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Within 1,800
flight cycles
after the effec-
tive date of
AD 2012-12-
04.
Before
35,000 total
flight cycles.
Option 1:
Do an external Detailed Inspection
(DI) of the fuselage skin chem-mill
steps for any crack in accordance with
Accomplishment Instructions, Para-
graph 3.B., PART 1.
Airplanes inspected in
accordance with the
original issue of this
service bulletin and the
last inspection was a
Non Destructive Inspec-
tion (NDI) procedure. AND
OR Do an external Non Destructive In-
spection (NDI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 1 using
one of the following procedures:
Airplanes inspected in
accordance with Boeing
Multi-Operator Mes-
sage MOM-MOM-09-
0807-01B (R1) and the
last inspection was a
Non Destructive Inspec-
tion (NDI) procedure.
1. Medium Frequency Eddy Current
(MFEC)
or
2. Magneto Optical Imaging (MOI)
or
3. C-Scan
(a) (c)
OR
-Within 1,800
flight cycles
after the effec-
tive date of
AD 2012-12-
04.
Before
35,000 total
flight cycles.
Option 2:
Do an external Detailed Inspection
(DI) of the fuselage skin chem-mill
steps for any crack in accordance with
Accomplishment Instructions, Para-
graph 3.B., PART 1.
AND
Do an external Non Destructive In-
spection (NDI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 1 using
the Ultrasonic Phased Array (UTPA)
procedure.
(a)
1,800 flight cy-
cles. (b)
Within 1,800 flight cycles af-
ter the last NDI. (b)
Repeat external DI and NDI of the
fuselage skin chem-mill steps for any
crack in accordance with Accomplish-
ment Instructions, Paragraph 3.B.,
PART 1.
No crack found in the
fuselage skin AND Op-
tion 1 used.
OR
2,400 flight cy-
cles. (b)
Within 2,400 flight cycles af-
ter the last NDI. (b)
No crack found in the
fuselage skin AND Op-
tion 2 used.
(a) (c)
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### Page 42

Group 1, Configuration 3, 5:
Table 3: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Before further flight.Contact Boeing for repair instructions
in accordance with Accomplishment
Instructions, Paragraph 3.B., PART 1
and do the repair.
Any crack found before
35,000 total flight cy-
cles.
OR
(d)Any crack found in four
or more tear strap bays.
OR AND (do Option 1 or Option 2)
1,800 flight cy-
cles. (b)
Within 1,800 flight cycles af-
ter the last NDI. (b)
Option 1: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a re-
pair) for any crack in accordance with
Accomplishment Instructions, Para-
graph 3.B., PART 3.
Any crack found longer
than 5 inches.
OR
Any crack found not
contained within the
skin cut-out.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair) for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 3 using one of
the following procedures:
1. MFEC
or
2. MOI
or
3. C-Scan
(a) (c)
OR
2,400 flight cy-
cles. (b)
Within 2,400 flight cycles af-
ter the last NDI. (b)
Option 2: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a re-
pair) for any crack in accordance with
Accomplishment Instructions, Para-
graph 3.B., PART 3.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair) for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 3 using UTPA
procedure.
(a)
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### Page 43

Group 1, Configuration 3, 5:
Table 3: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Before further flight.Do the repair in accordance with Ac-
complishment Instructions, Paragraph
3.B., PART 2. (d)
Any crack found at or
after 35,000 flight cy-
cles.
ORAND
Do the preventive modification in ac-
cordance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 9.
Any crack found in
three or fewer tear
strap bays.
(f)AND
Any crack found 5 inch-
es or shorter. AND (Do Option 1 or Option 2)
1,800 flight cy-
cles. (b)
Within 1,800 flight cycles af-
ter the last NDI. (b)
Option 1: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a re-
pair or preventive modification dou-
bler) for any crack in accordance with
Accomplishment Instructions, Para-
graph 3.B., PART 3.
AND
Any crack found con-
tained within the skin
cut-out.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair or preventive modification
doubler) for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 3 using one of
the following procedures:
1. MFEC
or
2. MOI
or
3. C-Scan
(a) (c) (e) (f)
OR
2,400 flight cy-
cles. (b)
Within 2,400 flight cycles af-
ter the last NDI. (b)
Option 2: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a re-
pair or preventive modification) for any
crack in accordance with Accomplish-
ment Instructions, Paragraph 3.B.,
PART 3.
