### Commercial **Airplanes** 

# 737 Service Bulletin **ALERT Number: 737-53A1319**  Original Issue: April 04, 2011 Revision 2: April 04, 2014 ATA System: 5331 **SUBJECT:** FUSELAGE - Skin - Crown Skin Lap Joint - Inspection for Lower Row Cracks at Stringer S-4, Between Body Station 360 and Body Station 1016 Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15 CFR 300-774). An export license may be required before it is used for development, production or use by foreign persons from specific countries. The controller of this data has the individual responsibility to abide by all export laws. 9E991 ECCN: 

## BOEING PROPRIETARY, CONFIDENTIAL AND/OR TRADE SECRET Copyright © 2011 Boeing. Unpublished Work. All Rights Reserved. Treatment of this document and its content is governed by contract with Boeing. Rights to use this document are licensed on a per aircraft basis and such rights may not be transferable. For more information, contact The Boeing Company. Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner, BBJ, DC-8, DC-9, DC-10, KC-10, KC-46, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8, Poseidon and Boeing liveries are all trademarks owned by The Boeing Company; and no trademark license is granted in connection with this document unless provided in writing by Boeing.

Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 1 of 62 4.0Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 2 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**

BLANK PAGE**Table of Contents** Revision Transmittal Sheet............................................ 5 Summary...................................................... 7 1. PLANNING INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 A. Effectivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1. Airplanes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2. Spares Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 B. Concurrent Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 C. Reason. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 D. Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 E. Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 F. Approval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 G. Manpower. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 H. Weight and Balance Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 I. Electrical Load Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 J. References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 1. Existing Data:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2. Data Supplied with this Service Bulletin:. . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3. Installation Drawings Used in the Preparation of this Service Bulletin:. . . . . . . . . . . 27 K. Publications Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 L. Interchangeability and Intermixability of Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . 28 M. Software Accomplishment Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 2. MATERIAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 A. Material - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 B. Industry Support Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 C. Parts Necessary for Each Airplane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 1. Kits/Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2. Parts and Materials Supplied by the Operator. . . . . . . . . . . . . . . . . . . . . . . . 29 3. Parts Modified and Reidentified. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 4. Parts Removed and Not Replaced. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 D. Parts Necessary to Change Spares. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 F. Special Tooling Necessary to do this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . 29 3. ACCOMPLISHMENT INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 A. GENERAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 B. WORK INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 FIGURE 1: EXTERNAL INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 FIGURE 2: INTERNAL INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 FIGURE 3: CONFIRMING A CRACK INDICATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 FIGURE 4: FIGURE DELETED AT REVISION 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 FIGURE 5: INSPECTION ZONES [Group 1-2, 4-7]. . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 FIGURE 6: INSPECTION ZONES [Group 3]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 FIGURE 7: INSPECTION ZONES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 FIGURE 8: INTERNAL GENERAL VISUAL INSPECTION - LOWER SKIN PANEL AT S-4R, BS 908 TO BS 1016 [Group 1, 4, 6]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 3 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 4 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**

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### Commercial **Airplanes** 

# 737 Service Bulletin **ALERT Revision Transmittal Sheet**  **Number: 737-53A1319** Original Issue: April 04, 2011 Revision 2: April 04, 2014 ATA System: 5331 **SUBJECT:** FUSELAGE - Skin - Crown Skin Lap Joint - Inspection for Lower Row Cracks at Stringer S-4, Between Body Station 360 and Body Station 1016 This revision includes all pages of the service bulletin. **COMPLIANCE INFORMATION RELATED TO THIS REVISION** Federal Aviation Administration (FAA) Airworthiness Directive AD 2011-08-51 is related to this service bulletin. The Federal Aviation Administration (FAA) will possibly release an additional Airworthiness Directive related to this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin mandatory. More work is necessary on the airplanes inspected in accordance with the Original Issue or Revision 1 of this service bulletin. Additional work requirements are in Paragraph 1.E., Compliance, Tables 3, 4, 5, and 6. Optional repeat inspection intervals are in Paragraph 1.E., Compliance, Table 2. **REASON FOR REVISION** This revision is sent to define new groups, provide new compliance tables, and add more inspections. In addition, the second external inspection in Figure 4 is deleted. The data given in Information Notice 737-53A1319 IN-01 is included in this revision. These sections were changed: 1. In Summary, changed Background, Action, Compliance, Industry Support Information, and Summary Figure. 2. In Paragraph 1.A.1., Airplanes, added Service Bulletin Index and defined new Groups. 3. In Paragraph 1.C., Reason, added fleet findings, Widespread Fatigue Damage (WFD) statement, Service Related Problem (SRP) number, and Fleet Team Digest (FTD) number. 4. In Paragraph 1.D., Description, changed to agree with Compliance and Work Instructions sections and added Maintenance Zone tables.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 5 of 625. In Paragraph 1.E., Compliance - added Airworthiness Directive (AD) effective date, inspection exceptions, new compliance requirements, and compliance tables. 6. In Paragraph 1.F., Approval, changed alternative method of compliance (AMOC) approval statement. 7. In Paragraph 1.G., Manpower, changed Manpower tables. 8. In Paragraph 1.J., References, changed Existing Data. 9. In Paragraph 1.M., Software Accomplishment Summary, added software accomplishment section. 10. In Paragraph 2.B., Industry Support Information, added warranty statement. 11. In Paragraph 3.A., General Information, changed Notes. 12. In Paragraph 3.B., Work Instructions, changed to agree with Description and Compliance sections. 13. Figure 1, added locator and changed Non-Destructive Testing (NDT) from Figure to Procedure to agree with the 737 NDT Manual. 14. Figure 2, added locator, changed illustration, and added inspection note for locations obstructed by the internal structures. 15. Figure 3, added locator, changed illustration, added inspection note for locations obstructed by the internal structures and removed the optional open hole rotary probe inspection. 16. Figure 4, deleted figure because Boeing has determined that the second external inspection is no longer required. 17. Figure 5, added Group heading. 18. Figures 6-7, added new figures for inspection zones. 19. Figure 8, added new figure for internal general visual inspection. Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity and format changes, to show the location of all content changes. Pages with no vertical lines have no important changes. **REVISION HISTORY** April 04, 2011 Original Issue: April 08, 2011 Revision 1: April 04, 2014 Revision 2:

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 6 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**

