### Commercial **Airplanes** 

# 737 Service Bulletin
**Number: 737-53-1058** Original Issue: April 04, 1980 Revision 4: January 09, 2014 ATA System: 5313 **SUBJECT:** FUSELAGE - Forward Airstair Stowage Doorway Inspection, Preventive Modification and Repair 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 © 1989 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 Unpublished Work.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, 1980 737-53-1058 Revision 4: January 09, 2014 1 of 81 4.0Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 2 of 81 **BOEING SERVICE BULLETIN 737-53-1058**

BLANK PAGE**Table of Contents** Revision Transmittal Sheet............................................ 5 Summary...................................................... 7 1. PLANNING INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 A. Effectivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1. Airplanes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2. Spares Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 B. Concurrent Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 C. Reason. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 D. Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 E. Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 F. Approval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 G. Manpower. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 H. Weight and Balance Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 I. Electrical Load Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 J. References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 1. Existing Data:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 2. Data Supplied with this Service Bulletin:. . . . . . . . . . . . . . . . . . . . . . . . . . . 36 3. Installation Drawings Used in the Preparation of this Service Bulletin:. . . . . . . . . . . 36 K. Publications Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 L. Interchangeability and Intermixability of Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . 36 M. Software Accomplishment Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 2. MATERIAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 A. Material - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 B. Industry Support Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 C. Parts Necessary for Each Airplane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 1. Kits/Parts:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 2. Parts and Materials Supplied by the Operator:. . . . . . . . . . . . . . . . . . . . . . . . 41 3. Parts Modified and Reidentified:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 4. Parts Removed and Not Replaced:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 D. Parts Necessary to Change Spares. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 F. Special Tooling Necessary to do this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . 41 3. ACCOMPLISHMENT INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 A. GENERAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 B. WORK INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 FIGURE 1: THIS FIGURE HAS BEEN REMOVED. . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 FIGURE 2: THIS FIGURE HAS BEEN REMOVED. . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 FIGURE 3: THIS FIGURE HAS BEEN REMOVED. . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 FIGURE 4: AIRSTAIR STOWAGE DOORWAY CORNER - LOCATION OF INSPECTION AREAS [Group 1-5]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 FIGURE 5: AIRSTAIR STOWAGE DOORWAY CORNER - INTERNAL INSPECTION OF THE BEARSTRAP [Group 1-5]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 FIGURE 6: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - NO PREVENTIVE MODIFICATION OR EXTERNAL TRIPLER INSTALLED [Group 1-2]. . . . . . . . . . . . . . . . . . . . . 62 FIGURE 7: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - PREVENTIVE MODIFICATION TRIPLER INSTALLED PER ORIGINAL ISSUE OF THIS SERVICE BULLETIN [Group 1-2] . 64

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 3 of 81 **BOEING SERVICE BULLETIN 737-53-1058**FIGURE 8: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - PREVENTIVE MODIFICATION TRIPLER INSTALLED PER REVISION 1, 2 OR 3 OF THIS SERVICE BULLETIN [Group 1-2] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 FIGURE 9: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - PRODUCTION MODIFICATION EXTERNAL TRIPLER INSTALLED [Group 3-5]. . . . . . . . . . . . . . . . . . . . . . . 68 FIGURE 10: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - REPAIR INSTALLED AT THE ORIGINAL ISSUE OF THIS SERVICE BULLETIN [Group 1]. . . . . . . . . . . . . . . . 70 FIGURE 11: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - REPAIR INSTALLED AT THE ORIGINAL ISSUE OF THIS SERVICE BULLETIN [Group 2]. . . . . . . . . . . . . . . . 73 FIGURE 12: AIRSTAIR STOWAGE DOORWAY CORNER - AREA OF CUTOUT FOR CRACK REMOVAL [Group 1-5]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 FIGURE 13: POST REPAIR AND POST PREVENTIVE MODIFICATION INSPECTION - OPTION A [Group 1-5]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 FIGURE 14: POST REPAIR AND POST PREVENTIVE MODIFICATION INSPECTION - OPTION B [Group 1-5]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 4 of 81 **BOEING SERVICE BULLETIN 737-53-1058**

### Commercial **Airplanes** 

# 737 Service Bulletin **Revision Transmittal Sheet Number: 737-53-1058**  Original Issue: April 04, 1980 Revision 4: January 09, 2014 ATA System: 5313 **SUBJECT:** FUSELAGE - Forward Airstair Stowage Doorway Inspection, Preventive Modification and Repair This revision includes all pages of the service bulletin. **COMPLIANCE INFORMATION RELATED TO THIS REVISION** More work is necessary on airplanes changed in accordance with the original issue or Revisions 1, 2 or 3 of this service bulletin. Airplanes with a repair installed in accordance with the original issue or preventive modification installed in accordance with the original issue or Revision 1, 2 or 3 of this service bulletin require additional inspections. 737 airplanes with a forward airstair stowage doorway, Line Numbers 599 and 640 thru 3132 are added to this service bulletin effectivity. Federal Aviation Administration (FAA) Airworthiness Directive AD 90-06-02, AD 98-11-04 R1, AD 2008-08-23 and AD 2008-09-13 are related to this service bulletin. **REASON FOR REVISION** This revision is sent to supply the operator with new inspection instructions and new repair and preventive modification kits for all airplanes. The new kits provide a different doubler profile to address the fuselage skin cracking below the lower aft corner of the forward airstair stowage door cutout. Terminology has been changed in the Work Instructions to agree with the terminology defined in Paragraph 3.A., General Information - Notes. These sections were changed: 1. Summary - Background section service history is updated. 2. Summary - Planning table is added. 3. Summary - Action section is updated. 4. Summary - Effectivity section, new airplane models are added. 5. Paragraph 1.C., Reason - Service history is updated 6. Paragraph 1.D., Description - New instructions are added and maintenance zone tables are added. 7. Paragraph 1.E., Compliance - New section is added.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 5 of 818. Paragraph 1.F., Approval - Alternative method of compliance paragraphs are added. 9. Paragraph 1.G., Manpower - Section is updated 10. Paragraph 1.H., Weight and Balance Changes - Section is updated for new repairs and preventive modifications. New airplane models are added. 11. Paragraph 1.J., References - Section is updated 12. Paragraph 1.K.2, Damage Tolerance Based Structural Inspections - Section is added. 13. Paragraph 1.M., Software Accomplishment Summary - Section is added. 14. Paragraph 2.A., Material - Price and Availability - New kits are added. 15. Paragraph 2.C.1, Kits/Parts - New kits are added. 16. Paragraph 2.C.2, Parts and Materials Supplied by the Operator - New parts are added. 17. Paragraph 3.A., GENERAL INFORMATION, added new standard notes. 18. Paragraph 3.B., WORK INSTRUCTIONS, added new instructions for all airplanes. 19. FIGURE 1, 2 and FIGURE 3, have been deleted. 20. FIGURE 4 thru FIGURE 14, have been added. Paragraph 1.A., Effectivity, shows changes of airplane operators. Each operator should examine the Effectivity paragraph for changes. Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity and format changes, to show the location of all content changes. Pages with no vertical lines have no important changes. **REVISION HISTORY** April 04, 1980 Original Issue: March 05, 1987 Revision 1: December 07, 1989 Revision 2: March 11, 1993 Revision 3: January 09, 2014 Revision 4:

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 6 of 81 **BOEING SERVICE BULLETIN 737-53-1058**

### Commercial **Airplanes** 

# 737 Service Bulletin **Summary Number: 737-53-1058**  Original Issue: April 04, 1980 Revision 4: January 09, 2014 ATA System: 5313 **SUBJECT:** FUSELAGE - Forward Airstair Stowage Doorway Inspection, Preventive Modification and Repair **CONCURRENT REQUIREMENTS** None. **BACKGROUND** Operators have reported cracks in the skin assembly and in the bearstrap at the aft lower corner of the forward airstair stowage doorway. The cracks, caused by fatigue from cyclic pressurization loading, originated in the radius of the doorway corner and ranged in length from 0.50 to 2.75 inches. Since the release of Revision 3, skin cracking was also found outside the existing inspection area at fastener holes in the skin assembly about 5 inches below the radius of the corner. At the time of crack detection the airplanes had accumulated between 16,177 and 74,036 total flight cycles. Continued operation with undetected doorway corner cracks could result in pressurization difficulties and unscheduled downtime for repairs. Based on a structural review of the 737 airplane, incorporation of the preventive modification per this service bulletin is recommended on aging airplanes. Since the original issue of this bulletin, two operators have reported subsequent crack growth on two airplanes with the crack repair installed in accordance with the original issue of this service bulletin. Since the release of Revision 3 there have also been reports of cracking on airplanes that are beyond the effectivity of the original issue and Revisions 1, 2, or 3 of this service bulletin. Boeing has received 20 reports of skin cracking at the aft lower corner of the forward airstair stowage doorway which ranged in length from 0.30 to 2.20 inches. The earliest report was on an airplane that had accumulated 22,328 total flight cycles. Boeing has also received 7 reports of skin cracking at fastener locations about 5 inches below the lower aft corner of the airstair cutout. The earliest report was on an airplane that had accumulated 42,120 total flight cycles. The maximum crack length found was 0.125 inches on an airplane that had accumulated 56,123 total flight cycles. Boeing Service Related Problem (SRP) 737-SRP-53-0381 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

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 7 of 81**Reference Affected**  **Planning Data** Paragraph 1.H., Weight and Balance Changes Yes 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 Yes Kits/Parts Required Paragraph 2.C.2., Parts and Materials Supplied by the Operator Yes Operator Supplied Material Paragraph 2.F., Special Tooling Necessary to do this Service Bulletin No Special Tooling Required
**ACTION (PRR 32882, PRR 35005-249RS)** Get access to the airstair stowage doorway area. At the times specified in Paragraph 1.E., Compliance, do High Frequency Eddy Current (HFEC), Low Frequency Eddy Current (LFEC) and detailed inspections of the bearstrap and skin assembly for any crack. If no crack is found, install the preventive modification in accordance with this service bulletin or do repeat inspections at the times given in Paragraph 1.E., Compliance. If any crack is found in the skin assembly or bearstrap, install the permanent repair in accordance with this service bulletin or contact The Boeing Company for repair instructions and do the repair. For repairs installed in accordance with original release or preventive modification installed in accordance with original release, revision 1, 2 or 3, do the inspection at the times specified in Paragraph 1.E., Compliance. If any crack is found, contact The Boeing Company for repair instructions and do the repair. On Group 6 airplanes, contact The Boeing Company to get instructions for the inspection, change and/or repair for this service bulletin, 737-53-1058 Revision 4, and do the instructions. **EFFECTIVITY** 737-100/-200/-200C/-300/-400/-500 Airplane(s) with a forward airstair stowage doorway. Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplane(s). **COMPLIANCE** Federal Aviation Administration (FAA) Airworthiness Directive AD 90-06-02, AD 98-11-04 R1, AD 2008-08-23 and AD 2008-09-13 are related to this service bulletin. The 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. On Group 6 airplanes, contact The Boeing Company to get instructions for the inspection, change and/or repair for this service bulletin, 737-53-1058 Revision 4, and do the instructions.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 8 of 81 **BOEING SERVICE BULLETIN 737-53-1058**Refer to Paragraph 1.E., Compliance. **INDUSTRY SUPPORT INFORMATION** Boeing warranty remedies are not available for the inspection, repair and preventive modification procedures given in this service bulletin. **MANPOWER** Refer to Paragraph 1.G., Manpower. **MATERIAL INFORMATION** Boeing Supplied Kits. Refer to Paragraph 2.A., Material - Price and Availability.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 9 of 81 **BOEING SERVICE BULLETIN 737-53-1058**Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 10 of 81 **BOEING SERVICE BULLETIN 737-53-1058**

