### Commercial **Airplanes** 

# 737 Service Bulletin **Number: 737-57A1302** Original Issue: December 15, 2008 Revision 1: October 18, 2010 ATA System: 5754 **SUBJECT:** WINGS - Leading Edge Slats- Main Track Down Stop Modification and Detailed Inspection Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15 CFR 730-774). An export license may be required before it is used for development, production or use by foreign persons from specific countries. The controller of this data has the individual responsibility to abide by all export laws.9E991 ECCN: 

## BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET Copyright © 2008 The Boeing Company Unpublished Work - All Rights Reserved Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable subject matter. Boeing also claims copyright in this document as a compilation and/or collective work. This document includes proprietary information owned by The Boeing Company and/or one or more third parties. Treatment of the document and the information it contains is governed by contract with Boeing. For more information, contact The Boeing Company, P.O. Box 3707, Seattle, Washington 98124. Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner, BBJ, DC-8, DC-9, DC-10, KC-10, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8A, Poseidon and the Boeing livery are all trademarks owned by The Boeing Company; and no trademark license is granted in connection with this document unless provided in writing by Boeing.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 1 of 42 7.0BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 2 of 42 **BOEING SERVICE BULLETIN 737-57A1302**

BLANK PAGE**Table of Contents** Revision Transmittal Sheet............................................ 5 Summary...................................................... 7 1. PLANNING INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 A. Effectivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1. Airplanes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2. Spares Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 B. Concurrent Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 C. Reason. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 D. Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 E. Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 F. Approval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 G. Manpower. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 H. Weight and Balance Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 I. Electrical Load Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 J. References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 1. Existing Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2. Data supplied with this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 3. Installation Drawings Used in the Preparation of this Service Bulletin. . . . . . . . . . . . 24 K. Publications Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 L. Interchangeability and Intermixability of Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2. MATERIAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 A. Material - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 B. Industry Support Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 C. Parts Necessary For Each Airplane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 1. Kits/Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2. Parts and Materials Supplied by the Operator. . . . . . . . . . . . . . . . . . . . . . . . 28 3. Parts Modified and Reidentified. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 4. Parts Removed and Not Replaced. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 D. Parts Necessary to Change Spares. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 F. Special Tooling Necessary to do this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . 29 3. ACCOMPLISHMENT INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 A. GENERAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 B. WORK INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 FIGURE 1: SHRINK-FIT BUSHING INSTALLATION. . . . . . . . . . . . . . . . . . . . . . . . . . . 35 FIGURE 2: SHRINK-FIT BUSHING REAMING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 FIGURE 3: SLAT MAIN TRACK DOWN STOP AND AFT SIDE GUIDE MODIFICATION. . . . . . . 37

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 3 of 42 **BOEING SERVICE BULLETIN 737-57A1302**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 4 of 42 **BOEING SERVICE BULLETIN 737-57A1302**

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### Commercial **Airplanes** 

# 737 Service Bulletin **Revision Transmittal Sheet Number: 737-57A1302**  Original Issue: December 15, 2008 Revision 1: October 18, 2010 ATA System: 5754 **SUBJECT:** WINGS - Leading Edge Slats- Main Track Down Stop Modification and Detailed Inspection This revision includes all pages of the service bulletin. **COMPLIANCE INFORMATION RELATED TO THIS REVISION** No more work is necessary on airplanes changed in accordance with the original issue of this service bulletin. Federal Aviation Administration (FAA) Airworthiness Directive FAA AD 2007-18-52 is related to this service bulletin. **REASON FOR REVISION** This revision is sent to add clarification to this service bulletin. Changes to this service bulletin include: – Added borescope inspection option for the slat main track and in the slat can. – Updated Industry Support Information with the applicable Boeing Program Letter. – Added Damage Tolerance Information to Publications Affected. – Added optional stainless steel lockwire to Operator Supplied Parts table and Figure 3. – Updated Special Tooling - Price and Availability section, with Boeing's offer of two free optional toolkits to all operators, and removed toolkit rental option. – Added HAND reaming recommendation in the event interference occurs between the new down stop assembly bolt and the hole in the slat main track, in the Accomplishment Instructions. – Added the option to remove the wing anti-icing duct elbows near the down stop assembly in the right wing near the fuel metering manifold in order to gain easier access, in the Accomplishment Instructions. If the duct is disassembled a leak test is required. – Added reference to Aircraft Maintenance Manual 737-600/700/800/900 AMM 57-41-02 when reinstalling lower leading edge wing panels at the end of the Accomplishment Instructions. – Changed lower hole tolerance limit to 0.4375 inches in the event a bushing repair becomes necessary for the slat main track, in Figure 2. – Added step to apply corrosion preventive compound, MIL-C-11796, Class 3, to new aft side guide bolts upon installation, in Figure 3. The data given in Information Notice 737-57A1302 IN 01 is included in this revision. Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity, to show the location of important changes. Pages with no vertical lines have no important changes.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 5 of 42**REVISION HISTORY** December 15, 2008 Original Issue: October 18, 2010 Revision 1:

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 6 of 42 **BOEING SERVICE BULLETIN 737-57A1302**

