### Commercial **Airplanes** 

# 737 Service Bulletin
**Number: 737-53A1293** Original Issue: August 13, 2008 Revision 2: August 10, 2011 ATA System: 5331 **SUBJECT:** FUSELAGE - Skin - Stringer S-1 and Stringer S-2R, Station 400 to Station 460 Inspection and Repair Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15 CFR 730-774). 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.9E991 ECCN: 

## BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET Copyright © 2008 The Boeing Company Unpublished Work - All Rights Reserved Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable subject matter. Boeing also claims copyright in this document as a compilation and/or collective work. This document includes proprietary information owned by The Boeing Company and/or one or more third parties. Treatment of the document and the information it contains is governed by contract with Boeing. For more information, contact The Boeing Company, P.O. Box 3707, Seattle, Washington 98124. Boeing, 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, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8A, Poseidon and the Boeing livery 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 1 of 105 4.0BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 2 of 105 **BOEING SERVICE BULLETIN 737-53A1293**

BLANK PAGE**Table of Contents** Revision Transmittal Sheet............................................ 5 Summary...................................................... 7 1. PLANNING INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 A. Effectivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1. Airplanes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2. Spares Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 B. Concurrent Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 C. Reason. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 D. Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 E. Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 F. Approval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 G. Manpower. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 H. Weight and Balance Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 I. Electrical Load Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 J. References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 1. Existing Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 2. Data supplied with this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 3. Installation Drawings Used in the Preparation of this Service Bulletin. . . . . . . . . . . . 46 K. Publications Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 L. Interchangeability and Intermixability of Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . 46 2. MATERIAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 A. Material - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 B. Industry Support Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 C. Parts Necessary For Each Airplane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 1. Kits/Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 2. Parts and Materials Supplied by the Operator. . . . . . . . . . . . . . . . . . . . . . . . 47 3. Parts Modified and Reidentified. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 4. Parts Removed and Not Replaced. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 D. Parts Necessary to Change Spares. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 F. Special Tooling Necessary to do this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . 49 3. ACCOMPLISHMENT INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 A. GENERAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 B. WORK INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 FIGURE 1: THIS FIGURE DELETED AT REVISION 1 [Group 1]. . . . . . . . . . . . . . . . . . . . . 59 FIGURE 2: EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION - STRINGERS S-1 AND S-2R, STA 400 - STA 460 [Group 1]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 FIGURE 3: THIS FIGURE DELETED AT REVISION 1 [Group 2]. . . . . . . . . . . . . . . . . . . . . 62 FIGURE 4: EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION - STRINGERS S-1 AND S-2R, STA 400 - STA 460 [Group 2]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 FIGURE 5: FUSELAGE SKIN - CRACK REMOVAL [Group 1]. . . . . . . . . . . . . . . . . . . . . . 65 FIGURE 6: 737-300,737-400 SERIES AIRPLANE - REPAIR DOUBLER FABRICATION AND INSTALLATION [Group 1]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 FIGURE 7: EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION AFTER REPAIR - STRINGERS S-1 AND S-2R, STA 400 - STA 460 [Group 1]. . . . . . . . . . . . . . . . . . . . . . . . . . 78

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 3 of 105 **BOEING SERVICE BULLETIN 737-53A1293**FIGURE 8: 737-500 SERIES AIRPLANES - REPAIR DOUBLER FABRICATION AND INSTALLATION [Group 1]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 FIGURE 9: EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION AFTER REPAIR - STRINGERS S-1 AND S-2R, STA 400 - STA 460 [Group 2]. . . . . . . . . . . . . . . . . . . . . . . . . . 91 FIGURE 10: FUSELAGE SKIN - CRACK REMOVAL [Group 2]. . . . . . . . . . . . . . . . . . . . . . 93 FIGURE 11: REPAIR DOUBLER FABRICATION AND INSTALLATION [Group 2]. . . . . . . . . . . . 96 FIGURE 12: POST REPAIR - CRITICAL FASTENER ROW INSPECTION [Group 2]. . . . . . . . . . 102 APPENDIX A: CHEM-MILL STEP CRACK DAMAGE CUT-OUT AND REPORT. . . . . . . . . . . . . 104 APPENDIX B: CHEM-MILL STEP CRACK DAMAGE REPORT. . . . . . . . . . . . . . . . . . . . . . 105

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 4 of 105 **BOEING SERVICE BULLETIN 737-53A1293**

### Commercial **Airplanes** 

# 737 Service Bulletin **Revision Transmittal Sheet Number: 737-53A1293**  Original Issue: August 13, 2008 Revision 2: August 10, 2011 ATA System: 5331 **SUBJECT:** FUSELAGE - Skin - Stringer S-1 and Stringer S-2R, Station 400 to Station 460 Inspection and Repair This revision includes all pages of the service bulletin. **COMPLIANCE INFORMATION RELATED TO THIS REVISION** No more work is necessary on the airplanes changed in accordance with Revision 1 of this service bulletin. **REASON FOR REVISION** This revision is sent to revise the group 1 repair figures and add the group 2 repair instructions and post repair inspection. These sections were changed: 1. Summary Background information Revised. 2. Summary Action Group 1 and Group 2 information revised. 3. Summary Industry Support Information, warranty statement revised. 4. Summary Material Information revised. 5. Paragraph 1.A.1., Airplanes, paragraph added. 6. Paragraph 1.C., Reason, information revised and revision 2 reason added. 7. Paragraph 1.D., Description, Group 1 and Group 2 repair instructions revised. 8. Paragraph 1.E., Compliance, Table 1, Table 2 and Table 3 Condition column revised and note (c) added. Table 4 Action column revised. Table 5 Condition column revised and repair compliance details, note (a) was revised and note (c) added. Table 6 added. 9. Paragraph 1.F., Approval, AMOC statement revised. 10. Paragraph 1.G., Manpower, Group 2 table revised to add repair and post repair inspection information. 11. Paragraph 1.H., Weight and Balance Changes, Table replaced with equating statement. 12. Paragraph 1.J.1., Existing Data, book references revised.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 5 of 10513. Paragraph 2.A., Material - Price and Availability, paragraph added. 14. Paragraph 2.B., Industry Support Information, warranty statement revised. 15. Paragraph 2.C.2., Parts and Materials Supplied by the Operator, Group 2 table added. 16. Paragraph 3.A., General information, notes revised. 17. Paragraph 3.B., Work instructions, changed as follows: a. PART 1 - step 5.d. and 6.d. added. b. PART 2 - step 3 revised. c. PART 3 - step 4.d. and 5.d. added. d. PART 5 - caution deleted. Step 5 revised and step 6 added. e. PART 6 - step 4 revised and step 5 added. f. PART 7 and PART 8 added. 18. Figure 5 revised to show crack removal information only. View A and B deleted. Flag note table deleted. View C, now view A, revised to show crack information only. Step 1 and 2 deleted. New step 2 added. Foot notes (a), (b), (c), and (d) deleted. New foot notes (a) and (d) revised. 19. Figure 6, new illustration added, new step 1 and footnotes (g) thru (j) added. 20. Figure 8, new illustration added, new step 1 and footnotes (g) thru (j)added. 21. Figure 10, Figure 11 and Figure 12 added. 22. Appendix A, Group reference deleted. Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity, to show the location of important changes. Pages with no vertical lines have no important changes. **REVISION HISTORY** August 13, 2008 Original Issue: July 07, 2010 Revision 1: August 10, 2011 Revision 2:

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 6 of 105 **BOEING SERVICE BULLETIN 737-53A1293**

### Commercial **Airplanes** 

# 737 Service Bulletin **Summary Number: 737-53A1293**  Original Issue: August 13, 2008 Revision 2: August 10, 2011 ATA System: 5331 **SUBJECT:** FUSELAGE - Skin - Stringer S-1 and Stringer S-2R, Station 400 to Station 460 Inspection and Repair **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); cracks have been found 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); cracks have only been found at S-1, 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. 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-53-0334 is related to this service bulletin. Multi-Operator Message (MOM) MOM-MOM-09-0807-01B (R1) is related to this service bulletin.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 7 of 105**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 cracks 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 cracks 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, do repeat external DI and NDI for cracks 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.
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 external DI and NDI of the fuselage skin chem-mill steps (not covered by a repair) for cracks in accordance with Paragraph 1.E., Compliance a. Crack(s) found before 35,000 total flight cycles. b. Crack(s) found in four or more tear strap bays. c. Crack(s) found longer than 5 inches. d. Crack(s) found are 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, the critical fastener row inspection and repeat external DI and NDI for cracks in the fuselage skin along the chem-mill steps not covered by a repair at intervals specified in Paragraph 1.E., Compliance. a. Crack(s) found at or after 35,000 total flight cycles. b. Crack(s) found in three or less strap bays. c. Crack(s) found 5 inches or shorter. d. Crack(s) found are contained within the skin cut-out.
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 external DI and NDI of the fuselage skin chem-mill steps (not covered by a repair) for cracks in accordance with Paragraph 1.E., Compliance.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 8 of 105 **BOEING SERVICE BULLETIN 737-53A1293**a. Crack(s) found before 33,000 total flight cycles. b. Crack(s) found between STA 400 and STA 420. c. Crack(s) found between STA 440 and STA 460. d. Crack(s) found longer than 12.5 inches. e. Crack(s) found are not contained within the skin cut-out. If all of the following are found as a result of the external DI and NDI, do the repair, the critical fastener row inspection and repeat external DI and NDI for cracks in the fuselage skin along the chem-mill steps not covered by a repair, at intervals specified in Paragraph 1.E., Compliance. a. Crack(s) found at or after 33,000 total flight cycles. b. Crack(s) found between STA 420 and STA 440. c. Crack(s) found 12.5 inches or shorter. d. Crack(s) found are contained within the skin cut-out. **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 2008-19-03 is related to this service bulletin. 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

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 9 of 105 **BOEING SERVICE BULLETIN 737-53A1293**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 10 of 105 **BOEING SERVICE BULLETIN 737-53A1293**

### Commercial **Airplanes** 

# 737 Service Bulletin
**Number: 737-53A1293** Original Issue: August 13, 2008 Revision 2: August 10, 2011 ATA System: 5331 **SUBJECT:** FUSELAGE - Skin - Stringer S-1 and Stringer S-2R, Station 400 to Station 460 Inspection and Repair
**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.
**DESCRIPTION CONFIGURATION**  **GROUP** 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

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 11 of 105**DESCRIPTION CONFIGURATION**  **GROUP** 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 **Group Variable Number**  1 PJ301 - PJ302 1 PJ551 2 PJ552 - PJ561 2 PJ601 - PJ615 2 PJ811 2 PJ816 - PJ817 1 PM389 - PM399 1 PM401 - PM417 1 PM541 - PM542 2 PM543 - PM550 1 PM551 - PM564 1 PP048 - PP054 1 PP140 - PP160 1 PP198 - PP199 1 PP221 1 PP508 - PP517 2 PP518 - PP520 1 PP805 - PP808 1 PP874 - PP875 2 PP876 - PP877 1 PP910 - PP930 1 PP951 - PP952 1 PP966 - PP967 1 PP984 - PP990 1 PP993 1 PQ013 - PQ016