### Commercial **Airplanes** 

# 737 Service Bulletin **ALERT Summary**  **Number: 737-53A1319** Original Issue: April 04, 2011 Revision 2: April 04, 2014 ATA System: 5331 **SUBJECT:** FUSELAGE - Skin - Crown Skin Lap Joint - Inspection for Lower Row Cracks at Stringer S-4, Between Body Station 360 and Body Station 1016 THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH 1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OWNER. **CONCURRENT REQUIREMENTS** None. **BACKGROUND** A 737-300 airplane, outside of the effectivity of Service Bulletin (SB) 737-53A1255, experienced a rapid decompression when the lap joint at stringer S-4L between BS 664 - BS 727 cracked and opened up. Investigation shows that the cracks were caused by fatigue cracks in the lower skin at the lower row of fasteners in the lap joint. The airplane had 39,781 total flight cycles and 48,740 total flight hours. This service bulletin gives instructions to inspect the lower row of fasteners at stringer S-4R and S-4L, from BS 360 to BS 908 for cracks in the lower skin of the lap joint. If cracks at this location go undetected, the cracks could link up, resulting in an uncontrolled decompression. After the original issue of this service bulletin, Non-Destructive Testing (NDT) inspections have resulted in additional fleet findings in the skin at the lap joint lower fastener row. Fourteen (14) aircraft were reported with crack indications between 38,222 - 44,784 total flight cycles and 46,822 - 54,434 total hours. Further investigation into these reports of cracks in the lower skin at the lap joint lower row fastener hole have identified small cracks and cracks from scratches. There were nine (9) findings with scratch cracks. Scratch cracks form in the lower skin at the lap joint lower fastener row, local to the hole, but may not intersect the hole. Internal crack confirmation common to doublers and tear straps using hole probe inspections have been removed from this service bulletin because scratch cracks may not intersect the fastener hole. Airplanes prior to Line Number 2553 are covered by Service Bulletin (SB) 737-53A1255. This SB covers airplanes from Line Number 2553 to 3132. The lap splice - fuselage lower fastener hole in the lower skin has been determined to be structure that is susceptible to Widespread Fatigue Damage (WFD). Boeing Service Related Problem (SRP) 737-SRP-53-0330 is related to this service bulletin.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 7 of 62Boeing Fleet Team Digest (FTD) 737 FTD 53-09004 is related to this service bulletin. This table is provided to operators for planning purposes only. Refer to the applicable sections for more information.
**Reference Affected**  **Planning Data** Paragraph 1.A.2., Spares Affected No Spares Affected Paragraph 1.E., Compliance and Paragraph 1.F., Approval Yes AD Related Paragraph 1.H., Weight and Balance Changes No Weight and Balance Change Paragraph 1.I., Electrical Load Data No Electrical Load Changed Paragraph 1.K., Publications Affected No Publications Affected Paragraph 1.K., Publications Affected No Airplane Flight Operations Affected (Flight CrewOperations Manual and/or FAA Approved Airplane Flight Manual) Paragraph 2.C.1., Kits/Parts No Kits/Parts Required Paragraph 2.C.2., Parts and Materials Supplied by the Operator No Operator Supplied Parts/Material Paragraph 2.F., Special Tooling Necessary to do this Service Bulletin No Special Tooling Required

**ACTION** This service bulletin gives instructions to do as follows: 1. Part 1: (Option 1) External eddy current inspection at S-4L and S-4R, BS 360 to BS 908 for cracks, excluding BS 540 to BS 727E for Group 3 airplanes. Or Part 1: (Option 2) Internal detailed and eddy current inspections at S-4L and S-4R, BS 360 to BS 908 for cracks, excluding BS 540 to BS 727E for Group 3 airplanes. 2. Part 2: One-time internal detailed and eddy current inspections at S-4L and S-4R, BS 360 to BS 908 for cracks, excluding BS 540 to BS 727E for Group 3 airplanes.
3. **Group 2-3, 5, 7:** Part 3: One-time internal detailed and eddy current inspections at S-4R, BS 908 to BS 1016 for cracks.
4. **Group 2-3, 5, 7:** Part 4: (Option 1) External eddy current inspection at S-4R, BS 908 to BS 1016 for cracks. Or Part 4: (Option 2) Internal detailed and eddy current inspections at S-4R, BS 908 to BS 1016 for cracks.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 8 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**5. **Group 1, 4, 6:** Part 5: Internal general visual inspection of lower skin panel at S-4R, BS 908 to BS 1016 for open or closed pockets. **EFFECTIVITY** 737-300, 737-400, and 737-500 Airplanes. Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplanes. **COMPLIANCE** The Federal Aviation Administration (FAA) will possibly release an additional Airworthiness Directive related to this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin mandatory. Federal Aviation Administration (FAA) Airworthiness Directive AD 2011-08-51 is related to this service bulletin. The effective date of AD 2011-08-51 is June 2, 2011. Refer to Paragraph 1.E., Compliance. **INDUSTRY SUPPORT INFORMATION** Boeing warranty remedies are not available for the inspection and/or repair procedures given in this service bulletin. **MANPOWER** Refer to Paragraph 1.G., Manpower. **MATERIAL INFORMATION** None.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 9 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 10 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**

### Commercial **Airplanes** 

# 737 Service Bulletin **ALERT Number: 737-53A1319**  Original Issue: April 04, 2011 Revision 2: April 04, 2014 ATA System: 5331 **SUBJECT:** FUSELAGE - Skin - Crown Skin Lap Joint - Inspection for Lower Row Cracks at Stringer S-4, Between Body Station 360 and Body Station 1016 THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH 1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OWNER. **1. PLANNING INFORMATION A. Effectivity**  1. Airplanes This service bulletin is for the airplane(s) shown below. Refer to Service Bulletin Index D6-19567 Part 3 for Airplane Variable Number, Line Number, and Serial Number data.
**DESCRIPTION CONFIGURATION**  **GROUP** 737-300 airplanes with specific inspection zones S-4R and S-4L, BS 360 to BS 908 and internal general visual inspection for open or closed pockets at S-4R, BS 908 to BS 1016. - 1

737-300 airplanes with specific inspection zones S-4R and S-4L, BS 360 to BS 908 and S-4R, BS 908 to BS 1016. - 2
737-300 airplanes with specific inspection zones S-4R and S-4L, BS 360 to BS 540 and BS 727E to BS 908 and S-4R, BS 908 to BS 1016. - 3

737-400 airplanes with specific inspection zones S-4R and S-4L, BS 360 to BS 908 and internal general visual inspection for open or closed pockets at S-4R, BS 908 to BS1016. - 4

737-400 airplanes with specific inspection zones S-4R and S-4L, BS 360 to BS 908 and S-4R, BS 908 to BS 1016. - 5

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 11 of 62**DESCRIPTION CONFIGURATION**  **GROUP** 737-500 airplanes with specific inspection zones S-4R and S-4L, BS 360 to BS 908 and internal general visual inspection for open or closed pockets at S-4R, BS 908 to BS 1016. - 6

737-500 airplanes with specific inspection zones S-4R and S-4L, BS 360 to BS 908 and S-4R, BS 908 to BS 1016. - 7

Airplane Models: 737-300, 737-400, 737-500 **Group Variable Number**  5 PJ552 - PJ559 4 PJ560 - PJ561 4 PJ601 - PJ615 4 PJ811 4 PJ816 - PJ817 2 PM543 - PM550 2 PP518 - PP520 1 PP876 - PP877 2 PQ297 - PQ299 2 PQ345 - PQ348 2 PQ370 - PQ373 2 PQ391 - PQ393 1 PQ394 - PQ395 2 PQ408 - PQ410 2 PQ414 1 PQ415 - PQ418 2 PQ431 - PQ438 2 PQ447 1 PQ448 1 PQ451 1 PQ454 2 PQ473 - PQ475 2 PQ772 2 PQ933 - PQ935

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 12 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT Group**  **Variable Number** 2 PQ951 2 PQ971 1 PQ972 - PQ997 1 PR001 - PR017 1 PR021 - PR034 1 PR041 - PR045 1 PR061 - PR072 1 PR077 - PR082 1 PR091 - PR092 1 PR096 1 PR101 1 PR121 - PR122 1 PR131 - PR132 1 PR141 - PR143 1 PR161 - PR172 1 PR181 2 PS617 - PS629 1 PS630 2 PS704 - PS706 3 PS763 - PS799 2 PS811 2 PS836 - PS837 2 PS841 - PS846 2 PS851 - PS852 2 PS856 2 PS861 - PS863 2 PS866 - PS868 1 PS871 - PS874 2 PS896 - PS897 3 PS901 - PS906 2 PS907 - PS924 1 PS925 - PS941 2 PS956 - PS957

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 13 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT Group**  **Variable Number** 1 PS961 - PS963 1 PS971 - PS978 7 PT012 - PT014 6 PT015 7 PT029 - PT031 7 PT064 7 PT126 - PT131 6 PT132 - PT138 7 PT188 7 PT307 - PT309 7 PT513 - PT517 7 PT585 6 PT586 7 PT643 - PT644 7 PT656 6 PT681 - PT685 7 PT716 - PT717 7 PT721 6 PT722 - PT725 7 PT801 - PT834 7 PT851 - PT853 6 PT854 7 PT871 - PT876 6 PT877 - PT886 6 PT901 - PT930 7 PT971 - PT973 6 PT981 - PT985 6 PT996 6 PU301 6 PU311 - PU313 5 PV204 - PV205 4 PV206 - PV209 5 PV226