### Commercial **Airplanes** 

# 737 Service Bulletin **Summary Number: 737-57A1302**  Original Issue: December 15, 2008 Revision 1: October 18, 2010 ATA System: 5754 **SUBJECT:** WINGS - Leading Edge Slats- Main Track Down Stop Modification and Detailed Inspection **CONCURRENT REQUIREMENTS** None. **BACKGROUND** Recently, a fuel leak and a subsequent fire resulted from loose down stop assembly hardware being pushed through the slat can while the slats were being retracted. FAA Airworthiness Directive FAA AD 2007-18-52 was initiated to inspect the 737NG fleet and re-torque the down stop assemblies as a result of this fire. Several issues were found including missing hardware, low torque, and improper assembly. This service bulletin requires 1) removal of the existing down stop assemblies and installation of a new down stop assembly on all 16 slat main tracks, and 2) removal of the existing aft side guide attach bolts at all 64 locations and replacement with identical bolts with drilled heads that are lock wired together on the ribs of the leading edge of the wing. Failure to incorporate this service bulletin could lead to conditions that allow the down stop assembly to fall off, or the aft side guides to become loose, and fall into the slat can. If the down stop assembly comes apart inside the slat can or the aft side guide falls into the slat can, then the slat main track may trap a down stop assembly component between the slat can and slat main track causing a puncture of the fuel tank creating a fuel leak and the risk of fire. As a part of a service bulletin validation program, this change was completed on airplane YC578 by Service Bulletin 737-57A1302 Original Issue before the release of Revision 1 of this service bulletin. The change completed on airplane YC578 by Service Bulletin 737-57A1302 Original Issue is equivalent to the release of Revision 1 of this service bulletin. Airplane YC578 has the configuration of a Group 1 airplane. Boeing Service Related Problem (SRP) 737-SRP-57-0209 is related to this service bulletin. **ACTION (PRR 38275-136S)** Remove the existing down stop assembly hardware from the slat main tracks of slats one through eight. Install the new down stop assembly hardware in the correct order and torque the nut. Install the cotter pin after all other hardware has been installed and bend the legs of the cotter pin. Remove the bolts which secure the aft side guides to the leading edge slat track ribs and replace them with the new drilled head bolts. Install the lock wire on the aft side guide boltheads. After the changes are done, do a detailed inspection or borescope inspection for debris on the slat main track and in the slat can. Special tooling is available from Boeing to assist with the installation of the down stop assembly hardware.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 7 of 42**EFFECTIVITY** 737-600, 700, 700C, 800, 900, 900ER airplanes. See Paragraph 1.A.1., Airplanes, for effectivity. **COMPLIANCE** Refer to Paragraph 1.E., Compliance. Federal Aviation Administration (FAA) Airworthiness Directive FAA AD 2007-18-52 is related to this service bulletin. **INDUSTRY SUPPORT INFORMATION** Boeing Industry Support information is provided in Program Letter BPL 6-1151-737-PGM-190, dated March 9, 2009 . Additional copies of program letters are available from Boeing Warranty and Product Assurance Contracts. **MANPOWER** Refer to Paragraph 1.G., Manpower. **MATERIAL INFORMATION** Boeing Supplied Kits/Parts. Refer to Paragraph 2.A., Material - Price and Availability

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 8 of 42 **BOEING SERVICE BULLETIN 737-57A1302**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 9 of 42 **BOEING SERVICE BULLETIN 737-57A1302**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 10 of 42 **BOEING SERVICE BULLETIN 737-57A1302**

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### Commercial **Airplanes** 

# 737 Service Bulletin **Number: 737-57A1302** Original Issue: December 15, 2008 Revision 1: October 18, 2010 ATA System: 5754 **SUBJECT:** WINGS - Leading Edge Slats- Main Track Down Stop Modification and Detailed Inspection **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. An equivalent change is on subsequent production airplanes. Refer to PRR 38275-136S for data about this change.
**DESCRIPTION CONFIGURATION**  **GROUP** 737-600/700/700C/800/900/900ER airplanes line numbers 1 through 2699 - 1

Airplane Models: 737-600, 737-700, 737-700C, 737-800, 737-900, 737-900ER **Group Variable Number**  1 YA001 - YA099 1 YA101 - YA199 1 YA201 - YA211 1 YA221 1 YA231 - YA242 1 YA251 - YA256 1 YA271 - YA272 1 YA291 1 YA301 - YA302

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 11 of 42**Group Variable Number**  1 YA311 - YA314 1 YA321 - YA323 1 YA336 - YA345 1 YA351 1 YA356 - YA357 1 YA366 - YA367 1 YA371 - YA377 1 YA501 - YA536 1 YA541 - YA552 1 YA571 - YA578 1 YA601 - YA615 1 YA621 - YA622 1 YA626 - YA631 1 YA635 - YA636 1 YA641 - YA642 1 YA645 - YA650 1 YA656 - YA659 1 YA666 - YA667 1 YA671 - YA672 1 YA681 - YA691 1 YA701 - YA710 1 YA721 - YA722 1 YA731 - YA734 1 YA751 - YA756 1 YA801 - YA803 1 YA809 1 YA811 - YA814 1 YA831 - YA835 1 YA841 - YA862 1 YA881 - YA882 1 YA891 - YA892 1 YA961 - YA978 1 YB001 - YB006