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 12 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group**  **Variable Number** 1 PQ038 - PQ041 1 PQ069 - PQ085 1 PQ101 - PQ199 1 PQ201 - PQ202 1 PQ230 1 PQ237 1 PQ251 - PQ267 1 PQ281 - PQ296 2 PQ297 - PQ299 1 PQ301 - PQ307 1 PQ331 - PQ332 1 PQ341 - PQ344 2 PQ345 - PQ348 1 PQ361 - PQ369 2 PQ370 - PQ373 2 PQ391 - PQ395 1 PQ401 - PQ407 2 PQ408 - PQ410 1 PQ411 - PQ413 2 PQ414 - PQ418 1 PQ421 2 PQ431 - PQ438 2 PQ447 - PQ448 2 PQ451 2 PQ454 1 PQ471 - PQ472 2 PQ473 - PQ475 1 PQ481 1 PQ486 - PQ487 1 PQ491 - PQ493 1 PQ771 2 PQ772 1 PQ791 - PQ793

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 13 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group**  **Variable Number** 1 PQ801 - PQ805 1 PQ931 - PQ932 2 PQ933 - PQ935 2 PQ951 2 PQ971 - PQ997 2 PR001 - PR017 2 PR021 - PR034 2 PR041 - PR045 2 PR061 - PR072 2 PR077 - PR082 2 PR091 - PR092 2 PR096 2 PR101 2 PR121 - PR122 2 PR131 - PR132 2 PR141 - PR143 2 PR161 - PR172 2 PR181 1 PS601 - PS616 2 PS617 - PS630 1 PS631 1 PS636 - PS638 1 PS641 - PS644 1 PS651 - PS657 1 PS666 - PS669 1 PS691 - PS692 1 PS701 - PS703 2 PS704 - PS706 1 PS751 - PS762 2 PS763 - PS799 2 PS811 2 PS836 - PS837 2 PS841 - PS846

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 14 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group**  **Variable Number**2 PS851 - PS852 2 PS856 2 PS861 - PS863 2 PS866 - PS868 2 PS871 - PS874 2 PS896 - PS897 2 PS901 - PS941 2 PS956 - PS957 2 PS961 - PS963 2 PS971 - PS978 1 PT001 - PT011 2 PT012 - PT015 1 PT021 - PT028 2 PT029 - PT031 1 PT041 - PT063 2 PT064 1 PT101 - PT105 1 PT121 - PT125 2 PT126 - PT138 1 PT146 - PT148 1 PT161 - PT170 1 PT181 - PT187 2 PT188 1 PT211 - PT220 1 PT295 1 PT301 - PT306 2 PT307 - PT309 1 PT331 - PT360 1 PT381 - PT399 1 PT401 - PT438 1 PT501 - PT512 2 PT513 - PT517 1 PT561 - PT565

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 15 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group**  **Variable Number** 1 PT581 - PT584 2 PT585 - PT586 1 PT611 - PT621 1 PT641 - PT642 2 PT643 - PT644 1 PT651 - PT655 2 PT656 1 PT671 - PT672 2 PT681 - PT685 1 PT701 - PT703 2 PT716 - PT717 2 PT721 - PT725 2 PT801 - PT834 2 PT851 - PT854 2 PT871 - PT886 2 PT901 - PT930 2 PT971 - PT973 2 PT981 - PT985 2 PT996 1 PU001 - PU025 2 PU301 2 PU311 - PU313 1 PV021 - PV055 1 PV201 - PV203 2 PV204 - PV209 2 PV226 - PV229 1 PV231 - PV237 1 PV271 - PV272 1 PV281 - PV283 2 PV284 - PV287 2 PV296 2 PV301 - PV302 2 PV351

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 16 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group**  **Variable Number**2 PV356 - PV357 1 PW027 - PW054 1 PW061 - PW068 1 PW072 2 PW086 - PW088 1 PW091 - PW094 1 PW101 - PW102 1 PW106 1 PW111 - PW120 1 PW156 - PW157 1 PW161 - PW167 2 PW168 - PW171 1 PW201 - PW244 2 PW245 - PW252 1 PW261 2 PW262 - PW264 1 PW265 - PW268 2 PW271 - PW276 1 PW278 1 PW281 2 PW282 - PW292 1 PW293 1 PW296 1 PW301 - PW327 2 PW401 - PW408 2 PW411 - PW418 2 PW421 - PW424 2 PW431 - PW435 2 PW441 - PW450 1 PW461 - PW467 1 PW501 - PW502 1 PW504 1 PW511 - PW520

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 17 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group**  **Variable Number**2 PW521 - PW522 2 PW524 - PW525 1 PW526 2 PW527 - PW530 1 PW531 - PW546 2 PW547 - PW550 1 PW556 - PW557 1 PW561 - PW564 1 PW571 - PW576 1 PW591 - PW596 1 PW611 - PW620 2 PW621 - PW622 1 PW631 - PW634 2 PW635 - PW637 1 PW661 - PW662 1 PW681 - PW683 1 PW701 - PW702 1 PW711 - PW717 1 PW741 - PW742 1 PW761 1 PW771 2 PW831 2 PW851 - PW856 2. Spares Affected None. **B. Concurrent Requirements** None.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 18 of 105 **BOEING SERVICE BULLETIN 737-53A1293 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); cracks have been found 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); cracks have only been found at S-1, 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. 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-53-0334 is related to this service bulletin. Multi-Operator Message (MOM) MOM-MOM-09-0807-01B (R1) is related to this service bulletin. 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 19 of 105 **BOEING SERVICE BULLETIN 737-53A1293 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 cracks 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 cracks 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, do repeat external DI and NDI for cracks 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.
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 external DI and NDI of the fuselage skin chem-mill steps (not covered by a repair) for cracks in accordance with Paragraph 1.E., Compliance. a. Crack(s) found before 35,000 total flight cycles. b. Crack(s) found in four or more tear strap bays. c. Crack(s) found longer than 5 inches. d. Crack(s) found are 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, the critical fastener row inspection and repeat external DI and NDI for cracks in the fuselage skin along the chem-mill steps not covered by a repair at intervals specified in Paragraph 1.E., Compliance. a. Crack(s) found at or after 35,000 total flight cycles. b. Crack(s) found in three or less strap bays. c. Crack(s) found 5 inches or shorter. d. Crack(s) found are contained within the skin cut-out.
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 external DI and NDI of the fuselage skin chem-mill steps (not covered by a repair) for cracks in accordance with Paragraph 1.E., Compliance.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 20 of 105 **BOEING SERVICE BULLETIN 737-53A1293**a. Crack(s) found before 33,000 total flight cycles. b. Crack(s) found between STA 400 and STA 420. c. Crack(s) found between STA 440 and STA 460. d. Crack(s) found longer than 12.5 inches. e. Crack(s) found are 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, the critical fastener row inspection and repeat external DI and NDI for cracks in the fuselage skin along the chem-mill steps not covered by a repair, at intervals specified in Paragraph 1.E., Compliance. a. Crack(s) found at or after 33,000 total flight cycles. b. Crack(s) found between STA 420 and STA 440. c. Crack(s) found 12.5 inches or shorter. d. Crack(s) found are contained within the skin cut-out. 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 line 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. The work in this service bulletin is done in the maintenance zone(s) given below.
**Affected Maintenance Zones Zone**  **Model** 107 737-300, 737-400, 737-500 **E. Compliance** Federal Aviation Administration (FAA) Airworthiness Directive AD 2008-19-03 is related to this service bulletin.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 21 of 105 **BOEING SERVICE BULLETIN 737-53A1293 NOTE:** If any repair in the Accomplishment Instructions, Paragraph 3.B., Work Instructions, is not applicable, contact Boeing for repair instructions and do the repair before further flight. **Group 1, Configuration 1: Table 1: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460**  **Repeat Interval (Not to Exceed)**  **Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Within 1,800 flight cycles after the date of Revision 1on this service bulletin. Before 35,000 total flight cycles. Option 1: Do external Detailed Inspection (DI) of the fuselage skin chem-mill stepsfor cracks in accordance with Accomplishment Instruction, Paragraph 3.B., PART 1. Airplanes not inspected in accordance with the original issue of this service bulletin.

ANDDo external Non Destructive Inspections (NDI) of the fuselage skin chemmill steps for cracks in accordance with Accomplishment Instructions, 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 date of Revision 1on this service bulletin. Before 35,000 total flight cycles. Option 2: Do external Detailed Inspection (DI) of the fuselage skin chem-mill stepsfor cracks in accordance with Accomplishment Instruction, Paragraph 3.B., PART 1. ANDDo external Non Destructive Inspections (NDI) of the fuselage skin chemmill steps for cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1 using theUltrasonic Phased Array (UTPA) procedure. (a)

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 22 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 1:**  **Table 1: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition** 1,800 flight cycles.Within 1,800 flight cycles after the last NDI.Do external DI and NDI of the fuselage skin chem-mill steps for cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1. No crack found in the fuselage skin. AND Option 1 used. (b) (b)
OR (a) (c) 2,400 flight cycles.Within 2,400 flight cycles after the last NDI. No crack found in the fuselage skin. (b) (b) AND Option 2 used.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 23 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 1:**  **Table 1: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition**

- Before further flight. Contact Boeing for repair instructions in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1 and do the repair. Crack(s) found before35,000 total flight cycles. OR Cracks found in four or more tear strap bays.AND (do Option 1 or Option 2 ) 1,800 flight cycles.Within 1,800 flight cycles after the last NDI. Option 1: Do external Detailed Inspection (DI) of the fuselage skin chem-mill steps (not covered by a repair) for cracks inaccordance with Accomplishment Instructions, Paragraph 3.B., PART 3. OR Crack(s) longer than 5 inches. OR Crack(s) found are not contained within the skin cut-out. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment 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 cycles.Within 2,400 flight cycles after the last NDI. Option 2: Do external Detailed Inspection (DI) of the fuselage skin chem-mill steps (not covered by a repair) for cracks inaccordance with Accomplishment Instructions, Paragraph 3.B., PART 3. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3 using UTPA procedure. (a)

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 24 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 1:**  **Table 1: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition**

- Before further flight. Do the repair in accordance with Ac- complishment Instructions, Paragraph 3.B., PART 2.Crack(s) found at or after 35,000 total flight cycles. AND Cracks(s) found in three or fewer tear strap bays. AND (do Option 1 or Option 2 ) 1,800 flight cycles.Within 1,800 flight cycles after the last NDI. Option 1: Do external Detailed Inspection (DI) of the fuselage skin chem-mill steps (not covered by a repair) for cracks inaccordance with Accomplishment Instructions, Paragraph 3.B., PART 3. AND Crack(s) found 5 inches or shorter. AND Crack(s) found are contained within the skin cut-out. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment 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 cycles.Within 2,400 flight cycles after the last NDI. Option 2: Do external Detailed Inspection (DI) of the fuselage skin chem-mill steps (not covered by a repair) for cracks inaccordance with Accomplishment Instructions, Paragraph 3.B., PART 3. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3 using UTPA procedure. (a)

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 25 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 1:**  **Table 1: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition** (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 line 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 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 26 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 2, 4:**  **Table 2: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition**

- Within 900 flight cycles after the date of Revision 1on this service bulletin. Before 35,000 total flight cycles. Option 1: Do external Detailed Inspection (DI) of the fuselage skin chem-mill stepsfor cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1. Airplanes inspected in accordance with the original issue of this service bulletin and thelast inspection was Detailed Inspection (DI) procedure. OR Airplanes inspected in accordance with BoeingMulti-Operator Message MOM-MOM-09- 0807-01B (R1) and thelast inspection was Detailed Inspection (DI) procedure. ANDDo external Non Destructive Inspections (NDI) of the fuselage skin chemmill steps for cracks in accordance with Accomplishment Instructions, 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 date of Revision 1on this service bulletin. Before 35,000 total flight cycles. Option 2: Do external Detailed Inspection (DI) of the fuselage skin chem-mill stepsfor cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1. ANDDo external Non Destructive Inspections (NDI) of the fuselage skin chemmill steps for cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1 using theUltrasonic Phased Array (UTPA) procedure. (a)