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 14 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT Group**  **Variable Number** 4 PV227 - PV229 5 PV284 - PV285 4 PV286 - PV287 5 PV296 5 PV301 4 PV302 4 PV351 4 PV356 - PV357 5 PW086 - PW088 4 PW168 - PW171 5 PW245 - PW251 4 PW252 5 PW262 4 PW263 - PW264 5 PW271 - PW275 4 PW276 5 PW282 - PW292 5 PW401 - PW403 4 PW404 - PW408 5 PW411 - PW413 4 PW414 - PW418 4 PW421 - PW424 4 PW431 - PW435 4 PW441 - PW450 5 PW521 - PW522 5 PW524 - PW525 5 PW527 - PW530 5 PW547 - PW550 5 PW621 - PW622 5 PW635 - PW637 4 PW831 4 PW851 - PW856

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 15 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**2. Spares Affected None. **B. Concurrent Requirements** None. **C. Reason** A 737-300 airplane, outside of the effectivity of Service Bulletin (SB) 737-53A1255, experienced a rapid decompression when the lap joint at stringer S-4L between BS 664 - BS 727 cracked and opened up. Investigation shows that the cracks were caused by fatigue cracks in the lower skin at the lower row of fasteners in the lap joint. The airplane had 39,781 total flight cycles and 48,740 total flight hours. This service bulletin gives instructions to inspect the lower row of fasteners at stringer S-4R and S-4L, from BS 360 to BS 908 for cracks in the lower skin of the lap joint. If cracks at this location go undetected, the cracks could link up, resulting in an uncontrolled decompression. After the original issue of this service bulletin, Non-Destructive Testing (NDT) inspections have resulted in additional fleet findings in the skin at the lap joint lower fastener row. Fourteen (14) aircraft were reported with crack indications between 38,222 - 44,784 total flight cycles and 46,822 - 54,434 total hours. Further investigation into these reports of cracks in the lower skin at the lap joint lower row fastener hole have identified small cracks and cracks from scratches. There were nine (9) findings with scratch cracks. Scratch cracks form in the lower skin at the lap joint lower fastener row, local to the hole, but may not intersect the hole. Internal crack confirmation common to doublers and tear straps using hole probe inspections have been removed from this service bulletin because scratch cracks may not intersect the fastener hole. Airplanes prior to Line Number 2553 are covered by Service Bulletin (SB) 737-53A1255. This SB covers airplanes from Line Number 2553 to 3132. The lap splice - fuselage lower fastener hole in the lower skin has been determined to be structure that is susceptible to Widespread Fatigue Damage (WFD). Boeing Service Related Problem (SRP) 737-SRP-53-0330 is related to this service bulletin. Boeing Fleet Team Digest (FTD) 737 FTD 53-09004 is related to this service bulletin. Revision 1 was sent to correct a figure label and to clarify figure details. Manpower estimates are also included. Revision 2 is sent to define new groups, provide new compliance tables, and add more inspections. In addition, the second external inspection in Figure 4 is deleted. The data given in Information Notice 737-53A1319 IN-01 is included in Revision 2.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 16 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT D. Description**  This service bulletin gives instructions to do as follows: 1. Part 1: (Option 1) External eddy current inspection at S-4L and S-4R, BS 360 to BS 908 for cracks, excluding BS 540 to BS 727E for Group 3 airplanes. Or Part 1: (Option 2) Internal detailed and eddy current inspections at S-4L and S-4R, BS 360 to BS 908 for cracks, excluding BS 540 to BS 727E for Group 3 airplanes. 2. Part 2: One-time internal detailed and eddy current inspections at S-4L and S-4R, BS 360 to BS 908 for cracks, excluding BS 540 to BS 727E for Group 3 airplanes.
3. **Group 2-3, 5, 7:** Part 3: One-time internal detailed and eddy current inspections at S-4R, BS 908 to BS 1016 for cracks.
4. **Group 2-3, 5, 7:** Part 4: (Option 1) External eddy current inspection at S-4R, BS 908 to BS 1016 for cracks. Or Part 4: (Option 2) Internal detailed and eddy current inspections at S-4R, BS 908 to BS 1016 for cracks.
5. **Group 1, 4, 6:** Part 5: Internal general visual inspection of lower skin panel at S-4R, BS 908 to BS 1016 for open or closed pockets. Revision 2 - More work is necessary on airplanes inspected in accordance with the Original Issue or Revision 1 of this service bulletin. Additional work requirements are in Paragraph 1.E., Compliance, Tables 3, 4, 5, and 6. Optional repeat inspection intervals are in Paragraph 1.E., Compliance, Table 2. The work in this service bulletin is done in the maintenance zone(s) given below. **Group 1-3:**
**Affected Maintenance Zones Zone**  **Model** 107, 108 737-300

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 17 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT Group 4-5:** 
**Affected Maintenance Zones Zone**  **Model** 107, 108 737-400 **Group 6-7:**
**Affected Maintenance Zones Zone**  **Model** 107, 108 737-500 **E. Compliance** The Federal Aviation Administration (FAA) will possibly release an additional Airworthiness Directive related to this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin mandatory. Federal Aviation Administration (FAA) Airworthiness Directive AD 2011-08-51 is related to this service bulletin. The effective date of AD 2011-08-51 is June 2, 2011. If the airplane has had a skin panel replaced common to the subject lap joint areas, the compliance times for inspection of the lower skin may be affected. Contact Boeing for alternate lap joint lower row inspections for the lap joint areas affected by skin panel replacements. Inspection Exceptions: 1. If an existing external repair doubler is common to the inspection area of the lap joint lower fastener row and meets the criteria shown below, then it is not required to inspect the lower skin at the lap joint lower fastener row under the existing repair doubler. a. The installed repair was approved by the FAA or by a Boeing Authorized Representative who was authorized by the FAA to make such findings. b. The installed repair extends a minimum of three rows of fasteners above the chem-mill step and three rows of fasteners below the lap joint lower row. 2. If the repair does not meet the above conditions, then inspect the lower skin lap joint lower row internally in the area covered by the doubler in accordance with FIGURE 2. If any inspection has not been accomplished in accordance with the Original Issue or Revision 1 of this service bulletin, then Table 1 requirements must be accomplished before starting Table 2 requirements. Follow-on repetitive inspections may be accomplished using Table 2. Do the required actions in accordance with Paragraph 3. Accomplishment Instructions. When more than one OPTION is given for a CONDITION, do only one of the OPTION numbers. When more than one ACTION is given for a CONDITION number or an OPTION number, do all of the ACTION numbers for that CONDITION number or OPTION number.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 18 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT Table 1: Eddy Current Inspections for Cracks at S-4L and S-4R, BS 360 to BS 908**  **Repeat Interval (Not to Exceed)**  **Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Within 20 days after the effective date of AD 2011-08-51 Before 30,000 total flight cyclesDo PART 1: (OPTION 1) EXTERNAL EDDY CURRENTINSPECTION AT S4L AND S-4R, BS 360 TO BS 908 for cracks. Airplanes with less than 30,000 total flight cycles as of the effective date of AD 2011-08-51

ORDo PART 1: (OPTION 2) INTERNALDETAILED AND EDDY CURRENT INSPECTIONS AT S4L AND S-4R, BS 360 TO BS 908 for cracks.

