# Boeing Alert Service Bulletin 747-53A2427: Boeing - Service Bulletin - Rights: © The Boeing Company. Filed by the FAA in regulations.gov docket FAA-2013-0425; AD 2014-07-01 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication. - Document: [Boeing Alert Service Bulletin 747-53A2427](https://openairdocs.org/service-documents/boeing/747-53a2427.md) - Title as filed: Boeing - Service Bulletin - Pages: 118 - PDF: https://openairdocs.org/files/sha256/d6/31/d631c7ba0d9a3cc52f5154fee398948d779a86753fc39d18a0e06719946c1570 - Page: https://openairdocs.org/service-documents/boeing/747-53a2427/file/d631c7ba0d9a ## Text Some pages are OCR from a scan. OCR can misread letters and numbers. Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 Commercial Airplanes 747 Service Bulletin ALERT Number: 747-53A2427 Original Issue: December 17, 1998 Revision 6: July 14, 2011 ATA System: 5313 SUBJECT: FUSELAGE - Tail Section - Body Station 2598 Bulkhead Inner Chord and Web 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all export laws. 9E991ECCN: BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET Copyright © 1998 The Boeing Company Unpublished Work - All Rights Reserved Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable subject matter.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 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details.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 17, 1998 747-53A2427Revision 6: July 14, 2011 1 of 118 2.0 ### Page 2 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 2 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT BLANK PAGE ### Page 3 Table of Contents Revision Transmittal Sheet ............................................ 5 Summary ...................................................... 9 1. PLANNING INFORMATION ........................................ 1 3 A. Effectivity ............................................... 1 3 1. Airplanes ............................................ 1 3 2. Spares Affected ........................................ 2 2 B. Concurrent Requirements ...................................... 2 2 C. Reason ................................................ 2 3 D. Description .............................................. 2 3 E. Compliance .............................................. 2 4 F. Approval ............................................... 3 5 G. Manpower .............................................. 3 5 H. Weight and Balance Changes .................................... 3 6 I. Electrical Load Data ......................................... 3 6 J. References .............................................. 3 6 1. Existing Data: ......................................... 3 6 2. Data supplied with this Service Bulletin: ........................... 3 7 3. Installation Drawings Used in the Preparation of this Service Bulletin: ........... 3 7 K. Publications Affected ........................................ 3 7 L. Interchangeability and Intermixability of Parts ........................... 3 8 2. MATERIAL INFORMATION ........................................ 3 9 A. Material - Price and Availability ................................... 3 9 B. Industry Support Information .................................... 3 9 C. Parts Necessary For Each Airplane ................................. 3 9 1. Kits/Parts: ........................................... 3 9 2. Parts and Materials Supplied by the Operator: ........................ 3 9 3. Parts Modified and Reidentified: ............................... 3 9 4. Parts Removed and Not Replaced: .............................. 3 9 D. Parts Necessary to Change Spares ................................. 3 9 E. Special Tooling - Price and Availability ............................... 3 9 F. Special Tooling Necessary to do this Service Bulletin ....................... 3 9 3. ACCOMPLISHMENT INSTRUCTIONS .................................. 4 1 A. GENERAL INFORMATION ..................................... 4 1 B. WORK INSTRUCTIONS ....................................... 4 2 FIGURE 1: DELETED ............................................ 4 7 FIGURE 2: INSPECTION .......................................... 4 8 FIGURE 3: DELETED ............................................ 5 5 FIGURE 4: WEB CRACK REMOVAL ................................... 5 6 FIGURE 5: INSPECTION - POST REPAIR / INTERIM MODIFICATION - REPAIRED/MODIFIED AREA .................................................. 5 9 FIGURE 6: INSPECTION - POST REPAIR / INTERIM MODIFICATION - FORWARD SIDE ...... 6 8 FIGURE 7: WEB REPAIR OR INTERIM MODIFICATION - NO EXISTING INNER CHORD REPAIR OR INTERIM MODIFICATION [Group 1, Configuration 1] .................... 7 2 FIGURE 8: WEB REPAIR OR INTERIM MODIFICATION - NO EXISTING INNER CHORD REPAIR OR INTERIM MODIFICATION [Group 2-3, Configuration 1] ................... 8 2 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 3 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 4 FIGURE 9: UPPER WEB REPAIR - EXISTING INNER CHORD REPAIR OR INTERIM MODIFICATION [Group 1, Configuration 2] ................................... 9 2 FIGURE 10: UPPER WEB REPAIR - EXISTING INNER CHORD REPAIR OR INTERIM MODIFICATION [Group 2-3, Configuration 2] ................................. 1 0 4 APPENDIX A: SERVICE HISTORY ..................................... 1 1 6 APPENDIX B: PREVIOUS REVISION CHANGE INFORMATION ..................... 1 1 8 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 4 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 5 Commercial Airplanes 747 Service Bulletin ALERT Revision Transmittal SheetNumber: 747-53A2427Original Issue: December 17, 1998 Revision 6: July 14, 2011 ATA System: 5313 SUBJECT: FUSELAGE - Tail Section - Body Station 2598 Bulkhead Inner Chord and Web Inspection 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 and Revisions 1 thru 5 of this service bulletin. Open hole and surface high-frequency eddy current (HFEC) inspections for cracks in the bulkhead upper and lower web panels are to be accomplished in accordance with this revision. The effectivity groups are changed with this revision. Airplanes with line numbers 1-1241 (group 1 airplanes before this revision) are now divided into group 1 (line number 1-695 airplanes) and group 2 (line number 696-1241 airplanes). The group 1 airplanes have a bonded doubler on the bulkhead web which has an affect on the web repair added with this revision. Airplanes with line numbers 1242-1307 (group 2 airplanes before this revision) are now group 3 airplanes. The interim modification given in this service bulletin is applicable to group 1 and group 2 airplanes only. Federal Aviation Administration (FAA) Airworthiness Directive AD 2010-14-07 is related to this service bulletin. AD 2010-14-07 supersedes AD 2006-05-06 which superseded AD 2001-15-03. REASON FOR REVISION After the release of Revision 5 of this service bulletin, several operators found cracks in the bulkhead upper and lower web panels near the inner chord to shear deck connection. Open hole and surface HFEC inspections for such cracks (plus web repairs and post-repair inspections) have been added with this revision as a result of these crack findings. These sections of the service bulletin have been changed: 1. Summary: updated the Background, Action and Manpower paragraphs and graphic to address added web inspections. 