### Commercial **Airplanes** 

# 737 Service Bulletin
**Number: 737-53-1058** Original Issue: April 04, 1980 Revision 4: January 09, 2014 ATA System: 5313 **SUBJECT:** FUSELAGE - Forward Airstair Stowage Doorway Inspection, Preventive Modification 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. Refer to PRR 35005-249RS for data about this change.
**DESCRIPTION CONFIGURATION**  **GROUP** Passenger airplanes line numbers 292 thru 598 and 600 thru 639 with a forward airstair stowage doorway. These airplanes have a bonded skin structure at the lower aft corner of the airstair stowage doorway. - 1

Cargo airplanes line numbers 292 thru 639 with a forward airstair stowage doorway. These airplanes have a bonded skin structure at the lower aft corner of the airstair stowage doorway. - 2

Passenger airplanes line numbers 599 and 640 thru 1922 with a forward airstair stowage doorway. These airplanes have a bonded skin structure at the lower aft corner of the airstair stowage doorway. - 3

Cargo airplanes line numbers 640 thru 1113 with a forward airstair stowage doorway. These airplanes have a bonded skin structure at the lower aft corner of the airstair stowage doorway. - 4

Passenger airplanes line numbers 1923 thru 3132 with a forward airstair stowage doorway. These airplanes have a solid skin structure at the lower aft corner of the airstair stowage doorway. - 5

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 11 of 81**DESCRIPTION CONFIGURATION**  **GROUP** Airplanes line numbers 1-291 with a forward airstair stowage doorway. These airplanes have a cold bonded skin. - 6

Airplane Models: 737-100, 737-200, 737-200C, 737-300, 737-400, 737-500 **Group Variable Number**  6 PA001 - PA022 6 PA099 6 PA231 - PA232 6 PC001 - PC005 6 PG001 - PG075 6 PG199 6 PG201 - PG230 6 PG251 - PG255 6 PG271 - PG279 6 PG301 - PG314 6 PG331 - PG332 6 PG351 - PG356 6 PG375 6 PG401 - PG403 6 PG431 - PG442 6 PG471 - PG475 6 PG501 - PG505 6 PG571 - PG583 1 PG584 - PG586 6 PG621 - PG630 6 PG651 - PG652 6 PG701 - PG705 1 PH001 1 PH011 - PH013 1 PH021 - PH024 6 PH701 - PH715

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 12 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group**  **Variable Number** 6 PH731 - PH732 6 PH741 - PH742 1 PH743 6 PJ001 - PJ002 1 PJ003 - PJ009 6 PJ031 - PJ032 6 PJ071 - PJ072 6 PJ101 - PJ104 1 PJ105 - PJ116 3 PJ117 - PJ119 1 PJ201 - PJ219 5 PJ816 - PJ817 1 PK026 - PK029 1 PK047 1 PK051 1 PK061 - PK070 1 PK081 3 PK082 1 PK091 - PK099 1 PK101 - PK103 1 PK111 - PK120 1 PK141 - PK146 1 PK201 - PK203 3 PK204 1 PK211 - PK213 3 PK214 - PK220 1 PK221 - PK223 1 PK231 - PK235 3 PK236 - PK240 1 PK241 1 PK251 - PK258 1 PK271 - PK273 3 PK274

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 13 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group**  **Variable Number** 1 PK281 - PK282 3 PK283 - PK284 1 PK285 - PK289 1 PK291 1 PK301 - PK306 3 PK307 - PK310 1 PK311 - PK318 1 PK341 1 PK351 - PK358 3 PK359 - PK361 1 PK391 1 PK451 - PK452 1 PK461 - PK469 1 PK495 1 PK501 3 PK502 - PK504 1 PK511 - PK512 3 PK513 - PK515 3 PK519 1 PK521 - PK523 3 PK524 - PK528 1 PK541 - PK551 3 PK552 - PK560 1 PK561 - PK562 3 PK563 - PK565 1 PK581 1 PK591 - PK597 3 PK598 - PK599 3 PK601 - PK610 1 PK611 - PK613 3 PK614 - PK617 1 PK621 - PK622 3 PK623 - PK637

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 14 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group**  **Variable Number** 1 PK641 - PK642 1 PK661 3 PK662 - PK666 1 PK671 3 PK672 - PK681 1 PK691 - PK693 3 PK694 - PK697 1 PK711 - PK716 3 PK731 1 PK732 - PK734 3 PK735 - PK765 3 PK771 - PK779 3 PK801 - PK804 3 PK819 - PK820 1 PK821 3 PK822 - PK827 3 PK830 1 PK861 3 PK862 - PK863 3 PK871 - PK874 3 PK881 - PK884 3 PK901 - PK910 1 PL001 - PL017 3 PL018 - PL028 3 PL061 3 PL081 3 PL151 3 PL171 - PL172 3 PL201 - PL203 3 PL221 1 PL401 - PL403 3 PL404 - PL417 1 PL421

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 15 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group**  **Variable Number** 1 PL441 3 PL451 - PL456 3 PL471 3 PL491 3 PL501 - PL506 3 PL551 - PL562 3 PL581 3 PL601 - PL603 3 PL611 3 PL621 - PL626 3 PL631 - PL632 6 PL711 - PL712 6 PL716 1 PL717 - PL735 1 PL756 1 PL761 - PL770 1 PL781 - PL782 3 PL783 - PL788 1 PL793 6 PL801 - PL803 3 PM001 - PM006 3 PM016 - PM017 3 PM021 - PM023 3 PM051 - PM066 3 PM101 - PM119 3 PM141 - PM142 3 PM171 3 PM181 3 PM251 - PM255 3 PM281 - PM283 3 PM381 - PM392 5 PM393 - PM399 5 PM401 - PM417

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 16 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group**  **Variable Number** 5 PM541 - PM564 3 PN001 - PN002 3 PN021 - PN043 3 PN081 - PN086 3 PN101 - PN117 3 PN131 - PN163 3 PN431 - PN433 3 PN451 - PN456 3 PN471 - PN474 3 PN481 3 PN491 - PN493 3 PN501 - PN502 3 PN511 - PN512 3 PN521 3 PP101 3 PP201 - PP205 3 PP221 3 PP351 - PP353 3 PP376 - PP384 3 PP391 - PP393 3 PP501 - PP510 5 PP511 - PP520 3 PP521 - PP522 3 PP651 - PP652 3 PP801 - PP808 3 PP821 - PP827 3 PP831 - PP848 3 PP851 - PP852 3 PP891 - PP899 3 PP901 - PP924 5 PP925 - PP930 3 PP931 - PP936 3 PP946 - PP948

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 17 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group**  **Variable Number** 3 PP951 - PP952 3 PP993 3 PQ221 - PQ229 5 PQ230 3 PQ241 - PQ243 3 PQ251 - PQ255 5 PQ256 - PQ267 3 PQ281 - PQ286 5 PQ287 - PQ291 5 PQ298 5 PQ361 - PQ373 5 PQ391 - PQ395 5 PQ401 - PQ418 5 PQ421 5 PQ447 - PQ448 5 PQ472 - PQ475 5 PQ951 5 PQ971 - PQ997 5 PR001 - PR017 5 PR021 - PR030 5 PR081 - PR082 5 PR091 - PR092 5 PR096 5 PR101 5 PR121 - PR122 5 PR131 - PR132 5 PR141 - PR143 5 PR161 - PR172 5 PS601 - PS631 5 PS636 - PS638 3 PS641 - PS642 5 PS651 - PS657 5 PS811

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 18 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group**  **Variable Number** 5 PS836 - PS837 5 PS841 - PS846 5 PS851 - PS852 5 PS856 5 PS861 - PS863 5 PS866 - PS868 5 PS871 - PS874 5 PS896 - PS897 5 PS956 - PS957 5 PS961 - PS963 5 PS971 - PS978 5 PT041 - PT064 3 PT121 - PT123 5 PT124 - PT138 3 PT146 5 PT147 - PT148 5 PT161 - PT170 3 PT181 - PT182 5 PT183 - PT185 3 PT211 - PT214 5 PT215 - PT220 3 PT295 5 PT501 - PT517 5 PT671 - PT672 5 PT721 - PT725 5 PT871 - PT886 5 PT996 5 PU301 5 PU311 - PU313 5 PV296 5 PV301 - PV302 5 PV356 - PV357 3 PW001 - PW036

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 19 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group**  **Variable Number** 5 PW037 - PW050 3 PW051 5 PW052 - PW054 3 PW061 5 PW072 5 PW086 - PW088 3 PW091 - PW093 5 PW094 5 PW101 - PW102 5 PW106 3 PW111 - PW117 5 PW118 - PW120 5 PW156 - PW157 3 PW161 - PW162 5 PW163 - PW171 5 PW261 - PW268 5 PW271 - PW276 5 PW278 5 PW281 - PW293 5 PW296 5 PW301 - PW327 3 PW501 - PW503 5 PW504 5 PW556 - PW557 3 PW591 - PW594 5 PW595 - PW596 3 PW661 5 PW662 5 PW701 - PW702 5 PW741 - PW742 5 PW831 5 PW851 - PW856 6 PX071