- Within 20 days after the effective date of AD 2011-08-51 - Do PART 1: (OP- TION 1) EXTERNAL EDDY CURRENTINSPECTION AT S4L AND S-4R, BS 360 TO BS 908 for cracks. Airplanes with 30,000 or more total flight cycles and less than 35,000 total flight cycles as of the effective date of AD 2011-08-51 ORDo PART 1: (OPTION 2) INTERNALDETAILED AND EDDY CURRENT INSPECTIONS AT S4L AND S-4R, BS 360 TO BS 908 for cracks.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 19 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT Table 1: Eddy Current Inspections for Cracks at S-4L and S-4R, BS 360 to BS 908**  **Repeat Interval (Not to Exceed)**  **Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Within 5 days after the effective date of AD 2011-08-51 - Do PART 1: (OP- TION 1) EXTERNAL EDDY CURRENTINSPECTION AT S4L AND S-4R, BS 360 TO BS 908 for cracks. Airplanes with 35,000 or more total flight cycles as of the effective date of AD 2011-08-51

ORDo PART 1: (OPTION 2) INTERNALDETAILED AND EDDY CURRENT INSPECTIONS AT S4L AND S-4R, BS 360 TO BS 908 for cracks. 500 flight cycles

- - Repeat inspection in PART 1: (OPTION 1) EXTERNAL EDDYCURRENT INSPECTION AT S-4L AND S-4R, BS 360 TO BS 908 for cracks. CONDITION 1: NO CRACK FOUND

- - - OR 500 flight cycles

- - Repeat inspections in PART 1: (OPTION2) INTERNAL DETAILED AND EDDYCURRENT INSPECTIONS AT S-4L AND S-4R, BS 360 TO BS 908 for cracks.

- Before further flight Contact Boeing for repair instructions and do the repair. CONDITION 2: ANY CRACK FOUND

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 20 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT Table 2: Airplanes on which any inspection specified in Table 1 or Table 2 of this service bulletin has**  **been accomplished - Optional Repeat Inspection Intervals Repeat Interval (Not**  **to Exceed) Compliance Time (Whichever Occurs**  **Later) Action**  **Condition** 2,000 flight cyclesuntil the accumulation of 38,001 total flight cycles - - Repeat inspection in PART 1: (OPTION 1) EXTERNAL EDDYCURRENT INSPECTION AT S-4L AND S-4R, BS 360 TO BS 908 for cracks. Airplanes with38,000 total flight cycles or less as of themost recent inspection CONDITION 1: NO CRACK FOUNDOR Repeat inspections in PART 1: (OPTION2) INTERNAL DETAILED AND EDDYCURRENT INSPECTIONS AT S-4L AND S-4R, BS 360 TO BS 908 for cracks. 1,500 flight cyclesuntil the accumulation of 42,501 total flight cycles - - Repeat inspection in PART 1: (OPTION 1) EXTERNAL EDDYCURRENT INSPECTION AT S-4L AND S-4R, BS 360 TO BS 908 for cracks. Airplanes with more than 38,000 total flight cycles but less than or equal to42,500 total flight cycles as of the most recent inspection CONDITION 1: NO CRACK FOUNDOR Repeat inspections in PART 1: (OPTION2) INTERNAL DETAILED AND EDDYCURRENT INSPECTIONS AT S-4L AND S-4R, BS 360 TO BS 908 for cracks.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 21 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT Table 2: Airplanes on which any inspection specified in Table 1 or Table 2 of this service bulletin has**  **been accomplished - Optional Repeat Inspection Intervals Repeat Interval (Not**  **to Exceed) Compliance Time (Whichever Occurs**  **Later) Action**  **Condition** 500 flight cycles

- - Repeat inspections in PART 1: (OPTION 1) EXTERNAL EDDYCURRENT INSPECTION AT S-4L AND S-4R, BS 360 TO BS 908 for cracks. Airplanes with more than 42,500 total flight cycles as of themost recent inspection CONDITION 1: NO CRACK FOUNDOR Repeat inspections in PART 1: (OPTION2) INTERNAL DETAILED AND EDDYCURRENT INSPECTIONS AT S-4L AND S-4R, BS 360 TO BS 908 for cracks.

- Before further flight Contact Boeing for repair instructions and do the repair. CONDITION 2: ANY CRACK FOUND **Table 3: One-Time Internal Detailed and Eddy Current Inspections for Cracks at S-4L and S-4R, BS 360 to BS 908**  **Repeat Interval (Not to Exceed)**  **Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Within 1,000 flightcycles after the Revision 2 date of this service bulletin Before 45,000 total flight cycles, but not earlier than 40,000 total flight cyclesDo PART 2: ONETIME INTERNALDETAILED AND EDDY CURRENT INSPECTIONS AT S4L AND S-4R, BS 360 TO BS 908 for cracks. (a) All Airplanes

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 22 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT Table 3: One-Time Internal Detailed and Eddy Current Inspections for Cracks at S-4L and S-4R, BS 360**  **to BS 908 Repeat Interval (Not**  **to Exceed) Compliance Time (Whichever Occurs**  **Later) Action**  **Condition**

In accordance with Table 1 or Table 2 - - Continue repeat in- spection in PART 1:(OPTION 1) EXTERNAL EDDY CURRENT INSPECTION AT S-4L AND S-4R, BS 360 TO BS 908 for cracks. CONDITION 3: NO CRACK FOUND

ORContinue repeat inspections in PART 1:(OPTION 2) INTERNAL DETAILED AND EDDY CURRENT INSPECTIONS AT S-4L AND S-4R, BS 360 TO BS 908 for cracks.

- Before further flight Contact Boeing for repair instructions and do the repair. CONDITION 4: ANY CRACK FOUND(a) Accomplishment of the one-time internal inspection is an acceptable method of compliance for the accomplishment of one Option 1 or one Option 2 inspection specified in Table 1 or Table 2. **Group 2-3, 5, 7: Table 4: One-Time Internal Detailed and Eddy Current Inspections for Cracks at S-4R, BS 908 TO BS**  **1016 Repeat Interval (Not**  **to Exceed) Compliance Time (Whichever Occurs**  **Later) Action**  **Condition**

- Within 1,000 flightcycles after the Revision 2 date of this service bulletin Before 76,000 total flight cycles, but not earlier than 75,000 total flight cyclesDo PART 3: ONETIME INTERNALDETAILED AND EDDY CURRENT INSPECTIONS AT S4R, BS 908 TO BS 1016 for cracks. All Airplanes

- - No further Table 4 work required. CONDITION 5: NO CRACK FOUNDDo the work in Table 5.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 23 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT Group 2-3, 5, 7:**  **Table 4: One-Time Internal Detailed and Eddy Current Inspections for Cracks at S-4R, BS 908 TO BS 1016**  **Repeat Interval (Not to Exceed)**  **Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Before further flight Contact Boeing for repair instructions and do the repair. CONDITION 6: ANY CRACK FOUND **Group 2-3, 5, 7: Table 5: Eddy Current Inspections for Cracks at S-4R, BS 908 TO BS 1016**  **Repeat Interval (Not to Exceed)**  **Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Within 1,500 flightcycles after the Revision 2 date of this service bulletin Before 76,500 total flight cyclesDo PART 4: (OPTION 1) EXTERNAL EDDY CURRENTINSPECTION AT S4R, BS 908 TO BS 1016 for cracks. All Airplanes

ORDo PART 4: (OPTION 2) INTERNALDETAILED AND EDDY CURRENT INSPECTIONS AT S4R, BS 908 TO BS 1016 for cracks. 1,500 flight cyclesuntil the accumulation of 80,000 total flight cycles - - Repeat inspection in PART 4: (OPTION 1) EXTERNAL EDDYCURRENT INSPECTION AT S-4R, BS 908 TO BS 1016 for cracks. CONDITION 7: NO CRACK FOUND

THEN 500 flight cycles after the accumulation of80,000 total flight cycles OR Repeat inspections in PART 4: (OPTION2) INTERNAL DETAILED AND EDDYCURRENT INSPECTIONS AT S-4R, BS 908 TO BS 1016 for cracks.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 24 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT Group 2-3, 5, 7:**  **Table 5: Eddy Current Inspections for Cracks at S-4R, BS 908 TO BS 1016 Repeat Interval (Not**  **to Exceed) Compliance Time (Whichever Occurs**  **Later) Action**  **Condition**