2. Planning Information BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 5 of 118 ### Page 6 a. Paragraph 1.A.1., Group Configuration table: revised airplane groups to account for differences in the bulkhead web configurations. b. Paragraph 1.C., Reason and Paragraph 1.D., Description: added information about bulkhead web cracks and associated inspections/repairs. c. Paragraph 1.E., Compliance: revised compliance tables to give new web inspection and repair data. Moved the interim modification data into Table 1 and moved the post-repair/modification data to Table 3. d. Paragraph 1.G., Manpower: revised manpower data to account for added web inspection. 3. Accomplishment Instructions: Part 1: added instruction for web inspections and repairs and changed to a table format to give the inspection/repair/modification alternatives. Part 3: created new Part 3 to give the post-repair/modification work. Part 4: created new Part 4 to give upper web repair work. 4. Figure 2: added upper and lower web inspection. 5. Figure 4: changed this figure to give the web crack removal work and removed the interim repair instruction which now appears in figures 7 and 8. 6. Figure 5: added post-repair/modification inspection of the upper web and added new post-repair configuration for the upper web repair. 7. Figure 7, 8: added these figures to give upper web repair for group 1 and group 2,3 airplanes respectively. These figures also give the instruction for the interim modification which is changed in configuration to be equivalent to the upper web repair minus the web trim out and the associated filler(s). 8. Figure 9, 10: added these figures to give upper web repair for airplanes that have an existing inner chord repair or interim modification. Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity, to show the location of important changes. Pages with no vertical lines have no important changes. REVISION HISTORY December 17, 1998Original Issue: October 28, 1999Revision 1: October 05, 2000Revision 2: September 27, 2001Revision 3: March 06, 2008Revision 4: October 01, 2009Revision 5: BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 6 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 7 July 14, 2011Revision 6: BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 7 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 8 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 8 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT BLANK PAGE ### Page 9 Commercial Airplanes 747 Service Bulletin ALERT SummaryNumber: 747-53A2427Original Issue: December 17, 1998 Revision 6: July 14, 2011 ATA System: 5313 SUBJECT: FUSELAGE - Tail Section - Body Station 2598 Bulkhead Inner Chord and Web Inspection THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH 1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OWNER. CONCURRENT REQUIREMENTS None. BACKGROUND Accomplishment of the inspections given in this service bulletin will make sure that cracks in the splice fitting, frame support, floor support, forward and aft inner chords, and upper and lower web panels of the Body Station (STA) 2598 bulkhead are found and repaired before the crack damage can have an affect on flight safety. The horizontal stabilizer hinge fittings are attached to the STA 2598 bulkhead. Cracks in the bulkhead splice fittings, frame supports, web, or inner chords that are not found and repaired could extend with continued use of the airplane and adversely affect the structural integrity of the bulkhead and the horizontal stabilizer support structure. Eleven operators have told Boeing about cracks that were found in the aft inner chord of the STA 2598 bulkhead on 14 airplanes. In addition, three operators have also told Boeing about cracks that were found in the forward inner chord of the STA 2598 bulkhead on three airplanes. These cracks were all found near the upper corners of the cutout for the horizontal stabilizer rear spar. Refer to Appendix A for more information about service history. NOTE: Refer to Appendix B for Revision 1, 2, 3, 4 and 5 change information previously described in this Service Bulletin. After the release of Revision 5 of this service bulletin, several operators reported cracks in the bulkhead upper and lower web panels near the inner chord to shear deck connection. Cracks found in the upper bulkhead web were 0.55 inch to 0.80 inches in length and cracks found in the lower bulkhead web were 0.20 inch to 1.30 inches in length. Two operators have reported web cracks on airplanes with 8,435 and 8,940 total flight-cycles while other reports were for web cracks found on airplanes with greater than 20,000 total flight cycles. Boeing Structural Item Interim Advisory (SIIA) 747-167 is related to this Service Bulletin. Boeing Service Related Problem (SRP) 747/747OP-SRP-53-0106; 747/747OP-SRP-53-0316 and 747-SRP-53-0343 are related to this service bulletin. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 9 of 118 ### Page 10 ACTION (PRR 85901-103RS) Do open hole and surface high frequency eddy current (HFEC) inspections for cracks in the left and right side splice fitting, frame support, forward and aft inner chords and floor support. In addition, do open hole and surface HFEC inspections for cracks in the bulkhead upper web (left and right sides) and lower web (left side only) near the aft inner chord to shear deck connection. If no crack(s) are found, repeat the open hole and surface HFEC inspections, or alternatively, accomplish a modification in accordance with Service Bulletin 747-53A2473. No further action is required by this service bulletin after modification in accordance with Service Bulletin 747-53A2473. If crack(s) are found in the aft inner chord only, accomplish the upper chord repair given in this service bulletin, or alternatively, accomplish a modification in accordance with Service Bulletin 747-53A2473. If a crack is found in the splice fitting, frame support, forward inner chord, or floor support, contact Boeing for repair data and do the repair. If a crack is found in the bulkhead upper web panel, accomplish the upper web repair given in this Service Bulletin, or alternatively, accomplish a bulkhead (Support Frame) modification in accordance with Service Bulletin 747-53A2473. If a crack is found in the bulkhead lower web, accomplish the bulkhead modification or contact Boeing for repair data and do the repair. For Group 1 and group 2 airplanes, an interim modification is to be accomplished by the time given in Paragraph 1.E., Compliance if the modification given in Service Bulletin 747-53A2473 is not accomplished by that time. EFFECTIVITY 747-100/-100B/-100B SUD/-200B/-200C/-200F/-300/-400/-400D/-400F/SP/SR Airplanes. Refer to Paragraph 1.A.1., Airplanes for the list of affected airplanes. COMPLIANCE See Paragraph 1.E., Compliance for compliance information. Federal Aviation Administration (FAA) Airworthiness Directive AD 2010-14-07 is related to this service bulletin. AD 2010-14-07 supersedes AD 2006-05-06 which superseded AD 2001-15-03. Also, Federal Aviation Administration (FAA) Airworthiness Directive AD 2004-07-22 R1 is related to this service bulletin. INDUSTRY SUPPORT INFORMATION Boeing warranty remedies are not available for the inspection and/or repair procedures given in this service bulletin. MANPOWER Refer to Paragraph 1.G., Manpower. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 10 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 11 (OCR) BOEING SERVICE BULLETIN 747-53A2427 ALERT ALERT MATERIAL INFORMATION None. STA ACCOMPLISH OPEN HOLE AND SURFACE 2598 HFEC INSPECTIONS FOR CRACKS IN THE FORWARD AND AFT INNER CHORDS, FRAME SUPPORT FITTING, SPLICE FITTINGS AND UPPER WEB PANEL. ACCOMPLISH REPAIRS AS NECESSARY AND REGULAR REPEAT INSPECTIONS, STA OR ALTERNATIVELY, ACCOMPLISH A 2598 BULKHEAD (SUPPORT FRAME) MODIFICATION. HORIZONTAL STABILIZER FRAME SUPPORT AFT INNER CHORD ACCOMPLISH OPEN HOLE HFEC INSPECTION FOR CRACKS IN THE LOWER WEB PANEL. ACCOMPLISH REGULAR REPEAT INSPECTIONS. IF CRACKS ARE FOUND ACCOMPLISH A BULKHEAD (SUPPORT UP FRAME) MODIFICATION, OR CONTACT BOEING FOR REPAIR DATA AND DO THE REPAIR. Original Issue: December 17, 1998 Revision 6: July 14, 2011 747-53A2427 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 11 of 118 ### Page 12 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 12 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT BLANK PAGE ### Page 13 Commercial Airplanes 747 Service Bulletin ALERT Number: 747-53A2427 Original Issue: December 17, 1998 Revision 6: July 14, 2011 ATA System: 5313 SUBJECT: FUSELAGE - Tail Section - Body Station 2598 Bulkhead Inner Chord and Web Inspection THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH 1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OWNER. 1. PLANNING INFORMATION A. Effectivity 1. Airplanes This service bulletin is for the airplanes shown below. Refer to Service Bulletin Index Document D6-30300 Part 3 for Airplane Variable Number, Line Number, and Serial Number data. DESCRIPTIONCONFIGURATIONGROUP Airplanes Line Number 1 to 695-1 Airplanes that do not have the interim modification or aft inner chord SRM repair 1 Airplanes that have the interim modification or aft inner chord SRM repair installed. 2 Airplanes Line Number 696 to 1241-2 Airplanes that do not have the interim modification or aft inner chord SRM repair 1 Airplanes that have the interim modification or aft inner chord SRM repair 2 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 13 of 118 ### Page 14 DESCRIPTIONCONFIGURATIONGROUP Airplanes Line Number 1242 to 1307-3 Airplanes that do not have an aft inner chord SRM repair1 Airplanes that have an aft inner chord SRM repair2 Airplane Models: 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SP, 747SR GroupVariable Number 1RA001 - RA034 1RA101 - RA115 1RA161 - RA164 1RA201 - RA203 1RA216 - RA217 1RA245 - RA246 1RA251 - RA266 1RA301 - RA318 1RA351 - RA360 1RA369 - RA373 1RA401 - RA418 1RA501 - RA502 1RA521 - RA528 1RA532 - RA548 1RA551 - RA552 1RA559 - RA561 1RA581 - RA582 1RA585 1RA601 - RA602 1RA631 - RA635 1RA651 - RA652 1RA671 - RA677 1RA701 - RA702 1RA721 - RA731 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 14 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 15 GroupVariable Number 1RA741 - RA745 1RA749 - RA750 1RA761 - RA762 1RA781 - RA784 1RA901 - RA916 1RB001 - RB016 1RB041 - RB044 1RB071 - RB075 1RB101 - RB102 1RB411 - RB412 2RB413 2RB421 1RB601 - RB607 1RB681 - RB697 1RB711 1RB721 - RB723 1RB741 - RB748 1RD001 - RD004 1RD021 - RD022 1RD041 - RD059 1RD071 - RD072 1RD081 - RD083 1RD091 - RD092 1RD101 - RD104 1RD121 - RD127 1RD131 - RD144 1RD166 - RD167 1RD171 - RD172 1RD181 - RD183 1RD201 - RD204 1RD221 - RD227 1RD231 - RD234 2RD235 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 15 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 16 GroupVariable Number 1RD241 - RD243 1RD251 - RD262 1RD271 - RD272 1RD291 - RD292 1RD301 - RD302 1RD311 1RD351 - RD358 1RD361 - RD366 1RD381 - RD383 1RD411 - RD414 1RD421 - RD426 1RD431 - RD435 1RD441 - RD442 1RD451 - RD456 1RD461 1RD471 - RD475 1RD513 - RD519 1RD531 - RD533 1RD551 1RD561 1RD571 1RD581 - RD583 1RD591 - RD593 1RD601 - RD607 1RD621 - RD623 1RD641 - RD649 1RD651 - RD659 1RD661 1RD671 1RD681 - RD682 1RD691 - RD692 1RD701 - RD702 1RD721 - RD722 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 16 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 17 GroupVariable Number 1RD741 - RD742 1RD751 - RD755 1RD761 1RD771 - RD775 1RD781 - RD783 1RD791 2RD792 1RE001 1RG001 - RG009 1RG091 1RG095 1RG101 - RG104 1RG121 - RG126 1RG141 - RG142 1RG161 - RG164 1RG171 - RG174 1RG191 - RG193 1RG211 - RG213 1RG221 - RG222 1RH101 - RH102 1RH111 - RH112 1RH121 - RH122 1RJ131 - RJ133 1RJ151 - RJ152 1RJ301 - RJ303 1RJ321 2RJ322 1RJ331 - RJ333 3RL401 - RL402 3RL411 - RL419 3RL651 - RL654 3RL751 2RM001 - RM003 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 17 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 18 GroupVariable Number 3RM004 - RM007 3RM010 2RM011 - RM012 3RM013 2RM021 - RM024 2RM026 - RM027 3RM028 - RM029 2RM036 - RM038 3RM039 - RM040 2RM041 3RM042 - RM045 2RM051 3RM052 2RM071 2RM081 - RM084 2RM091 2RM096 - RM097 2RM116 - RM117 2RM126 - RM131 3RM132 2RM136 - RM147 2RM156 - RM157 3RM158 2RM166 - RM176 3RM177 2RM191 - RM192 2RM231 - RM232 3RM233 2RM241 - RM244 3RM245 - RM246 2RM261 - RM264 2RM316 3RM317 - RM318 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 18 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 19 GroupVariable Number 2RM331 - RM333 3RM341 3RM351 - RM355 3RM366 - RM367 2RM801 3RM802 - RM803 2RM811 - RM813 2RM851 - RM852 3RM853 - RM858 2RM861 3RM862 2RM871 3RM872 - RM876 2RM881 - RM885 3RM886 2RM891 - RM899 2RM901 3RM902 - RM905 2RM911 1RR001 - RR005 1RR021 - RR023 2RR024 - RR025 1RR031 1RR201 - RR205 2RR206 1RR221 - RR226 1RR261 - RR267 1RR301 - RR306 2RR307 - RR310 1RR331 - RR332 1RR336 1RR341 - RR345 1RR361 - RR362 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 19 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 20 GroupVariable Number 1RR421 - RR422 1RR431 - RR432 1RR441 2RR442 2RR451 1RR501 - RR504 1RR521 2RR522 2RR526 1RR531 1RR551 - RR554 2RR555 - RR556 1RR561 2RR566 2RR701 2RR721 - RR724 2RR746 - RR748 2RR851 - RR856 2RR861 - RR862 2RR951 - RR952 1RS001 - RS002 1RS201 1RS211 - RS212 1RS221 - RS222 1RS231 - RS241 1RS251 - RS259 2RS263 1RS265 - RS268 1RS271 - RS276 1RS291 - RS292 1RS301 - RS305 2RS306 1RS311 - RS320 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 20 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 21 GroupVariable Number 2RS331 - RS333 1RS341 - RS342 1RS699 1RS701 - RS703 1RS711 - RS713 1RS721 - RS722 2RS731 - RS732 1RS741 - RS743 1RS751 - RS752 1RS761 2RS762 1RS771 2RS781 - RS782 2RS786 2RT001 - RT014 2RT021 - RT022 2RT031 - RT035 2RT041 - RT047 2RT061 2RT071 - RT075 2RT101 - RT103 2RT121 2RT131 - RT137 2RT151 - RT152 2RT161 - RT168 2RT401 - RT412 2RT431 - RT447 2RT451 - RT469 2RT471 - RT499 2RT501 - RT535 2RT551 - RT568 2RT571 - RT591 2RT601 - RT657 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 21 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 22 GroupVariable Number 2RT671 - RT673 2RT681 - RT682 2RT691 - RT699 2RT701 - RT704 2RT711 - RT717 2RT741 - RT757 2RT776 - RT777 2RT781 - RT784 2RT801 - RT803 2RT811 - RT814 2RT831 - RT837 2RT861 - RT864 2RT876 - RT880 2RT931 - RT932 2RT945 - RT949 2RT951 - RT955 2RT966 - RT967 2RU001 - RU006 2RU016 - RU017 2RU031 - RU032 2RU051 - RU052 2RU059 - RU062 2RU081 - RU083 2RU101 - RU102 2RU121 - RU132 2RU801 - RU809 2RU831 - RU841 2. Spares Affected None. B. Concurrent Requirements None. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 22 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 23 C. Reason Accomplishment of the inspections given in this service bulletin will make sure that cracks in the splice fitting, frame support, floor support, forward and aft inner chords, and upper and lower web panels of the Body Station (STA) 2598 bulkhead are found and repaired before the crack damage can have an affect on flight safety. The horizontal stabilizer hinge fittings are attached to the STA 2598 bulkhead. Cracks in the bulkhead splice fittings, frame supports, web, or inner chords that are not found and repaired could extend with continued use of the airplane and adversely affect the structural integrity of the bulkhead and the horizontal stabilizer support structure. Eleven operators have told Boeing about cracks that were found in the aft inner chord of the STA 2598 bulkhead on 14 airplanes. In addition, three operators have also told Boeing about cracks that were found in the forward inner chord of the STA 2598 bulkhead on three airplanes. These cracks were all found near the upper corners of the cutout for the horizontal stabilizer rear spar. Refer to Appendix A for more information about service history. NOTE: Refer to Appendix B for Revision 1, 2, 3, 4 and 5 change information previously described in this Service Bulletin. After the release of Revision 5 of this service bulletin, several operators reported cracks in the bulkhead upper and lower web panels near the inner chord to shear deck connection. Cracks found in the upper bulkhead web were 0.55 inch to 0.80 inches in length and cracks found in the lower bulkhead web were 0.20 inch to 1.30 inches in length. Two operators have reported web cracks on airplanes with 8,435 and 8,940 total flight-cycles while other reports were for web cracks found on airplanes with greater than 20,000 total flight cycles. Boeing Structural Item Interim Advisory (SIIA) 747-167 is related to this Service Bulletin. Boeing Service Related Problem (SRP) 747/747OP-SRP-53-0106, 747/747OP-SRP-53-0316, and 747-SRP-53-0343 are related to this service bulletin. Revision 6 is sent to give instruction for open hole and surface HFEC inspections for cracks in the bulkhead upper and lower web panels and to give associated repair data. D. Description Do open hole and surface high frequency eddy current (HFEC) inspections for cracks in the left and right side splice fitting, frame support, forward and aft inner chords and floor support. In addition, do open hole and surface HFEC inspections for cracks in the bulkhead upper web (left and right sides) and lower web (left side only) near the aft inner chord to shear deck connection. If no crack(s) are found, repeat the open hole and surface HFEC inspections, or alternatively, accomplish a bulkhead (Support Frame) modification in accordance with Service Bulletin 747-53A2473. No further action is required by this service bulletin after modification in accordance with Service Bulletin 747-53A2473. If crack(s) are found in the aft inner chord only, accomplish the chord repair given in this service bulletin, or alternatively, accomplish a modification in accordance with Service Bulletin 747-53A2473. If a crack is found in the splice fitting, frame support, forward inner chord, or floor support, contact Boeing for repair data and do the repair. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 23 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 24 If a crack is found in the bulkhead upper web panel, accomplish the upper web repair given in this Service Bulletin, or alternatively, accomplish a modification in accordance with Service Bulletin 747-53A2473. If a crack is found in the bulkhead lower web, accomplish the modification or contact Boeing for repair data and do the repair. For Group 1 and group 2 airplanes, an interim modification is to be accomplished by the time given in Paragraph 1.E., Compliance if the modification given in Service Bulletin 747-53A2473 is not accomplished by that time. NOTE: Refer to Appendix B for Revision 1, 2, 3, 4 and 5 change information previously described in this Service Bulletin. Revision 6 - More work is necessary on airplanes changed as shown in the original issue and revisions 1 thru 5 of this service bulletin. Open hole and surface high-frequency eddy current (HFEC) inspections for cracks in the bulkhead upper and lower web panels are to be accomplished in accordance with this revision. The work in this service bulletin is done in the maintenance zone(s) given below. Group 1: Affected Maintenance Zones ZoneModel 315, 316747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SP, 747SR Group 2: Affected Maintenance Zones ZoneModel 315, 316747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F Group 3: Affected Maintenance Zones ZoneModel 315, 316747-400, 747-400F E. Compliance Refer to the tables below to find the applicable compliance times. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 24 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 25 Applicable Compliance Ta- bles Airplanes 1, 3Group 1,2 2, 3Group 3 Group 1-2: Table 1: Bulkhead Inspection, Repair and Modification - Group 1, 2 Airplanes Repeat Interval (Not to Exceed) Compliance TimeActionCondition --The work given in this service bulletin is not necessary. Bulkhead (Support Frame) modification given in Boe- ing service bulletin 747- 53A2473 or 747-53-2473 has been accomplished. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 25 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 26 Group 1-2: Table 1: Bulkhead Inspection, Repair and Modification - Group 1, 2 Airplanes Repeat Interval (Not to Exceed) Compliance TimeActionCondition -Before 6,000 total flight cycles or within 500 flight cy- cles after the date on Revision 2 of this service bul- letin, whichever occurs later. Do a surface high frequen- cy eddy current (HFEC) inspection for cracks at specified locations in the bulkhead splice fitting, frame support, and for- ward and aft inner chords in accordance with Ac- complishment Instruc- tions 3.B., Part 1. Bulkhead (Support Frame) modification given in Boe- ing service bulletin 747- 53A2473 or 747-53-2473 has not been accom- plished. See note (b). -Before 6,000 total flight cycles or within 1,500 flight cycles after the date on Revision 4 of this service bul- letin, whichever occurs later. Do an open hole and sur- face HFEC inspection for cracks at specified loca- tions in the bulkhead splice fitting, frame sup- port, forward and aft inner chords, and floor support in accordance with Ac- complishment Instruc- tions 3.B., Part 1. -Before 6,000 total flight cycles or within 1,500 flight cycles after the date on Revision 6 of this Service Bul- letin, whichever occurs later. Do a surface HFEC in- spection for cracks in the bulkhead upper web in accordance with Accom- plishment Instructions 3.B., Part 1. -Before 6,000 total flight cycles or within 3,000 flight cycles after the date on Revision 6 of this service bul- letin, whichever occurs later. Do an open hole and sur- face HFEC inspection for cracks in the bulkhead lower web in accordance with Accomplishment In- structions 3.B., Part 1. -Before further flight. Accomplish the modifica- tion given in Boeing ser- vice bulletin 747-53A2473 Lower web has a crack. Or Contact Boeing for repair data and do the repair. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 26 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 27 Group 1-2: Table 1: Bulkhead Inspection, Repair and Modification - Group 1, 2 Airplanes Repeat Interval (Not to Exceed) Compliance TimeActionCondition 3,000 flight cyclesWithin 3,000 flight- cycles after the ini- tial inspection. Repeat the open hole and surface HFEC inspec- tions for cracks in the bulkhead lower web in accordance with Accom- plishment Instructions 3.B., Part 1. Lower web doesn't have a crack. See note (a), (b). --Repair in accordance in accordance with Accom- plishment Instructions 3.B., Part 1 and do post- repair inspections in ac- cordance with Table 3. Crack in the aft inner chord and/or a crack in the upper web that is contained within the allowed trim out area. Continue lower web in- spections in accordance with this table Or Accomplish the modifica- tion given in Boeing ser- vice bulletin 747- 53A2473. -Before further flight. Contact Boeing for repair data and do the repair. Crack(s) found in the splice fitting, frame support, for- ward inner chord, or floor support Or Crack in the upper web that extends outside the al- lowed trim area. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 27 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 28 Group 1-2: Table 1: Bulkhead Inspection, Repair and Modification - Group 1, 2 Airplanes Repeat Interval (Not to Exceed) Compliance TimeActionCondition 1,500 flight cyclesWithin 1,500 flight- cycles after the ini- tial inspection. Repeat the forward and aft side open hole and surface HFEC inspec- tions for cracks in the bulkhead splice fitting, frame support, forward and aft inner chords and the bulkhead upper web in accordance with Ac- complishment Instruc- tions 3.B., Part 1. No cracks found in the bulkhead splice fitting, frame support, forward and aft inner chords, upper web, or floor support. See note (a), (b), (c). 3,000 flight cyclesWithin 3,000 flight- cycles after the ini- tial inspection. Repeat the open hole and surface HFEC inspec- tions for cracks in the bulkhead lower web in accordance with Accom- plishment Instructions 3.B., Part 1. See note (a), (b). -Before 12,000 total flight cycles or within 1,500 flight cycles after the date on Revision 4 of this service bul- letin, whichever occurs later. Install interim modification in accordance with Ac- complishment Instruc- tions 3.B., Part 2. See note (a), (b), (d). Do post-modification in- spections in accordance with Table 3. Interim modification in- stalled Continue lower web in- spections in accordance with this table See note (a), (b). (a) As an alternative to repeat inspections, accomplish the modification given in Boeing service bulletin 747-53A2473. No further action is required by this service bulletin after modification in accordance with Boeing service bulletin 747-53A2473. (b) Federal Aviation Administration (FAA) Airworthiness Directive 2010-14-07 requires that the modification given in Boeing service bulletin 747-53A2473 be accomplished before 20,000 total flight cycles, or within 18 months after the effective date of the AD, whichever occurs later. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 28 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 29 Group 1-2: Table 1: Bulkhead Inspection, Repair and Modification - Group 1, 2 Airplanes Repeat Interval (Not to Exceed) Compliance TimeActionCondition (c) As an alternative to repeat inspections at the given intervals, accomplish the interim modification and do post-modification inspections in accordance with Table 3. (d) If the aft inner chord repair or upper web repair has been accomplished in accordance with this service bulletin, it is not necessary to accomplish the interim modification on the side of the airplane that has the repair. Group 3: Table 2: Bulkhead Inspection, Repair and Modification - Group 3 Airplanes Repeat Interval (Not to Exceed) Compliance TimeActionCondition --The work given in this service bulletin is not necessary. Bulkhead (Support Frame) modification given in Boe- ing service bulletin 747- 53A2473 or 747-53-2473 has been accomplished. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 29 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 30 Group 3: Table 2: Bulkhead Inspection, Repair and Modification - Group 3 Airplanes Repeat Interval (Not to Exceed) Compliance TimeActionCondition -Before 16,000 total flight cycles or within 500 flight cy- cles after the date on Revision 2 of this service bul- letin, whichever occurs later. Do a surface high frequen- cy eddy current (HFEC) inspection for cracks at specified locations in the bulkhead splice fitting, frame support, and for- ward and aft inner chords in accordance with Ac- complishment Instruc- tions 3.B., Part 1. Bulkhead (Support Frame) modification given in Boe- ing service bulletin 747- 53A2473 or 747-53-2473 has not been accom- plished. See note (b). -Before 16,000 total flight cycles or within 1,500 flight cycles after the date on Revision 4 of this service bul- letin, whichever occurs later. Do an open hole and sur- face HFEC inspection for cracks at specified loca- tions in the bulkhead splice fitting, frame sup- port, forward and aft inner chords, and floor support in accordance with Ac- complishment Instruc- tions 3.B., Part 1. -Before 16,000 total flight cycles or within 1,500 flight cycles after the date on Revision 6 of this Service Bul- letin, whichever occurs later. Do a surface HFEC in- spection for cracks in the bulkhead upper web in accordance with Accom- plishment Instructions 3.B., Part 1. -Before 16,000 flight cycles or within 3,000 flight cycles after the date on Revision 6 of this service bul- letin, whichever occurs later. Do an open hole and sur- face HFEC inspection for cracks in the bulkhead lower web in accordance with Accomplishment In- structions 3.B., Part 1. -Before further flight. Accomplish the modifica- tion given in Boeing ser- vice bulletin 747-53A2473 Lower web has a crack. Or Contact Boeing for repair data and do the repair. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 30 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 31 Group 3: Table 2: Bulkhead Inspection, Repair and Modification - Group 3 Airplanes Repeat Interval (Not to Exceed) Compliance TimeActionCondition 3,000 flight cyclesWithin 3,000 flight- cycles after the ini- tial inspection. Repeat the open hole and surface HFEC inspec- tions for cracks in the bulkhead lower web in accordance with Accom- plishment Instructions 3.B., Part 1. Lower web doesn't have a crack. See note (a), (b). --Repair in accordance in accordance with Accom- plishment Instructions 3.B., Part 1 and do post- repair inspections in ac- cordance with Table 3. Crack in the aft inner chord and/or a crack in the upper web that is contained within the allowed trim out area. Continue lower web in- spections in accordance with this table Or Accomplish the modifica- tion given in Boeing ser- vice bulletin 747- 53A2473. -Before further flight. Contact Boeing for repair data and do the repair. Crack(s) found in the splice fitting, frame support, for- ward inner chord, or floor support Or Crack in the upper web that extends outside the al- lowed trim area. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 31 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 32 Group 3: Table 2: Bulkhead Inspection, Repair and Modification - Group 3 Airplanes Repeat Interval (Not to Exceed) Compliance TimeActionCondition 1,500 flight cyclesWithin 1,500 flight- cycles after the ini- tial inspection. Repeat the forward and aft side open hole and surface HFEC inspec- tions for cracks in the bulkhead splice fitting, frame support, forward and aft inner chords and the bulkhead upper web in accordance with Ac- complishment Instruc- tions 3.B., Part 1. No cracks found in the bulkhead splice fitting, frame support, forward and aft inner chords, upper web, or floor support. See note (a), (b). 3,000 flight cyclesWithin 3,000 flight- cycles after the ini- tial inspection. Repeat the open hole and surface HFEC inspec- tions for cracks in the bulkhead lower web in accordance with Accom- plishment Instructions 3.B., Part 1. See note (a), (b). (a) As an alternative to repeat inspections, accomplish the modification given in Boeing service bulletin 747-53A2473. No further action is required by this service bulletin after modification in accordance with Boeing service bulletin 747-53A2473. (b) Federal Aviation Administration (FAA) Airworthiness Directive 2010-14-07 requires that the modification given in Boeing service bulletin 747-53A2473 be accomplished before 20,000 total flight cycles, or within 18 months after the effective date of the AD, whichever occurs later. NOTE: In addition to the post-repair/modification inspection given in Table 3 below, inspection of the lower web is to continue in accordance with Table 1 until a bulkhead (Support Frame) modification is accomplished. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 32 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 33 Table 3: Post-Repair Inspection or Post-Interim Modification Inspection Repeat Interval (Not to Exceed) Compliance TimeActionCondition 1,500 flight cyclesWithin 1,500 flight cycles after the last forward side surface HFEC inspection. Do forward side surface high frequency eddy cur- rent (HFEC) post-repair inspection for cracks in accordance with Accom- plishment Instructions 3.B., Part 3. Existing Interim modifica- tion or aft inner chord re- pair. No upper web repair. See note (a), (b), (c). 1,500 flight cyclesWithin 6,000 flight cycles after ac- complishment of the chord and/or web repair. Do surface and open hole HFEC post-repair inspec- tions for cracks in the re- paired area of the bulk- head in accordance with Accomplishment Instruc- tions 3.B., Part 3. See note (a), (b). 1,500 flight cyclesWithin 1,500 flight cycles after the last forward side surface HFEC inspection. Do forward side surface high frequency eddy cur- rent (HFEC) post-repair inspection for cracks in accordance with Accom- plishment Instructions 3.B., Part 3. Existing upper web repair. See note (d). See note (a), (b), (c). 1,500 flight cyclesWithin 3,000 flight cycles after ac- complishment of the chord and/or web repair. Do surface and open hole HFEC post-repair inspec- tions for cracks in the re- paired area of the bulk- head in accordance with Accomplishment Instruc- tions 3.B., Part 3. See note (a), (b). -Before further flight.Accomplish the modifica- tion given in Boeing ser- vice bulletin 747-53A2473 Crack found in the aft inner chord with chord post-re- pair inspection or post-inter- im modification inspection. See note (b) Or Contact Boeing for repair data and do the repair. -Before further flight.Contact Boeing for repair data and do the repair. Crack found in the upper web and crack extends outside the allowed trim out area. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 33 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 34 Table 3: Post-Repair Inspection or Post-Interim Modification Inspection Repeat Interval (Not to Exceed) Compliance TimeActionCondition -Before further flight.Remove the existing re- pair/modification parts and accomplish an upper web repair in accordance with Accomplishment In- structions 3.B., Part 4. Continue post-repair in- spections as given above in this table. Crack found in the upper web and crack is contained within the allowed trim out area. See note (a), (b). Or Accomplish the modifica- tion given in Boeing ser- vice bulletin 747-53A2473 See note (b) Or Contact Boeing for repair data and do the repair. -Before further flight.Contact Boeing for repair data and do the repair. Crack found in the splice fitting, frame support, for- ward inner chord, or floor support with post-repair in- spection. (a) As an alternative to a repair and post-repair inspections, accomplish the modification given in Boeing service bulletin 747-53A2473. No further action is required by this service bulletin after modification in accordance with Boeing service bulletin. (b) Federal Aviation Administration (FAA) Airworthiness Directive 2010-14-07 requires the modification given in Boeing service bulletin 747-53A2473 be accomplished before 20,000 total flight cycles, or within 18 months after the effective date of the AD, whichever occurs later. (c) The SRM refers to this Service Bulletin for continued (post-repair) inspection in 'the non-repaired areas." This inspection of the forward side of the bulkhead is the inspection in the non-repaired areas. (d) This condition is for an upper web repair installed as a stand alone repair, or as a replacement for a previously installed inner chord repair or a previously installed Interim Modification. For the condition where the upper web repair is a replacement repair, the given compliance times refer to when the replace- ment web repair was accomplished. Federal Aviation Administration (FAA) Airworthiness Directive AD 2010-14-07 is related to this service bulletin. AD 2010-14-07 supersedes AD 2006-05-06 which superseded AD 2001-15-03. Also, Federal Aviation Administration (FAA) Airworthiness Directive AD 2004-07-22 R1 is related to this service bulletin. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 34 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 35 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. The Manager of the FAA Seattle Aircraft Certification Office (ACO) approves the inspections, repairs and interim modification with the corresponding compliance times specified in Tables 1, 2 and 3, under paragraph 1.E., "Compliance," of SB 747-53A2427, Revision 6 as an AMOC to the inspections, repairs and interim modification at the STA 2598 bulkhead required by paragraphs (i), (j), (o), (s), (t), (u) and (v) of AD 2010-14-07. This AMOC is valid only for areas where inspections, repairs or interim modification are done in accordance with this SB. When this SB specifies contacting Boeing for repair data, the repair data must be approved by the FAA in accordance with paragraph (x) of the AD. All provisions of AD 2010-14-07 that are not specifically referenced in this paragraph remain fully applicable and must be complied with. In addition, the Manager of the FAA Seattle Aircraft Certification Office (ACO) approves the inspections, repairs and interim modification with the corresponding compliance times specified in Tables 1, 2 and 3, under paragraph 1.E., "Compliance," of SB 747-53A2427, Revision 6 as an AMOC to the inspections, repairs and interim modification at the STA 2598 required by paragraphs (h), (i), and (j) of AD 2004-07-22 R1 for the areas inspected by Boeing 747 Supplemental Structural Inspection Document (SSID) D6-35022, Revision G, Significant Structural Items F-49B, F-49C, and F-49J. This AMOC only applies to the areas that are inspected as given in this service bulletin. When this service bulletin specifies contacting Boeing for repair, rework, or modification data, the data must be approved by the FAA in accordance with paragraph (l) of the AD. All provisions of AD 2004-07-22 R1 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 inspection for each airplane. This estimate is for direct labor only, done by an experienced crew. Adjust the estimate with operator task hour data if necessary. The estimate does not include lost time. These are some examples of lost time: — Time to adjust to the workplace — Time to schedule the work — Time to inspect the work — Time to cure the materials — Time to make the parts — Time to find the tools. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 35 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 36 Group 1 Airplanes Elapsed HoursTask HoursNumber of Per- sons Task 0.750.751Open Access 9.2518.52Inspect 1.753.502Interim Modification 0.750.751Close Access 12.523.5TOTAL FOR EACH AIRPLANE Note: More time will be required if cracks are found and repair(s) installed. H. Weight and Balance Changes NOTE: Weight and balance changes reflect an interim modification installation on the left and right side of the airplane. Group 1 Change in Moment (Pound-Inches) Change in Weight (Pounds)Airplane + 22180.0+ 1.0747SP/SR Group 2, 3 Change in Moment (Pound-Inches) Change in Weight (Pounds)Airplane ++ 1.0747-100 / -100B / - 100BSUD / -200B / 200C / -300 / -400 / -400D ++ 1.0747-200F / -400F I. Electrical Load Data Not changed. J. References 1. Existing Data: a. Engineering Change Memo PRR 85901-103RS b. Service Related Problem (SRP) 747/747OP-SRP-53-0106 c. Service Related Problem (SRP) 747/747OP-SRP-53-0316 d. Service Related Problem (SRP) 747-SRP-53-0343 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 36 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 37 e. 747 Structural Item Interim Advisory 747-167 f. Boeing Parts Standards Document D-590 g. Boeing Service Bulletin 747-53-2473, 747-53A2473 h. Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2001-15-03, 2004-07-22, 2006-05-06, 2010-14-07 i. Standard Overhaul Practices Manual (SOPM) 20-10-03, 20-20-02, 20-41-02, 20-43-01, 20-43-03 j. 747 Non-Destructive Testing (NDT) Manual Part 6, 51-00-00 k. 747-100/200/300 Aircraft Maintenance Manual (AMM) 27-41-02 l. 747-400 Aircraft Maintenance Manual (AMM) 27-41-02 m. 747-100/200/300 Structural Repair Manual (SRM) 53-10-04 n. 747-400 Structural Repair Manual (SRM) 53-80-08 o. 747-SP Structural Repair Manual (SRM) 53-19-02 p. 747-400F SRM 53-80-08 2. Data supplied with this Service Bulletin: None. 3. Installation Drawings Used in the Preparation of this Service Bulletin: TitleDrawing Number BULKHEAD INSTL - UPPER LOBE, STA 259865B02502 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. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 37 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 38 L. Interchangeability and Intermixability of Parts Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 38 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 39 2. MATERIAL INFORMATION A. Material - Price and Availability None. B. Industry Support Information Boeing warranty remedies are not available for the configuration changes, inspection and/or repairs given in this service bulletin. C. Parts Necessary For Each Airplane 1. Kits/Parts: None. 2. Parts and Materials Supplied by the Operator: The parts and fasteners needed to accomplish the interim modification on a group 1 airplane are identified in the step and fastener tables of FIGURE 7. The parts and fasteners needed to accomplish the interim modification on a group 2 or group 3 airplane are identified in the step and fastener tables of FIGURE 8. See the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data. NOTE: Boeing plans to provide kit data in an Information Notice or a future revision to this service bulletin. 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. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 39 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 40 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 40 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT BLANK PAGE ### Page 41 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 – Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus or minus 0.03 inch – Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch – Angular tolerance is plus or minus 2 degrees – Hole dimensions for standard solid rivets are given in 747 SRM, Chapter 51 – Torque limits to tighten nuts and bolts are given in 747 SRM, Chapter 51 5. For approved fastener and process material substitutions, refer to 747 SRM, Chapter 51. Alternate fasteners are given in 747 SRM Chapter 51 and Boeing Drawing 747, 021W6100. 6. If the length of any fastener specified in this service bulletin does not meet the 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. 7. 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. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 41 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 42 8. Unless otherwise noted, all fasteners to be installed with head on the near side at fastener symbol locations. 9. 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. 10. Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2010-14-07 supersedes AD 2006-05-06 and requires the support frame modification as given in Boeing service bulletin 747-53A2473 be accomplished before the accumulation of 20,000 total flight cycles or within 18 months after the effective date of the AD, whichever occurs later. B. WORK INSTRUCTIONS PART 1: INSPECTION AND REPAIR 1. Remove electrical and hydraulic power. Refer to 747-100/200/300 AMM 27-41-02 or 747-400 AMM 27-41-02 as an accepted procedure. 2. For access to the aft side of the of the STA 2598 bulkhead, open APU Battery Access Door 315A. Open Horizontal Stabilizer Jackscrew Access Door 312A to get access to the forward side of the STA 2598 bulkhead through the access holes in the bulkheads at STA 2484, 2502, and 2517. CAUTION: DO NOT USE THE JACK POINT AT BODY STATION 2596 (PRIMARY TAIL JACK POINT III) DURING OPEN HOLE HFEC INSPECTIONS OR INSTALLATION OF REPAIRS. 3. Accomplish open hole and surface high frequency eddy current (HFEC) inspections for cracks in the forward and aft inner chords, frame supports, splice fittings, floor supports, and upper and lower web panels in accordance with FIGURE 2 and Paragraph 1.E., Compliance. 4. If a crack is indicated at a fastener hole with the open hole inspection, an attempt can be made to remove the crack by increasing the fastener hole diameter in accordance with FIGURE 2. Repeat the open hole inspection in accordance with FIGURE 2 after the hole is oversized. If the inspections given in FIGURE 2 are accomplished with no crack indications (following hole oversize and reinspection if/where necessary), go to step 5 of Part 1 below. If a crack is indicated by an inspection given in FIGURE 2, make a repair or modification in accordance with the table below and Paragraph 1.E., Compliance. Repair/Modification AlternativesCrack Description/Location Bulkhead (Support Frame) modification (a)Aft inner chord crack only. Chord repair (b) Bulkhead (Support Frame) modification (a)Upper web crack only and crack is contained within the maximum allowed trim out area. Upper web repair (c) BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 42 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 43 Repair/Modification AlternativesCrack Description/Location Bulkhead (Support Frame) modification (a)Aft inner chord crack plus upper web crack, and web crack is contained within the maximum al- lowed trim out area. Chord trim plus upper web repair (f) Special Repair (d) Bulkhead (Support Frame) modification (e)Lower web crack. Special Repair (d) Special repair (d)Crack in the Splice fitting, frame support, forward inner chord, floor support, or upper web crack that extends outside the maximum allowed trim area. (a) Accomplish a bulkhead (Support Frame) modification in accordance with 747-53A2473. No further action is required by this service bulletin after the modification is accomplished. Federal Aviation Administration (FAA) Airworthiness Directive 2010-14-07 requires the modification given in Boeing service bulletin 747-53A2473. (b) If a crack is found in the aft inner chord only (no cracks found in other components), accomplish a repair in accordance with 747-100/200/300 SRM 53-10-04 Figure 72, 747-SP SRM 53-19- 02 or 747-400 SRM 53-80-08, Repair 11 as applicable and Paragraph 1.E., Compliance. Do post-repair inspections in accordance with Paragraph 3.B., Work Instructions, Part 3. (c) Accomplish the upper web repair in accordance with Paragraph 3.B., Work Instructions, Part 4 and Paragraph 1.E., Compliance. Do post-repair inspections in accordance with Paragraph 3.B., Work Instructions, Part 3. (d) Contact Boeing for repair data and do the repair. (e) A lower web crack repair can be accomplished with bulkhead (Support Frame) modification in accordance with 747-53A2473. (f) Remove the crack from the aft inner chord and inspect the chord to make sure that the crack is removed in accordance with 747-100/200/300 SRM 53-10-04 Figure 72, 747-SP SRM 53- 19-02 or 747-400 SRM 53-80-08, Repair 11 as applicable. After trim of the chord, accomplish a web repair in accordance with Paragraph 3.B., Work Instructions, Part 4 and Paragraph 1.E., Compliance. Do post-repair inspections in accordance with Paragraph 3.B., Work Instruc- tions, Part 3. 