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 12 of 42 **BOEING SERVICE BULLETIN 737-57A1302 Group**  **Variable Number** 1 YB101 - YB132 1 YB151 - YB153 1 YB156 - YB158 1 YB161 - YB164 1 YB171 - YB172 1 YB181 - YB184 1 YB201 - YB208 1 YB271 1 YB276 1 YB301 - YB310 1 YB371 - YB392 1 YB501 - YB502 1 YB521 - YB526 1 YB541 - YB544 1 YB551 1 YB561 - YB598 1 YB601 - YB632 1 YB651 1 YB656 1 YB671 - YB672 1 YB851 - YB863 1 YB871 - YB874 1 YB881 - YB893 1 YB901 - YB903 1 YB911 1 YB961 - YB974 1 YB986 - YB987 1 YC001 - YC030 1 YC051 - YC084 1 YC091 - YC094 1 YC101 - YC104 1 YC111 - YC113 1 YC121

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 13 of 42 **BOEING SERVICE BULLETIN 737-57A1302 Group**  **Variable Number** 1 YC126 - YC127 1 YC136 - YC141 1 YC146 - YC147 1 YC151 - YC156 1 YC166 - YC171 1 YC176 - YC179 1 YC186 - YC190 1 YC201 - YC203 1 YC206 - YC207 1 YC301 - YC305 1 YC321 - YC387 1 YC391 - YC394 1 YC396 1 YC401 - YC417 1 YC421 - YC422 1 YC426 - YC428 1 YC436 - YC439 1 YC441 - YC448 1 YC451 - YC455 1 YC459 1 YC461 - YC467 1 YC471 - YC499 1 YC501 - YC526 1 YC571 - YC583 1 YC587 - YC589 1 YC591 - YC593 1 YC601 - YC655 1 YC681 - YC696 1 YC701 - YC715 1 YC720 - YC725 1 YC727 - YC752 1 YC761 - YC770 1 YC781 - YC793

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 14 of 42 **BOEING SERVICE BULLETIN 737-57A1302 Group**  **Variable Number** 1 YC801 - YC892 1 YC901 - YC907 1 YC921 - YC922 1 YC931 - YC932 1 YC941 - YC951 1 YC971 - YC978 1 YC981 - YC983 1 YD001 - YD007 1 YD021 - YD025 1 YD041 - YD057 1 YD081 - YD084 1 YD101 - YD110 1 YD121 - YD126 1 YD151 - YD159 1 YD171 - YD172 1 YD201 - YD203 1 YD206 - YD209 1 YD216 - YD219 1 YD251 - YD254 1 YD256 - YD257 1 YD261 1 YD301 - YD334 1 YD391 1 YD401 - YD410 1 YD412 - YD415 1 YD481 - YD485 1 YD491 - YD499 1 YD501 - YD512 1 YD531 - YD535 1 YD541 - YD547 1 YD561 - YD564 1 YD571 - YD572 1 YD591 - YD595

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 15 of 42 **BOEING SERVICE BULLETIN 737-57A1302 Group**  **Variable Number** 1 YD601 - YD612 1 YD651 - YD655 1 YE001 - YE020 1 YE051 1 YE101 - YE109 1 YE151 - YE157 1 YE171 - YE172 1 YE201 - YE206 1 YE301 - YE305 1 YE321 - YE326 1 YE371 - YE383 1 YF001 1 YF021 - YF026 1 YF051 - YF052 1 YF086 1 YF106 - YF107 1 YF111 1 YF176 - YF178 1 YG001 - YG044 1 YG061 - YG064 1 YG066 - YG089 1 YG091 - YG099 1 YG101 - YG103 1 YG111 - YG114 1 YG116 - YG120 1 YG201 - YG205 1 YG211 - YG214 1 YG251 - YG252 1 YG501 - YG509 1 YG601 - YG602 1 YG701 1 YG711 1 YH001 - YH012

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 16 of 42 **BOEING SERVICE BULLETIN 737-57A1302 Group**  **Variable Number** 1 YH051 - YH054 1 YH101 - YH114 1 YH201 - YH202 1 YH206 - YH207 1 YH301 1 YJ001 - YJ013 1 YJ021 1 YJ471 - YJ480 1 YJ501 - YJ517 1 YJ531 - YJ566 1 YJ591 - YJ597 1 YJ631 - YJ632 1 YJ671 - YJ694 1 YJ801 - YJ867 1 YJ871 - YJ875 1 YJ901 - YJ904 1 YJ908 1 YJ911 - YJ929 1 YJ931 - YJ937 1 YJ941 - YJ956 1 YJ976 - YJ977 1 YK001 - YK007 1 YK101 - YK104 1 YK111 - YK112 1 YK121 - YK122 1 YK131 - YK133 1 YK136 - YK139 1 YK141 - YK142 1 YK146 - YK148 1 YK151 - YK154 1 YK161 - YK167 1 YK171 1 YK176

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 17 of 42 **BOEING SERVICE BULLETIN 737-57A1302 Group**  **Variable Number** 1 YK301 - YK309 1 YK321 - YK338 1 YK361 - YK375 1 YK401 - YK406 1 YK426 - YK427 1 YK431 - YK450 1 YK456 - YK460 1 YK476 1 YK480 - YK485 1 YK495 1 YK511 - YK516 1 YK521 - YK523 1 YK551 - YK569 1 YK571 1 YK576 - YK577 1 YK580 - YK585 1 YK601 - YK602 1 YK606 - YK607 1 YK611 - YK616 1 YK621 - YK627 1 YK631 - YK634 1 YK641 - YK644 1 YK651 - YK661 1 YK671 1 YK701 - YK712 1 YK716 - YK719 1 YK721 - YK741 1 YK751 - YK759 1 YK791 - YK792 1 YK796 - YK797 1 YK801 - YK887 1 YK901 - YK911 1 YK918