AND
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Group 1, Configuration 3, 5:
Table 3: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair or preventive modification) for
any crack in accordance with Accom-
plishment Instructions, Paragraph
3.B., PART 3 using UTPA procedure.
(a) (e) (f)
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Group 1, Configuration 3, 5:
Table 3: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Within 2,500
flight cycles
after the Revi-
sion 3 date of
this service
bulletin.
Before
45,000 total
flight cycles.
Do the preventive modification in ac-
cordance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 9.
(f)
All airplanes.
AND (do Option 1 or Option 2)
1,800 flight cy-
cles. (b)
Within 1,800 flight cycles af-
ter the last NDI. (b)
Option 1: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a
preventive modification) for any crack
in accordance with Accomplishment
Instructions, Paragraph 3.B., PART
3.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a preventive modification) for any
crack in accordance with Accomplish-
ment Instructions, Paragraph 3.B.,
PART 3 using MFEC procedure.
(e) (f)
OR
2,400 flight cy-
cles. (b)
Within 2,400 flight cycles af-
ter the last NDI. (b)
Option 2: Repeat external Detailed
Inspection (DI) of the fuselage skin
chem-mill steps (not covered by a
preventive modification) for any crack
in accordance with Accomplishment
Instructions, Paragraph 3.B., PART
3.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a preventive modification) for any
crack in accordance with Accomplish-
ment Instructions, Paragraph 3.B.,
PART 3 using UTPA procedure.
(e) (f)
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Group 1, Configuration 3, 5:
Table 3: External Fuselage Skin Chem-Mill Step Inspection, Repair and Preventive Modification - Stringers
S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
(a) It is not necessary to inspect the chem-mill steps under an external repair doubler provided all of the following
apply:
1. The repair was installed in accordance with this service bulletin, or approved by the FAA, or approved
by a Boeing company authorized representative who was authorized by the FAA to make such findings.
2. The repair extends a minimum of three rows of fasteners on each side of the chem-mill step in the
circumferential direction.
Installation of an external repair that meets the requirements of items 1 and 2 above is terminating action for
repeat inspections under the repair area only.
(b) It is acceptable to change inspection procedures from Option 1 to Option 2 or from Option 2 to Option 1 if
you do as follows:
1. If the inspection procedure is being changed from Option 1 to Option 2, the first two Option 2 inspections
must be done within 1,800 flight cycle repeat intervals. The Option 2 inspections that follow must be
done within 2,400 flight cycle repeat intervals.
2. If the inspection procedure is being changed from Option 2 to Option 1, the first Option 1 inspection
must be done within 2,400 flight cycles after the Option 2 inspection. The Option 1 inspections that
follows must be done within 1,800 flight cycle repeat intervals.
(c) Magneto Optical Imaging (MOI) and C-Scan NDI inspection options cannot be used within 4 inches of an
existing repair or preventive modification doubler edge. Within 4 inches of an existing repair or preventive
modification doubler edge, the Medium Frequency Eddy Current (MFEC) or Ultrasonic Phased Array (UTPA)
NDI inspection options must be used.
(d) The repair must be removed and replaced by the preventive modification in accordance with Accomplishment
Instructions, Paragraph 3.B., PART 9 at the compliance time given in this table.
(e) It is not necessary to inspect the chem-mill steps under an external preventive modification doubler installed
in accordance with this service bulletin. Installation of the doubler is terminating action for repeat inspections
under the preventive modification doubler only.
(f) For airplanes with an existing skin repair accomplished in accordance with FIGURE 6 or FIGURE 8 of this
service bulletin that covers all eight chem-mill step inspection areas between STA 410 and STA 450 it is not
necessary to remove the existing repair. Installation of a skin repair meeting this requirement is terminating
action for the PART 9 - Preventive Modification and the repeat inspections under the repair doubler only.
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Group 1:
Table 4: Post Repair or Post Preventive Modification - Critical Fastener Row Inspection
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Within 60,000 flight cycles
after the time the repair was
installed.