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 27 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 2, 4:**  **Table 2: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition** 1,800 flight cycles.Within 1,800 flight cycles after the last NDI. Do repeat external DI and NDI of the fuselage skin chem-mill steps forcracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1. No crack found in the fuselage skin. AND Option 1 used. (b) (b)
OR (a) (c) 2,400 flight cycles.Within 2,400 flight cycles after the last NDI. No crack found in the fuselage skin. (b) (b) AND Option 2 used.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 28 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 2, 4:**  **Table 2: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition**

- Before further flight. Contact Boeing for repair instructions in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1 and do the repair Crack(s) found before35,000 total flight cycles. OR Cracks found in four or more tear strap bays.AND (do Option 1 or Option 2) 1,800 flight cycles.Within 1,800 flight cycles after the last NDI. Option 1: Do external DI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3. OR Crack(s) found longer than 5 inches. OR Crack(s) found are not contained within the skin cut-out. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment 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 cycles.Within 2,400 flight cycles after the last NDI. Option 2: Do external DI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3 using UTPA procedure. (a)

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 29 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 2, 4:**  **Table 2: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition**

- Before further flight. Do the repair in accordance with Ac- complishment Instructions, Paragraph 3.B., PART 2.Crack(s) found at or after 35,000 total flight cycles. AND Cracks(s) found in three or fewer tear strap bays. AND (do Option 1 or Option 2) 1,800 flight cycles.Within 1,800 flight cycles after the last NDI. Option 1: Do external DI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3. AND Crack(s) found 5 inches or shorter. AND Crack(s) found are contained within the skin cut-out. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment 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 cycles.Within 2,400 flight cycles after the last NDI. Option 2: Do external DI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3 using UTPA procedure. (a)

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 30 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 2, 4:**  **Table 2: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition** (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 line 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 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 31 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 3, 5:**  **Table 3: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition**

- Within 1,800 flight cycles after the date of Revision 1on this service bulletin. Before 35,000 total flight cycles. Option 1: Do external Detailed Inspections (DI) of the fuselage skin chem-mill stepsfor cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1. Airplanes inspected in accordance with the original issue of this service bulletin and the last inspection was aNon Destructive Inspection (NDI) procedure. ANDOR Do external Non Destructive Inspection (NDI) of the fuselage skin chemmill steps for cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1 using one of the following procedures: Airplanes inspected in accordance with BoeingMulti-Operator Message MOM-MOM-09- 0807-01B (R1) and the last inspection was aNon Destructive Inspection (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 date of Revision 1on this service bulletin. Before 35,000 total flight cycles. Option 2: Do external Detailed Inspections (DI) of the fuselage skin chem-mill stepsfor cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1. ANDDo external Non Destructive Inspection (NDI) of the fuselage skin chemmill steps for cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1 using theUltrasonic Phased Array (UTPA) procedure. (a)

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 32 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 3, 5:**  **Table 3: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition** 1,800 flight cycles.Within 1,800 flight cycles after the last NDI. Do repeat external DI and NDI of the fuselage skin chem-mill steps forcracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1. No crack found in the fuselage skin. AND Option 1 used. (b) (b)
OR (a) (c) 2,400 flight cycles.Within 2,400 flight cycles after the last NDI. No crack found in the fuselage skin. (b) (b) AND Option 2 used.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 33 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 3, 5:**  **Table 3: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition**

- Before further flight. Contact Boeing for repair instructions in accordance with Accomplishment Instructions, Paragraph 3.B., PART 1 and do the repair. Crack(s) found before35,000 total flight cycles. OR Crack(s) found in four or more tear strap bays.AND (do Option 1 or Option 2) 1,800 flight cycles.Within 1,800 flight cycles after the last NDI. Option1: Do external DI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3. OR Crack(s) found longer than 5 inches. OR Crack(s) found are not contained within the skin cut-out. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment 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 cycles.Within 2,400 flight cycles after the last NDI. Option 2: Do external DI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3 using UTPA procedure. (a)

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 34 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 3, 5:**  **Table 3: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition**

- Before further flight. Do the repair in accordance with Ac- complishment Instructions, Paragraph 3.B., PART 2.Crack(s) found at or after 35,000 total flight cycles. AND Cracks(s) found in three or fewer tear strap bays. AND (do Option 1 or Option 2) 1,800 flight cycles.Within 1,800 flight cycles after the last NDI. Option1: Do external DI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3. AND Crack(s) found 5 inches or shorter. AND Crack(s) found are contained within the skin cut-out. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment 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 cycles.Within 2,400 flight cycles after the last NDI. Option 2: Do external DI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 3 using UTPA procedure. (a)

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 35 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1, Configuration 3, 5:**  **Table 3: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition** (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 line 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 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 1: Table 4: Post Repair - Critical Fastener Row Inspection**  **Repeat Interval (Not to Exceed)**  **Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Within 60,000 flight cycles from the time the repair was installed Do Detailed Inspections (DI) or Non Destructive Inspections (NDI) of the skin at the critical row of fasteners in the repair for cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 4. Airplanes with a repair installed in accordancewith this service bulletin.

In accordancewith Repair Assessment Guidelines D6-38669Revision C Figure 2-9. In accordance with Repair Assessment Guidelines D6- 38669 Revision C Figure 2- 9. Do repeat DI or NDI of the skin at the critical row of fasteners in the repairfor cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 4. No crack found.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 36 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1:**  **Table 4: Post Repair - Critical Fastener Row Inspection Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition**

- 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 37 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 2:**  **Table 5: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition**

- Within 500 flight cyclesafter the release date of Revision 1 on this service bulletin. Before 33,000 total flight cycles. Option 1: Do external Detailed Inspections (DI) of the fuselage skin chem-mill stepsfor cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 5. AND All Airplanes

Do external Non Destructive Inspections (NDI) of the fuselage skin chemmill steps for cracks in accordance with Accomplishment Instructions, 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 cyclesafter the release date of Revision 1 on this service bulletin. Before 33,000 total flight cycles. Option 2: Do external Detailed Inspections (DI) of the fuselage skin chem-mill stepsfor cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 5. ANDDo external Non Destructive Inspections (NDI) of the fuselage skin chemmill steps for cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 5 using theUltrasonic Phased Array (UTPA) procedure. (a)

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 38 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 2:**  **Table 5: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition** 500 flight cycles. Within 500 flight cycles after the last NDI. Do repeat external NDI of the fuselageskin chem-mill steps for cracks in accordance with Accomplishment Instructions, Paragraph 3.B., PART 5. No crack found in the fuselage skin. AND Option 1 used. (b) (b) (a) (c) OR 1,000 flight cycles.Within 1,000 flight cycles after the last NDI. No crack found in the fuselage skin. (b) (b) AND Option 2 used.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 39 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 2:**  **Table 5: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition**

- Before further flight. Contact Boeing for repair instructions in accordance with Accomplishment Instructions, Paragraph 3.B., PART 5 and do the repair. Crack(s) found before33,000 total flight cycles. OR Crack(s) found between STA 400 and STA 420.AND (do Option 1 or Option 2) 500 flight cycles. Within 500 flight cycles after the last NDI. Option 1: Do external DI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 6. OR Crack(s) found between STA 440 and STA 460. OR Crack(s) found longer than 12.5 inches. OR (b) (b)

AND Crack(s) found are not contained within the skin cut-out. Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment 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 cycles.Within 1,000 flight cycles after the last NDI. Option 2: Do external DI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 6. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 6 using UTPA procedure. (a)

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 40 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 2:**  **Table 5: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition**

- Before further flight. Do the repair in accordance with Ac- complishment Instructions, Paragraph 3.B., PART 7.Crack(s) found at or after 33,000 total flight cycles. AND Crack(s) found between STA 420 and STA 440.AND (do Option 1 or Option 2) 500 flight cycles. Within 500 flight cycles after the last NDI. Option 1: Do external DI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 6. AND Crack(s) found 12.5 inches or shorter. AND Crack(s) found are contained within the skin cut-out. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment 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 cycles.Within 1,000 flight cycles after the last NDI. Option 2: Do external DI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 6. (b) (b)

AND Do external NDI of the fuselage skinchem-mill steps (not covered by a repair) for cracks in accordance withAccomplishment Instructions, Paragraph 3.B., PART 6 using UTPA procedure. (a)

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 41 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 2:**  **Table 5: External Fuselage Skin Chem-Mill Inspection - Stringers S-1 and S-2R, STA 400 - STA 460 Repeat Interval**  **(Not to Exceed) Compliance Time**  **(Whichever Occurs Later) Action**  **Condition** (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 line 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)**  **Action Condition** 

- Within 60,000 flight cycles from the time the repair was installed. Do a Non Destructive inspection (NDI)of the skin at the critical row of fasteners in the repair for cracks in accordance with Accomplishment Instructions, Paragraph 3.B., Part 8. Airplanes with a repair installed in accordancewith this service bulletin. 6,000 flight cycles.Within 6,000 flight cycles after the last NDI. Do a repeat NDI of the skin at the critical row of fasteners in the repairfor cracks in accordance with Accomplishment 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 42 of 105 **BOEING SERVICE BULLETIN 737-53A1293 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. In addition the Manager of the FAA Seattle Aircraft Certification Office approves the inspection methods and corrective actions in Tables 1, 2, 3 and 5 under Paragraph 1.E., Compliance of this service bulletin, as an alternative method of compliance to the inspection methods and corrective actions specified in Table 1 and 2, under Paragraph 1.E., Compliance of the Original Issue of this service bulletin, dated August 13, 2008, required by paragraphs (f) and (g) of AD 2008-19-03. The compliance times remain unchanged from those defined in AD 2008-19-03. When this service bulletin specifies contacting Boeing for repair instructions, the repair instructions must be approved by the FAA in accordance with paragraph (h) of AD 2008-19-03. All provisions of AD 2008-19-03 that are not specifically referenced in this paragraph remain fully applicable and must be complied with accordingly. **G. Manpower** The table below shows 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 Hours Task Hours**  **Number of Per- sons**  **Task**

0.25 0.25 1 Get Access 2.75 5.50 2 FIGURE 2 or FIGURE 7 (a)

- - FIGURE 5 (a)

- - FIGURE 6 or FIGURE 8

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 43 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 1:**  **Table 1 - Skin Panel Inspection and Repair. Elapsed Hours**  **Task Hours Number of Per-**  **sons Task**  4.25 (b) 8.50 (b) 2 Inspection 0.25 0.25 1 Close Access 5.75 14.50 TOTAL FOR EACH AIRPLANE (a) The time to make any repair is not included. More time is required for repairs if any damage is found. (b) Includes time to access interior and inspect interior and exterior of one typical repair location for the critical fastener row. **Group 2: Table 2 - Skin Panel Inspection and Repair.**  **Elapsed Hours Task Hours**  **Number of Per- sons**  **Task**

0.25 0.25 1 Get Access 3.00 6.00 2 FIGURE 4 or FIGURE 9 (a)

- - FIGURE 10 (a)

- - FIGURE 11 1.50 (b) 3.00 2 FIGURE 12 0.25 0.25 1 Close Access 5.00 9.50 TOTAL FOR EACH AIRPLANE (a) The time to make any repair is not included. More time is required for repairs if any damage is found. (b) Includes time to access interior and inspect interior and exterior of one typical repair location for the critical fastener row. **H. Weight and Balance Changes** All airplanes: 1. Calculate the change in weight for each repair installation as follows: a. Calculate the gross area of each repair doubler in square inches (Length x Width).