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 18 of 42 **BOEING SERVICE BULLETIN 737-57A1302 Group**  **Variable Number** 1 YK921 - YK927 1 YK941 - YK952 1 YK961 - YK971 1 YK981 - YK985 1 YL001 - YL005 1 YL011 - YL016 1 YL021 - YL024 1 YL051 - YL052 1 YL056 - YL057 1 YL061 1 YL066 - YL069 1 YL076 - YL077 1 YL101 - YL116 1 YL201 - YL208 1 YL271 - YL272 1 YL281 - YL282 1 YL301 - YL303 1 YL311 - YL312 1 YL316 - YL319 1 YL371 - YL373 1 YL421 - YL426 1 YL431 - YL437 1 YL461 - YL473 1 YL501 - YL505 1 YL531 - YL533 1 YL561 - YL565 1 YL591 - YL592 1 YL601 - YL606 1 YL611 1 YL661 - YL663 1 YL901 - YL906 1 YL931 - YL932 1 YL951 - YL952

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 19 of 42 **BOEING SERVICE BULLETIN 737-57A1302 Group**  **Variable Number** 1 YM101 - YM103 1 YM201 - YM238 1 YM251 - YM299 1 YM301 - YM374 1 YM471 1 YM481 - YM484 1 YM501 - YM515 1 YM521 - YM522 1 YM541 1 YM551 - YM553 1 YM571 - YM572 1 YM581 - YM582 1 YM591 - YM593 1 YM631 - YM634 1 YM641 - YM651 1 YM671 - YM672 1 YM691 1 YM701 - YM702 1 YN001 - YN016 1 YN021 - YN024 1 YN061 1 YN071 - YN079 1 YN091 - YN092 1 YN101 - YN112 1 YN121 1 YN201 1 YN211 - YN216 1 YN231 - YN232 2. Spares Affected None. **B. Concurrent Requirements** None.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 20 of 42 **BOEING SERVICE BULLETIN 737-57A1302 C. Reason**  Recently, a fuel leak and a subsequent fire resulted from loose down stop assembly hardware being pushed through the slat can while the slats were being retracted. FAA Airworthiness Directive FAA AD 2007-18-52 was initiated to inspect the 737NG fleet and re-torque the down stop assemblies as a result of this fire. Several issues were found including missing hardware, low torque, and improper assembly. This service bulletin requires 1) removal of the existing down stop assemblies and installation of a new down stop assembly on all 16 slat main tracks, and 2) removal of the existing aft side guide attach bolts at all 64 locations and replacement with identical bolts with drilled heads that are lock wired together on the ribs of the leading edge of the wing. Failure to incorporate this service bulletin could lead to conditions that allow the down stop assembly to fall off, or the aft side guides to become loose, and fall into the slat can. If the down stop assembly comes apart inside the slat can or the aft side guide falls into the slat can, then the slat main track may trap a down stop assembly component between the slat can and slat main track causing a puncture of the fuel tank creating a fuel leak and the risk of fire. As a part of a service bulletin validation program, this change was completed on airplane YC578 by Service Bulletin 737-57A1302 Original Issue before the release of Revision 1 of this service bulletin. The change completed on airplane YC578 by Service Bulletin 737-57A1302 Original Issue is equivalent to the release of Revision 1 of this service bulletin. Airplane YC578 has the configuration of a Group 1 airplane. Revision 1: This revision is sent to add clarification to this service bulletin. Changes to this service bulletin include: – Added borescope inspection option for the slat main track and in the slat can. – Updated Industry Support Information with the applicable Boeing Program Letter. – Updated the Compliance Time in the Compliance Table. – Updated Reference Listing. – Added Damage Tolerance Information to Publications Affected. – Added optional stainless steel lockwire to Operator Supplied Parts table and Figure 3. – Updated Special Tooling - Price and Availability section, with Boeing's offer of two free optional toolkits to all operators, and removed toolkit rental option. – Added HAND reaming recommendation in the event interference occurs between the new down stop assembly bolt and the hole in the slat main track, in the Accomplishment Instructions. – Added the option to remove the wing anti-icing duct elbows near the down stop assembly in the right wing near the fuel metering manifold in order to gain easier access, in the Accomplishment Instructions. If the duct is disassembled a leak test is required. – Added reference to Aircraft Maintenance Manual 737-600/700/800/900 AMM 57-41-02 when reinstalling lower leading edge wing panels at the end of the Accomplishment Instructions. – Changed lower hole tolerance limit to 0.4375 inches in the event a bushing repair becomes necessary for the slat main track, in Figure 2. – Added step to apply corrosion preventive compound, MIL-C-11796, Class 3, to new aft side guide bolts upon installation, in Figure 3. Boeing Service Related Problem (SRP) 737-SRP-57-0209 is related to this service bulletin.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 21 of 42 **BOEING SERVICE BULLETIN 737-57A1302 D. Description**  Remove the existing down stop assembly hardware from the slat main tracks of slats one through eight. Install the new down stop assembly hardware in the correct order and torque the nut. Install the cotter pin after all other hardware has been installed and bend the legs of the cotter pin. Remove the bolts which secure the aft side guides to the leading edge slat track ribs and replace them with the new drilled head bolts. Install the lock wire on the aft side guide boltheads. After the changes are done, do a detailed inspection or borescope inspection for debris on the slat main track and in the slat can. Special tooling is available from Boeing to assist with the installation of the down stop assembly hardware. Revision 1 - No more work is necessary on airplanes changed in accordance with the original issue of this service bulletin. The work in this service bulletin is done in the maintenance zone(s) given below.
**Affected Maintenance Zones Zone**  **Model** 522, 523, 524, 525, 622, 623, 624, 625 737-600, 737-700, 737-700C, 737-800, 737-900, 737-900ER **E. Compliance** Federal Aviation Administration (FAA) Airworthiness Directive FAA AD 2007-18-52 is related to this service bulletin. **Table 1: Slats 1 through 8 Main Track Down Stop Assembly- Modification Repeat Interval**  **(Not to Exceed) Compliance Time**  **Action Condition** 