Do an external Low Frequency Eddy
Current (LFEC) inspection of the
fuselage skin at the critical row of
fasteners for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 4.
Airplanes with a repair
installed in accordance
with this service bul-
letin.
-Within 12,000
flight cycles
after the time
the preven-
tive modifica-
tion or repair
was installed.
Before
66,000 total
flight cycles.
Do an external LFEC inspection of the
fuselage skin at the critical row of
fasteners for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 4.
Airplanes with a preven-
tive modification in-
stalled in accordance
with this service bul-
letin.
OR
Airplanes with a repair
installed in accordance
with this service bulletin
that satisfy the require-
ments of Accomplish-
ment Instructions,
Paragraph 3.B., PART
9 - Preventive Modifica-
tion.
6,000 flight cy-
cles.
-Repeat external LFEC inspections of
the fuselage skin at the critical row of
fasteners for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 4.
No crack found.
-Before further flight.Contact Boeing for repair instructions
in accordance with Accomplishment
Instructions, Paragraph 3.B., PART 4
and do the repair.
Any crack found.
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Group 2:
Table 5: External Fuselage Skin Chem-Mill Step Inspection - Stringers S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Within 500
flight cycles
after the effec-
tive date of
AD 2012-12-
04.
Before
33,000 total
flight cycles.
Option 1: Do an external Detailed In-
spection (DI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 5.
AND
All Airplanes.
Do an external Non Destructive In-
spection (NDI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 5 using
one of the following procedures:
1. Medium Frequency Eddy Current
(MFEC)
or
2. Magneto Optical Imaging (MOI)
or
3. C-Scan
(a) (c)
OR
-Within 500
flight cycles
after the effec-
tive date of
AD 2012-12-
04.
Before
33,000 total
flight cycles.
Option 2: Do an external Detailed In-
spection (DI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 5.
AND
Do an external Non Destructive In-
spection (NDI) of the fuselage skin
chem-mill steps for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 5 using
the Ultrasonic Phased Array (UTPA)
procedure.
(a)
500 flight cycles.
(b)
Within 500 flight cycles after
the last NDI.
Repeat external NDI of the fuselage
skin chem-mill steps for any crack in
accordance with Accomplishment In-
structions, Paragraph 3.B., PART 5.
No crack found in the
fuselage skin AND Op-
tion 1 used. (b)
OR (a) (c)
1,000 flight cy-
cles.
Within 1,000 flight cycles af-
ter the last NDI.
No crack found in the
fuselage skin AND Op-
tion 2 used. (b)(b)
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Group 2:
Table 5: External Fuselage Skin Chem-Mill Step Inspection - Stringers S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Before further flight.Contact Boeing for repair instructions
in accordance with Accomplishment
Instructions, Paragraph 3.B., PART 5
and do the repair.
Any crack found before
33,000 total flight cy-
cles.
OR
Any crack found be-
tween STA 400 and
STA 420.
AND (do Option 1 or Option 2)
500 flight cycles.
(b)
Within 500 flight cycles after
the last NDI. (b)
Option 1: Repeat external DI of the
fuselage skin chem-mill steps (not
covered by a repair) for any crack in
accordance with Accomplishment In-
structions, Paragraph 3.B., PART 6.
OR
Any crack found be-
tween STA 440 and
STA 460.
OR AND
Any crack found longer
than 12.5 inches.
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair) for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 6 using one of
the following procedures:
OR
Any crack found not
contained within the
skin cut-out.
1. MFEC
or
2. MOI
or
3. C-Scan
(a) (c)
OR
1,000 flight cy-
cles. (b)
Within 1,000 flight cycles af-
ter the last NDI. (b)
Option 2: Repeat external DI of the
fuselage skin chem-mill steps (not
covered by a repair) for any crack in
accordance with Accomplishment In-
structions, Paragraph 3.B., PART 6.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair) for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 6 using UTPA
procedure.
(a)
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Group 2:
Table 5: External Fuselage Skin Chem-Mill Step Inspection - Stringers S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Before further flight.Do the repair in accordance with Ac-
complishment Instructions, Paragraph
3.B., PART 7.
Any crack found at or
after 33,000 total flight
cycles.
AND
Any crack found be-
tween STA 420 and
STA 440.