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 44 of 105 **BOEING SERVICE BULLETIN 737-53A1293**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 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 installation as follows: a. Record the station of the geometric center of each repair doubler. Example for FIGURE 6: By inspection, station = 435. b. To calculate the change in moment for each repair 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. 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-53-0334 c. Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2008-19-03 d. Standard Overhaul Practices Manual (SOPM) 20-43-03, 20-44-03 , 20-44-04 e. 737 Non-Destructive Testing (NDT) Manual Part 4, 53-30-07, Part 6, 51-00-00, Figure 16, Part 6, 51-00-00 Figure 23 , Part 6, 51-00-00 Figure 4, Part 6, 53-30-00, Figure 5, Part 6, 53-30-00, Figure 6, Part 6, 53-30-09, Part 6, 53-30-18, Part 6, 53-30-19, Part 6, 53-30-25

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 45 of 105 **BOEING SERVICE BULLETIN 737-53A1293**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, 51-40-08 h. 737-400 Structural Repair Manual (SRM) 51-10-01, 51-20-01 , 51-20-05, 51-30-01, 51-40, 51-40-08 i. 737-500 Structural Repair Manual (SRM) 51-10-01, 51-20-01 , 51-20-05, 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. Repair Assessment Guidelines - Model 737-100 to -500 Document Number D6-38669 Rev C m. Service Bulletin Index Document D6-19567 Part 3 2. Data supplied with this Service Bulletin None. 3. Installation Drawings Used in the Preparation of this Service Bulletin
**Title Drawing Number** SKIN PANEL INSTALLATION - S-10L TO S-10R STA 360 - STA 540 65-45765 SKIN INSTALLATION - S-10L TO S-10R, STA 360 TO STA 540 65C35765 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 46 of 105 **BOEING SERVICE BULLETIN 737-53A1293 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** 
**Notes Name**  **QTY Part Number /**  **Specification** (a) (b) (c) (d) RIVET

- BACR15BB5D (a) (b) (c) (d) RIVET

- BACR15BB6AD (a) (b) (c) (d) RIVET

- BACR15BB6D (a) (b) (c) (d) RIVET

- BACR15CE5D (b) (c) ORGANIC CORROSION INHIBIT- ING COMPOUND - 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 MATERI- AL - 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. (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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 47 of 105 **BOEING SERVICE BULLETIN 737-53A1293 Group 2:**  **Table 2**
**Notes Name**  **QTY Part 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 5 inches AMS QQ-A-250/5

(c) (d) Rivet 16 BACR15BB6D5C (c) (d) Rivet 32 BACR15BB6D6C (c) (d) Rivet 124 BACR15GF5D4 (c) (d) Rivet 166 BACR15GF5D5 (c) (d) Rivet 51 BACR15GF5D6 (c) (d) Rivet 68 BACR15BB6AD5C (e) Chemical Conversion Coating 2 ounces TYPE 2, CLASS A (f) Primer 3 ounces BMS 10-79, TYPE III (f) Sealant 5 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. (f) Refer to the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data.
3. Parts Modified and Reidentified None.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 48 of 105 **BOEING SERVICE BULLETIN 737-53A1293**4. Parts Removed and Not Replaced None. **D. Parts Necessary to Change Spares** None. **E. Special Tooling - Price and Availability** None. **F. Special Tooling Necessary to do this Service Bulletin** No special tools or equipment are necessary to do the change in this service bulletin. But, maintenance and overhaul tools in the manuals given in Paragraph 1.J., References, can be necessary. Examine operator tool supply to make sure all necessary tools are available.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 49 of 105 **BOEING SERVICE BULLETIN 737-53A1293**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 50 of 105 **BOEING SERVICE BULLETIN 737-53A1293**

BLANK PAGE**3. ACCOMPLISHMENT INSTRUCTIONS A. GENERAL INFORMATION**  **CAUTION:**KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED MATERIAL, METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES CAN CAUSE DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE SPARKS OR OTHER ELECTRICAL DAMAGE. **NOTE:**1. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for definition of the acronyms. 2. Obey all of the warnings and cautions given in the specified manual sections. 3. Unless shown differently, these dimensions and tolerances are used: – Linear dimensions are in inches – Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus or minus 0.03 inch – Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch – Angular tolerance is plus or minus 2 degrees – Hole dimensions for standard solid rivets are in 737-300/-400/-500 SRM Chapter 51. 4. Maintain a 2D minimum edge margin on all parts unless otherwise stated. 5. All machined surfaces must have a finish of 125 micro-inch Ra or better. Refer to Figure 1 of 737-300 SRM 51-10-01, 737-400 SRM 51-10-01, 737-500 SRM 51-10-01 as an accepted procedure. 6. Clean repair parts and mating surfaces. Refer to 737-300 SRM 51-20-05, 737-400 SRM 51-20-05, and 737-500 SRM 51-20-05 as an accepted procedure. 7. For fastener installation refer to 737-300 SRM 51-40, 737-400 SRM 51-40 or 737-500 SRM 51-40 as an accepted procedure. 8. Use the approved fastener and process material substitutions in accordance with SRM Chapter 51. 9. If the length of any fastener specified in this service bulletin does not meet installation standards given in SRM Chapter 51, then a fastener of the same specification, or an approved substitute, with a length which meets the installation standards given in SRM Chapter 51 may be used. In addition, washers may be installed for fastener grip length in accordance with SRM Chapter 51. 10. Boeing Service Letter 737-SL-51-042, Damage Reporting and Repair Plan/Design Guidelines, is an acceptable procedure to request information from Boeing for additional structural repair instructions. The Service Letter describes what information must be provided to Boeing before a structural repair can be provided.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 51 of 105 **BOEING SERVICE BULLETIN 737-53A1293**11. A Detailed Inspection is defined as: An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirrors, magnifying lenses, etc. may be necessary. Surface cleaning and elaborate access procedures may be required. 12. These work instructions refer to procedures included in other Boeing documents. When the words "refer to" are used and the operator has an accepted alternative procedure, the accepted alternative procedure can be used. When the words "in accordance with" are included in the instruction, the procedure in the Boeing document must be used. 13. If chem-mill step crack damage is found and the damage is within the SB damage limits and the airplane is above the SB threshold, Boeing would still like to obtain the information relative to the damage in order to develop more refined inspection requirements. Report crack damage in accordance with APPENDIX B. 14. If it is necessary to remove more parts for access, you can remove those parts. If you can get access without removing identified parts, it is not necessary to remove all of the identified parts. Jacking and shoring limitations must be observed. 15. Where the work instructions include installation of a kept part, a new or serviceable part with the same part number can be installed as an alternative to the kept part. The removed part can be discarded if a new or serviceable part is installed. **B. WORK INSTRUCTIONS Group 1:**  **PART 1 - EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION - STRINGERS S-1 AND S-2R, STA 400 - STA 460**  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 cracks in the fuselage skin along the chem-mill steps at stringers S-1 and S-2R, between STA 400 and STA 460 in accordance with FIGURE 2. 3. Do external Non Destructive Inspection (NDI) using one of the following options/procedures for cracks in the fuselage skin along the chem-mill steps at stringers S-1 and S-2R, between STA 400 and STA 460 in accordance with FIGURE 2. a. Option 1: Medium Frequency Eddy Current (MFEC) or Magneto Optical Imaging (MOI) or C-Scan. b. Option 2: Ultrasonic Phased Array (UTPA). 4. If no crack is found, do repeat external DI and NDI in accordance with PART 1 at intervals in accordance with Paragraph 1.E., Compliance. 5. If any of the following is found as a result of the external DI and NDI, contact Boeing for repair instructions in accordance with APPENDIX A, do the repair and do the inspection of the fuselage skin not covered by a repair in accordance with PART 3 at intervals in accordance with Paragraph 1.E., Compliance.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 52 of 105 **BOEING SERVICE BULLETIN 737-53A1293**a. Crack(s) found before 35,000 total flight cycles. b. Crack(s) found in four or more tear strap bays. c. Crack(s) found longer than 5 inches. d. Crack(s) found are not contained within the skin cut-out shown in FIGURE 5. 6. If all of the following are found as result of the external DI and NDI, do the skin repair in accordance with PART 2 and do the inspection of the fuselage skin not covered by a repair in accordance with PART 3 at intervals in accordance with Paragraph 1.E., Compliance. a. Crack(s) found at or after 35,000 total flight cycles. b. Crack(s) found in three or fewer tear strap bays. c. Crack(s) found 5 inches or shorter. d. Crack(s) found are contained within the skin cut-out shown in FIGURE 5. 7. Put the airplane back to a serviceable condition. **Group 1: PART 2 - SKIN REPAIR**  1. In the passenger cabin, remove and keep the equipment listed in the table below to access the area of repair. Refer to the listed Aircraft Maintenance Manual (AMM) as an accepted procedure. **AMM Chapter/Section/Subject Equipment**  737-300/400/500 AMM 25-22-00 Passenger Seats 737-300/400/500 AMM 25-21-46 Sidewall Lining 737-300/400/500 AMM 25-21-39 Sidewall insulation 737-300/400/500 AMM 25-24-31 Overhead Stowage Bins 737-300/400/500 AMM 25-23-61 Passenger Service Units 737-300/400/500 AMM 25-21-45 Ceiling Panels 2. Remove and keep ATC antenna if required, refer to 737-300/400/500 AMM 34-53-11 as an accepted procedure. 3. Remove the crack in accordance with FIGURE 5 . 4. Make and install the repair doubler and tear strap doublers in accordance with figure listed below: **Figure Airplanes Series**  FIGURE 6 737-300, 737-400 FIGURE 8 737-500