- Within 3 years after the original issue date of this service bulletinReplace down stop assembly hardware with new down stop assemblyhardware and do a detailed inspection of the slat cans and slat maintracks for debris in accordance with Paragraph 3.B., Work Instructions, Step 2, at all 16 slat main track locations.(a) All Airplanes

- Within 3 years after the original issue date of this service bulletin Replace aft side guide bolts with new aft side guide bolts in accordance with Paragraph 3.B., Work Instructions, Step 2, at all 16 slat main track locations.(a) All Airplanes

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 22 of 42 **BOEING SERVICE BULLETIN 737-57A1302 Table 1: Slats 1 through 8 Main Track Down Stop Assembly- Modification**  **Repeat Interval (Not to Exceed)**  **Compliance Time Action**  **Condition**

- Before Further FlightRemove debris in accordance with Paragraph 3.B., Work Instructions, Step 2.b. Debris found in slat can

(a) Replacement of down stop assembly hardware and detailed inspection for debris on slat main track and in slat can, in accordance with this service bulletin, terminates the repeat inspections in FAA AD 2007-18-52. **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. This service bulletin has been approved by the FAA. In addition, the Manager of the FAA Seattle Aircraft Certification Office approves the inspections and installation of the modification defined in this service bulletin as an alternative method of compliance to the inspections and torquing required by paragraphs (f) and (g) of AD 2007-18-52. All provisions of AD 2007-18-52 that are not specifically referenced in this paragraph remain fully applicable and must be complied with. **G. Manpower** The table below shows an estimate of the task hours necessary to do this 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 inspect the work • Time to cure the materials • Time to make the parts • Time to find the tools. **Elapsed Hours Task Hours**  **Number of Per- sons**  **Task**
2.75 11.00 4 Open Access

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 23 of 42 **BOEING SERVICE BULLETIN 737-57A1302 Elapsed Hours**  **Task Hours Number of Per-**  **sons Task** 
4.50 18.00 4 Figure 3 (16 loca- tions) 3.00 6.00 2 Close Access 10.25 35.00 TOTAL FOR EACH AIRPLANE **H. Weight and Balance Changes Change in Moment**  **(Pound-Inches) Change in Weight**  **(Pounds) Airplane**  -270 Pound-Inches -0.4 Pounds
**I. Electrical Load Data** Not applicable. **J. References** 1. Existing Data a. Engineering Change Memo PRR 38275-136S b. Boeing Program Letter 6-1151-737-PGM-190, dated March 9, 2009 c. Boeing Service Bulletin 737-57-1293, 737-57A1301 d. Federal Aviation Administration (FAA) Airworthiness Directive 2007-18-52 e. Standard Overhaul Practices Manual (SOPM) 20-30-03, 20-44-04, 20-50-02, 20-50-03 f. 737-600/700/800/900 Aircraft Maintenance Manual (AMM) 12-22, 27-81, 27-81-21, 30-11-00, 57-41-02 g. 737-600/700/800/900 Illustrated Parts Catalog (IPC) 57-54 2. Data supplied with this Service Bulletin None. 3. Installation Drawings Used in the Preparation of this Service Bulletin

**Title Drawing Number**  SLAT RIGGING INSTL-OUTBD LE 114A4001 SLAT INSTL-OUTBD LEADING EDGE, WING 114A4002 SIDE GUIDE AND ROLLER INSTL-OUTBD FIXED LE 116A8300

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 24 of 42 **BOEING SERVICE BULLETIN 737-57A1302**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: **Chapter-Section Publication**  737-600/700/800/900 AMM 27-81, 737-600/700/800/900 AMM 12-22 737 Maintenance Manual
737-600/700/800/900 IPC 57-54 737 Illustrated Parts Catalog 2. Damage Tolerance Based Structural Inspections: Boeing has evaluated this service bulletin for effects on Fatigue Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the Maintenance Program. This service bulletin does not affect FCS, therefore DTIs are not necessary. **L. Interchangeability and Intermixability of Parts**
Refer to Paragraph 2.C., Parts Necessary for Each Airplane, for interchangeability and intermixability information.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 25 of 42 **BOEING SERVICE BULLETIN 737-57A1302**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 26 of 42 **BOEING SERVICE BULLETIN 737-57A1302**

BLANK PAGE**2. MATERIAL INFORMATION A. Material - Price and Availability**  Boeing can supply the kit shown in Paragraph 2.C., Parts Necessary for Each Airplane as shown below. If there is a limit in the quantity (QTY) of kits, a supply sequence is given by Spares.
**Unit Price thru 12/31/2008**  **QTY Date**  **Name Number**  $5,388.00 1 10/31/08 TOP KIT, RETROFIT -DOWNSTOP REPLACEMENT 002A0001-90