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 20 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group**  **Variable Number** 6 PY031 2 PY051 - PY053 2 PY101 - PY103 2 PY161 2 PY221 - PY222 2 PY231 2 PY281 2 PY286 6 PY321 - PY323 6 PY341 - PY346 6 PY361 - PY362 6 PY381 2 PY411 4 PY441 2 PY611 - PY612 2 PY621 4 PY631 4 PY651 4 PY741 2. Spares Affected None **B. Concurrent Requirements** None. **C. Reason** Operators have reported cracks in the skin assembly and in the bearstrap at the aft lower corner of the forward airstair stowage doorway. The cracks, caused by fatigue from cyclic pressurization loading, originated in the radius of the doorway corner and ranged in length from 0.50 to 2.75 inches. Since the release of Revision 3, skin cracking was also found outside the existing inspection area at fastener holes in the skin assembly about 5 inches below the radius of the corner. At the time of crack detection the airplanes had accumulated between 16,177 and 74,036 total flight cycles. Continued operation with undetected doorway corner cracks could result in pressurization difficulties and unscheduled downtime for repairs.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 21 of 81 **BOEING SERVICE BULLETIN 737-53-1058**As a result of the FAA sponsored Aging Fleet Conference, a 737 Structures Working Group with Airline and Boeing members and FAA observers was formed to review structural service bulletin modifications and recommend selected bulletins for incorporation of aging airplanes. This service bulletin preventive modification has been recommended for incorporation on aging 737 airplanes. Inspection and preventive modification as given in this service bulletin will provide timely crack detection in the forward airstair stowage doorway and reduce the possibility of future corner cracks. Since the original issue of this bulletin, two operators have reported subsequent crack growth on two airplanes with the crack repair installed in accordance with the original issue of this service bulletin. Since the release of Revision 3 there have also been reports of cracking on airplanes that are beyond the effectivity of the original issue and Revisions 1, 2, or 3 of this service bulletin. Boeing has received 20 reports of skin cracking at the aft lower corner of the forward airstair stowage doorway which ranged in length from 0.30 to 2.20 inches. The earliest report was on an airplane that had accumulated 22,328 total flight cycles. Boeing has also received 7 reports of skin cracking at fastener locations about 5 inches below the lower aft corner of the airstair cutout. The earliest report was on an airplane that had accumulated 42,120 total flight cycles. The maximum crack length found was 0.125 inches on an airplane that had accumulated 56,123 total flight cycles. Boeing Service Related Problem (SRP) 737-SRP-53-0381 is related to this service bulletin. Terminology has been changed in the Work Instructions to agree with the terminology defined in Paragraph 3.A., General Information - Notes. Revision 1 was issued to provide improved preventive modification and repair information and to call for inspection of airplanes repaired per the original issue. Notice of Status Change dated November 21, 1980 was incorporated in Revision 1. Revision 2 of this bulletin was issued to provide the recommendations of the Aging Fleet 737 Structures Working Group. Revision 3 was sent to supply the operator with supplemental kits and new kit information. The new kits and supplemental kits supplied larger parts with material for additional edge margin. The supplemental fastener kit was added to supply oversize fasteners when the new repair replaces the original issue repair. Also, the repeat inspection interval was changed from "C" check to 4,500 flight cycles. This revision also clarified the procedure of the inspection and crack termination in FIGURE 1. Revision 4 is sent to supply the operator with new inspection instructions and new repair and preventive modification kits for all airplanes. The new kits provide a different doubler profile to address the fuselage skin cracking below the lower aft corner of the forward airstair stowage door cutout. **D. Description** Get access to the airstair stowage doorway area. At the times specified in Paragraph 1.E., Compliance, do High Frequency Eddy Current (HFEC), Low Frequency Eddy Current (LFEC) and detailed inspections of the bearstrap and skin assembly for any crack. If no crack is found, install the preventive modification in accordance with this service bulletin or do repeat inspections at the times given in Paragraph 1.E., Compliance.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 22 of 81 **BOEING SERVICE BULLETIN 737-53-1058**If any crack is found in the skin assembly or bearstrap, install the permanent repair in accordance with this service bulletin or contact The Boeing Company for repair instructions and do the repair. For repairs installed in accordance with original release or preventive modification installed in accordance with original release, revision 1, 2 or 3, do the inspection at the times specified in Paragraph 1.E., Compliance. If any crack is found, contact The Boeing Company for repair instructions and do the repair. On Group 6 airplanes, contact The Boeing Company to get instructions for the inspection, change and/or repair for this service bulletin, 737-53-1058 Revision 4, and do the instructions. Revision 4 - More work is necessary on airplanes changed in accordance with the original issue or Revisions 1, 2 or 3 of this service bulletin. Airplanes with a repair installed in accordance with the original issue or preventive modification installed in accordance with the original issue or Revision 1, 2 or 3 of this service bulletin require additional inspections. The work in this service bulletin is done in the maintenance zone(s) given below. **Group 1, 3:**
**Affected Maintenance Zones Zone**  **Model** 2-6 737-200 **Group 2, 4:**
**Affected Maintenance Zones Zone**  **Model** 2-6 737-200C **Group 3, 5:**
**Affected Maintenance Zones Zone**  **Model** 206 737-300, 737-400, 737-500 **Group 6:**
**Affected Maintenance Zones Zone**  **Model** 2-6 737-100, 737-200, 737-200C **E. Compliance** Federal Aviation Administration (FAA) Airworthiness Directive AD 90-06-02, AD 98-11-04 R1, AD 2008-08-23 and AD 2008-09-13 are related to this service bulletin.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 23 of 81 **BOEING SERVICE BULLETIN 737-53-1058**The 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. As recommended by the model 737 Aging Fleet Structures Task Group, accomplish the preventive modification per the accomplishment instructions at or before the accumulation of 75,000 flight cycles. The repair/preventive modifications of this service bulletin have been reviewed as required by AD 98-11-04 R1 paragraphs (e) or (g), AD 2008-08-23 paragraphs (g) and (h) and AD 2008-09-13 paragraphs (g) and (h). The repair/preventive modifications, per Revision 4, are found to affect SSI F-14A and makes the F-14A inspections ineffective in the repair/preventive modification area. The alternate inspection intervals for the repair/preventive modification are shown in Table 3: Post Repair and Post Preventive Modification Inspections. The repair/preventive modification also affects SSI F-14B and prohibits the external LFEC inspection of F-14B. However the internal inspection options of F-14B provides the required Damage Tolerance Rating (DTR) in this area. Therefore, an alternate inspection for F-14B is not necessary in the area of the repair/preventive modification. Boeing repairs that were previously approved by Boeing Authorized Representative (AR) via FAA 8100-9 Form terminates the inspections of this service bulletin. For post repair inspection, refer to the approval documents. **Group 1-2: Table 1: Skin Assembly and Bearstrap Inspections**  **Repeat Inter val (Not to**  **Exceed) Compliance Time (whichever oc**  **curs later) Action**  **Condition**

4,500 flight cycles Within 4,500 flightcycles after the Revision 4 date of this service bulletin. Before 20,000total flight cyclesDo a HFEC inspection and detailed inspection for any crack in the bearstrap in accordancewith Paragraph 3.B., Work Instructions, PART 2, step 1.Airplanes without a Preventive Modification orRepair installed in accordance with the original issue or Revision 1, 2 or 3 of this service bulletin. (a) (b) 4,500 flight cycles Within 4,500 flightcycles after the Revision 4 date of this service bulletin. Before 20,000total flight cyclesDo a HFEC inspection and detailed inspection for any crackin the skin assembly in accordance with Paragraph 3.B., Work Instructions, PART 2, step 1. (a) (b)

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 24 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group 1-2:**  **Table 1: Skin Assembly and Bearstrap Inspections Repeat Inter**  **val (Not to Exceed)** **Compliance Time (whichever oc curs later)**  **Action Condition** 

4,500 flight cycles Within 4,500 flightcycles after the Revision 4 date of this service bulletin. Before 20,000total flight cyclesDo a HFEC inspection and detailed inspection for any crack in the bearstrap in accordancewith Paragraph 3.B., Work Instructions, PART 2, step 1. Airplanes with a Repair installed in accordance with the original issue of this service bulletin. (a) (b) 4,500 flight cycles Within 4,500 flightcycles after the Revision 4 date of this service bulletin. Before 20,000total flight cycles Do a detailed inspection for any crack in the skin assembly in accordance with Paragraph 3.B., Work Instructions, PART 2, step 1. (a) (b) 4,500 flight cycles Within 4,500 flightcycles after the Revision 4 date of this service bulletin. Before 20,000total flight cycles Do a LFEC inspection for any crack in the skin assembly and bearstrap in accordance withParagraph 3.B., Work Instructions, PART 2, step 1. (a) (b) 6,000 flight cycles Within 4,500 flightcycles after the Revision 4 date of this service bulletin. Before 30,000total flight cyclesDo a HFEC Inspection and Detailed Inspection for any crack in the Bearstrap in accordancewith Paragraph 3.B., Work Instructions, PART 2, step 1.Airplanes with a Preventive Modification installed in accordance with the original issue, Revision 1,2 or 3 of this service bulletin. (a) (b) 6,000 flight cycles Within 4,500 flightcycles after the Revision 4 date of this service bulletin. Before 30,000total flight cycles Do a LFEC Inspection for any crack in the skin assembly and Bearstrap in accordance withParagraph 3.B., Work Instructions, PART 2, step 1. (a) (b) 6,000 flight cycles Within 4,500 flightcycles after the Revision 4 date of this service bulletin. Before 30,000total flight cycles Do a Detailed Inspection for any crack in the skin assembly in accordance with Paragraph 3.B., Work Instructions, PART 2, step 1. (a) (b)

- Before further flight Install a repair in accordancewith Paragraph 3.B., Work Instructions, PART 2, step 1.e. If any crack is found in the skin assembly or bearstrap, but not both.(b)

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 25 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group 1-2:**  **Table 1: Skin Assembly and Bearstrap Inspections Repeat Inter**  **val (Not to Exceed)** **Compliance Time (whichever oc curs later)**  **Action Condition** 

- Before further flight Install a repair in accordancewith Paragraph 3.B., Work Instructions, PART 2, step 1.f. If any crack is found in both the skin assembly and bearstrap. (b) (a) Installation of the Preventive Modification in accordance with Paragraph 3.B., Work Instructions, PART 2, step 1.a. or PART 2, step 1.b or PART 2, step 1.c. terminates this inspection. Post preventive modification inspections are provided in Table 3. (b) Installation of the Repair in accordance with Paragraph 3.B., Work Instructions, PART 2, step 1.e. or PART2 step 1.f. terminates this inspection. Repairs that were previously accomplished in accordance with Revision 1, 2 or 3 of this service bulletin terminate this inspection. Post repair inspections are provided in Table 3. **Group 3-5: Table 2: Skin Assembly and Bearstrap Inspections**  **Repeat Inter val (Not to**  **Exceed) Compliance Time (whichever oc**  **curs later) Action**  **Condition**

6,000 flight cycles Within 4,500 flightcycles after the Revision 4 date of this service bulletin. Before 20,000total flight cyclesDo a HFEC and Detailed Inspection for any crack in the Bearstrap in accordance withParagraph 3.B., Work Instructions, PART 2, step 1. All Airplanes.

(a) (b) 6,000 flight cycles Within 4,500 flightcycles after the Revision 4 date of this service bulletin. Before 20,000total flight cycles Do a LFEC Inspection for any crack in the skin assembly and Bearstrap in accordance withParagraph 3.B., Work Instructions, PART 2, step 1. (a) (b) 6,000 flight cycles Within 4,500 flightcycles after the Revision 4 date of this service bulletin. Before 20,000total flight cycles Do a Detailed Inspection for any crack in the skin assembly in accordance with Paragraph 3.B., Work Instructions, PART 2, step 1. (a) (b)

- Before further flight Install a repair in accordancewith Paragraph 3.B., Work Instructions, PART 2, step 1.e. If any crack is found in the skin assembly or bearstrap, but not both.(b)

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 26 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group 3-5:**  **Table 2: Skin Assembly and Bearstrap Inspections Repeat Inter**  **val (Not to Exceed)** **Compliance Time (whichever oc curs later)**  **Action Condition** 

- Before further flight Install a repair in accordancewith Paragraph 3.B., Work Instructions, PART 2, step 1.f. If any crack is found in both the skin assembly and bearstrap. (b) (a) Installation of the Preventive Modification in accordance with Paragraph 3.B., Work Instructions, PART 2, step 1.d. terminates this inspection. Post preventive modification inspections are provided in Table 4. (b) Installation of the Repair in accordance with Paragraph 3.B., Work Instructions, PART 2, step 1.e. or PART 2, step 1.f. terminates this inspection. Post repair inspections are provided in Table 4. **Group 1-2: Table 3: Post Repair and Post Preventive Modification Inspections**  **Repeat Interval**  **(Not to Exceed)** **Compliance Time (whichever occurs lat er)**  **Action Condition** 

24,000flight cycles Within 4,500 flight cyclesafter the Revision 4 date of this service bulletin. Within 12,000 flight cyclesafter the installation of the repair or preventive modification. Before 60,000 total flight cycles.Do an Internal HFEC Inspection for any crack in theBearstrap and Skin Assembly and an Internal General Visual Inspection for any crack in the frame outer chord in accordance withParagraph 3.B., Work Instructions PART 3, step 1.(Option A) Airplanes that have a Repair installed in accordance with the Revision 1, 2, or 3of this service bulletin.

OR 4,000flight cycles Within 4,500 flight cyclesafter the Revision 4 date of this service bulletin. Within 12,000 flight cyclesafter the installation of the repair or preventive modification. Before 60,000 total flight cycles.Do an External LFEC Inspection for any crack in theBearstrap and Skin Assembly in accordance with Paragraph 3.B., Work Instructions PART 3, step 1. (Option B)

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 27 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group 1-2:**  **Table 3: Post Repair and Post Preventive Modification Inspections Repeat**  **Interval (Not to**  **Exceed) Compliance Time (whichever occurs lat**  **er) Action**  **Condition**

24,000flight cycles Within 12,000 flight cyclesafter the installation of the repair or preventive modification. Before 60,000 total flight cycles.Do an Internal HFEC Inspection for any crack in theBearstrap and Skin Assembly and an Internal General Visual Inspection for any crack in the frame outer chord in accordance withParagraph 3.B., Work Instructions, PART 3, step 2. (Option A) Airplanes that havea Repair or Preventive Modification installed in accordance with Revision 4 of this Service Bulletin.