- Before further flight Contact Boeing for repair instructions and do the repair. CONDITION 8: ANY CRACK FOUND **Group 1, 4, 6: Table 6: Internal General Visual Inspection of Lower Skin Panel at S-4R, BS 908 to BS 1016**  **Repeat Interval (Not to Exceed)**  **Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Within 1,500 flightcycles after the Revision 2 date of this service bulletin. Before 75,000 total flight cyclesDo PART 5: INTERNAL GENERAL VISUAL INSPECTION OF LOWER SKIN PANEL AT S-4R, BS 908 TO BS 1016 foropen or closed pockets. (a) All Airplanes

- - - No further work re- quired at S-4R, BS 908 TO BS 1016. CONDITION 9: ANY CLOSED POCKETS FOUND ADJACENT TO THE S-4R LAP JOINT, BS 908 TO BS 1016 (b) Before further flight Contact Boeing for inspections or repair instructions and do the work instructed by Boeing. CONDITION 10:ANY OPEN POCKETS FOUND ADJACENT TO THE S-4R LAP JOINT, BS 908 TO BS 1016 (a) Refer to FIGURE 8 for illustrations of open or closed pockets. (b) Depending on configuration information, the repair instructions may result in repetitive inspection instructions similar to Part 3 and Part 4 for Group 2-3, 5, and 7 airplanes. **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.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 25 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**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 accomplishment of the Stringer S-4L and S-4R, BS 360 to BS 908 inspections and compliance times in accordance with Boeing Alert Service Bulletin 737-53A1319 Revision 2 as an alternative method of compliance to the inspections required by paragraphs (g), (i) and (k) of AD 2011-08-51. All provisions of AD 2011-08-51 that are not specifically referenced in the above statement 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 inspections 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, 4, 6: Elapsed Hours**  **Task Hours Number of Persons**  **Task** 3.00 6.00 2 Part 1 (Option 1) 213.50 4270.00 20 Part 1 (Option 2) 213.50 4270.00 20 Part 2 55.00 550.00 10 Part 5 (b) (b) TOTAL FOR EACH AIRPLANE (a) (a) Additional hours will be required for repair if any crack is found. (b) Total hours dependent upon Parts and Options accomplished. **Group 2-3, 5, 7: Elapsed Hours**  **Task Hours Number of Persons**  **Task** 3.00 6.00 2 Part 1 (Option 1) 213.50 4270.00 20 Part 1 (Option 2) 213.50 4270.00 20 Part 2 55.00 550.00 10 Part 3 2.00 4.00 2 Part 4 (Option 1) 55.00 550.00 10 Part 4 (Option 2)

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 26 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT Group 2-3, 5, 7:**  **Elapsed Hours Task Hours**  **Number of Persons Task**  (b) (b) TOTAL FOR EACH AIRPLANE (a) (a) Additional hours will be required for repair if any crack is found. (b) Total hours dependent upon Parts and Options accomplished. **H. Weight and Balance Changes** None. **I. Electrical Load Data** None. **J. References** 1. Existing Data: a. Boeing Service Bulletin 737-53A1255 b. Boeing Service Letter 737-SL-51-042 c. Boeing Service Related Problem (SRP) 737-SRP-53-0330 d. Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2011-08-51 e. Service Bulletin Index D6-19567 f. Standard Overhaul Practices Manual (SOPM) 20-50-01 g. 737 Fleet Team Digest (FTD) 53-09004 h. 737 Non-Destructive Testing (NDT) Manual Part 6, 53-30-00 Procedure 9, Part 6, 53-30-12, Part 6, 53-30-16 i. 737-300/400/500 Aircraft Maintenance Manual (AMM) 21-23-25, 25-21-39, 25-21-45, 25-21-71, 25-23-61, 25-24-31, 25-31-21, 25-31-31, 25-31-61, 25-40-01 2. Data Supplied with this Service Bulletin: None. 3. Installation Drawings Used in the Preparation of this Service Bulletin: None.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 27 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT K. Publications Affected**  1. Publications: None. 2. Damage Tolerance Based Structural Inspections: Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the Maintenance Program. This service bulletin does not affect FCS, therefore DTIs are not necessary. **L. Interchangeability and Intermixability of Parts** None. **M. Software Accomplishment Summary** Not affected.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 28 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT 2. MATERIAL INFORMATION**  **A. Material - Price and Availability** None. **B. Industry Support Information** Boeing warranty remedies are not available for the inspection and/or 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 None. 3. Parts Modified and Reidentified None. 4. Parts Removed and Not Replaced None. **D. Parts Necessary to Change Spares** None. **E. Special Tooling - Price and Availability** None. **F. Special Tooling Necessary to do this Service Bulletin** No special tools or equipment are necessary to do the change in this service bulletin. But, maintenance and overhaul tools in the manuals given in Paragraph 1.J., References, can be necessary. Examine operator tool supply to make sure all necessary tools are available.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 29 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 30 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**

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 and fasteners are in Structural Repair Manual (SRM) Chapter 51 – Torque Values: — Values for structural fasteners are given in 737 Structural Repair Manual, Chapter 51. — Values for airframe maintenance tasks are included in Chapter 20 of 737 Airplane Maintenance Manual (AMM).