200 1/09/09 300 1/16/09 300 1/23/09 500 1/30/09 500 3/12/09 500 3/20/09 **B. Industry Support Information** Boeing Industry Support information is provided in Program Letter BPL 6-1151-737-PGM-190, dated March 9, 2009 . Additional copies of program letters are available from Boeing Warranty and Product Assurance Contracts. **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. **Figure Kit 3**  **Top Kit** 1 002A0001-90
**ALL**
**KIT 002A0001-90**

**NOTES Existing Part**  **Number Name**  **Figure**

**New Part Number 3** **QTY** DOWN STOP FITTING - SLAT MAIN TRACK 32 114A4103-5

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 27 of 42 **BOEING SERVICE BULLETIN 737-57A1302 ALL** 
**KIT 002A0001-90**

**NOTES Existing Part**  **Number Name**  **Figure**

**New Part Number 3** **QTY** BOLT, HEX HEAD 64 BACB30NM4HK13 BOLT 16 BACB30NR7DK12 SELF-LOCKING NUT 16 BACN10YR7CM
PIN 16 BACP18BC03A06P WASHER 32 BACW10P22CC 2. Parts and Materials Supplied by the Operator
**Notes Name**  **QTY Part Number/ Specification**  Sealant 4 Oz BMS 5-95, TYPE I, CLASS B Bushing

- BACB28AW06A017C Primer 1 Oz BMS 10-79, TYPE III Paint 1 Oz BMS 10-60, TYPE II Corrosion Inhibiting Material 4 Oz BMS 3-38 Corrosion Preventive Compound 4 Oz MIL-C-11796, CLASS 3
Lockwire 32 ft MS20995NC32 (MS20995C32 optional)
3. Parts Modified and Reidentified None. 4. Parts Removed and Not Replaced None. **D. Parts Necessary to Change Spares** None.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 28 of 42 **BOEING SERVICE BULLETIN 737-57A1302 E. Special Tooling - Price and Availability**  No special tooling is necessary to do this service bulletin. However, special tooling is available to help with the installation of the down stop assembly hardware. Boeing will supply two optional toolkits free of charge to all operators. Refer to BPL 6-1151-737-PGM-190, dated March 9, 2009 . Send a Purchase Order to the Director of Spares. Give this service bulletin number and the date the tools will be used. **NOTE:**Customers with a fleet consisting of 737NG and Classic airplanes will receive only (2) toolkits, one toolkit for their 737NG fleet and one for their 737 Classic fleet (refer to Boeing Service Bulletin 737-57A1301). Additional toolkits are available for purchase. **Purchase Data:**
**Unit Price thru 12/31/2008**  **Name Tool Kit Number**  $2,678.00 Miscellaneous Tool Main Slat Downstop Installation Collector MIT002A0001-90
The kits are subject to the terms and conditions of the Boeing standard purchase order acknowledgement. After the Price date, new price data is applicable. Prices are in United States dollars. Terms: Net 30 days. Reference this service bulletin number and submit purchase order by one of the methods that follow: 1. Order on-line via ATA Spec 2000 or Boeing Part Page 2. Fax to (206) 662-7145 3. Spares Customer Support - MC 36-65 Boeing Spares Department P.O. Box 3707 Seattle, Washington 98124-2207 USA (Service Bulletin 737-57A1302) **F. Special Tooling Necessary to do this Service Bulletin** No special tooling is necessary to do this service bulletin. However, special tooling is available to help with the installation of the down stop assembly hardware. Refer to Paragraph 2.E., Special Tooling - Price and Availability. Maintenance and overhaul tools in the manuals shown in Paragraph 1.J., References, can also be necessary. Examine operator tool supply to make sure all necessary tools are available.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 29 of 42 **BOEING SERVICE BULLETIN 737-57A1302**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 30 of 42 **BOEING SERVICE BULLETIN 737-57A1302**