AND (do Option 1 or Option 2)
500 flight cycles.
(b)
Within 500 flight cycles after
the last NDI. (b)
Option 1: Repeat external DI of the
fuselage skin chem-mill steps (not
covered by a repair) for any crack in
accordance with Accomplishment In-
structions, Paragraph 3.B., PART 6.
AND
Any crack found 12.5
inches or shorter.
AND AND
Any crack found con-
tained within the skin
cut-out.
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair) for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 6 using one of
the following procedures:
1. MFEC
or
2. MOI
or
3. C-Scan
(a) (c)
OR
1,000 flight cy-
cles. (b)
Within 1,000 flight cycles af-
ter the last NDI. (b)
Option 2: Repeat external DI of the
fuselage skin chem-mill steps (not
covered by a repair) for any crack in
accordance with Accomplishment In-
structions, Paragraph 3.B., PART 6.
AND
Repeat external NDI of the fuselage
skin chem-mill steps (not covered by
a repair) for any crack in accordance
with Accomplishment Instructions,
Paragraph 3.B., PART 6 using UTPA
procedure.
(a)
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Group 2:
Table 5: External Fuselage Skin Chem-Mill Step Inspection - Stringers S-1 and S-2R, STA 400 - STA 460
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
(a) It is not necessary to inspect the chem-mill steps under an external repair doubler provided all of the following
apply:
1. The repair was installed in accordance with this service bulletin, or approved by the FAA, or approved
by a Boeing company authorized representative who was authorized by the FAA to make such findings.
2. The repair extends a minimum of three rows of fasteners on each side of the chem-mill step in the
circumferential direction.
Installation of an external repair that meets the requirements of items 1 and 2 above is terminating action for
repeat inspections under the repair area only.
(b) It is acceptable to change inspection procedures from Option 1 to Option 2 or from Option 2 to Option 1 if
you do as follows:
1. If the inspection procedure is being changed from Option 1 to Option 2, the first two Option 2 inspections
must be done within 500 flight cycle repeat intervals. The Option 2 inspections that follow must be
done within 1000 flight cycle repeat intervals.
2. If the inspection procedure is being changed from Option 2 to Option 1, the first Option 1 inspection
must be done within 1000 flight cycles after the Option 2 inspection. The Option 1 inspections that
follow must be done within 500 flight cycle repeat intervals.
(c) Magneto Optical Imaging (MOI) and C-Scan NDI inspection options cannot be used within 4 inches of an
existing repair doubler edge. Within 4 inches of an existing repair doubler edge, the Medium Frequency Eddy
Current (MFEC) or Ultrasonic Phased Array (UTPA) NDI inspection options must be used.
Group 2:
Table 6: Post Repair - Critical Fastener Row Inspection
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Within 60,000 flight cycles
after the time the repair was
installed.
Do a Non Destructive inspection (NDI)
of the skin at the critical row of fasten-
ers in the repair for any crack in accor-
dance with Accomplishment Instruc-
tions, Paragraph 3.B., PART 8.
Airplanes with a repair
installed in accordance
with this service bul-
letin.
6,000 flight cy-
cles.
Within 6,000 flight cycles af-
ter the last NDI.
Repeat NDI of the skin at the critical
row of fasteners in the repair for any
crack in accordance with Accomplish-
ment Instructions, Paragraph 3.B.,
PART 8.
No crack found.
-Before further flight.Contact Boeing for repair instructions
in accordance with Accomplishment
Instructions, Paragraph 3.B., PART 8
and do the repair.
Any crack found.
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The following instructions in Table 7 apply to Supplemental Structural Items (SSI's) defined in the 737
Supplemental Structural Inspection Document (SSID) (737-300/-400/-500) D6-82669 Revision New
that are common to the fuselage skin repair or preventive modification accomplished in accordance
with this service bulletin. The SSI affected is the fuselage crown skin and stringers (F-39). Federal
Aviation Administration (FAA) Airworthiness Directive AD 2008-09-13 is related to this SSI.
Table 7: Alternate SSID Inspection Requirements for SSI's F-39B and F-39F on airplanes with Repair or
Preventive Modification.