4. Use the approved fastener, process and material substitutions in accordance with SRM Chapter 51. 5. If the length of any fastener specified in this service bulletin does not meet installation standards given in SRM Chapter 51, then a fastener of the same specification, or an approved substitute, with a length which meets the installation standards given in SRM Chapter 51 may be used. In addition, washers may be installed for fastener grip length in accordance with SRM Chapter 51. Refer to SOPM 20-50-01 for alternate full threaded fasteners (screws) needed for installation in this service bulletin. 6. A Detailed Inspection is defined as: An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirrors, magnifying lenses, etc. may be necessary. Surface cleaning and elaborate procedures may be required. 7. A General Visual Inspection is defined as: A visual examination of an interior or exterior area, installation or assembly to detect obvious damage, failure or irregularity.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 31 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight or drop-light and may require removal or opening of access panels or doors. Stands, ladders or platforms may be required to gain proximity to the area being checked. 8. 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. 9. 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. 10. The instructions in Paragraph 3.B., Work Instructions and the figures can include operation of tools or test equipment. Boeing Engineering Tool Drawings, the Illustrated Tool and Equipment Manual, and the Special Tool and Ground Handling Drawing Index contain data on versions of the tools or test equipment that you can use. It is permitted to use replaced tools. It is not permitted to use superseded tools. 11. 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. 12. 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. 13. If shading is used, shaded areas in Figures are to separate the non-critical and non-authoritative information from the critical and authoritative information. 14. When more than one OPTION is given for a CONDITION, do only one of the OPTION numbers. When more than one ACTION is given for a CONDITION number or an OPTION number, do all of the ACTION numbers for that CONDITION number or OPTION number. 15. The compliance times for the actions in Paragraph 3.B., WORK INSTRUCTIONS are in Paragraph 1.E., Compliance. 16. Inspection Exceptions: — If an existing external repair doubler is common to the inspection area of the lap joint lower fastener row and meets the criteria shown below, then it is not required to inspect the lower skin at the lap joint lower fastener row under the existing repair doubler. — The installed repair was approved by the FAA or by a Boeing Authorized Representative who was authorized by the FAA to make such findings.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 32 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**— The installed repair extends a minimum of three rows of fasteners above the chem-mill step and three rows of fasteners below the lap joint lower row. — If the repair does not meet the above conditions, then inspect the lower skin lap joint lower row internally in the area covered by the doubler in accordance with FIGURE 2. **B. WORK INSTRUCTIONS** 1. Do PART 1: (OPTION 1) EXTERNAL EDDY CURRENT INSPECTION AT S-4L AND S-4R, BS 360 TO BS 908 for cracks. Or Do PART 1: (OPTION 2) INTERNAL DETAILED AND EDDY CURRENT INSPECTIONS AT S-4L AND S-4R, BS 360 TO BS 908 for cracks. **CONDITION 1: NO CRACK FOUND** a. Repeat inspection in PART 1: (OPTION 1) EXTERNAL EDDY CURRENT INSPECTION AT S-4L AND S-4R, BS 360 TO BS 908 for cracks. Or Repeat inspections in PART 1: (OPTION 2) INTERNAL DETAILED AND EDDY CURRENT INSPECTIONS AT S-4L AND S-4R, BS 360 TO BS 908 for cracks. **CONDITION 2: ANY CRACK FOUND** a. Contact Boeing for repair instructions and do the repair. 2. Do PART 2: ONE-TIME INTERNAL DETAILED AND EDDY CURRENT INSPECTIONS AT S-4L AND S-4R, BS 360 TO BS 908 for cracks. **CONDITION 3: NO CRACK FOUND** a. Continue repeat inspection in PART 1: (OPTION 1) EXTERNAL EDDY CURRENT INSPECTION AT S-4L AND S-4R, BS 360 TO BS 908 for cracks. Or Continue repeat inspections in PART 1: (OPTION 2) INTERNAL DETAILED AND EDDY CURRENT INSPECTIONS AT S-4L AND S-4R, BS 360 TO BS 908 for cracks. **CONDITION 4: ANY CRACK FOUND** a. Contact Boeing for repair instructions and do the repair.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 33 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**3. **Group 2-3, 5, 7:** Do PART 3: ONE-TIME INTERNAL DETAILED AND EDDY CURRENT INSPECTIONS AT S-4R, BS 908 TO BS 1016 for cracks. **CONDITION 5: NO CRACK FOUND** a. Do PART 4: (OPTION 1) EXTERNAL EDDY CURRENT INSPECTION AT S-4R, BS 908 TO BS 1016 for cracks. Or Do PART 4: (OPTION 2) INTERNAL DETAILED AND EDDY CURRENT INSPECTIONS AT S-4R, BS 908 TO BS 1016 for cracks. **CONDITION 6: ANY CRACK FOUND** a. Contact Boeing for repair instructions and do the repair.
4. **Group 2-3, 5, 7:** Do PART 4: (OPTION 1) EXTERNAL EDDY CURRENT INSPECTION AT S-4R, BS 908 TO BS 1016 for cracks. Or Do PART 4: (OPTION 2) INTERNAL DETAILED AND EDDY CURRENT INSPECTIONS AT S-4R, BS 908 TO BS 1016 for cracks. **CONDITION 7: NO CRACK FOUND** a. Repeat inspection in PART 4: (OPTION 1) EXTERNAL EDDY CURRENT INSPECTION AT S-4R, BS 908 TO BS 1016 for cracks. Or Repeat inspections in PART 4: (OPTION 2) INTERNAL DETAILED AND EDDY CURRENT INSPECTIONS AT S-4R, BS 908 TO BS 1016 for cracks. **CONDITION 8: ANY CRACK FOUND** a. Contact Boeing for repair instructions and do the repair.
5. **Group 1, 4, 6:** Do PART 5: INTERNAL GENERAL VISUAL INSPECTION OF LOWER SKIN PANEL AT S-4R, BS 908 TO BS 1016 for open or closed pockets. **CONDITION 9: ANY CLOSED POCKETS FOUND ADJACENT TO THE S-4R LAP JOINT, BS 908 TO BS 1016**  a. No further work required at S-4R, BS 908 TO BS 1016.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 34 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT CONDITION 10: ANY OPEN POCKETS FOUND ADJACENT TO THE S-4R LAP JOINT, BS 908**  **TO BS 1016** a. Contact Boeing for inspections or repair instructions and do the work instructed by Boeing. **NOTE:** Depending on configuration information, the repair instructions may result in repetitive inspection instructions similar to Part 3 and Part 4 for Group 2-3, 5, and 7 airplanes. **PART 1: (OPTION 1) EXTERNAL EDDY CURRENT INSPECTION AT S-4L AND S-4R, BS 360 TO BS 908** 
1. **Group 1-2, 4-7:** Do the external eddy current inspection for cracks in the lower skin lap joint lower fastener row at S-4L and S-4R from BS 360 to BS 908 in accordance with FIGURE 5 inspection zones.
2. **Group 3:** Do the external eddy current inspection for cracks in the lower skin lap joint lower fastener row at S-4L and S-4R from BS 360 to BS 540 and BS 727E to BS 908 in accordance with FIGURE 6 inspection zones. 3. Do the external eddy current inspection for cracks along the centerline of the lap joint lower fastener row at stringers S-4L and S-4R in accordance with FIGURE 1. 4. Optional. Airplanes with any crack indication when external eddy current inspections are accomplished, do internal eddy current inspections at crack indication in accordance with FIGURE 3 to confirm crack indications. 5. Put the airplane back to a serviceable condition. **PART 1: (OPTION 2) INTERNAL DETAILED AND EDDY CURRENT INSPECTIONS AT S-4L AND S-4R, BS 360 TO BS 908**  1. Remove and keep interior equipment at the inspection body station locations. Refer to the applicable AMM reference below as an accepted procedure. **737-300/-400/-500 AMM Subject Equipment**  737-300/400/500 AMM 25-31-21 Galley No. 2 737-300/400/500 AMM 25-31-31 Galley No. 3 737-300/400/500 AMM 25-31-61 Galley No. 6 737-300/400/500 AMM 25-40-01 Lavatory 737-300/400/500 AMM 25-21-45 Sculptured Ceiling Panels 737-300/400/500 AMM 25-21-71 Lowered Ceiling Panels 737-300/400/500 AMM 25-21-39 Sidewall and Ceiling 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 21-23-25 Overhead Air Distribution Duct

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 35 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**2. **Group 1-2, 4-7:** a. Do internal detailed and eddy current inspections for cracks in the lower skin at the lap joint lower fastener row at S-4L and S-4R from BS 360 to BS 908 in accordance with FIGURE 5 inspection zones. 3. **Group 3:** a. Do internal detailed and eddy current inspections for cracks in the lower skin at the lap joint lower fastener row at S-4L and S-4R from BS 360 to BS 540 and BS 727E to BS 908 in accordance with FIGURE 6 inspection zones. 4. Do internal detailed and eddy current inspections for cracks in the lower skin at the lap joint lower fastener row at S-4L and S-4R in accordance with FIGURE 2. a. At locations where the stringer channel prevents the inspection probe from scanning 360 degrees around the fastener formed tail, do an internal eddy current inspection for cracks in the lower skin in accordance with FIGURE 2, View A-A. **NOTE:** Inspection procedures 737 NDT Manual Part 6, 53-30-12 and 737 NDT Manual Part 6, 53-30-16 show limited effectivity. The inspections applicable to the lower skin at the lap joint lower fastener row at stringers S-4L and S-4R in these procedures are applicable to the full effectivity in this service bulletin. 5. Install kept interior equipment at the inspection body station locations. Refer to the applicable AMM reference below as an accepted procedure. **737-300/-400/-500 AMM Subject Equipment**  737-300/400/500 AMM 25-31-21 Galley No. 2 737-300/400/500 AMM 25-31-31 Galley No. 3 737-300/400/500 AMM 25-31-61 Galley No. 6 737-300/400/500 AMM 25-40-01 Lavatory 737-300/400/500 AMM 25-21-45 Sculptured Ceiling Panels 737-300/400/500 AMM 25-21-71 Lowered Ceiling Panels 737-300/400/500 AMM 25-21-39 Sidewall and Ceiling 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 21-23-25 Overhead Air Distribution Duct 6. Put the airplane back to a serviceable condition. **PART 2: ONE-TIME INTERNAL DETAILED AND EDDY CURRENT INSPECTIONS AT S-4L AND S-4R, BS 360 TO BS 908**  1. Remove and keep interior equipment at the inspection body station locations. Refer to the applicable AMM reference below as an accepted procedure.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 36 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT NOTE:**  Accomplishment of the one-time internal inspection is an acceptable method of compliance for the accomplishment of one Option 1 or one Option 2 inspection specified in PART 1. **737-300/-400/-500 AMM Subject Equipment**  737-300/400/500 AMM 25-31-21 Galley No. 2 737-300/400/500 AMM 25-31-31 Galley No. 3 737-300/400/500 AMM 25-31-61 Galley No. 6 737-300/400/500 AMM 25-40-01 Lavatory 737-300/400/500 AMM 25-21-45 Sculptured Ceiling Panels 737-300/400/500 AMM 25-21-71 Lowered Ceiling Panels 737-300/400/500 AMM 25-21-39 Sidewall and Ceiling 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 21-23-25 Overhead Air Distribution Duct