OR 4,000flight cycles . Within 12,000 flight cyclesafter the installation of the repair or preventive modification. Before 60,000 total flight cycles.Do an External LFEC Inspection for any crack in theBearstrap and Skin Assembly in accordance with Paragraph 3.B., Work Instructions, PART 3, step 2. (Option B)

- Before further flight Contact The Boeing Compa- ny for repair instructions and do the repair. If any crack is found.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 28 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group 3-5:**  **Table 4: Post Repair and Post Preventive Modification Inspections Repeat**  **Interval (Not to**  **Exceed) Compliance Time (whichever occurs lat**  **er) Action**  **Condition**

24,000flight cycles Within 12,000 flight cycles after the installation of therepair or preventive modification. Before 60,000 total flight cycles.Do an Internal HFEC Inspection for any crack in theBearstrap and Skin Assembly and an Internal General Visual Inspection for any crack in the frame outer chord in accordance withParagraph 3.B., Work Instructions, PART 3, step 2. (Option A) Airplanes that havea Repair or Preventive Modification installed in accordance with Revision 4 of this Service Bulletin.

OR 4,000flight cycles Within 12,000 flight cycles after the installation of therepair or preventive modification. Before 60,000 total flight cycles.Do an External LFEC Inspection for any crack in theBearstrap and Skin Assembly in accordance with Paragraph 3.B., Work Instructions, PART 3, step 2. (Option B)

- Before further flight Contact The Boeing Compa- ny for repair instructions and do the repair. If any crack is found.

**Group 6:** On Group 6 airplanes, contact The Boeing Company to get instructions for the inspection, change and/or repair for this service bulletin, 737-53-1058 Revision 4, and do the instructions within 120 days of the issue date of revision 4 to this service bulletin. **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.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 29 of 81 **BOEING SERVICE BULLETIN 737-53-1058**The Manager of the FAA Seattle Aircraft Certification Office (ACO) approves the action (i.e. repair or preventive modification) defined in this service bulletin, 737-53-1058 Revision 4 as an alternative method of compliance to the modifications per SB 737-53-1058 Revision 1, of the Aging Airplane Service Bulletin Structural Modification Program - Model 737-100/-200/-200C of paragraph (A) of AD 90-06-02. This alternative method of compliance applies only to the modification specified in Boeing document D6-38505 for service bulletin 737-53-1058. All provisions of AD 90-06-02 that are not specifically referenced in the above statement remain fully applicable and must be complied with. For Boeing Model 737-100/200 series airplanes, the Manager of the FAA Seattle ACO approves the supplemental inspection methods, thresholds and repeat intervals as given in Tables 3 and 4 of Paragraph 1.E, Compliance for the repair or preventive modification defined in the applicable tables of Paragraph 1.E., Compliance, of Boeing Alert Service Bulletin 737-53-1058, Revision 4 as a method of compliance (MOC) to Paragraph (g) of AD 98-11-04 R1 for the inspections of Structurally Significant Item (SSI) F-14A. This approval applies to this SSI and only for the portions of the bear strap and skin that have been repaired in accordance with this service bulletin. If operators choose this MOC, then they must revise their FAA-approved maintenance or inspection program to incorporate these alternative inspections. All provisions of AD 98-11-04 R1 that are not specifically referenced above remain fully applicable and must be complied with accordingly. In addition, for Boeing Model 737-200C series airplanes, the Manager of the FAA Seattle ACO approves the inspection methods, thresholds, repeat intervals, as given in Table 3 and 4 of Paragraph 1.E for the repairs and preventive modification defined in the applicable tables of Paragraph 1.E., Compliance , of Boeing Alert Service Bulletin 737-53A1058, Revision 4 as an AMOC to the inspections of SSI F-14A required by paragraphs (g) and (h) of AD 2008-08-23. This approval applies to this SSI and only for the portions of the bearstrap and skin that have been repaired in accordance with this service bulletin. If operators choose this AMOC, then they must revise their FAA-approved maintenance or inspection program to incorporate these alternative inspections. All provisions of AD 2008-08-23 that are not specifically referenced above remain fully applicable and must be complied with accordingly. In addition, for Boeing Model 737-300/-400/-500 series airplanes, the Manager of the FAA Seattle ACO approves the inspection methods, thresholds, repeat intervals as given in Table 4 for the repairs or preventive modification defined in the applicable tables of Paragraph 1.E., Compliance, of Boeing Alert Service Bulletin 737-53A1058, Revision 4 as an AMOC to the inspections of SSI F-14A as required by paragraphs (g) and (h) of AD 2008-09-13. This approval applies to this SSI and only for the portions of the bearstrap and frame chord that have been repaired in accordance with this service bulletin. If operators choose this AMOC, then they must revise their FAA-approved maintenance or inspection program to incorporate these alternative inspections. All provisions of AD 2008-09-13 that are not specifically referenced above 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 change 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 examine the work — Time to cure the materials — Time to make the parts — Time to find the tools.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 30 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group 1-2:**  **Table 1: No preventive modification or repair installed at the original issue of this service bulletin Elapsed Hours**  **Task Hours Number of Persons**  **Task** 0.25 0.50 2 Open Access 1.75 1.75 1 FIGURE 5 1.75 1.75 1 FIGURE 6 0.25 0.50 2 Close Access 4.00 4.50 TOTAL FOR EACH AIRPLANENote: If a repair is required more time will be needed but cannot be specified as the extent of the repair is unknown and can be different on each airplane. **Group 1-2: Table 2: Preventive modification installed at the original issue of this service bulletin**  **Elapsed Hours Task Hours**  **Number of Persons Task**  0.25 0.50 2 Open Access 1.75 1.75 1 FIGURE 5 1.75 1.75 1 FIGURE 7 0.25 0.50 2 Close Access 4.00 4.50 TOTAL FOR EACH AIRPLANENote: If a repair is required more time will be needed but cannot be specified as the extent of the repair is unknown and can be different on each airplane. **Group 1: Table 3: Preventive modification installed at Revision 1, 2 or 3 of this service bulletin**  **Elapsed Hours Task Hours**  **Number of Persons Task**  0.25 0.50 2 Open Access 1.75 1.75 1 FIGURE 5 2.00 2.00 1 FIGURE 8 0.25 0.50 2 Close Access 4.25 4.75 TOTAL FOR EACH AIRPLANENote: If a repair is required more time will be needed but cannot be specified as the extent of the repair is unknown and can be different on each airplane.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 31 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group 2:**  **Table 4: Preventive modification installed at Revision 1, 2 or 3 of this service bulletin Elapsed Hours**  **Task Hours Number of Persons**  **Task** 0.25 0.50 2 Open Access 1.75 1.75 1 FIGURE 5 2.00 2.00 1 FIGURE 8 0.25 0.50 2 Close Access 4.25 4.75 TOTAL FOR EACH AIRPLANENote: If a repair is required more time will be needed but cannot be specified as the extent of the repair is unknown and can be different on each airplane. **Group 1: Table 5: Repair installed at the original issue of this service bulletin**  **Elapsed Hours Task Hours**  **Number of Persons Task**  0.25 0.50 2 Open Access 1.75 1.75 1 FIGURE 5 1.50 1.50 1 FIGURE 10 0.25 0.50 2 Close Access 3.75 4.25 TOTAL FOR EACH AIRPLANENote: If a repair is required more time will be needed but cannot be specified as the extent of the repair is unknown and can be different on each airplane. **Group 2: Table 6: Repair installed at the original issue of this service bulletin**  **Elapsed Hours Task Hours**  **Number of Persons Task**  0.25 0.50 2 Open Access 1.75 1.75 1 FIGURE 5 1.50 1.50 1 FIGURE 11 0.25 0.50 2 Close Access 3.75 4.25 TOTAL FOR EACH AIRPLANENote: If a repair is required more time will be needed but cannot be specified as the extent of the repair is unknown and can be different on each airplane.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 32 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group 3-5:**  **Table 7: Inspection Elapsed Hours**  **Task Hours Number of Persons**  **Task** 0.25 0.50 2 Open Access 1.75 1.75 1 FIGURE 5 2.00 2.00 1 FIGURE 9 0.25 0.50 2 Close Access 4.25 4.75 TOTAL FOR EACH AIRPLANENote: If a repair is required more time will be needed but cannot be specified as the extent of the repair is unknown and can be different on each airplane. **Group 1-5: Table 8: Open Hole Inspection Before Repair and Preventive Modification Installation**  **Elapsed Hours Task Hours**  **Number of Persons Task**  1.6 1.6 1 Inspection **Group 1-5: Table 9: Post Repair and Post Preventive Modification Inspections**  **Elapsed Hours Task Hours**  **Number of Persons Task**  0.25 0.50 2 Open Access 1.50 1.50 1 FIGURE 13 (Option A) 1.00 1.00 1 FIGURE 14 (Option B) 0.25 0.50 1 Close Access 2.00 2.50 TOTAL FOR EACH AIRPLANE (Option A) 1.5 2.00 TOTAL FOR EACH AIRPLANE (Option B) **H. Weight and Balance Changes Group 1-5:**  **Modification - Skin Assembly or Bearstrap (Kits 65C20843-35, 65C20843-36, 65C20843-39) without previous preventive modification or repair installed**  **Change in Moment (Pounds-Inches)**  **Change in Weight (Pounds)**  **Applicability**
+3,010 +9.0 737-100 +2,690 +9.0 737-200/-200C +2,300 +9.0 737-300

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 33 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group 1-5:**  **Modification - Skin Assembly or Bearstrap (Kits 65C20843-35, 65C20843-36, 65C20843-39) without previous preventive modification or repair installed**  **Change in Moment (Pounds-Inches)**  **Change in Weight (Pounds)**  **Applicability**
+1,650 +9.0 737-400 +2,780 +9.0 737-500 **Group 1-5: Modification - Skin Assembly and Bearstrap (Kits 65C20843-37, 65C20843-38, 65C20843-40) without**  **previous preventive modification or repair installed Change in Moment**  **(Pounds-Inches) Change in Weight**  **(Pounds) Applicability** 
+3,690 +11.0 737-100 +3,290 +11.0 737-200/-200C +2,800 +11.0 737-300 +2,010 +11.0 737-400 +3,400 +11.0 737-500 **Group 1-5: With Aluminum Doubler and One Steel Tripler Replacing Previously Installed Preventive Modification**  **or Repair Change in Moment**  **(Pounds-Inches) Change in Weight**  **(Pounds) Applicability** 
+1,010.0 +3.0 737-100 +900.0 +3.0 737-200/-200C +770.0 +3.0 737-300 +550.0 +3.0 737-400 + 920.0 +3.0 737-500 **Group 1-5: With Aluminum Doubler and Two Steel Tripler Replacing Previously Installed Preventive Modification**  **or Repair Change in Moment**  **(Pounds-Inches) Change in Weight**  **(Pounds) Applicability** 
+1,680.0 +5.0 737-100 +1,500.0 +5.0 737-200/-200C

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 34 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group 1-5:**  **With Aluminum Doubler and Two Steel Tripler Replacing Previously Installed Preventive Modification or Repair**  **Change in Moment (Pounds-Inches)**  **Change in Weight (Pounds)**  **Applicability**
+1,280.0 +5.0 737-300 +920.0 +5.0 737-400 + 1,540.0 +5.0 737-500 **Group 6:** None. **I. Electrical Load Data** Not changed **J. References** 1. Existing Data: a. Engineering Change Memo PRR 35005-249RS b. Standard Overhaul Practices Manual (SOPM) 20-41-02, 20-43-03, 20-50-19 c. 737 Non-Destructive Testing (NDT) Manual Part 6, 51-00-00, Part 6, 53-30-00 d. 737-100/200 Aircraft Maintenance Manual (AMM) 52-61-0 e. 737-300/400/500 Aircraft Maintenance Manual (AMM) 52-61-50 f. Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2008-08-23, 2008-09-13, 90-06-02, 98-11-04 R1 g. Boeing Service Letter 737-SL-51-042 h. Boeing Service Related Problem (SRP) 737-SRP-53-0381 i. Boeing Document D6-37089: “737 Supplemental Structural Inspection Document (SSID) Revision E". j. Boeing Document D6-38505: “Aging Airplane Service Bulletin Structural Modification Program - Model 737-100/-200/-200C. k. 737-100/200 Structural Repair Manual (SRM) 51-30-02 l. 737-300 Structural Repair Manual (SRM) 51-40-02 m. 737-400 Structural Repair Manual (SRM) 51-40-02