Repeat Interval (Not
to Exceed)
Compliance Time (Whichever Occurs
Later)
ActionCondition
6,000 flight cycles.Within 12,000 flight
cycles after the time
the repair or preven-
tive modification was
installed.
Before 66,000 total
flight cycles.
The installation of
this service bulletin
repair or preventive
modification will have
an impact on SSI F-
39B and F-39F at
stringer S-1 and S-
2R. However perform-
ing the inspections of
the fuselage skin in
accordance with Ac-
complishment Instruc-
tions Paragraph 3.B.,
PART 4 or PART 8,
as applicable, meets
requirements of
these SSI details at
the repair or preven-
tive modification loca-
tion only. Accomplish
these inspections at
the Compliance Time
given in this table.
SSI F-39B and F-
39F. Fuselage skin
at crown stringers S-
1 and S-2R common
to the repair or pre-
ventive 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 accomplishment of the inspection methods, corrective
actions, modifications, and compliance times in Tables 1, 2, 3, and 5 under Paragraph 1.E., Compliance
of this service bulletin as an Alternative Method of Compliance (AMOC) to the requirements of
paragraphs (g), (h) and (i) of Airworthiness Directive (AD) 2012-12-04. When this service bulletin
specifies contacting Boeing for repair instructions, the repair must be approved by the FAA in accordance
with paragraph (l) of AD 2012-12-04. All provisions of AD 2012-12-04 that are not specifically referenced
in the above statement remain fully applicable and must be complied with accordingly.
For airplane identified in this service bulletin, Revision 3, the repairs and modification of this service
bulletin have been reviewed as required by paragraphs (g) and (i) of Airworthiness Directive (AD)
2008-09-13. The repairs and modification are found to affect Structurally Significant Items (SSIs) F-39A
and F-39E of Supplemental Structural Inspection Document (SSID) D6-82669, but the SSIs F-39A and
F-39E inspections remain effective with the repairs and modification installed. Therefore, an alternative
inspection is not necessary for SSIs F-39A and F-39E. Do the existing SSIs F-39A and F-39E inspections
as required by paragraphs (g) and (h) of AD 2008-09-13.
The Manager of the FAA Seattle ACO approves the inspection methods, compliance times and repeat
intervals defined in Paragraph 1.E., Compliance, Table 7, as an AMOC to the inspections of SSIs F-39B
and F-39F as applicable of SSID D6-82669 required by paragraphs (g) and (h) of AD 2008-09-13. This
approval applies only to SSIs F-39B and F-39F and only for the areas covered by the repairs or
modification. All provisions of AD 2008-09-13 that are not specifically referenced in the above statement
remain fully applicable and must be complied with accordingly. If operators choose this AMOC, then
they must revise their FAA approved maintenance or inspection program to incorporate these alternative
inspections.
G. Manpower
The tables below show an estimate of the task hours necessary to do this inspection 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.
Group 1:
Table 1 - Skin Panel Inspection and Repair.
Elapsed HoursTask HoursNumber of Per-
sons
Task
0.250.251Get Access
2.755.502FIGURE 2
or
FIGURE 7
(a)--FIGURE 5
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Group 1:
Table 1 - Skin Panel Inspection and Repair.
Elapsed HoursTask HoursNumber of Per-
sons
Task
(a)--FIGURE 6
or
FIGURE 8
1.53.002Inspection
0.250.251Close Access
5.7514.50TOTAL FOR EACH AIRPLANE
(a) The time to make any repair is not included. More time is required for repairs
if any damage is found.
Group 2:
Table 2 - Skin Panel Inspection and Repair.
Elapsed HoursTask HoursNumber of Per-
sons
Task
0.250.251Get Access
3.006.002FIGURE 4
or
FIGURE 9
(a)--FIGURE 10
(a)--FIGURE 11
1.503.002FIGURE 12
0.250.251Close Access
5.009.50TOTAL FOR EACH AIRPLANE
(a) The time to make any repair is not included. More time is required for repairs
if any damage is found.