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 53 of 105 **BOEING SERVICE BULLETIN 737-53A1293**5. If ATC antenna was removed to do the repair, install kept ATC antenna on top of repair doubler. Refer to 737-300/400/500 AMM 34-53-11 as an accepted procedure. 6. Install kept equipment in the passenger cabin that was removed for access. 7. Accomplish the Part 4 - Post Repair inspections at the times specified in Table 4 of Paragraph 1.E., Compliance. 8. Put airplane back in a serviceable condition. **Group 1: PART 3 - EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION AFTER REPAIR - STRINGERS**  **S-1 AND S-2R, STA 400 - STA 460** 1. Get external access to skin repair area at stringers S-1 and S-2R, between STA 400 and STA 460. 2. Do external Detailed Inspection (DI) for cracks in the fuselage skin along the chem-mill steps at stringers S-1 and S-2R, between STA 400 and STA 460 not covered by a repair in accordance with FIGURE 7. 3. Do external Non Destructive Inspection (NDI) using one of the following options/procedures for cracks in the fuselage skin along the chem-mill steps at stringers S-1 and S-2R, between STA 400 and STA 460 not covered by a repair in accordance with FIGURE 7. a. Option 1: Medium Frequency Eddy Current (MFEC) or Magneto Optical Imaging (MOI) or C-Scan. b. Option 2: Ultrasonic Phased Array (UTPA). 4. If any of the following is found as a result of the external DI and NDI, contact Boeing for repair instructions in accordance with APPENDIX A and do the repair: a. Crack(s) found before 35,000 total flight cycles. b. Crack(s) found in four or more tear strap bays. c. Crack(s) found longer than 5 inches. d. Crack(s) found are not contained within the skin cut-out shown in FIGURE 5. 5. If all of the following are found as result of the external DI and NDI, do the skin repair in accordance with PART 2.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 54 of 105 **BOEING SERVICE BULLETIN 737-53A1293**a. Crack(s) found at or after 35,000 total flight cycles. b. Crack(s) found in three or fewer tear strap bays. c. Crack(s) found 5 inches or shorter. d. Crack(s) found are contained within the skin cut-out shown in FIGURE 5. 6. Repeat external DI and NDI in accordance with PART 3 at intervals in accordance with Paragraph 1.E., Compliance. 7. Put the airplane back to a serviceable condition. **Group 1: PART 4 - POST REPAIR - CRITICAL FASTENER ROW INSPECTION**  1. Get access to skin repair at stringers S-1 and S-2R, between STA 400 and STA 460. 2. Do Non Destructive Inspection (NDI) or Detailed Inspection (DI) of the skin at the critical row of fasteners in the repair for cracks in accordance with Repair Assessment Guidelines D6-38669 Revision C Figure 2-9. **NOTE:**The NDI procedures given in the Options column of Figure 2-9 in D6-38669 Revision C should be changed as follows: 1. Use 737 NDT Part 6, 53-30-00, Figure 6 in place of 53-30-3 Figure 6. 2. Use 737 NDT Part 6, 53-30-00, Figure 5 in place of 53-30-3 Figure 5. 3. If crack is found contact Boeing for repair instructions and do the repair. 4. Repeat post repair inspection in accordance with PART 4 at intervals in accordance with Paragraph 1.E., Compliance. 5. Put the airplane back to a serviceable condition. **Group 2: PART 5 - EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION - STRINGERS S-1 AND S-2R,**  **STA 400 - STA 460** 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 Detail Inspection (DI) for cracks in the fuselage skin along the chem-mill steps at stringers S-1 and S-2R, between STA 400 and STA 460 in accordance with FIGURE 4. 3. Do external Non Destructive Inspection (NDI) using one of the following options/procedures for cracks in the fuselage skin along the chem-mill steps at stringers S-1 and S-2R, between STA 400 and STA 460 in accordance with FIGURE 4.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 55 of 105 **BOEING SERVICE BULLETIN 737-53A1293**a. Option 1: Medium Frequency Eddy Current (MFEC), or Magneto Optical Imaging (MOI) or C-Scan b. Option 2: Ultrasonic Phased Array (UTPA). 4. If no crack is found, repeat external DI and NDI in accordance with PART 5 at intervals in accordance with Paragraph 1.E., Compliance. 5. If any of the following is found as a result of the external DI and NDI, contact Boeing for repair instructions in accordance with APPENDIX A, do the repair and do the inspection of the fuselage skin not covered by a repair in accordance with PART 6 at intervals in accordance with Paragraph 1.E., Compliance. a. Crack(s) found before 33,000 total flight cycles. b. Crack(s) found between STA 400 and STA 420. c. Crack(s) found between STA 440 and STA 460. d. Crack(s) found longer than 12.5 inches. e. Crack(s) found are not contained within the skin cut-out shown in FIGURE 10. 6. If all of the following are found as result of the external DI and NDI, do the skin repair in accordance with PART 7 and do the inspection of the fuselage skin not covered by a repair in accordance with PART 6 at intervals in accordance with Paragraph 1.E., Compliance. a. Crack(s) found at or after 33,000 total flight cycles. b. Crack(s) found between STA 420 and STA 440. c. Crack(s) found 12.5 inches or shorter. d. Crack(s) found are contained within the skin cut-out shown in FIGURE 10. 7. Put the airplane back to a serviceable condition. **Group 2: PART 6 - EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION AFTER REPAIR - STRINGERS**  **S-1 AND S-2R, STA 400 - STA 460** 1. Get external access to skin repair area at stringers S-1 and S-2R, between STA 400 and STA 460. 2. Do external Detailed Inspection (DI) for cracks in the fuselage skin along the chem-mill steps at stringers S-1 and S-2R, between STA 400 and STA 460 not covered by a repair in accordance with FIGURE 9. 3. Do external Non Destructive Inspection (NDI) using one of the following options/procedures for cracks in the fuselage skin along the chem-mill steps at stringers S-1 and S-2R, between STA 400 and STA 460 not covered by a repair in accordance with FIGURE 9.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 56 of 105 **BOEING SERVICE BULLETIN 737-53A1293**a. Option 1: Medium Frequency Eddy Current (MFEC) or Magneto Optical Imaging (MOI) or C-Scan. b. Option 2: Ultrasonic Phased Array (UTPA). 4. If any of the following is found as a result of the external DI and NDI, contact Boeing for repair instructions in accordance with APPENDIX A, and do the repair. a. Crack(s) found before 33,000 total flight cycles. b. Crack(s) found between STA 400 and STA 420. c. Crack(s) found between STA 440 and STA 460. d. Crack(s) found longer than 12.5 inches. e. Crack(s) found are not contained within the skin cut-out shown in FIGURE 10. 5. If all of the following are found as result of the external DI and NDI, do the skin repair in accordance with PART 7. a. Crack(s) found at or after 33,000 total flight cycles. b. Crack(s) found between STA 420 and STA 440. c. Crack(s) found 12.5 inches or shorter. d. Crack(s) found are contained within the skin cut-out shown in FIGURE 10. 6. Repeat external DI and NDI in accordance with PART 6 at intervals in accordance with Paragraph 1.E., Compliance. 7. Put the airplane back to a serviceable condition. **Group 2: PART 7 - SKIN REPAIR**  1. In the passenger cabin, remove and keep the equipment listed in the table below to access the area of repair. Refer to the listed Aircraft Maintenance Manual (AMM) as an accepted procedure. **AMM Chapter/Section/Subject Equipment**  737-300/400/500 AMM 25-22-00 Passenger Seats 737-300/400/500 AMM 25-21-46 Sidewall Lining 737-300/400/500 AMM 25-21-39 Sidewall insulation 737-300/400/500 AMM 25-24-31 Overhead Stowage Bins 737-300/400/500 AMM 25-23-61 Passenger Service Units

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 57 of 105 **BOEING SERVICE BULLETIN 737-53A1293 AMM Chapter/Section/Subject**  **Equipment** 737-300/400/500 AMM 25-21-45 Ceiling Panels 2. Remove and keep the ATC antenna, refer to 737-300/400/500 AMM 34-53-11 as an accepted procedure. 3. Remove the crack in accordance with FIGURE 10. 4. Make and install the repair doubler and tear strap doublers in accordance with FIGURE 11. 5. Install the kept ATC antenna on top of the repair doubler. Refer to 737-300/400/500 AMM 34-53-11 as an accepted procedure. **NOTE:**Longer ATC antenna mounting screws may be necessary as a result of installing the repair doubler. 6. Install kept equipment in the passenger cabin that was removed for access. 7. Accomplish the Part 8 - Post Repair inspections at the times specified in Table 6 of Paragraph 1.E., Compliance. 8. Put airplane back in a serviceable condition. **Group 2: PART 8 - POST REPAIR - CRITICAL FASTENER ROW INSPECTION**  1. Get external access to the skin repair at stringers S-1 and S-2R, between STA 400 and STA 460. 2. Do an external Non Destructive Inspection (NDI) in accordance with FIGURE 12 for cracks in the fuselage skin, at the critical row of fasteners in the repair. a. If any crack is found contact Boeing for repair instructions and do the repair. 3. Repeat post repair inspection in accordance with PART 8 at intervals in accordance with Paragraph 1.E., Compliance. 4. Put the airplane back to a serviceable condition.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2: August 10, 2011 58 of 105 **BOEING SERVICE BULLETIN 737-53A1293 This Figure applies only to: Group 1.** 

**FIGURE 1: THIS FIGURE DELETED AT REVISION 1 (SHEET 1 OF 1)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 59 of 105 **BOEING SERVICE BULLETIN 737-53A1293 This Figure applies only to: Group 1.** 

**FIGURE 2: EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION - STRINGERS S-1 AND S-2R, STA 400 - STA 460**  **(SHEET 1 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 60 of 105 **BOEING SERVICE BULLETIN 737-53A1293**The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for one airplane.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  (a)

- - SKIN Inspect 1 Do the procedure listed in note (b) or (c) or (d) or (e).

- - SKIN Inspect 2 (a) Do Detailed Inspection for cracks. (b) Do Medium Frequency Eddy Current (MFEC) Inspection in accordance with 737 NDT Part 6, 53-30-09 or 737 NDT Part 6, 53-30-18 for cracks. (c) Do Magneto Optical Imaging (MOI) Inspection in accordance with 737 NDT Part 6, 53-30-19 for cracks. Magneto Optical Imaging (MOI) NDI inspection option 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 (see note (b) or (e) ). (d) Do C-Scan Inspection in accordance with 737 NDT Part 6, 53-30-25 for cracks. C-Scan NDI inspection option 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 (see note (b) or (e) ). (e) Do Ultrasonic Phased Array (UTPA) inspection in accordance with 737 NDT Part 4, 53-30-07 for cracks.

**FIGURE 2: EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION - STRINGERS S-1 AND S-2R, STA 400 - STA 460**  **(SHEET 2 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 61 of 105 **BOEING SERVICE BULLETIN 737-53A1293 This Figure applies only to: Group 2.** 

**FIGURE 3: THIS FIGURE DELETED AT REVISION 1 (SHEET 1 OF 1)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 62 of 105 **BOEING SERVICE BULLETIN 737-53A1293 This Figure applies only to: Group 2.** 

**FIGURE 4: EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION - STRINGERS S-1 AND S-2R, STA 400 - STA 460**  **(SHEET 1 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 63 of 105 **BOEING SERVICE BULLETIN 737-53A1293**The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for one airplane.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  (a)

- - SKIN Inspect 1 Do the procedure listed in note (b) or (c) or (d) or (e).

- - SKIN Inspect 2 (a) Do Detailed Inspection for cracks. (b) Do Medium Frequency Eddy Current (MFEC) Inspection in accordance with 737 NDT Part 6, 53-30-09 or 737 NDT Part 6, 53-30-18 for cracks. (c) Do Magneto Optical Imaging (MOI) Inspection in accordance with 737 NDT Part 6, 53-30-19 for cracks. Magneto Optical Imaging (MOI) NDI inspection option 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 Ultra Sonic Phased Array (UTPA) NDI inspection options must be used (see note (b) or (e) ). (d) Do C-Scan Inspection in accordance with 737 NDT Part 6, 53-30-25 for cracks. C-Scan NDI inspection option 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 Ultra Sonic Phased Array (UTPA) NDI inspection options must be used (see note (b) or (e) ). (e) Do Ultrasonic Phased Array (UTPA) inspection in accordance with 737 NDT Part 4, 53-30-07 for cracks.