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 35 of 81 **BOEING SERVICE BULLETIN 737-53-1058**n. 737-500 Structural Repair Manual (SRM) 51-40-02 2. Data Supplied with this Service Bulletin: a. Drawings:
**ADCN DCN/REV**  **Sheet Title**  **Drawing No** 1 A 1 Fwd Airstairs Reinforcement STA.302.6 - 352.6 65C20843 4 B 2

- - 3 11 C PL 3. Installation Drawings Used in the Preparation of this Service Bulletin:
**Title Drawing Number**  Skin and Stringer Installation - Section 41 65-45800 Skin and Stringer Installation - Forward Entry and Galley Doors 65C34778 These drawings were used to prepare this service bulletin. These drawings are not necessary to make the specified changes, and are not supplied with this service bulletin. These drawings may not be applicable to all airplane configurations or operators. **K. Publications Affected** 1. Publications: None. 2. Damage Tolerance Based Structural Inspections: Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the Maintenance Program. This service bulletin affects FCS. DTI requirements for the structure affected are contained in Paragraph 1.E., Compliance of this service bulletin. **L. Interchangeability and Intermixability of Parts** Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts. **M. Software Accomplishment Summary** Not affected.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 36 of 81 **BOEING SERVICE BULLETIN 737-53-1058 2. MATERIAL INFORMATION**  **A. Material - Price and Availability** Boeing can supply the kits shown in Paragraph 2.C., Parts Necessary for Each Airplane. Operators are encouraged to share schedule requirements with Boeing for incorporation of the service bulletin. The kits are subject to the terms and conditions of the Boeing standard purchase order acknowledgment. Prices are in United States Dollars. Terms: Net 30 days. Reference this service bulletin and submit your purchase order by one of these methods: 1. Order on-line via ATA Spec 2000 or The Boeing PART Page 2. Fax to (206) 662-7145 **REFER TO THE BOEING PART PAGE ON MYBOEINGFLEET.COM OR CONTACT FIRST RESPONDER AT FR@BOEING.COM FOR THE LATEST REORDER LEAD TIME (ROLT) AND PRICE INFORMATION** 
**Unit Price as of the Revision 4 date of**  **this Service Bulletin (US Dollars)** **ROLT as of the Revi sion 4 date of this** **Service Bulletin (Cal endar Days)**  **QTY Date**  **Name Kit Number** 

Inactive For Procurement

- - Modification Kit 65-91127-1 Inactive For Procurement

- - Repair Kit 65-91127-2 Inactive For Procurement

- - Repair Kit 65-91127-3 Inactive For Procurement

- - Kit 65C20843-13 Inactive For Procurement

- - Kit 65C20843-14 Inactive For Procurement

- - Kit 65C20843-15 Inactive For Procurement

- - Kit 65C20843-16 Inactive For Procurement

- - Kit 65C20843-17 Inactive For Procurement

- - Kit 65C20843-18 Inactive For Procurement

- - Supplemental Kit 65C20843-23 Inactive For Procurement

- - Supplemental Kit 65C20843-24 Inactive For Procurement

- - Supplemental Kit 65C20843-25 Inactive For Procurement

- - Supplemental Kit 65C20843-26 Inactive For Procurement

- - Supplemental Kit 65C20843-27 Inactive For Procurement

- - Supplemental Kit 65C20843-28 Inactive For Procurement

- - Kit 65C20843-29 Inactive For Procurement

- - Kit 65C20843-30 Inactive For Procurement

- - Kit 65C20843-31 Inactive For Procurement

- - Kit 65C20843-32

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 37 of 81 **BOEING SERVICE BULLETIN 737-53-1058 REFER TO THE BOEING PART PAGE ON MYBOEINGFLEET.COM OR CONTACT FIRST RESPONDER**  **AT FR@BOEING.COM FOR THE LATEST REORDER LEAD TIME (ROLT) AND PRICE INFORMATION**
**Unit Price as of the Revision 4 date of**  **this Service Bulletin (US Dollars)** **ROLT as of the Revi sion 4 date of this** **Service Bulletin (Cal endar Days)**  **QTY Date**  **Name Kit Number** 

Inactive For Procurement

- - Kit 65C20843-33 Inactive For Procurement

- - Kit 65C20843-34 Inactive For Procurement

- - Fastener Kit 65C36884-1 $2,024.00 555 30 13-May-2013 Top Kit 65C20843-35 $1,841.00 555
- - Top Kit 65C20843-36 $1,863.00 555 70 13-May-2013 Top Kit 65C20843-37 $2,142.00 555
- - Top Kit 65C20843-38 $1,756.00 555 30 13-May-2013 Top Kit 65C20843-39 $1,779.00 555 70 13-May-2013 Top Kit 65C20843-40 **B. Industry Support Information** Boeing warranty remedies are not available for the inspection, repair and modification procedures given in this service bulletin. **C. Parts Necessary for Each Airplane** 1. Kits/Parts: To get the kits/parts shown below, refer to Paragraph 2.A., Material - Price and Availability. **NOTE:**One top kit and the items shown in Paragraph 2.C.2., Parts and Materials Supplied by the Operator , are necessary for each airplane.
**Kit Number Usage**  **Applicability** 65C20843-35 Repair Crack in Skin, Bonded Doubler or Bearstrap Groups 1 and 3

65C20843-37 Repair Crack in Skin, Bonded Doubler and Bearstrap 65C20843-36 Repair Crack in Skin, Bonded Doubler or Bearstrap Groups 2 and 4

65C20843-38 Repair Crack in Skin, Bonded Doubler and Bearstrap

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 38 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Kit Number**  **Usage Applicability**  65C20843-39 Repair Crack in Skin, Bonded Doubler or Bearstrap Group 5

65C20843-40 Repair Crack in Skin, Bonded Doubler and Bearstrap
**NOTE:**The table below lists the inactive kits and what the superseding replacement kit is. **Superseding Kit Inactive Supplemen-**  **tal Kit Inactive Kit** 
65C20843-35 65C20843-24 65C20843-13, 29 65C20843-36 65C20843-25 65C20843-14, 30 65C20843-37 65C20843-26 65C20843-15, 31 65C20843-38 65C20843-27 65C20843-16, 32 65C20843-39 65C20843-23 65C20843-17, 33 65C20843-40 65C20843-28 65C20843-18, 34
**Kit 65C20843 - AIRSTAIRS REINFORCEMENT STA 302.6 - STA 352.6 Notes**  **Existing Part Number**  **Name QTY**  **New Part Number -35**  **-36 -37**  **-38 -39**  **-40** 65C20843-29 TOP KIT -AIRSTAIR REINFORCEMENT - . . . . . 65C20843-35

65C20843-30 TOP KIT -AIRSTAIR REINFORCEMENT . - . . . . 65C20843-36

65C20843-31 TOP KIT -AIRSTAIR REINFORCEMENT . . - . . . 65C20843-37

65C20843-32 TOP KIT -AIRSTAIR REINFORCEMENT . . . - . . 65C20843-38

65C20843-33 TOP KIT -AIRSTAIR REINFORCEMENT . . . . - . 65C20843-39

65C20843-34 TOP KIT -AIRSTAIR REINFORCEMENT . . . . . - 65C20843-40

(a) (b) (c) EXTERNAL TRIPLER 1 1 1 1 1 1 65C20843-21

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 39 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Kit 65C20843 - AIRSTAIRS REINFORCEMENT STA 302.6 - STA 352.6**  **Notes Existing Part**  **Number Name**  **QTY New Part Number**  **-35 -36**  **-37 -38**  **-39 -40**  (a) (b) (c) EXTERNAL TRIPLER . . 1 1

. 1 65C20843-22 (a) (b) (c) KIT DETAIL - EX- TERNAL DOUBLER 1 1 1 1 1 1 65C20843-41 (d) BOLT 2 2 4 4 2 4 BACB30KF6A10 (d) BOLT, 100 DEG HEX D . 3 7 4

. 7 BACB30KF6A11 (d) BOLT

. . . 1

. . BACB30KF6A12 (d) BOLT 44 34 44 34 44 44 BACB30KF6A3 (d) BOLT 9 8 9 8 9 9 BACB30KF6A4 (d) BOLT, 100 DEG HEX D 23 27 23 27 23 23 BACB30KF6A5 (d) BOLT 128 36 128 28 128 128 BACB30KF6A6 (d) BOLT, HEX DRIVE 42 106 13 108 42 13 BACB30KF6A7 (d) BOLT 14 47 42 18 14 42 BACB30KF6A8 (d) BOLT, 100 DEG HEX D 4 7 1 36 4 1 BACB30KF6A9 (d) BOLT 5

. 5

. 5 5 BACB30KF8A7 (d) BOLT 2

. 2

. 2 2 BACB30KF8A8 (d) BOLT 1

. 1

. 1 1 BACB30KF8A9 COLLAR 272 273 278 273 272 278 BACC30R6 COLLAR 8

. 8

. 8 8 BACC30R8 (d) RIVET, 100 DEG 33

. 33

. 33 33 BACR15GF5D7 (d) RIVET, 100 DEG

. 33

. 33

. . BACR15GF5D8 (d) RIVET, 100 DEG 6

. 1 12 6 1 BACR15GF6D10 (d) RIVET, 100 DEG

. . 5

. . 5 BACR15GF6D11 (d) RIVET, 100 DEG 1 1 1 1 1 1 BACR15GF6D7 (d) RIVET, 100 DEG 10 12 10

. 10 10 BACR15GF6D8 (d) RIVET, 100 DEG 11 15 11 3 11 11 BACR15GF6D9 (a) Discard the existing part. (b) This part is not used in production. (c) You cannot use the existing part to replace the new or changed part

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 40 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Kit 65C20843 - AIRSTAIRS REINFORCEMENT STA 302.6 - STA 352.6**  **Notes Existing Part**  **Number Name**  **QTY New Part Number**  **-35 -36**  **-37 -38**  **-39 -40**  (d) If grip length shown is not available at Boeing, fasteners supplied in kits may be one grip length longer than indicated. Also, if any fasteners part numbers listed are not available or have been superseded, substitute fasteners may be supplied in kits. 2. Parts and Materials Supplied by the Operator:
**Notes Name**  **QTY Part Number / Specifica-**  **tion** (a) Chemical Conversion Coating 1 Ounce Type 2, Class A (b) Primer 2 Ounce BMS 10-11, Type I (b) Sealant 8 Ounce BMS 5-95, Type I or II, Class B-1/2 or 2 Maximum size 10 x 4 inches. (c) Filler (Skin Assembly) 1 2024-T3 Maximum size 10 x 4 inches. (d) Filler (Bearstrap) 1 2024-T3 (a) Refer to SOPM 20-43-03 for material sources. (b) See the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data (c) Fabricate from 0.072 inch thick material. Refer to FIGURE 12. (d) Fabricate from 0.100 inch thick material. Refer to FIGURE 12.
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, 1980 737-53-1058 Revision 4: January 09, 2014 41 of 81 **BOEING SERVICE BULLETIN 737-53-1058**Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 42 of 81 **BOEING SERVICE BULLETIN 737-53-1058**