Group 1:
Table 3 - Preventive Modification, Preventive Modification on Existing Repair and Post
Repair or Post Preventive Modification Skin Panel Inspection
Elapsed HoursTask HoursNumber of Per-
sons
Task
19.2577.004Get Access
37.5075.002FIGURE 13
or
FIGURE 14
1.501.501FIGURE 15
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Group 1:
Table 3 - Preventive Modification, Preventive Modification on Existing Repair and Post
Repair or Post Preventive Modification Skin Panel Inspection
Elapsed HoursTask HoursNumber of Per-
sons
Task
2.505.002FIGURE 16
19.2577.004Close Access
(a)(a)TOTAL FOR EACH AIRPLANE
(a) Time for each airplane will be dependent upon task required.
H. Weight and Balance Changes
All airplanes:
1. Calculate the change in weight for each repair or preventive modification installation as follows:
a. Calculate the gross area of each repair or preventive modification doubler in square inches
(Length x Width).
Example for FIGURE 6: Length = approximately 20 inches and Width = approximately 12
inches. Area = 240 square inches. (Calculation ignores the curvature of the fuselage, holes
and rounding of corners).
b. To calculate the weight for each repair or preventive modification doubler installed, including
fasteners, paint and sealant, multiply the repair doubler area (from step 1.a) by 0.006 lb per
sq in.
Example for FIGURE 6: Change in Weight = 240 x 0.006 = 1.4 pounds rounded to nearest
1/10 pound.
2. Calculate the change in moment for each repair or preventive modification installation as follows:
a. Record the station of the geometric center of each repair or preventive modification doubler.
Example for FIGURE 6: By inspection, station = 435.
b. To calculate the change in moment for each repair or preventive modification doubler, use
the formula for each model as follows:
– For Model 737-300: change in weight from step 1.b. x (station from step 2.a. - 80) =
Change in Moment.
– For Model 737-400: change in weight from step 1.b. x (station from step 2.a. - 152) =
Change in Moment.
– For Model 737-500: change in weight from step 1.b. x (station from step 2.a. - 26) =
Change in Moment.
Example for FIGURE 6, Model 737-300: 1.4 x (435 - 80) = 500 Pound-Inches rounded to
nearest 10 pound-inch.
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3. If multiple repair doublers are installed, treat each one individually and then sum the weights and
moments.
I. Electrical Load Data
Not changed.
J. References
1. Existing Data:
a. Boeing Service Letter 737-SL-51-042
b. Boeing Service Related Problem (SRP) 737-SRP-53-0406
c. Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2008-09-13, 2008-19-03,
2012-12-04
d. Standard Overhaul Practices Manual (SOPM) 20-30-03, 20-43-03, 20-44-04, 20-50-19
e. 737 Non-Destructive Testing (NDT) Manual Part 4, 53-30-12, Part 6, 51-00-00 Procedure 4,
16 and 23, Part 6, 53-30-00 Procedure 4 and 5, Part 6, 53-30-09, Part 6, 53-30-18, Part 6,
53-30-19, Part 6, 53-30-25
f. 737-300/400/500 Aircraft Maintenance Manual (AMM) 25-21-39, 25-21-45, 25-21-46, 25-22-00,
25-23-61, 25-24-31, 34-53-11, 51-21-00
g. 737-300 Structural Repair Manual (SRM) 51-10-01, 51-20-01, 51-20-05, 51-30-01, 51-40,
51-40-02, 51-40-08
h. 737-400 Structural Repair Manual (SRM) 51-10-01, 51-20-01, 51-20-05, 51-30-01, 51-40,
51-40-02, 51-40-08
i. 737-500 Structural Repair Manual (SRM) 51-10-01, 51-20-01, 51-20-05, 51-30-01, 51-30-01,
51-40, 51-40-08
j. Multi-Operator Message (MOM) MOM-MOM-09-0807-01B (R1)
k. Airplane Flight Manual Appendix 53
l. Service Bulletin Index Document D6-19567 Part 3
m. Supplemental Structural Inspection Document D6-82669
2. Data Supplied with this Service Bulletin:
None.
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
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ALERTALERT

### Page 57

3. Installation Drawings Used in the Preparation of this Service Bulletin:
TitleDrawing Number
SKIN PANEL INSTALLATION - S-10L TO S-10R STA 360 - STA 54065-45765
SKIN INSTALLATION - S-10L TO S-10R, STA 360 TO STA 54065C35765
These drawings were used to prepare this service bulletin. These drawings are not necessary to
make the specified changes, and are not supplied with this service bulletin. These drawings may
not be applicable to all airplane configurations or operators.