**FIGURE 4: EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION - STRINGERS S-1 AND S-2R, STA 400 - STA 460**  **(SHEET 2 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 64 of 105 **BOEING SERVICE BULLETIN 737-53A1293 This Figure applies only to: Group 1.** 

**FIGURE 5: FUSELAGE SKIN - CRACK REMOVAL (SHEET 1 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 65 of 105 **BOEING SERVICE BULLETIN 737-53A1293**The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each repair location. **CAUTION:**WHEN REMOVING THE CRACK, MAKE SURE THE CUT-OUT IS COMMON TO THE SKIN ONLY. TAKE CARE NOT TO DAMAGE OR CUT THE BONDED DOUBLER.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  (a) (b) (c)

- - SKIN Cut 1 (d)

- - SKIN Inspect 2 (e)

- ALODINE 1200S TYPE 2 CLASS ACHEMICAL CONVERSION COATING Apply 3 (f)

- BMS 10-79 TYPE 2 (BMS 10-79 TYPE 3 optional) PRIMER Apply

(a) Cut and remove damaged skin as shown. Maintain 0.5 inch radius on the skin cut-out. (b) Maintain 2D minimum edge margin from all fastener holes. (c) Maintain a minimum of 63 micro inch Ra or better surface roughness. (d) Do a High Frequency Eddy Current inspection of the edge of the skin cut-out in accordance with 737 NDT Part 6, 51-00-00 Figure 4 or 737 NDT Part 6, 51-00-00 Figure 23. If any crack is found, contact Boeingfor repair instructions and do the repair. If no cracks are found, remove an additional 0.040 inch of material at the inspected area as an insurance (area in bold at each end of the skin cut-out). Make sure there is a smooth transition from the insurance cut area to the non-insurance cut area. Maintain a minimum of 63 micro inches Ra or better surface roughness.

**FIGURE 5: FUSELAGE SKIN - CRACK REMOVAL (SHEET 2 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 66 of 105 **BOEING SERVICE BULLETIN 737-53A1293 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** (e) Apply to bare aluminium surfaces. Refer to SOPM 20-43-03 as an accepted procedure. (f) Apply to bare aluminium surfaces. Refer to SOPM 20-44-04 as an accepted procedure.

**FIGURE 5: FUSELAGE SKIN - CRACK REMOVAL (SHEET 3 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 67 of 105 **BOEING SERVICE BULLETIN 737-53A1293 This Figure applies only to: Group 1.** 

**FIGURE 6: 737-300,737-400 SERIES AIRPLANE - REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 1 OF 10)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 68 of 105 **BOEING SERVICE BULLETIN 737-53A1293 FIGURE 6: 737-300,737-400 SERIES AIRPLANE - REPAIR DOUBLER FABRICATION AND INSTALLATION**  **(SHEET 2 OF 10)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 69 of 105 **BOEING SERVICE BULLETIN 737-53A1293**The flag note letters shown below agree with the letters shown in the flag note symbols in the figure.
**DESCRIPTION FLAG**  **NOTE**Extend the doubler a minimum of four (4) fastener rows beyond all sides of the skin cut-out. A If the doubler will terminate within 3.00 inches of the skin cut-out for the ATC antenna, extend the doubler beyond the antenna in all directions by two (2) additional fastener rows. B In the hoop direction, do not terminate the doubler common to the ATC antenna support structure. Extend the doubler beyond the ATC antenna support structure by two (2) additional fasteners. C In the longitudinal direction, do not terminate the doubler at the edge of the ATC antenna support structure. Extend the doubler beyond the ATC antenna support structure by one (1) additional fastener row. D

Do not terminate the doubler within 0.5 inch of any chem-mill step. E The repair should extend a minimum of three (3) fastener rows beyond any longitudinal chem-mill step that is covered by the repair. F The repair should extend a minimum of two (2) fastener rows beyond rows beyond any circumferential chem-mill step that is covered by the repair. G
Make the doubler from 2024-T3 CLAD sheet, 0.050 inch thick. H Tear strap doublers are required at repair locations where skin pockets are located directly forward and aft of the production tear strap. I The tear strap doubler should have the same width as the production tear strap. J Stagger fasteners common to the 1.5 inch wide tear straps as shown in the figure. The staggered row of fasteners counts as one (1) row of fasteners in the longitudinal direction. K Do not end the tear strap doubler on a stringer. If the end of the tear strap doubler is on a stringer, extend the tear strap doubler beyond the stringer by one (1) additional fastener row. L If the tear strap doubler crosses a stringer, install tapered fillers on each side of the tear strap doubler between the skin and the stringer. Make the tapered fillers from 2024-T3 CLAD sheet, 0.040 inch thick, tapered to .010/.020 inch, maintaining a 50 to 1 minimum taper ratio. M

Make the tear strap doublers from 2024-T3 CLAD sheet, 0.040 inch thick. N

**FIGURE 6: 737-300,737-400 SERIES AIRPLANE - REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 3 OF 10)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 70 of 105 **BOEING SERVICE BULLETIN 737-53A1293 FIGURE 6: 737-300,737-400 SERIES AIRPLANE - REPAIR DOUBLER FABRICATION AND INSTALLATION**  **(SHEET 4 OF 10)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 71 of 105 **BOEING SERVICE BULLETIN 737-53A1293 FIGURE 6: 737-300,737-400 SERIES AIRPLANE - REPAIR DOUBLER FABRICATION AND INSTALLATION**  **(SHEET 5 OF 10)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 72 of 105 **BOEING SERVICE BULLETIN 737-53A1293 FIGURE 6: 737-300,737-400 SERIES AIRPLANE - REPAIR DOUBLER FABRICATION AND INSTALLATION**  **(SHEET 6 OF 10)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 73 of 105 **BOEING SERVICE BULLETIN 737-53A1293 CAUTION:** WHEN DRILLING NEW FASTENER HOLES, USE CARE NOT TO DRILL NEAR EDGE OF THE TEAR STRAP. TEAR STRAP FASTENERS SHOULD BE DRILLED FROM THE INNER FACE OF THE PANEL. The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each repair location.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  Locate repair area in accordance with Flag Notes A through K. - - REPAIR AREA Locate 1

(g) (h) (i) (j)

- - FASTENER Remove 2 Make in accordance with foot notes (a)(c) (d) (e) (f). Determine size of repairdoubler in accordance with Flag Notes A through K. - - REPAIR DOUBLER Make 3

Make in accordance with foot notes (b) (c) (f). Locate and determine size of tear strap doubler in accordance with Flag Notes I through N. - - TEAR STRAP DOU- BLER Make 4

**FIGURE 6: 737-300,737-400 SERIES AIRPLANE - REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 7 OF 10)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 74 of 105 **BOEING SERVICE BULLETIN 737-53A1293 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** Apply to all bare surfaces of doublers. Refer to 737-300 SRM 51-20-01 or - ALODINE 1200S TYPE 2 CLASS ACHEMICAL CONVERSION COATING Apply 5

737-400 SRM 51- 20-01 and SOPM 20-44-03 asan accepted procedure.2 primer coats required. Apply to all bare surfaces of doublers. Refer to 737-300 SRM 51- 20-01 or - BMS 10-79 TYPE II PRIMER Apply

737-400 SRM 51- 20-01 and SOPM 20-44-04 asan accepted procedure.Make and install, refer to 737-300 SRM 51-40-08 or - - COUNTERSINK RE- PAIR WASHER Install (New) 6

737-400 SRM 51- 40-08as an accepted procedure. Fay surface seal all mating parts. - BMS 5-95 SEALANT Apply 7

- - REPAIR DOUBLER Install (New) 8

- - TEAR STRAP DOU- BLER Install (New) 9 Apply a fillet sealaround edges of repair - BMS 5-95 SEALANT Apply 10

**FIGURE 6: 737-300,737-400 SERIES AIRPLANE - REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 8 OF 10)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 75 of 105 **BOEING SERVICE BULLETIN 737-53A1293 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** Apply corrosion inhibiting compound to internal surfaces of repair after sealant in area has cured. Refer to 737-300 SRM 51-20-01 or - BMS 3-23 TYPE II ORGANIC CORRO- SION INHIBITING COMPOUND Apply 11

737-400 SRM 51- 20-01as an accepted procedure. Apply external finish to match adjacent structure. Refer to 737-300/400/500 AMM 51-21-00 asan accepted procedure. - - EXTERNAL FINISH Apply 12

(a) Use 2024-T3 CLAD sheet x 0.050 inch thick material. (b) Use 2024-T3 CLAD sheet x 0.040 inch thick material. (c) Refer to 737-300 SRM 51-30-01 or 737-400 SRM 51-30-01 as an accepted procedure. (d) Pre-form or roll doubler to match the contour of the fuselage. (e) Chamfer edges. Refer to 737-300 SRM 51-10-01 or 737-400 SRM 51-10-01 as an accepted procedure. (f) Keep a 0.50 inch outside radius and 2.00 inch inside radius on all repair part corners. (g) Remove existing fasteners common to the area to be repaired.(h) Do an open hole High Frequency Eddy Current inspection of all the existing open holes in the skin in accordance with 737 NDT Part 6, 51-00-00, Figure 16 to make sure there is no crack. If crack is detected, contact Boeing for repair instructions and do the repair. (i) Make sure the area under the repair does not show signs of bond separation of the bonded doubler or have corrosion. If bond separation or corrosion is found, contact Boeing for repair instructions and do the repair. (j) Make sure the underlying structure in the area of repair does not have corrosion or cracks. If corrosion or cracks are found, contact Boeing for repair instructions and do the repair.

**FIGURE 6: 737-300,737-400 SERIES AIRPLANE - REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 9 OF 10)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 76 of 105 **BOEING SERVICE BULLETIN 737-53A1293**The codes shown below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. The QTY numbers shown below are the number of fasteners necessary for this figure.
**MORE DATA HOLE DIA**  **QTY IDENTIFICATION**  **NAME CODE**  Install fastener at thesame time as antenna installation. 0.218 - 0.229

- - - A

(d) (e) 0.191 - 0.202

- BACR15BB6AD RIVET B (d) (e) 0.191 -0.202

- BACR15BB6D RIVET C (c) (e) 0.159 - 0.171

- BACR15BB5D RIVET D (b) (c) (e) 100 degree countersink on repair doubler. 0.159 - 0.165

- BACR15CE5D RIVET E

(a) (c) (e) 0.191 - 0.202

- BACR15BB6D RIVET F (a) Fastener holes may be oversized by 1/32 inch. Install BACR15ET7AD in place of BACR15BB6D fasteners after hole is oversized by 1/32 inch. (b) Fastener holes are not permitted to be oversized, if oversized is required contact Boeing for instructions. (c) Install countersink washers between skin and external doubler. Refer to 737-300 SRM 51-40-08 or 737- 400 SRM 51-40-08 as an accepted procedure. (d) At new fastener locations, maintain 5-6 diameter spacing and 2 diameter edge margin, unless otherwise specified. (e) Over drive rivets to a minimum 1.4 times the diameter.

**FIGURE 6: 737-300,737-400 SERIES AIRPLANE - REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 10 OF 10)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 77 of 105 **BOEING SERVICE BULLETIN 737-53A1293 This Figure applies only to: Group 1.** 

**FIGURE 7: EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION AFTER REPAIR - STRINGERS S-1 AND S-2R, STA 400 - STA 460**  **(SHEET 1 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 78 of 105 **BOEING SERVICE BULLETIN 737-53A1293**The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each inspection.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  (a) (f) (g)

- - SKIN Inspect 1 (f) (g). Do the procedure listed in note (b) or (c) or (d) or (e). - - SKIN Inspect 2

(a) Do Detail Inspection for cracks. (b) Do Medium Frequency Eddy Current (MFEC) Inspection in accordance with 737 NDT Part 6, 53-30-09 or 737 NDT Part 6, 53-30-18 for cracks. (c) Do Magneto Optical Imaging (MOI) Inspection in accordance with 737 NDT Part 6, 53-30-19 for cracks. Magneto Optical Imaging (MOI) NDI inspection option 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 (see note (b) or (e) ). (d) Do C-Scan Inspection in accordance with 737 NDT Part 6, 53-30-25 for cracks. C-Scan NDI inspection option 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 (see note (b) or (e) ). (e) Do Ultrasonic Phased Array (UTPA) inspection in accordance with 737 NDT Part 4, 53-30-07 for cracks. (f) For repair(s) done in accordance with this service bulletin, it is not required to inspect chem-mill steps under external doublers. (g) For other FAA approved repair(s) with external doubler that extends a minimum of three fasteners on each side of the chem-mill, not required to inspect chem-mill steps under external doublers.