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 limits to tighten nuts and bolts are in SRM Chapter 51 4. Use the approved fastener and process 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. 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. 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.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 43 of 81 **BOEING SERVICE BULLETIN 737-53-1058**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. Refer to Appendix A for the Flight Safety Section. 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. Group 1-5: General repair notes in addition to 65C20843 parts list notes: – Maintain a minimum 2D edge margin on all repair/preventive modification parts except for repair filler. Maintain a 1.5D edge margin on fillers. – Install all rivets dry and over-driven to a minimum of 1.4D driven head. Install all hi-lok fasteners wet with BMS 5-95 sealant in transition fit or close reamed holes as defined within 65C20843 parts list. – Before clamp up, shim all gaps greater than 0.01 inches up to a maximum of 0.04 inches. Contact The Boeing Company for additional instructions and do the instructions for any gap greater than 0.04 inches. – Install all parts wet with faying surface seal BMS 5-95 sealant. Refer to SOPM 20-50-19 as an accepted procedure. – When installing repair or modification parts in accordance with Revision 4 of this Service Bulletin, it is structurally acceptable to install a 1/64 oversize fastener (BACB30LW6A) at existing BACB30KF6A locations such that either transition or close ream fastener installation is maintained. Hole size for a close ream fit is, 0.2339 - 0.2349 inch diameter hole,and hole size for a transition fit is, 0.232 - 0.235 inch diameter hole. 14. Group 1-2: Fastener hole oversize notes in addition to 65C20843 parts list notes for airplanes that have an existing repair or preventive modification installed: – It is structurally acceptable to install a 1/64 oversize fastener (BACB30LW6A) at existing BACB30KF6A locations such that either transition or close ream fastener installation is maintained. Use a close ream hole when the hole is through both stainless steel and aluminum parts. Use a transition fit hole when the hole is through aluminum parts only. Close ream hole diameter is 0.2339 - 0.2349 and transition fit hole diameter is 0.232 - 0.235.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 44 of 81 **BOEING SERVICE BULLETIN 737-53-1058**– It is structurally acceptable to install a 1/64 oversize fastener (BACB30LW8A) at existing BACB30KF8A locations such that either transition or close ream fastener installation is maintained. Use a close ream hole when the hole is through both stainless steel and aluminum parts. Use a transition fit hole when the hole is through aluminum parts only. Close ream hole diameter is 0.2963 - 0.2973 and transition fit hole diameter is 0.294 - 0.297. – It is structurally acceptable to install a BACR15GF6D rivet at existing BACR15GF5D locations. – It is structurally acceptable to install a BACR15GF7D rivet at existing BACR15GF6D locations. **B. WORK INSTRUCTIONS Group 6:**  On Group 6 airplanes, contact The Boeing Company to get instructions for the inspection, change and/or repair for this service bulletin, 737-53-1058 Revision 4, and do the instructions. **Group 1-5: PART 1 - GET ACCESS**  1. For airplanes with a forward airstair installed, extend the forward airstair. For airplanes without a forward airstair installed, open the forward airstair door. Refer to 737-100/200 AMM 52-61-0 and 737-300/400/500 AMM 52-61-50 as an accepted procedure to open the forward airstair door. **Group 1-5: PART 2 - SKIN ASSEMBLY AND BEARSTRAP INSPECTIONS**  1. Determine what preventive modification or repair (if any) is currently installed on the airplane and do the applicable inspections in accordance with the appropriate Figure listed in the tables below. Refer to Table 1 for Group 1 airplanes, Table 2 for Group 2 airplanes, and Table 3 for Group 3, 4 and 5 airplanes. Refer to FIGURE 4 that shows the inspection areas. **Group 1: Table 1: Inspection**  **Action - Inspection Condition**  Do a HFEC inspection and detailed inspection for any crackin the bearstrap and skin assembly in accordance with FIGURE 5 and FIGURE 6. Airplanes without a preventive modification or repair installed in accordance with the original issue or Revision 1, 2 or 3 of this service bulletin

Do a HFEC inspection and detailed inspection for any crack in the bearstrap in accordance with FIGURE 5, and do a LFEC inspection of the skin assembly and bearstrap, and a detailed inspection of the skin assembly for any crack in accordance with FIGURE 7. Airplanes with preventive modification installedin accordance with the original issue of this service bulletin.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 45 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group 1:**  **Table 1: Inspection Action - Inspection**  **Condition** Do a HFEC inspection and detailed inspection for any crack in the bearstrap in accordance with FIGURE 5, and do anLFEC inspection of the skin assembly and bearstrap, and a detailed inspection of the skinassembly for any crack in accordance with FIGURE 8. Airplanes with preventive modification installed in accordance with Revisions 1, 2 or 3 of this service bulletin.

Do a HFEC inspection and detailed inspection for any crack in the bearstrap in accordancewith FIGURE 5, and do a detailed inspection of the skin assembly, and a LFEC inspection of the skin assembly andbearstrap for any crack in accordance with FIGURE 10. Airplanes with repair installed in accordance with the original issue of this service bulletin.

**Group 2: Table 2: Inspection**  **Action - Inspection Condition**  Do a HFEC inspection and detailed inspection for any crack in the bearstrap and skin assembly in accordance with FIGURE 5 and FIGURE 6. Airplanes without a preventive modification or repair installed in accordance with the original issue or Revision 1, 2 or 3 of this service bulletin Do a HFEC inspection and detailed inspection for any crack in the bearstrap in accordance with FIGURE 5, and do a LFEC inspection of the skin assembly and bearstrap and a detailed inspection of the skin assembly for any crack in accordance with FIGURE 7.Airplanes with preventive modification installed in accordance with the original issue of this service bulletin.

Do a HFEC inspection and detailed inspection for any crack in the bearstrap in accordance with FIGURE 5, and do a LFEC inspection of the skin assembly and bearstrap and a detailed inspection of the skin assembly for any crack in accordance with FIGURE 8.Airplanes with preventive modification installed in accordance with Revisions 1, 2 or 3 of this service bulletin.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 46 of 81 **BOEING SERVICE BULLETIN 737-53-1058 Group 2:**  **Table 2: Inspection Action - Inspection**  **Condition** Do a HFEC inspection and detailed inspection for any crack in the bearstrap in accordance with FIGURE 5, and do a detailed inspection of the skin assemblyand a LFEC inspection of the skin assembly and bearstrap for any crack in accordance with FIGURE 11.Airplanes with repair installed in accordance with the original issue of this service bulletin.

**Group 3-5: Table 3: Inspection**  **Action - Inspection Condition**  Do a HFEC and detailed inspection for any crack in the bearstrap in accordancewith FIGURE 5, and do a LFEC inspection of the skin assembly and bearstrap,and a detailed inspection of the skin assembly for any crack in accordance with FIGURE 9. All airplanes.

a.**Group 1-2:** For airplanes that do not have a repair or preventive installed in accordance with the original issue or revision 1, 2 or 3 of this service bulletin and no cracks are found in the skin assembly or bearstrap, do repeat inspections at the times given in Paragraph 1.E., Compliance or do the preventive modification as follows: (1) Remove all fasteners that will be common to the 65C20843-35 or 65C20843-36 preventive modification doubler. (2)**Group 1:** Do an open hole High Frequency Eddy Current (HFEC) inspection in accordance with 737 NDT Part 6, 51-00-00, Figure 16 for any crack at all fastener holes that will be common to the new preventive modification (or repair) given in 65C20843-35 . (a) If no crack is found, install the preventive modification in accordance with 65C20843-35 and Paragraph 3.A., General Information, Note 13. (b) If any crack is found in the skin assembly or bearstrap, but not both, repair in accordance with Part 2, step 1.e. (c) If any crack is in both the skin assembly and bearstrap, repair in accordance with Part 2, step 1.f.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 47 of 81 **BOEING SERVICE BULLETIN 737-53-1058**(3)**Group 2:** Do an open hole HFEC inspection in accordance with 737 NDT Part 6, 51-00-00, Figure 16 for any crack in all fastener holes that will be common to the new preventive modification given in 65C20843-36 . (a) If no crack is found, install the preventive modification in accordance with 65C20843-36 and Paragraph 3.A., General Information, Note 13. (b) If any crack is found in the skin assembly or bearstrap, but not both, repair in accordance with Part 2, step 1.e. (c) If any crack is in both the skin assembly and bearstrap, repair in accordance with Part 2, step 1.f. b.**Group 1-2:** For airplanes that have a repair installed in accordance with the original issue of this service bulletin and no cracks are found in the skin assembly and bearstrap, do repeat inspections at the times given in Paragraph 1.E., Compliance or remove the existing repair and install a new repair as follows: (1) Remove the previous repair parts. (2) Cut out the previously stop drilled cracks in accordance with FIGURE 12. (a) If the cutout is larger than the maximum cutout area given in FIGURE 12, contact The Boeing Company for repair instructions and do the repair. (3) If the cutout is in the skin assembly or bearstrap, but not both, repair in accordance with Part 2, step 1.e. (4) If the cutout is in the skin assembly and bearstrap, repair in accordance with Part 2, step 1.f.

c.**Group 1-2:** For airplanes that have a preventive modification installed in accordance with the original issue, Revision 1, 2 or 3 of this service bulletin and no cracks are found in the skin assembly and bearstrap, do the repeat inspections at times given in Paragraph 1.E., Compliance or do the preventive modification as follows: (1) Remove the previous preventive modification parts and all fasteners that will be common to the 65C20843-35 or 65C20843-36 preventive modification doubler. (2)**Group 1:** Do an open hole HFEC inspection in accordance with 737 NDT Part 6, 51-00-00 Figure 16 for any crack in all fastener holes that will be common to the new 65C20843-35 preventive modification doubler. (a) If no crack is found, install the new preventive modification in accordance with 65C20843-35 and Paragraph 3.A., General Information, Note 13. Make sure any fillers fabricated in FIGURE 12 are installed wet with BMS 5-95 sealant at the same time as the preventive modification. Refer to SOPM 20-50-19 as an accepted procedure. It is acceptable to oversize existing holes in accordance with Paragraph 3.A., General Information, Note 14.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 48 of 81 **BOEING SERVICE BULLETIN 737-53-1058**(b) If any crack is found in the skin assembly or bearstrap, but not both, repair in accordance with Part 2, step 1.e. (c) If any crack is found in the skin assembly and bearstrap, repair in accordance with Part 2, step 1.f. (3)**Group 2:** Do an open hole HFEC inspection in accordance with 737 NDT Part 6, 51-00-00 Figure 16 for any crack in all fastener holes that will be common to the new 65C20843-36 preventive modification doubler (or repair). (a) If no crack is found, install the new preventive modification in accordance with 65C20843-36 and Paragraph 3.A., General Information, Note 13. Make sure any fillers fabricated in FIGURE 12 are installed wet with BMS 5-95 sealant at the same time as the preventive modification. Refer to SOPM 20-50-19 as an accepted procedure. It is acceptable to oversize existing holes in accordance with Paragraph 3.A., General Information, Note 14. (b) If any crack is found in the skin assembly or bearstrap, but not both, repair in accordance with Part 2, step 1.e. (c) If any crack is found in the skin assembly and bearstrap, repair in accordance with Part 2, step 1.f. d.**Group 3-5:** If no crack is found in the skin assembly, or bearstrap, do repeat inspections at the times given in Paragraph 1.E., Compliance or do the preventive modification as follows: (1) Remove the external tripler 65-45800-1115 production modification parts. (2)**Group 3:** Do an open hole HFEC inspection in accordance with 737 NDT Part 6, 51-00-00 Figure 16 for any crack in all fastener holes that will be common to the new preventive modification (or repair) given in 65C20843-35. (a) If no crack is found, install the preventive modification in accordance with 65C20843-35 and Paragraph 3.A., General Information, Note 13. (b) If any crack is found in the skin or bearstrap, but not both, repair in accordance with Part 2, step 1.e. (c) If any crack is found in both the skin and bearstrap, repair in accordance with Part 2, step 1.f. (3)**Group 4:** Do an open hole HFEC inspection in accordance with 737 NDT Part 6, 51-00-00 Figure 16 for any crack in all fastener holes that will be common to the new preventive modification (or repair) given in 65C20843-36. (a) If no crack is found, install the preventive modification in accordance with 65C20843-36 and Paragraph 3.A., General Information, Note 13.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 49 of 81 **BOEING SERVICE BULLETIN 737-53-1058**(b) If any crack is found in the skin or bearstrap, but not both, repair in accordance with Part 2, step 1.e. (c) If any crack is found in both the skin and bearstrap, repair in accordance with Part 2, step 1.f. (4)**Group 5:** Do an open hole HFEC inspection in accordance with 737 NDT Part 6, 51-00-00 Figure 16 for any crack in all fastener holes that will be common to the new preventive modification (or repair) given in 65C20843-39. (a) If no crack is found, install the preventive modification in accordance with 65C20843-39 and Paragraph 3.A., General Information, Note 13. (b) If any crack is found in the skin or bearstrap, but not both, repair in accordance with Part 2, step 1.e. (c) If any crack is found in both the skin and bearstrap, repair in accordance with Part 2, step 1.f. e. If any crack is found in either the skin assembly or bearstrap, but not both: (1) Remove the previous modification or repair parts (if applicable). (2) Cut out all cracks found in accordance with FIGURE 12. **NOTE:**Existing cracks that have been previously stop-drilled must be cut out in accordance with FIGURE 12. (a) If the cutout is larger than the maximum cutout area shown in FIGURE 12, contact The Boeing Company for repair instructions and do the repair. (3)**Group 1, 3:** Do an open hole HFEC inspection in accordance with 737 NDT Part 6, 51-00-00 Figure 16 for any crack in all fastener holes that will be common to the new repair given in 65C20843-35. (a) If no crack is found, install the repair in accordance with Boeing drawing 65C20843 Sheet 3 and Paragraph 3.A., General Information, Note 13. Reference kit 65C20843-35. Make sure any fillers fabricated in FIGURE 12 are installed at the same time as the repair. For Group 1 airplanes that had an existing repair or preventive modification installed, it is acceptable to oversize existing holes in accordance with Paragraph 3.A., General Information, Note 14. (b) If any additional crack is found and is within the maximum cutout area shown in FIGURE 12: 1) Remove the damage in accordance with FIGURE 12.