K. Publications Affected
1. Publications:
None.
2. Damage Tolerance Based Structural Inspections:
Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue
Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the
Maintenance Program. This service bulletin affects FCS. DTI requirements for the structure affected
are contained in Paragraph 1.E., Compliance of this service bulletin.
L. Interchangeability and Intermixability of Parts
Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.
M. Software Accomplishment Summary
Not affected.
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
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### Page 58

Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.
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BLANK PAGE

### Page 59

2.    MATERIAL INFORMATION
A. Material - Price and Availability
The operator can supply the parts and materials shown in Paragraph 2.C., Parts Necessary for Each
Airplane . As an alternative, operators can purchase the parts from Boeing Spares. This service bulletin
does not show the Boeing price and supply data.
B. Industry Support Information
Boeing warranty remedies are not available for the inspection and repair procedures given in this
service bulletin.
C. Parts Necessary for Each Airplane
1. Kits/Parts
None.
2. Parts and Materials Supplied by the Operator
Group 1:
Table 1 - Repair
NotesNameQTYPart Number / Specification
(a) (b) (c) (d)Rivet-BACR15BB5D5C
(a) (b) (c) (d)Rivet-BACR15BB6AD5C
(a) (b) (c) (d)Rivet-BACR15BB6D5C
(a) (b) (c) (d)Rivet-BACR15BB6D6C
(a) (b) (c) (d)Rivet-BACR15GF5D4
(a) (b) (c) (d)Rivet-BACR15GF5D5
(a) (b) (c) (d)Rivet-BACR15GF5D6
(b) (e)Chemical Conversion Coating-TYPE 2, CLASS A
(b) (c)Primer-BMS 10-79, TYPE II (BMS 10-
79, TYPE III optional)
(b) (c)Organic Corrosion Inhibiting Com-
pound
-BMS 3-23, TYPE II
(b) (c)Sealant-BMS 5-95
(b) (c)Repair Doubler Material-2024-T3 CLAD Sheet X 0.050
thick
(b) (c)Tear Strap Doubler Material-2024-T3 CLAD Sheet X 0.040
thick
(a) Refer to 737-300/-400/-500 Structural Repair Manual Chapter 51 for alternate fasteners.
(b) Quantities to be determined by the size of the repair.
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### Page 60

Group 1:
Table 1 - Repair
NotesNameQTYPart Number / Specification
(c) Refer to the Qualified Products List at the end of the Boeing Material Specification (BMS)
for supplier data.
(d) Fastener grip length to be determined on assembly.
(e) Refer to SOPM 20-43-03 for material sources.
Group 2:
Table 2 - Repair
NotesNameQTYPart Number / Specification
(a)2024-T3 Clad Sheet x 0.050 inches
thick.
40
inches
x 30
inches
AMS QQ-A-250/5
(b)2024-T3 Clad Sheet x 0.040 inches
thick.
24
inches
x 6
inches
AMS QQ-A-250/5
(c) (d)Rivet16BACR15BB6D5C
(c) (d)Rivet32BACR15BB6D6C
(c) (d)Rivet124BACR15GF5D4
(c) (d)Rivet166BACR15GF5D5
(c) (d)Rivet51BACR15GF5D6
(c) (d)Rivet68BACR15BB6AD5C
(e)Chemical Conversion Coating2
ounces
TYPE 2, CLASS A
(f)Primer3
ounces
BMS 10-79, TYPE III
(f)Sealant5
ounces
BMS 5-95, TYPE I, CLASS B-
1/2 OR B-2
(f)Organic Corrosion Inhibiting Com-
pound
2
ounces
BMS 3-23, TYPE II
(a) Use to make the external repair doubler in accordance with FIGURE 11.
(b) Use to make tear strap doublers in accordance with FIGURE 11.
(c) Refer to 737-300/-400/-500 Structural Repair Manual Chapter 51 for alternate fasteners.
(d) Fastener grip length to be determined on assembly.
(e) Refer to SOPM 20-43-03 for material sources.
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