**FIGURE 7: EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION AFTER REPAIR - STRINGERS S-1 AND S-2R, STA 400 - STA 460**  **(SHEET 2 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 79 of 105 **BOEING SERVICE BULLETIN 737-53A1293 This Figure applies only to: Group 1.** 

**FIGURE 8: 737-500 SERIES AIRPLANES - REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 1 OF 11)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 80 of 105 **BOEING SERVICE BULLETIN 737-53A1293 FIGURE 8: 737-500 SERIES AIRPLANES - REPAIR DOUBLER FABRICATION AND INSTALLATION**  **(SHEET 2 OF 11)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 81 of 105 **BOEING SERVICE BULLETIN 737-53A1293**The flag note letters shown below agree with the letters shown in the flag note symbols in the figure.
**DESCRIPTION FLAG**  **NOTE**Extend the doubler a minimum of four (4) fastener rows beyond all sides of the skin cut-out. A If the doubler will terminate within 3.00 inches of the skin cut-out for the ATC antenna, extend the doubler beyond the antenna in all directions by two (2) additional fastener rows. B In the hoop direction, do not terminate the doubler common to the ATC antenna support structure. Extend the doubler beyond the ATC antenna support structure by two (2) additional fasteners. C In the longitudinal direction, do not terminate the doubler at the edge of the ATC antenna support structure. Extend the doubler beyond the ATC antenna support structure by one (1) additional fastener row. D

Do not terminate the doubler within 0.5 inch of any chem-mill step. E The repair should extend a minimum of three (3) fastener rows beyond any longitudinal chem-mill step that is covered by the repair. F The repair should extend a minimum of two (2) fastener rows beyond rows beyond any circumferential chem-mill step that is covered by the repair. G
Make the doubler from 2024-T3 CLAD sheet, 0.050 inch thick. H Tear strap doublers are required at repair locations where skin pockets are located directly forward and aft of the production tear strap. The tear strap doubler can be a different shape at the different locations. Select the appropriate tear strap detail. I

The tear strap doubler should have the same width as the production tear strap. J Stagger fasteners common to the 1.5 inch wide tear straps as shown in the figure. The staggered row of fasteners counts as one (1) row of fasteners in the longitudinal direction. K Do not end the tear strap doubler on a stringer. If the end of the tear strap doubler is on a stringer, extend the tear strap doubler beyond the stringer by one (1) additional fastener row. L If the tear strap doubler crosses a stringer, install tapered fillers on each side of the tear strap doubler between the skin and the stringer. Make the tapered fillers from 2024-T3 CLAD sheet, 0.040 inch thick, tapered to .010/.020 inch, maintaining a 50 to 1 minimum taper ratio. M

Make the tear strap doublers from 2024-T3 CLAD sheet, 0.040 inch thick. N

**FIGURE 8: 737-500 SERIES AIRPLANES - REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 3 OF 11)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 82 of 105 **BOEING SERVICE BULLETIN 737-53A1293 FIGURE 8: 737-500 SERIES AIRPLANES - REPAIR DOUBLER FABRICATION AND INSTALLATION**  **(SHEET 4 OF 11)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 83 of 105 **BOEING SERVICE BULLETIN 737-53A1293 FIGURE 8: 737-500 SERIES AIRPLANES - REPAIR DOUBLER FABRICATION AND INSTALLATION**  **(SHEET 5 OF 11)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 84 of 105 **BOEING SERVICE BULLETIN 737-53A1293 FIGURE 8: 737-500 SERIES AIRPLANES - REPAIR DOUBLER FABRICATION AND INSTALLATION**  **(SHEET 6 OF 11)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 85 of 105 **BOEING SERVICE BULLETIN 737-53A1293 FIGURE 8: 737-500 SERIES AIRPLANES - REPAIR DOUBLER FABRICATION AND INSTALLATION**  **(SHEET 7 OF 11)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 86 of 105 **BOEING SERVICE BULLETIN 737-53A1293 CAUTION:** WHEN DRILLING NEW FASTENER HOLES, USE CARE NOT TO DRILL NEAR EDGE OF THE TEAR STRAP. TEAR STRAP FASTENERS SHOULD BE DRILLED FROM THE INNER FACE OF THE PANEL. The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each repair location.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  Locate repair area in accordance with Flag Notes A through K. - - REPAIR AREA Locate 1

(g) (h) (i) (j)

- - FASTENER Remove 2 Make in accordance with foot notes (a)(c) (d) (e) (f). Determine size of repairdoubler in accordance with Flag Notes A through K. - - REPAIR DOUBLER Make 3

Make in accordance with foot notes (b) (c) (f). Locate and determine size of tear strap doubler in accordance with Flag Notes I through N. - - TEAR STRAP DOU- BLER Make 4

Apply to all bare surfaces of doublers. Refer to 737-500 SRM 51-20-01 and SOPM 20-44-03 asan accepted procedure. - ALODINE 1200S TYPE 2 CLASS ACHEMICAL CONVERSION COATING Apply 5

2 primer coats required. Apply to all bare surfaces of doublers. Refer to 737-500 SRM 51- 20-01 and SOPM20-44-04 as an accepted procedure. - BMS 10-79 TYPE 2 (BMS 10-79 TYPE 3 optional) PRIMER Apply

**FIGURE 8: 737-500 SERIES AIRPLANES - REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 8 OF 11)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 87 of 105 **BOEING SERVICE BULLETIN 737-53A1293 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** Make and install, refer to 737-500 SRM51-40-08 as an accepted procedure. - - COUNTERSINK RE- PAIR WASHER Install (New) 6

Fay surface seal all mating parts. - BMS 5-95 SEALANT Apply 7

- - REPAIR DOUBLER Install (New) 8

- - TEAR STRAP DOU- BLER Install (New) 9 Apply a fillet sealaround edges of repair - BMS 5-95 SEALANT Apply 10

Apply corrosion inhibiting compound to internal surfaces of repair after sealant in area has cured. Refer to 737-500 SRM 51-20-01 as an accepted procedure. - BMS 3-23 TYPE II ORGANIC CORRO- SION INHIBITING COMPOUND Apply 11

Apply external finish to match adjacent structure. Refer to 737-300/400/500 AMM 51-21-00 asan accepted procedure. - - EXTERNAL FINISH Apply 12

(a) Use 2024-T3 CLAD sheet x 0.050 inch thick material. (b) Use 2024-T3 CLAD sheet x 0.040 inch thick material. (c) Refer to 737-500 SRM 51-30-01 as an accepted procedure. (d) Pre-form or roll doubler to match the contour of the fuselage. (e) Chamfer edges. Refer to 737-500 SRM 51-10-01 as an accepted procedure. (f) Keep 0.50 inch outside radius and 2.00 inch inside radius on all repair part corners. (g) Remove existing fasteners common to the area to be repaired.(h) Do an open hole High Frequency Eddy Current inspection of all the existing open holes in the skin in accordance with 737 NDT Part 6, 51-00-00, Figure 16 to make sure there is no crack. If crack is detected, contact Boeing for repair instructions and do the repair. (i) Make sure the area under the repair does not show signs of bond separation of the bonded doubler or have corrosion. If bond separation or corrosion is found, contact Boeing for repair instructions and do the repair.

**FIGURE 8: 737-500 SERIES AIRPLANES - REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 9 OF 11)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 88 of 105 **BOEING SERVICE BULLETIN 737-53A1293 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** (j) Make sure the underlying structure in the area of repair does not have corrosion or cracks. If corrosion or cracks are found, contact Boeing for repair instructions and do the repair.

The codes shown below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. The QTY numbers shown below are the number of fasteners necessary for this figure.
**MORE DATA HOLE DIA**  **QTY IDENTIFICATION**  **NAME CODE**  Install fastener at thesame time as antenna installation. 0.218 - 0.229

- - - A

(d) (e) 0.191 - 0.202

- BACR15BB6AD RIVET B (d) (e) 0.191 -0.202

- BACR15BB6D RIVET C (c) (e) 0.159 - 0.171

- BACR15BB5D RIVET D (b) (c) (e) 100 degree countersink on repair doubler. 0.159 - 0.165

- BACR15CE5D RIVET E

(a) (c) (e) 0.191 - 0.202

- BACR15BB6D RIVET F (a) Fastener holes may be oversized by 1/32 inch. Install BACR15ET7AD in place of BACR15BB6D fasteners after hole is oversized by 1/32 inch. (b) Fastener holes are not permitted to be oversized, if oversized is required contact Boeing for instructions. (c) Install countersink washers between skin and external doubler. Refer to 737-300 SRM 51-40-08 or 737- 400 SRM 51-40-08 as an accepted procedure. (d) At new fastener locations, maintain 5-6 diameter spacing and 2 diameter edge margin, unless otherwise specified.

**FIGURE 8: 737-500 SERIES AIRPLANES - REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 10 OF 11)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 89 of 105 **BOEING SERVICE BULLETIN 737-53A1293 MORE DATA**  **HOLE DIA QTY**  **IDENTIFICATION NAME**  **CODE** (e) Over drive rivets to a minimum 1.4 times the diameter.

**FIGURE 8: 737-500 SERIES AIRPLANES - REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 11 OF 11)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 90 of 105 **BOEING SERVICE BULLETIN 737-53A1293 This Figure applies only to: Group 2.** 

**FIGURE 9: EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION AFTER REPAIR - STRINGERS S-1 AND S-2R, STA 400 - STA 460**  **(SHEET 1 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 91 of 105 **BOEING SERVICE BULLETIN 737-53A1293**The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each inspection.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  (a) (f) (g)

- - SKIN Inspect 1 (f) (g). Do the procedure listed in note (b) or (c) or (d) or (e). - - SKIN Inspect 2

(a) Do Detail Inspection for cracks. (b) Do Medium Frequency Eddy Current (MFEC) Inspection in accordance with 737 NDT Part 6, 53-30-09 or 737 NDT Part 6, 53-30-18 for cracks. (c) Do Magneto Optical Imaging (MOI) Inspection in accordance with 737 NDT Part 6, 53-30-19 for cracks. Magneto Optical Imaging (MOI) NDI inspection option 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 (see note (b) or (e) ). (d) Do C-Scan Inspection in accordance with 737 NDT Part 6, 53-30-25 for cracks. C-Scan NDI inspection option 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 (see note (b) or (e) ). (e) Do Ultrasonic Phased Array (UTPA) inspection in accordance with 737 NDT Part 4, 53-30-07 for cracks. (f) For repair(s) done in accordance with this service bulletin, it is not required to inspect chem-mill steps under external doublers. (g) For other FAA approved repair(s) with external doubler that extends a minimum of three fasteners on each side of the chem-mill, it is not required to inspect chem-mill steps under external doublers.