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. The instructions identified in Paragraph 3.B., Work Instructions and the Figure(s) give the recommended sequence of steps. The sequence of steps to do this service bulletin can be changed. 2. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for definition of the acronyms. 3. Obey all of the warnings and cautions given in the specified manual sections. 4. Unless shown differently, these dimensions and tolerances are used: – Linear dimensions are in inches 5. 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. 6. 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. **B. WORK INSTRUCTIONS** 1. PART 1 - Access a. Do the following steps for each slat main track for slats one through eight: (1) Remove the applicable panels from the lower leading edge surface of the wing in order to gain access to the slat main track. Refer to 737-600/700/800/900 AMM 27-81-21 as an accepted procedure. (2) Align the down stop assembly with the access holes in the ribs to get access to the down stop assembly. The slats may be positioned using the hydraulic system as given in the following procedure.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 31 of 42 **BOEING SERVICE BULLETIN 737-57A1302**(a) Pressurize hydraulic system B by toggling the Hydraulic System B electric motor pump switch, located on the P5-8 panel, to ON. (b) Place the flap handle to detent 40. (c) Allow the leading edge slats to fully extend. (d) Toggle the hydraulic system B electric motor pump switch to OFF. (e) Place the flap handle to detent 5. (f) Turn ON, and then immediately turn OFF (Pulse), the hydraulic system B electric motor pump switch. (g) If the down stop assembly has not moved far enough to line up with the access holes in the ribs, then pulse the hydraulic system B electric motor pump switch again. Repeat this step until the down stop assembly lines up with the access holes. **NOTE:**Successive start up cycles (pulses) of the hydraulic system B electric motor pump can overheat the pump and damage it. Do not let the pump get too hot to touch. If the pump gets hot and/or the overheat light on the P5-8 panel is illuminated, wait until the pump is cool enough to touch and the warning light goes off before pulsing or turning on the pump. (h) Once the down stop assembly lines up with the access holes, place the flap handle to detent 40. (i) After using the hydraulic system to align the down stop assembly with the access holes, install DO-NOT-OPERATE Tags on the hydraulic switch and flap lever in the cockpit. WARNING: Failure to do this may result in the slats being retracted which could cause serious bodily injury and damage to the slats. (3) As an option to the above procedure, you can deactivate the slats, disconnect the actuator from the slat, and move the slat manually to line up the down stop assembly with the access holes in the ribs. Refer to 737-600/700/800/900 AMM 27-81-21 as an accepted procedure to disconnect the actuator. b. It is optional to remove the wing anti-icing duct elbows near the aft side of the fuel metering manifold in the right wing in order to gain access to the down stop assembly near that location. 2. PART 2 - Preventive Modification a. Do the following steps for each slat main track for slats one through eight: (1) Remove the existing down stop assembly hardware (bolt, washer, down stop fitting, sleeve, stop locator, down stop fitting, washer and nut) from the slat main track. Refer to 737-600/700/800/900 AMM 27-81-21 as an accepted procedure.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 32 of 42 **BOEING SERVICE BULLETIN 737-57A1302 NOTE:** Be careful in handling the small parts. Do not drop them. Dropping a part into the slat can can result in unscheduled downtime. A part left in the slat can also create a risk of puncturing the slat can, which in turn could allow fuel to leak and pose a risk of fire. (2) Check the fit of the new down stop assembly bolt in the hole in the slat main track (the new down stop bolt is identified in Figure 3): (a) If the hole diameter is less than the bolt's shank diameter, then ream the hole up to a max of 0.4375 inches. It is recommended that you hand ream the hole. Clean in accordance with Boeing SOPM 20-30-03. Apply BMS 3-38, corrosion inhibiting material, to reamed hole. If slat removal is necessary, refer to 737-600/700/800/900 AMM 27-81-21 as an accepted procedure. (b) If the bolt has side-to-side play in the hole, then measure the hole. If the hole diameter is less than 0.4421 no further modification is needed for the slat track. If the hole diameter is 0.4421 to 0.5005 inches, then install a bushing in accordance with Figures 1 and 2. If slat removal is necessary, refer to 737-600/700/800/900 AMM 27-81-21 as an accepted procedure for removal and installation of the slat. (c) If the hole diameter is greater than 0.5005 inches, then contact Boeing for further repair instructions, or replace the slat main track. (3) Install the new down stop assembly hardware and aft side guide bolts in accordance with Figure 3. Optional tooling is available from Boeing to assist in installing the new down stop assembly hardware. Refer to Paragraph 2.E., Special Tooling - Price and Availability. **NOTE:**Be careful in handling the small parts. Do not drop them. Dropping a part into the slat can can result in unscheduled downtime. A part left in the slat can also create a risk of puncturing the slat can, which in turn could allow fuel to leak and pose a risk of fire. b. After all the down stop assemblies and aft side guide bolts have been modified, do a detailed inspection or a borescope inspection for debris in the slat cans of each wing. Also look for debris that may have fallen onto the lower rail of the slat main track. If debris is found, remove the debris. c. If an actuator was disconnected, then reconnect it. Refer to 737-600/700/800/900 AMM 27-81-21 as an accepted procedure. Remove the DO-NOT-OPERATE tags from the hydraulic switch and flap lever in the cockpit if they were installed earlier. d. If the wing anti-icing duct was disassembled, then reassemble it, and perform a leak test on the wing anti-icing duct. Refer to 737-600/700/800/900 AMM 30-11-00 as an accepted procedure. 3. PART III - Close Access a. Reinstall the panels that were removed from the lower leading edge of the wing. Refer to 737-600/700/800/900 AMM 57-41-02 as an accepted procedure.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 33 of 42 **BOEING SERVICE BULLETIN 737-57A1302 NOTE:** Before reinstalling the panels that were removed from the lower leading edge of the wing, you may want to do the changes in Service Bulletin 737-57-1293. b. Return the airplane to a serviceable condition.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1: October 18, 2010 34 of 42 **BOEING SERVICE BULLETIN 737-57A1302 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** Ream the hole in main slat track to 0.5000 - 0.5005 inches diameter. - - Slat Main Track Drill / Ream 1

Clean hole in slat main track. Refer to Boeing SOPM 20-30-03 as an accepted procedure. - - Slat Main Track Clean 2

Apply to the hole in the slat main track. - BMS 5-95, TYPE I, CLASS B Sealant Apply 3 Install Bushing, wet with BMS 5-95 sealant, using the shrink-fit method. Refer to Boeing SOPM 20-50-03 asan accepted procedure. Wipe off any excess sealant. - BACB28AW06A017C Bushing Install (New)

**FIGURE 1: SHRINK-FIT BUSHING INSTALLATION (SHEET 1 OF 1)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1 October 18, 2010 35 of 42 **BOEING SERVICE BULLETIN 737-57A1302 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** Ream bushing inner diameter to 0.4375 - 0.4420 inches. - BACB28AW06A017C Bushing Drill / Ream 1

Clean bushing. Refer to Boeing SOPM20-30-03 as an accepted procedure. - BACB28AW06A017C Bushing Clean 2