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 50 of 81 **BOEING SERVICE BULLETIN 737-53-1058**2) Install the repair in accordance with Boeing drawing 65C20843 Sheet 3. Reference kit 65C20843-35 and Paragraph 3.A., General Information, Note 13. Make sure any fillers fabricated in FIGURE 12 are installed at the same time as the repair. For Group 1 airplanes that had an existing repair or preventive modification installed, it is acceptable to oversize existing holes in accordance with Paragraph 3.A., General Information, Note 14. (c) If any additional crack is found and is not within the maximum cutout area shown in Figure 12, contact The Boeing Company for repair instructions and do the repair. (4)**Group 2, 4:** Do an open hole HFEC inspection in accordance with 737 NDT Part 6, 51-00-00 Figure 16 for any crack in all fastener holes that will be common to the new repair given in 65C20843-36. (a) If no crack is found, install the repair in accordance with Boeing drawing 65C20843 Sheet 3 and Paragraph 3.A., General Information, Note 13. Reference kit 65C20843-36. Make sure any fillers fabricated in FIGURE 12 are installed wet with BMS 5-95 sealant at the same time as the repair. Refer to SOPM 20-50-19 as an accepted procedure. For Group 2 airplanes that had an existing repair or preventive modification installed, it is acceptable to oversize existing holes in accordance with Paragraph 3.A., General Information, Note 14. (b) If any additional crack is found and is within the maximum cutout area shown in FIGURE 12: 1) Remove the damage in accordance with FIGURE 12. 2) Install the repair in accordance with Boeing drawing 65C20843 Sheet 3 and Paragraph 3.A., General Information, Note 13. Reference kit 65C20843-36. Make sure any fillers fabricated in FIGURE 12 are installed wet with BMS 5-95 sealant at the same time as the repair. Refer to SOPM 20-50-19 as an accepted procedure. For Group 2 airplanes that had an existing repair or preventive modification installed, it is acceptable to oversize existing holes in accordance with Paragraph 3.A., General Information, Note 14. (c) If any additional crack is found and is not within the maximum cutout area shown in FIGURE 12, contact The Boeing Company for repair instructions and do the repair. (5)**Group 5:** Do an open hole HFEC inspection in accordance with 737 NDT Part 6, 51-00-00 Figure 16 for any crack in all fastener holes that will be common to the new repair given in 65C20843-39. (a) If no crack is found, install the repair in accordance with Boeing drawing 65C20843 Sheet 3 and Paragraph 3.A., General Information, Note 13. Reference kit 65C20843-39. Make sure any fillers fabricated in FIGURE 12 are installed wet with BMS 5-95 sealant at the same time as the repair. Refer to SOPM 20-50-19 as an accepted procedure. (b) If any additional crack is found and is within the maximum cutout area shown in FIGURE 12:

Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4: January 09, 2014 51 of 81 **BOEING SERVICE BULLETIN 737-53-1058**1) Remove the damage in accordance with FIGURE 12. 2) Install the repair in accordance with Boeing drawing 65C20843 Sheet 3 and Paragraph 3.A., General Information, Note 13. Reference kit 65C20843-39. Make sure any fillers fabricated in FIGURE 12 are installed wet with BMS 5-95 sealant at the same time as the repair. Refer to SOPM 20-50-19 as an accepted procedure. (c) If any additional crack is found and is not within the maximum cutout area shown in FIGURE 12, contact The Boeing Company for repair instructions and do the repair. f. If any crack is found in both the skin assembly and bearstrap: (1) Remove the previous modification or repair parts (if applicable). (2) Cut out the cracks in accordance with FIGURE 12. **NOTE:**Existing cracks that have been previously stop-drilled must be cut out in accordance with Figure 12. (a) If the cutout is larger than the maximum cutout area shown in FIGURE 12, contact The Boeing Company for repair instructions and do the repair. (3)**Group 1, 3:** Do an open hole HFEC inspection in accordance with 737 NDT Part 6, 51-00-00 Figure 16 for any crack in all fastener holes that will be common to the new repair given in 65C20843-37. (a) If no crack is found, install the repair in accordance with drawing 65C20843 Sheet 3 and Paragraph 3.A., General Information, Note 13. Reference kit 65C20843-37. Make sure any fillers fabricated in FIGURE 12 are installed wet with BMS 5-95 sealant at the same time as the repair. Refer to SOPM 20-50-19 as an accepted procedure. For Group 1 airplanes that had an existing repair or preventive modification installed, it is acceptable to oversize existing holes in accordance with Paragraph 3.A., General Information, Note 14. (b) If any additional crack is found and is within the maximum cutout area shown in FIGURE 12: 1) Remove the damage as shown in FIGURE 12. 2) Install the repair in accordance with Boeing drawing 65C20843 Sheet 3 and Paragraph 3.A., General Information, Note 13. Reference kit 65C20843-37. Make sure any fillers fabricated in FIGURE 12 are installed wet with BMS 5-95 sealant at the same time as the repair. Refer to SOPM 20-50-19 as an accepted procedure. (c) If any additional crack is found and is not within the maximum cutout area shown in FIGURE 12, contact The Boeing Company 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, 1980 737-53-1058 Revision 4: January 09, 2014 52 of 81 **BOEING SERVICE BULLETIN 737-53-1058**(4)**Group 2, 4:** Do an open hole HFEC inspection in accordance with 737 NDT Part 6, 51-00-00 Figure 16 for any crack in all fastener holes that will be common to the new repair given in 65C20843-38. (a) If no crack is found, install the repair in accordance with drawing 65C20843 Sheet 3 and Paragraph 3.A., General Information, Note 13. Reference kit 65C20843-38. Make sure any fillers fabricated in FIGURE 12 are installed wet with BMS 5-95 sealant at the same time as the repair. Refer to SOPM 20-50-19 as an accepted procedure. For Group 2 airplanes that had an existing repair or preventive modification installed, it is acceptable to oversize existing holes in accordance with Paragraph 3.A., General Information, Note 14. (b) If any additional crack is found and is within the maximum cutout area shown in FIGURE 12: 1) Remove the damage in accordance with FIGURE 12. 2) Install the repair in accordance with Boeing drawing 65C20843 Sheet 3 and Paragraph 3.A., General Information, Note 13. Reference kit 65C20843-38. Make sure any fillers fabricated in FIGURE 12 are installed wet with BMS 5-95 sealant at the same time as the repair. Refer to SOPM 20-50-19 as an accepted procedure. For Group 1 airplanes that had an existing repair or preventive modification installed, it is acceptable to oversize existing holes in accordance with Paragraph 3.A., General Information, Note 14. (c) If any additional crack is found and is not within the maximum cutout area shown in FIGURE 12, contact The Boeing Company for repair instructions and do the repair. (5)**Group 5:** Do an open hole HFEC inspection in accordance with 737 NDT Part 6, 51-00-00 Figure 16 for any crack in all fastener holes that will be common to the new repair given in 65C20843-40. (a) If no crack is found, install the repair in accordance with drawing 65C20843 Sheet 3 and Paragraph 3.A., General Information, Note 13. Reference kit 65C20843-40. Make sure any fillers fabricated in FIGURE 12 are installed wet with BMS 5-95 sealant at the same time as the repair. Refer to SOPM 20-50-19 as an accepted procedure. (b) If any additional crack is found and is within the maximum cutout area shown in FIGURE 12: 1) Remove the damage in accordance with FIGURE 12. 2) Install the repair in accordance with Boeing drawing 65C20843 Sheet 3 and Paragraph 3.A., General Information, Note 13. Reference kit 65C20843-40. Make sure any fillers fabricated in FIGURE 12 are installed wet with BMS 5-95 sealant at the same time as the repair. Refer to SOPM 20-50-19 as an accepted procedure. (c) If any additional crack is found and is not within the maximum cutout area shown in FIGURE 12, contact The Boeing Company 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, 1980 737-53-1058 Revision 4: January 09, 2014 53 of 81 **BOEING SERVICE BULLETIN 737-53-1058**g. Accomplishment of the repair or preventive modification in accordance with 65C20843-35, 65C20843-36, 65C20843-37, 65C20843-38, 65C20843-39, 65C20843-40 as given in paragraph a, c, d, e and f above terminates the inspection of this service bulletin. Post repair or preventive modification inspections are provided in Paragraph 1.E, Compliance Table 3 and Table 4 as applicable. **Group 1-5: PART 3 - POST REPAIR AND POST PREVENTIVE MODIFICATION INSPECTIONS** 
1.**Group 1-2:** Do an Internal HFEC Inspection for any crack in the Bearstrap and Skin Assembly and an Internal General Visual Inspection for any crack in the frame outer chord in accordance with FIGURE 13 (OPTION A) at the times specified in Paragraph 1.E., Compliance, Table 3 or do an External LFEC Inspection for any crack in the Bearstrap and Skin Assembly in accordance with FIGURE 14 (OPTION B) at the times specified in Paragraph 1.E., Compliance, Table 3. If any crack is found, contact The Boeing Company for repair instructions and do the repair.
2.**Group 3-5:** Do an Internal HFEC Inspection for any crack in the Bearstrap and Skin Assembly and an Internal General Visual Inspection for any crack in the frame outer chord in accordance with FIGURE 13 (OPTION A) at the times specified in Paragraph 1.E., Compliance, Table 4 or do an External LFEC Inspection for any crack in the Bearstrap and Skin Assembly in accordance with FIGURE 14 (OPTION B) at the times specified in Paragraph 1.E., Compliance, Table 4. If any crack is found, contact The Boeing Company for repair instructions and do the repair. **Group 1-5: PART 4 - CLOSE ACCESS**  1. 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, 1980 737-53-1058 Revision 4: January 09, 2014 54 of 81 **BOEING SERVICE BULLETIN 737-53-1058 FIGURE 1: THIS FIGURE HAS BEEN REMOVED**  **(SHEET 1 OF 1)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 55 of 81 **BOEING SERVICE BULLETIN 737-53-1058 FIGURE 2: THIS FIGURE HAS BEEN REMOVED**  **(SHEET 1 OF 1)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 56 of 81 **BOEING SERVICE BULLETIN 737-53-1058 FIGURE 3: THIS FIGURE HAS BEEN REMOVED**  **(SHEET 1 OF 1)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 57 of 81 **BOEING SERVICE BULLETIN 737-53-1058 This Figure applies only to: Group 1-5.** 

**FIGURE 4: AIRSTAIR STOWAGE DOORWAY CORNER - LOCATION OF INSPECTION AREAS (SHEET 1 OF 2)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 58 of 81 **BOEING SERVICE BULLETIN 737-53-1058**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)

- - Eddy current in- spection area Locate 1 (b)

- - Detailed inspection area Locate 2 (a) Area to be inspected using eddy current inspections. (b) Area to be inspected using detailed inspections.