**FIGURE 9: EXTERNAL FUSELAGE SKIN CHEM-MILL INSPECTION AFTER REPAIR - STRINGERS S-1 AND S-2R, STA 400 - STA 460**  **(SHEET 2 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 92 of 105 **BOEING SERVICE BULLETIN 737-53A1293 This Figure applies only to: Group 2.** 

**FIGURE 10: FUSELAGE SKIN - CRACK REMOVAL (SHEET 1 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 93 of 105 **BOEING SERVICE BULLETIN 737-53A1293**The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for one airplane. **CAUTION:**WHEN REMOVING THE CRACK, MAKE SURE THE CUT-OUT IS COMMON TO THE SKIN ONLY. TAKE CARE NOT TO DAMAGE OR CUT THE BONDED DOUBLER.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  (a) (b) (c)

- - SKIN Cut 1 (d)

- - SKIN Inspect 2 (e)

- ALODINE 1200S TYPE 2 CLASS ACHEMICAL CONVERSION COATING Apply 3 (f)

- BMS 10-79, TYPE III PRIMER Apply (a) Cut and remove damaged skin as shown. Maintain 0.5 inch radius on the skin cut-outs. The skin must be cut out at both S-1 and S-2R locations as shown, even if the skin is only cracked at one location.

**FIGURE 10: FUSELAGE SKIN - CRACK REMOVAL (SHEET 2 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 94 of 105 **BOEING SERVICE BULLETIN 737-53A1293 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** (b) Maintain 2D minimum edge margin from all fastener holes. (c) Maintain a minimum of 63 micro inch Ra or better surface roughness. (d) Do a High Frequency Eddy Current inspection of the edge of the skin cut-out in accordance with 737 NDT Part 6, 51-00-00 Figure 4 or 737 NDT Part 6, 51-00-00 Figure 23. If any crack is found, contact Boeingfor repair instructions and do the repair. If no cracks are found, remove an additional 0.040 inch of material at the inspected area as an insurance (area in bold at each end of the skin cut-out). Make sure there is a smooth transition from the insurance cut area to the non-insurance cut area. Maintain a minimum of 63 micro inches Ra or better surface roughness. (e) Apply to bare aluminium surfaces. Refer to SOPM 20-43-03 as an accepted procedure. (f) Apply to chemical conversion coated surfaces. Refer to SOPM 20-41-02 as an accepted procedure.

**FIGURE 10: FUSELAGE SKIN - CRACK REMOVAL (SHEET 3 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 95 of 105 **BOEING SERVICE BULLETIN 737-53A1293 This Figure applies only to: Group 2.** 

**FIGURE 11: REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 1 OF 6)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 96 of 105 **BOEING SERVICE BULLETIN 737-53A1293 FIGURE 11: REPAIR DOUBLER FABRICATION AND INSTALLATION**  **(SHEET 2 OF 6)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 97 of 105 **BOEING SERVICE BULLETIN 737-53A1293 FIGURE 11: REPAIR DOUBLER FABRICATION AND INSTALLATION**  **(SHEET 3 OF 6)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 98 of 105 **BOEING SERVICE BULLETIN 737-53A1293 CAUTION:** WHEN DRILLING NEW FASTENER HOLES, USE CARE NOT TO DRILL NEAR EDGE OF THE TEAR STRAP. TEAR STRAP FASTENERS SHOULD BE DRILLED FROM THE INNER FACE OF THE PANEL. The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for one airplane.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  (a) (b) (c)

- - FASTENER Remove 1 Make in accordance with foot notes (d) (f) (g) (h) (i) (j). 1

- REPAIR DOUBLER Make 2

Make in accordance with foot notes (e) (f) (g) (j). 4

- TEAR STRAP DOU- BLER Make 3

To all repair parts (k)

- ALODINE 1200S TYPE 2 CLASS ACHEMICAL CONVERSION COATING Apply 4 To all repair parts (l)

- BMS 10-79, TYPE III PRIMER Apply (m)

- - COUNTERSINK RE- PAIR WASHER Install (New) 5 Fay surface seal all mating parts. (n) - BMS 5-95 SEALANT Apply 6
See fastener table. 1

- REPAIR DOUBLER Install (New) 7 See fastener table. 4

- TEAR STRAP DOU- BLER Install (New) 8 Apply a fillet sealaround edges of repair parts. (n) - BMS 5-95 SEALANT Apply 9

(o)

- BMS 3-23 TYPE II ORGANIC CORRO- SION INHIBITING COMPOUND Apply 10

(p)

- - EXTERNAL FINISH Apply 11 (a) Remove existing fasteners common to the area to be repaired.(b) Do an open hole High Frequency Eddy Current inspection of all the existing open holes in the skin in accordance with 737 NDT Part 6, 51-00-00, Figure 16 for cracks. If crack is detected, contact Boeing for repair instructions and do the repair. (c) Do an internal detailed inspection of the skin in the area of the repair for corrosion or disbonded doublers. If corrosion or disbonded doubler is found, contact Boeing for repair instructions and do the repair. (d) Size the repair doubler as shown. Make from 2024-T3 CLAD sheet (AMS QQ-A-250/5) x 0.050 inch thick material. Refer to the fastener table for hole sizes. Break all sharp edges. Maintain a minimum of 125 micro inches Ra surface finish.

**FIGURE 11: REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 4 OF 6)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 99 of 105 **BOEING SERVICE BULLETIN 737-53A1293 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** (e) Size the tear strap doublers as shown. Make from 2024-T3 CLAD sheet (AMS QQ-A-250/5) x 0.040 inch thick material. Refer to the fastener table for hole sizes. Break all sharp edges. Maintain a minimum of 125 micro inches Ra surface finish. (f) Refer to 737-300 SRM 51-30-01 or 737-400 SRM 51-30-01 or 737-500 SRM 51-30-01 as an accepted procedure. (g) Where fastener spacing is not shown, maintain a fastener spacing of 5D-6D, based on the largest size of adjacent fasteners. Maintain a minimum of 2D edge margin at all fastener locations. Make sure that the fasteners will not ride the radius of the chem-milled pockets. Make sure the fastener row above the chem-milled step has a 2D minimum distance from the edge of the step. (h) Pre-form or roll doubler to match the contour of the fuselage. (i) Chamfer edges. Refer to 737-300 SRM 51-10-01 or 737-400 SRM 51-10-01 or 737-500 SRM 51-10-01 as an accepted procedure. (j) Keep a 0.50 inch outside radius and 2.00 inch inside radius on all repair part corners. (k) Apply to bare aluminium surfaces. Refer to SOPM 20-43-03 as an accepted procedure. (l) Apply to chemical conversion coated surfaces. Refer to SOPM 20-41-02 as an accepted procedure. (m) Make the repair washers in accordance with 737-300 SRM 51-40-08 or 737-400 SRM 51-40-08 or 737- 500 SRM 51-40-08. Install in existing countersink holes underneath the external doubler. Install wet with BMS 5-95, TYPE 1, CLASS B-1/2 or B-2 sealant. (n) Refer to SOPM 20-50-19 as an accepted procedure. (o) Apply to all of the internal repair parts and surrounding skin and structure. Refer to 737-300 SRM 51-20- 01 or 737-400 SRM 51-20-01 or 737-500 SRM 51-20-01 as an accepted procedure. (p) Apply external finish to match adjacent structure. Refer to 737-300/400/500 AMM 51-21-00 as an accepted procedure.

**FIGURE 11: REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 5 OF 6)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 100 of 105 **BOEING SERVICE BULLETIN 737-53A1293**The codes shown below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. The QTY numbers shown below are the number of fasteners necessary for this figure.
**MORE DATA HOLE DIA**  **QTY IDENTIFICATION**  **NAME CODE**  (a) (b) 0.190 - 0.196 16 BACR15BB6D5C RIVET A (a) (b) 0.190 - 0.196 32 BACR15BB6D6C RIVET (a) (b) 0.159 -0.165 124 BACR15GF5D4 RIVET B (a) (b) 0.159 - 0.165 166 BACR15GF5D5 RIVET (a) (b) 0.159 - 0.165 51 BACR15GF5D6 RIVET (a) (b) 0.190 - 0.196 68 BACR15BB6AD5C RIVET C (a) Fastener length to be determined on installation. Grip lengths shown are for reference only. (b) Over drive all rivets to a 1.4 times the diameter.

**FIGURE 11: REPAIR DOUBLER FABRICATION AND INSTALLATION (SHEET 6 OF 6)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 101 of 105 **BOEING SERVICE BULLETIN 737-53A1293 This Figure applies only to: Group 2.** 

**FIGURE 12: POST REPAIR - CRITICAL FASTENER ROW INSPECTION (SHEET 1 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 102 of 105 **BOEING SERVICE BULLETIN 737-53A1293**The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each inspection.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  (a)

- - SKIN Inspect 1 (a) Do an external Non Destructive Inspection (NDI) for cracks in the skin under the doubler, at the fastener locations in the shaded areas shown, in accordance with 737 NDT Part 6, 53-30-00, Figure 5.

**FIGURE 12: POST REPAIR - CRITICAL FASTENER ROW INSPECTION (SHEET 2 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 103 of 105 **BOEING SERVICE BULLETIN 737-53A1293**If crack damage is found that exceeds the limits of the repair or that is found prior to the SB inspection threshold, Boeing requests as follows: 1. Contact Boeing for instructions on cutting out the damaged skin. Make sure that the skin cut-out includes the full length of the chem-mill step, i.e. tear strap to tear strap. 2. Damage information: a. Number of cracks: ______________________________ b. Length of crack(s): _____________________________ c. Body station of crack(s):__________________________ d. Location of crack(s) relative to adjacent stringer:____________________________ 3. Airplane information: a. Series: ________________________ b. Line Number: ________________________ c. Variable Number: ________________________ d. Flight cycles: ________________________ e. Flight hours: ________________________ 4. Inspection procedure used: a. When the crack was found: ________________________ b. At the previous inspection: ________________________ 5. Number of flight cycles accumulated since the last inspection of the cracked detail: ___________________ 6. Send the skin cut-out and inspection reports to Boeing for metallurgical evaluation. Boeing Commercial Airplane Company Spares Distribution Center Repair Overhaul and Exchange Services, SSA 111 2201 South 142nd, Door W10 Seatac, Washington 98168, USA Attention Airline Support Manager, forward to Post Production Fuselage Stress for engineering evaluation.

**APPENDIX A: CHEM-MILL STEP CRACK DAMAGE CUT-OUT AND REPORT (SHEET 1 OF 1)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 104 of 105 **BOEING SERVICE BULLETIN 737-53A1293**If crack damage is found that can be repaired within the limits of this service bulletin, Boeing would still like to obtain the information relative to the damage in order to develop more refined inspection requirements. It is not necessary to send these damaged skin cut-outs into Boeing, but please send Boeing the inspection information, as outlined below. 1. Damage Information: a. Number of cracks: ________________________ b. Length of crack(s): ________________________ c. Body station of crack(s): ________________________ d. Location of crack(s) relative to adjacent stringer: ________________________ 2. Airplane information: a. Series: ________________________ b. Line Number: ________________________ c. Variable number: ________________________ d. Flight cycles: ________________________ e. Flight hours: ________________________ 3. Inspection procedure used: a. When the crack was found: ________________________ b. At the previous inspection: ________________________ 4. Number of flight cycles accumulated since the last inspection of the cracked detail: ___________________

**APPENDIX B: CHEM-MILL STEP CRACK DAMAGE REPORT (SHEET 1 OF 1)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 13, 2008 737-53A1293 Revision 2 August 10, 2011 105 of 105 **BOEING SERVICE BULLETIN 737-53A1293**