2. **Group 1-2, 4-7:** a. Do internal detailed and eddy current inspections for cracks in the lower skin at the lap joint lower fastener row at S-4L and S-4R from BS 360 to BS 908 in accordance with FIGURE 5 inspection zones. 3. **Group 3:** a. Do internal detailed and eddy current inspections for cracks in the lower skin at the lap joint lower fastener row at S-4L and S-4R from BS 360 to BS 540 and BS 727E to BS 908 in accordance with FIGURE 6 inspection zones. 4. Do internal detailed and eddy current inspections for cracks in the lower skin at the lap joint lower fastener row at S-4L and S-4R in accordance with FIGURE 2. a. At locations where the stringer channel prevents the inspection probe from scanning 360 degrees around the fastener formed tail, do an internal eddy current inspection for cracks in the lower skin in accordance with FIGURE 2, View A-A. **NOTE:** Inspection procedures 737 NDT Manual Part 6, 53-30-12 and 737 NDT Manual Part 6, 53-30-16 show limited effectivity. The inspections applicable to the lower skin at the lap joint lower fastener row at stringers S-4L and S-4R in these procedures are applicable to the full effectivity in this service bulletin. 5. Install kept interior equipment at the inspection body station locations. Refer to the applicable AMM reference below as an accepted procedure. **737-300/-400/-500 AMM Subject Equipment**  737-300/400/500 AMM 25-31-21 Galley No. 2 737-300/400/500 AMM 25-31-31 Galley No. 3

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 37 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT 737-300/-400/-500 AMM Subject**  **Equipment** 737-300/400/500 AMM 25-31-61 Galley No. 6 737-300/400/500 AMM 25-40-01 Lavatory 737-300/400/500 AMM 25-21-45 Sculptured Ceiling Panels 737-300/400/500 AMM 25-21-71 Lowered Ceiling Panels 737-300/400/500 AMM 25-21-39 Sidewall and Ceiling 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 21-23-25 Overhead Air Distribution Duct 6. Put the airplane back to a serviceable condition. **Group 2-3, 5, 7: PART 3: ONE-TIME INTERNAL DETAILED AND EDDY CURRENT INSPECTIONS AT S-4R, BS**  **908 TO BS 1016** 1. Remove and keep interior equipment at S-4R from BS 908 to BS 1016. Refer to the applicable AMM reference below as an accepted procedure. **737-300/-400/-500 AMM Subject Equipment**  737-300/400/500 AMM 25-31-31 Galley No. 3 737-300/400/500 AMM 25-40-01 Lavatory 737-300/400/500 AMM 25-21-45 Sculptured Ceiling Panels 737-300/400/500 AMM 25-21-71 Lowered Ceiling Panels 737-300/400/500 AMM 25-21-39 Sidewall and Ceiling 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 21-23-25 Overhead Air Distribution Duct 2. Do internal detailed and eddy current inspections for cracks in the lower skin at the lap joint lower fastener row at stringer S-4R from BS 908 to BS 1016 in accordance with FIGURE 7 inspection zones. 3. Do internal detailed and eddy current inspections for cracks in the lower skin at the lap joint lower fastener row at S-4R in accordance with FIGURE 2. a. At locations where the stringer channel prevents the inspection probe from scanning 360 degrees around the fastener formed tail, do an internal eddy current inspection for cracks in the lower skin in accordance with FIGURE 2, View A-A.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 38 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT NOTE:**  Inspection procedures 737 NDT Manual Part 6, 53-30-12 and 737 NDT Manual Part 6, 53-30-16 show limited effectivity. The inspections applicable to the lower skin at the lap joint lower fastener row at stringer S-4R in these procedures are applicable to the full effectivity in this service bulletin. 4. Install kept interior equipment at the inspection body station locations. Refer to the applicable AMM reference below as an accepted procedure. **737-300/-400/-500 AMM Subject Equipment**  737-300/400/500 AMM 25-31-31 Galley No. 3 737-300/400/500 AMM 25-40-01 Lavatory 737-300/400/500 AMM 25-21-45 Sculptured Ceiling Panels 737-300/400/500 AMM 25-21-71 Lowered Ceiling Panels 737-300/400/500 AMM 25-21-39 Sidewall and Ceiling 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 21-23-25 Overhead Air Distribution Duct 5. Put the airplane back to a serviceable condition. **Group 2-3, 5, 7: PART 4: (OPTION 1) EXTERNAL EDDY CURRENT INSPECTION AT S-4R, BS 908 TO BS 1016**  1. Do the external eddy current inspection for cracks in the lower skin lap joint lower fastener row at stringer S-4R from BS 908 to BS 1016 in accordance with FIGURE 7 inspection zones. 2. Do the external eddy current inspection for cracks along the centerline of the lower skin at the lap joint lower fastener row at stringer S-4R from BS 908 to BS 1016 in accordance with FIGURE 1. 3. Optional. Airplanes with any crack indication when external eddy current inspections are accomplished, do internal eddy current inspections at crack indication in accordance with FIGURE 3 to confirm crack indications. 4. Put the airplane back to a serviceable condition. **Group 2-3, 5, 7: PART 4: (OPTION 2) INTERNAL DETAILED AND EDDY CURRENT INSPECTIONS AT S-4R, BS**  **908 TO BS 1016** 1. Remove and keep interior equipment at S-4R from BS 908 to BS 1016. Refer to the applicable AMM reference below as an accepted procedure. **737-300/-400/-500 AMM Subject Equipment**  737-300/400/500 AMM 25-31-31 Galley No. 3 737-300/400/500 AMM 25-40-01 Lavatory 737-300/400/500 AMM 25-21-45 Sculptured Ceiling Panels