**FIGURE 4: AIRSTAIR STOWAGE DOORWAY CORNER - LOCATION OF INSPECTION AREAS (SHEET 2 OF 2)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 59 of 81 **BOEING SERVICE BULLETIN 737-53-1058 This Figure applies only to: Group 1-5.** 

**FIGURE 5: AIRSTAIR STOWAGE DOORWAY CORNER - INTERNAL INSPECTION OF THE BEARSTRAP (SHEET 1 OF 2)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 60 of 81 **BOEING SERVICE BULLETIN 737-53-1058**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)

- - Bearstrap Inspect 1 (b)

- - Bearstrap Inspect 2(a) Do an internal HFEC surface inspection for any crack in the bearstrap within the area shown in accordance with 737 NDT Part 6, 51-00-00, Figure 4 or Figure 23. (b) Do an Internal Detailed Inspection for any crack in the visible inboard side of the bearstrap within the area shown.

**FIGURE 5: AIRSTAIR STOWAGE DOORWAY CORNER - INTERNAL INSPECTION OF THE BEARSTRAP (SHEET 2 OF 2)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 61 of 81 **BOEING SERVICE BULLETIN 737-53-1058 This Figure applies only to: Group 1-2.** 

**FIGURE 6: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - NO PREVENTIVE MODIFICATION OR EXTERNAL TRIPLER INSTALLED**  **(SHEET 1 OF 2)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 62 of 81 **BOEING SERVICE BULLETIN 737-53-1058**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)

- - Skin Assembly Inspect 1 (b)

- - Skin Assembly Inspect 2 (a) Do an external HFEC inspection for any crack in the skin assembly surface in accordance with 737 NDT Part 6, 51-00-00, Figure 4 or Figure 23. (b) Do an external Detailed Inspection for any crack in the skin assembly within the inspection area shown.

**FIGURE 6: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - NO PREVENTIVE MODIFICATION OR EXTERNAL TRIPLER INSTALLED**  **(SHEET 2 OF 2)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 63 of 81 **BOEING SERVICE BULLETIN 737-53-1058 This Figure applies only to: Group 1-2.** 

**FIGURE 7: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - PREVENTIVE MODIFICATION TRIPLER INSTALLED PER ORIGINAL ISSUE OF THIS SERVICE BULLETIN**  **(SHEET 1 OF 2)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 64 of 81 **BOEING SERVICE BULLETIN 737-53-1058**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)

- - Bearstrap Inspect 1 (a)

- - Skin Assembly (b)

- - Skin Assembly Inspect 2 (a) Do an external LFEC inspection for any crack in the surface of the skin assembly and bear strap through an external preventive modification tripler installed per the original issue of this service bulletin in accordance with 737 NDT Manual Part 6, 53-30-00, Figure 5. (b) Do an external Detailed Inspection for any crack in the visible skin assembly within the inspection area shown.

**FIGURE 7: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - PREVENTIVE MODIFICATION TRIPLER INSTALLED PER ORIGINAL ISSUE OF THIS SERVICE BULLETIN**  **(SHEET 2 OF 2)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 65 of 81 **BOEING SERVICE BULLETIN 737-53-1058 This Figure applies only to: Group 1-2.** 

**FIGURE 8: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - PREVENTIVE MODIFICATION TRIPLER INSTALLED PER REVISION 1, 2 OR 3 OF THIS SERVICE BULLETIN**  **(SHEET 1 OF 2)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 66 of 81 **BOEING SERVICE BULLETIN 737-53-1058**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)

- - Bearstrap Inspect 1 (a)

- - Skin Assembly (b)

- - Skin Assembly Inspect 2 (a) Do an external LFEC inspection for any crack in the surface of the skin assembly and bearstrap throughan external preventive modification tripler installed per Revision 1, 2 or 3 of this service bulletin in accordance with 737 NDT Manual Part 6, 53-30-00, Figure 5. (b) Do an external Detailed Inspection for any crack in the skin assembly within the inspection area shown.

**FIGURE 8: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - PREVENTIVE MODIFICATION TRIPLER INSTALLED PER REVISION 1, 2 OR 3 OF THIS SERVICE BULLETIN**  **(SHEET 2 OF 2)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 67 of 81 **BOEING SERVICE BULLETIN 737-53-1058 This Figure applies only to: Group 3-5.** 

**FIGURE 9: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - PRODUCTION MODIFICATION EXTERNAL TRIPLER INSTALLED**  **(SHEET 1 OF 2)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 68 of 81 **BOEING SERVICE BULLETIN 737-53-1058**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)

- - Bearstrap Inspect 1 (a)

- - Skin Assembly (b)

- - Skin Assembly Inspect 2 (a) Do external LFEC inspection for any crack in the surface of the skin assembly and bearstrap through the 65-45800-1115 external production modification tripler in accordance with 737 NDT Manual Part 6, 53- 30-00, Figure 5. (b) Do an external Detailed Inspection for any crack in the skin assembly within the inspection area shown.

**FIGURE 9: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - PRODUCTION MODIFICATION EXTERNAL TRIPLER INSTALLED**  **(SHEET 2 OF 2)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 69 of 81 **BOEING SERVICE BULLETIN 737-53-1058 This Figure applies only to: Group 1.** 

**FIGURE 10: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - REPAIR INSTALLED AT THE ORIGINAL ISSUE OF THIS SERVICE BULLETIN**  **(SHEET 1 OF 3)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 70 of 81 **BOEING SERVICE BULLETIN 737-53-1058 FIGURE 10: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - REPAIR INSTALLED AT THE**  **ORIGINAL ISSUE OF THIS SERVICE BULLETIN (SHEET 2 OF 3)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 71 of 81 **BOEING SERVICE BULLETIN 737-53-1058**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)

- - Skin Assembly Inspect 1 (b)

- - Skin Assembly Inspect 2 (b)

- - Bearstrap (a) Do an external Detailed Inspection for any crack in the skin assembly within the inspection area shown. (b) Do an external LFEC inspection for any crack in the skin assembly and bearstrap within the inspection area shown in accordance with 737 NDT Manual Part 6, 53-30-00, Figure 5.

**FIGURE 10: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - REPAIR INSTALLED AT THE ORIGINAL ISSUE OF THIS SERVICE BULLETIN**  **(SHEET 3 OF 3)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 72 of 81 **BOEING SERVICE BULLETIN 737-53-1058 This Figure applies only to: Group 2.** 

**FIGURE 11: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - REPAIR INSTALLED AT THE ORIGINAL ISSUE OF THIS SERVICE BULLETIN**  **(SHEET 1 OF 3)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 73 of 81 **BOEING SERVICE BULLETIN 737-53-1058 FIGURE 11: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - REPAIR INSTALLED AT THE**  **ORIGINAL ISSUE OF THIS SERVICE BULLETIN (SHEET 2 OF 3)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 74 of 81 **BOEING SERVICE BULLETIN 737-53-1058**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)

- - Skin Assembly Inspect 1 (b)

- - Skin Assembly Inspect 2 (b)

- - Bearstrap (a) Do an external Detailed Inspection for any crack in the skin assembly within the inspection area shown.(b) Do an external LFEC inspection for any crack in the skin assembly and bearstrap within the inspection area shown in accordance with 737 NDT Manual Part 6, 53-30-00, Figure 5.

**FIGURE 11: AIRSTAIR STOWAGE DOORWAY CORNER INSPECTION - REPAIR INSTALLED AT THE ORIGINAL ISSUE OF THIS SERVICE BULLETIN**  **(SHEET 3 OF 3)**
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 75 of 81 **BOEING SERVICE BULLETIN 737-53-1058 This Figure applies only to: Group 1-5.** 

**FIGURE 12: AIRSTAIR STOWAGE DOORWAY CORNER - AREA OF CUTOUT FOR CRACK REMOVAL (SHEET 1 OF 2)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 76 of 81 **BOEING SERVICE BULLETIN 737-53-1058**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)

- - Skin Assembly Cut 1 (a)

- - Bearstrap (b)

- - Cutout Inspect 2 (c)

- - Skin Assembly Cut 3 (c)

- - Bearstrap (d) (e) 2 2024-T3 Filler Make 4 (e) 1 Type 2, Class A Chemical Conversion Coating Apply 5 (f) 1 BMS 10-11, Type 1 Primer Apply 6 (a) Cut out the crack in the structure with a minimum 0.5 inch radius. Cut must not exceed the maximum dimension shown. Maintain 2D edge margin to adjacent fasteners. For skin assemblies, cut both skin and doubler together. (b) Do a High Frequency Eddy Current (HFEC) inspection of the cutout for any crack in accordance with 737 NDT Part 6, 51-00-00, Figure 4, or Figure 23. (c) If there are no crack indications, oversize the cutout by a minimum of 0.04 inches. Maintain a minimum of 63 RMS finish on the cutout and 2D edge margin for adjacent fasteners. (d) Size of filler to be determined by size of cutout and thickness of filler to be determined by build up of repair thickness at the crack location. (e) Apply chemical conversion coating to the edge of the cutout and the filler. Refer to SOPM 20-43- 03 as an accepted procedure. (f) Apply two coats of primer BMS 10-11, Type 1 to the edge of the cutout and the filler. Refer to SOPM 20-41-02 as an accepted procedure.

**FIGURE 12: AIRSTAIR STOWAGE DOORWAY CORNER - AREA OF CUTOUT FOR CRACK REMOVAL (SHEET 2 OF 2)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 77 of 81 **BOEING SERVICE BULLETIN 737-53-1058 This Figure applies only to: Group 1-5.** 

**FIGURE 13: POST REPAIR AND POST PREVENTIVE MODIFICATION INSPECTION - OPTION A (SHEET 1 OF 2)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 78 of 81 **BOEING SERVICE BULLETIN 737-53-1058**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)

- - Frame Inspect 1 (b)

- - Bearstrap Inspect 2 (b)

- - Skin Assembly (a) Do an internal General Visual Inspection for any crack in the frame. (b) Do a internal HFEC inspection for any crack in the Skin Assembly and Bearstrap in accordance with 737 NDT Part 6, 51-00-00 , Figure 4 or 23.

**FIGURE 13: POST REPAIR AND POST PREVENTIVE MODIFICATION INSPECTION - OPTION A (SHEET 2 OF 2)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 79 of 81 **BOEING SERVICE BULLETIN 737-53-1058 This Figure applies only to: Group 1-5.** 

**FIGURE 14: POST REPAIR AND POST PREVENTIVE MODIFICATION INSPECTION - OPTION B (SHEET 1 OF 2)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 80 of 81 **BOEING SERVICE BULLETIN 737-53-1058**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)

- - Bearstrap Inspect 1 (a)

- - Skin Assembly (a) Do a external Low Frequency Eddy Current (LFEC) inspection for any crack in the Skin Assembly and Bearstrap in accordance with 737 NDT Manual Part 6, 53-30-00, Figure 5.

**FIGURE 14: POST REPAIR AND POST PREVENTIVE MODIFICATION INSPECTION - OPTION B (SHEET 2 OF 2)** 
Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 04, 1980 737-53-1058 Revision 4 January 09, 2014 81 of 81 **BOEING SERVICE BULLETIN 737-53-1058**