Apply 1 layer of primer to bushingface. Refer to Boeing SOPM 20-44-04as an accepted procedure. - BMS 10-79, TYPE III Primer Apply 3

Apply 1 layer of gloss enamel to bushing face. Refer to Boeing SOPM 20-44-04 as an accepted procedure. - BMS 10-60, TYPE II Paint Apply 4

**FIGURE 2: SHRINK-FIT BUSHING REAMING (SHEET 1 OF 1)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1 October 18, 2010 36 of 42 **BOEING SERVICE BULLETIN 737-57A1302 FIGURE 3: SLAT MAIN TRACK DOWN STOP AND AFT SIDE GUIDE MODIFICATION**  **(SHEET 1 OF 6)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1 October 18, 2010 37 of 42 **BOEING SERVICE BULLETIN 737-57A1302 FIGURE 3: SLAT MAIN TRACK DOWN STOP AND AFT SIDE GUIDE MODIFICATION**  **(SHEET 2 OF 6)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1 October 18, 2010 38 of 42 **BOEING SERVICE BULLETIN 737-57A1302 FIGURE 3: SLAT MAIN TRACK DOWN STOP AND AFT SIDE GUIDE MODIFICATION**  **(SHEET 3 OF 6)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1 October 18, 2010 39 of 42 **BOEING SERVICE BULLETIN 737-57A1302 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** One bolt for each slat main track, 16 per airplane. Mark reference line on threaded end of bolt to show cotter pin hole using felt-tip pen. Install bolt with BMS 3-38 corrosion inhibiting material.(a) (b) 16 BACB30NR7DK12 BOLT Install (New) 1

One washer under the bolt head for each slat main track, 16 per airplane(b) 16 BACW10P22CC WASHER Install (New)

One down stop fitting on each side of slat main track, 2 per slat main track, 32 per airplane. Install down stop fitting with BMS 3-38 corrosion inhibiting material.(b) 32 114A4103-5 DOWN STOP FITTING - SLAT MAIN TRACK Install (New)

Apply corrosion inhibiting material to bolt shank and inner faces of both down stop fittings. - BMS 3-38 Corrosion Inhibiting Material Apply

One washer under the nut for each slat main track, 16 per airplane(b) 16 BACW10P22CC WASHER Install (New)

Torque the nut to 180-200 inch pounds. One nut per slat main track, 16 per airplane(b) 16 BACN10YR7CM SELF-LOCKING NUT Install (New)

16 BACP18BC03A06P PIN Install (New)

**FIGURE 3: SLAT MAIN TRACK DOWN STOP AND AFT SIDE GUIDE MODIFICATION (SHEET 4 OF 6)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1 October 18, 2010 40 of 42 **BOEING SERVICE BULLETIN 737-57A1302 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** Using marked line as reference, rotate bolt so that cotter pincan be installed. Install cotter pin approximately asshown in the illustration. Be careful not to damage the boltthreads when installing the cotter pin. One cotter pin for each slat maintrack, 16 per airplane.(b) Remove/Install one bolt at a time per aftside guide. If you remove both of the existing bolts from an aft side guide, then it is possible youmay have to remove/reinstall theslat main track to reinstall the aft side guide. Keep existing washers. 32 BACB30() BOLT Remove 2

32 per airplane, 2 at each slat main track location. Install bolt with MIL-C-11796, Class 3, corrosionpreventive compound. Re-Install existing washers. 32 BACB30NM4HK13 BOLT, HEX HEAD Install (New)

Apply to new bolts before installation. - MIL-C-11796, CLASS 3 Corrosion Preventive Compound Apply Torque bolts to 78- 82 inch pounds. 32 per airplane, 2 at each slat main track location. 32 BACB30NM4HK13 BOLT, HEX HEAD Torque

**FIGURE 3: SLAT MAIN TRACK DOWN STOP AND AFT SIDE GUIDE MODIFICATION (SHEET 5 OF 6)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1 October 18, 2010 41 of 42 **BOEING SERVICE BULLETIN 737-57A1302 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** Remove/Install one bolt at a time per aftside guide. If you remove both of the existing bolts from an aft side guide, then it is possible youmay have to remove/reinstall theslat main track to reinstall the aft side guide. Keep existing washers. 32 BACB30() BOLT Remove 3

32 per airplane, 2 at each slat main track location. Install bolt with MIL-C-11796, Class 3, corrosionpreventive compound. Re-Install existing washers. 32 BACB30NM4HK13 BOLT, HEX HEAD Install (New)

Apply to new bolts before installation. - MIL-C-11796, CLASS 3 Corrosion Preventive Compound Apply Torque bolts to 78- 82 inch pounds. 32 per airplane, 2 at each slat main track location. 32 BACB30NM4HK13 BOLT, HEX HEAD Torque

Refer to Boeing SOPM 20-50-02 asan accepted procedure. - MS20995NC32 (MS20995C32 optional) Lockwire Install (New) 4

(a) The down stop assembly can be installed with the bolt head on either the inboard side or the outboard side of the slat main track (b) Optional Tool MIT002A0001-90 will ease installation of the down stop assembly and cotter pin.

**FIGURE 3: SLAT MAIN TRACK DOWN STOP AND AFT SIDE GUIDE MODIFICATION (SHEET 6 OF 6)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 15, 2008 737-57A1302 Revision 1 October 18, 2010 42 of 42 **BOEING SERVICE BULLETIN 737-57A1302**