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 39 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT 737-300/-400/-500 AMM Subject**  **Equipment** 737-300/400/500 AMM 25-21-71 Lowered Ceiling Panels 737-300/400/500 AMM 25-21-39 Sidewall and Ceiling 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 21-23-25 Overhead Air Distribution Duct 2. Do internal detailed and eddy current inspections for cracks in the lower skin at the lap joint lower fastener row at stringer S-4R from BS 908 to BS 1016 in accordance with FIGURE 7 inspection zones. 3. Do internal detailed and eddy current inspections for cracks in the lower skin at the lap joint lower fastener row at S-4R in accordance with FIGURE 2. a. At locations where the stringer channel prevents the inspection probe from scanning 360 degrees around the fastener formed tail, do an internal eddy current inspection for cracks in the lower skin in accordance with FIGURE 2, View A-A. **NOTE:** Inspection procedures 737 NDT Manual Part 6, 53-30-12 and 737 NDT Manual Part 6, 53-30-16 show limited effectivity. The inspections applicable to the lower skin at the lap joint lower fastener row at stringer S-4R in these procedures are applicable to the full effectivity in this service bulletin. 4. Install kept interior equipment at the inspection body station locations. Refer to the applicable AMM reference below as an accepted procedure. **737-300/-400/-500 AMM Subject Equipment**  737-300/400/500 AMM 25-31-31 Galley No. 3 737-300/400/500 AMM 25-40-01 Lavatory 737-300/400/500 AMM 25-21-45 Sculptured Ceiling Panels 737-300/400/500 AMM 25-21-71 Lowered Ceiling Panels 737-300/400/500 AMM 25-21-39 Sidewall and Ceiling 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 21-23-25 Overhead Air Distribution Duct 5. Put the airplane back to a serviceable condition. **Group 1, 4, 6: PART 5: INTERNAL GENERAL VISUAL INSPECTION OF LOWER SKIN PANEL AT S-4R, BS 908**  **TO BS 1016** 1. Remove and keep interior equipment at S-4R from BS 908 to BS 1016. Refer to the applicable AMM reference below as an accepted procedure.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 40 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT 737-300/-400/-500 AMM Subject**  **Equipment** 737-300/400/500 AMM 25-31-31 Galley No. 3 737-300/400/500 AMM 25-40-01 Lavatory 737-300/400/500 AMM 25-21-45 Sculptured Ceiling Panels 737-300/400/500 AMM 25-21-71 Lowered Ceiling Panels 737-300/400/500 AMM 25-21-39 Sidewall and Ceiling 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 21-23-25 Overhead Air Distribution Duct 2. Do an internal general visual inspection of the lower skin panel at S-4R, from BS 908 to BS 1016 for open or closed pockets adjacent to the S-4R lap joint in accordance with FIGURE 7 inspection zones. 3. Do an internal general visual inspection of the lower skin panel at S-4R, from BS 908 to BS 1016 for open or closed pockets adjacent to the S-4R lap joint in accordance with FIGURE 8. 4. Install kept interior equipment at the inspection body station locations. Refer to the applicable AMM reference below as an accepted procedure. **737-300/-400/-500 AMM Subject Equipment**  737-300/400/500 AMM 25-31-31 Galley No. 3 737-300/400/500 AMM 25-40-01 Lavatory 737-300/400/500 AMM 25-21-45 Sculptured Ceiling Panels 737-300/400/500 AMM 25-21-71 Lowered Ceiling Panels 737-300/400/500 AMM 25-21-39 Sidewall and Ceiling 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 21-23-25 Overhead Air Distribution Duct 5. Put the airplane back to a serviceable condition.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2: April 04, 2014 41 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT FIGURE 1: EXTERNAL INSPECTION**  **(SHEET 1 OF 2)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 42 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  (a)

- - Crown Lap Joints Lower Skin Inspect 1 (a) Do an external eddy current inspection for cracks along the centerline of the lap joint lower fastener row in accordance with 737 NDT Manual Part 6, 53-30-00 Procedure 9.

**FIGURE 1: EXTERNAL INSPECTION (SHEET 2 OF 2)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 43 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT FIGURE 2: INTERNAL INSPECTION**  **(SHEET 1 OF 4)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 44 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT FIGURE 2: INTERNAL INSPECTION**  **(SHEET 2 OF 4)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 45 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  Between tear straps (a) (b) (e) - - Crown Lap Joints Lower Skin Inspect 1 At tear straps (a) (c) (e)

- - Crown Lap Joints Lower Skin Inspect 2

Where lower skin doubler is not chem-milled at the lap joint (a) (d) (e) - - Crown Lap Joints Lower Skin Inspect 3

(a) Do a Detailed Inspection of the lap joint lower fastener row for cracks. (b) Do an internal Mid Frequency Eddy Current (MFEC) inspection for cracks in the lap joint lower fastener row between tear straps in accordance with 737 NDT Manual Part 6, 53-30-16. (c) Do an internal Low Frequency Eddy Current (LFEC) inspection for cracks in the lap joint lower fastener row through the tear strap in accordance with 737 NDT Manual Part 6, 53-30-12. (d) Do an internal Low Frequency Eddy Current (LFEC) inspection for cracks in the lap joint lower fastener row through the lower doubler in accordance with 737 NDT Manual Part 6, 53-30-12.

**FIGURE 2: INTERNAL INSPECTION (SHEET 3 OF 4)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 46 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** (e) View A-A provides an alternative inspection method to note (b), (c), or (d) the full 360-degree probe scanning around the fastener formed tail that is obstructed by the internal structures. View A-A is illustratedfor between tear straps, but the method can be used at tear straps and where the lower skin is not chemmilled at the lap joint.

**FIGURE 2: INTERNAL INSPECTION (SHEET 4 OF 4)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 47 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT FIGURE 3: CONFIRMING A CRACK INDICATION**  **(SHEET 1 OF 4)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 48 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT FIGURE 3: CONFIRMING A CRACK INDICATION**  **(SHEET 2 OF 4)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 49 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  Between tear straps (a) (d)

- - Crown Lap Joints Lower Skin Inspect 1 At tear straps (b) (d)

- - Crown Lap Joints Lower Skin Inspect 2

Where lower skin doubler is not chem-milled at the lap joint (c) (d) - - Crown Lap Joints Lower Skin Inspect 3

(a) If there was a crack indication at this location as a result of the external eddy current inspection: Do aninternal Mid Frequency Eddy Current (MFEC) inspection for cracks in the lap joint lower fastener row between tear straps in accordance with 737 NDT Manual Part 6, 53-30-16. (b) If there was a crack indication at this location: Do an internal Low Frequency Eddy Current (LFEC) inspection for cracks in the lap joint lower fastener row through the tear strap in accordance with 737 NDT Manual Part 6, 53-30-12. (c) If there was a crack indication at this location: Do an internal Low Frequency Eddy Current (LFEC) inspectionfor cracks in the lap joint lower fastener row through the lower doubler in accordance with 737 NDT Manual Part 6, 53-30-12.

**FIGURE 3: CONFIRMING A CRACK INDICATION (SHEET 3 OF 4)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 50 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** (d) View A-A provides an alternative inspection method to note (a), (b), or (c) the full 360-degree probe scanning around the fastener formed tail that is obstructed by the internal structures. View A-A is illustratedfor between tear straps, but the method can be used at tear straps and where the lower skin is not chemmilled at the lap joint.

**FIGURE 3: CONFIRMING A CRACK INDICATION (SHEET 4 OF 4)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 51 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT FIGURE 4: FIGURE DELETED AT REVISION 2**  **(SHEET 1 OF 1)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 52 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT This Figure applies only to: Group 1-2, 4-7.** 

**FIGURE 5: INSPECTION ZONES (SHEET 1 OF 3)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 53 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT FIGURE 5: INSPECTION ZONES**  **(SHEET 2 OF 3)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 54 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT FIGURE 5: INSPECTION ZONES**  **(SHEET 3 OF 3)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 55 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT This Figure applies only to: Group 3.** 

**FIGURE 6: INSPECTION ZONES (SHEET 1 OF 1)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 56 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT FIGURE 7: INSPECTION ZONES**  **(SHEET 1 OF 3)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 57 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT FIGURE 7: INSPECTION ZONES**  **(SHEET 2 OF 3)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 58 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT FIGURE 7: INSPECTION ZONES**  **(SHEET 3 OF 3)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 59 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT This Figure applies only to: Group 1, 4, 6.** 

**FIGURE 8: INTERNAL GENERAL VISUAL INSPECTION - LOWER SKIN PANEL AT S-4R, BS 908 TO BS 1016**  **(SHEET 1 OF 3)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 60 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT FIGURE 8: INTERNAL GENERAL VISUAL INSPECTION - LOWER SKIN PANEL AT S-4R, BS 908 TO BS**  **1016 (SHEET 2 OF 3)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 61 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  (a)

- - Lower Skin Panel Inspect 1 (a) Do an Internal General Visual Inspection of the lower skin panel at S-4R, from STA 908 to STA 1016 for any open or closed pockets adjacent to the S-4R lap joint.

**FIGURE 8: INTERNAL GENERAL VISUAL INSPECTION - LOWER SKIN PANEL AT S-4R, BS 908 TO BS 1016**  **(SHEET 3 OF 3)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 2011 737-53A1319 Revision 2 April 04, 2014 62 of 62 **BOEING SERVICE BULLETIN 737-53A1319 ALERT**  **ALERT**