5. If the inspections given in FIGURE 2 are accomplished with no crack indications (following hole oversize and reinspection if/where necessary), install fasteners at the open hole inspection locations in accordance with FIGURE 2. Repeat the surface and open hole HFEC inspections in accordance with Paragraph 1.E., Compliance. As an alternative to repeat inspections, accomplish bulkhead (Support Frame) modification in accordance with 747-53A2473. No further action is required by this service bulletin after the bulkhead modification is accomplished. 6. For Group 1, 2 airplanes that do not have the bulkhead modification, accomplish the interim modification in accordance with Paragraph 3.B., Work Instructions, Part 2 by the time given in Paragraph 1.E., Compliance. It is not necessary to accomplish this interim modification on the side of the bulkhead where a chord repair or an upper web repair has been accomplished in accordance with this service bulletin. After accomplishment of the interim modification, do post-modification inspections in accordance with Paragraph 3.B., Work Instructions, Part 3. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 43 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 44 Group 1-2: PART 2: INTERIM MODIFICATION CAUTION: DO NOT USE THE JACK POINT AT BODY STATION 2596 (PRIMARY TAIL JACK POINT III) DURING INSTALLATION OF INTERIM MODIFICATION. 1. Accomplish the interim modification where necessary in accordance with Paragraph 1.E., Compliance and FIGURE 7 (Group 1 airplanes) or FIGURE 8 (Group 2, 3 airplanes) as applicable. Accomplish post-modification inspections in accordance with Paragraph 1.E., Compliance and Paragraph 3.B., Work Instructions, Part 3. PART 3: POST-REPAIR OR POST-INTERIM MODIFICATION INSPECTION 1. After a repair is accomplished in accordance with Part 1 or an interim modification is accomplished in accordance with Part 2, do forward side surface HFEC inspections for cracks in the bulkhead forward inner chord, splice fitting and frame support in accordance with FIGURE 6 and Paragraph 1.E., Compliance. After a repair is accomplished in accordance with Part 1 or an interim modification is accomplished in accordance with Part 2, do open hole and surface high frequency eddy current (HFEC) inspections for cracks in the modified area of the bulkhead in accordance with FIGURE 5 and Paragraph 1.E., Compliance. Continue inspections of the lower web in accordance with FIGURE 2 and Paragraph 1.E., Compliance. As an alternative to the above inspections, accomplish a bulkhead (Support Frame) modification in accordance with 747-53A2473. No further action is required by this service bulletin after the bulkhead modification is accomplished. 2. If/where a crack is indicated with the above post-repair/interim modification inspections, accomplish a repair or modification in accordance with the table below and Paragraph 1.E., Compliance. Repair/Modification AlternativesCrack Description/Location Bulkhead (Support Frame) modification (a)Aft inner chord crack or lower web crack. Special repair (c) Special repair (c)Crack in the Splice fitting, frame support, forward inner chord, floor support. Bulkhead (Support Frame) modification(a)Upper web crack that is within the maximum al- lowed trim out area. Upper web repair (b) Special repair (c) Special repair (c)Upper web crack that is outside of the maximum allowed trim out area. (a) Accomplish bulkhead (Support Frame) modification in accordance with 747-53A2473. No further action is required by this service bulletin after the modification is accomplished. Federal Aviation Administration (FAA) Airworthiness Directive 2010-14-07 requires the modification given in Boeing service bulletin 747-53A2473. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 44 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 45 Repair/Modification AlternativesCrack Description/Location (b) Remove the existing repair/modification parts and accomplish an upper web repair in accor- dance with Paragraph 3.B., Work Instructions, Part 4. Continue post-repair inspections as given above in this table. (c) Contact Boeing for repair data and do the repair. PART 4: UPPER WEB REPAIR 1. Accomplish an upper web repair if necessary/applicable as given below: Group 1, Configuration 1: Remove the crack from the upper web in accordance with FIGURE 4. The upper web repair is applicable only if the web crack is contained within the maximum allowed trim out area. After the web is trimmed and inspected in accordance with FIGURE 4, complete the upper web repair in accordance with FIGURE 7. Following the upper web repair, do post-repair open hole and surface high frequency eddy current (HFEC) inspections in accordance with Paragraph 3.B., Work Instructions, Part 3, and Paragraph 1.E., Compliance. If the web crack extends outside the maximum allowed trim out area, contact Boeing for repair data and do the repair. Group 1, Configuration 2: Remove the existing repair/modification parts and remove the crack from the upper web in accordance with FIGURE 4. The upper web repair is applicable only if the web crack is contained within the maximum allowed trim out area. After the web is trimmed and inspected in accordance with FIGURE 4, complete the upper web repair in accordance with FIGURE 9. Following the upper web repair, do post-repair open hole and surface high frequency eddy current (HFEC) inspections in accordance with Paragraph 3.B., Work Instructions, Part 3, and Paragraph 1.E., Compliance. If the web crack extends outside the maximum allowed trim out area, contact Boeing for repair data and do the repair. Group 2-3, Configuration 1: Remove the crack from the upper web in accordance with FIGURE 4. The upper web repair is applicable only if the web crack is contained within the maximum allowed trim out area. After the web is trimmed and inspected in accordance with FIGURE 4, complete the upper web repair in accordance with FIGURE 8. Following the upper web repair, do post-repair open hole and surface high frequency eddy current (HFEC) inspections in accordance with Paragraph 3.B., Work Instructions, Part 3, and Paragraph 1.E., Compliance. If the web crack extends outside the maximum allowed trim out area, contact Boeing for repair data and do the repair. Group 2-3, Configuration 2: Remove the existing repair/modification parts and remove the crack from the upper web in accordance with FIGURE 4. The upper web repair is applicable only if the web crack is contained within the maximum allowed trim out area. After the web is trimmed and inspected in accordance with FIGURE 4, complete the upper web repair in accordance with FIGURE 10. Following the upper web repair, do post-repair open hole and surface high frequency eddy current (HFEC) inspections in accordance with Paragraph 3.B., Work Instructions, Part 3, and Paragraph 1.E., Compliance. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 45 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 46 If the web crack extends outside the maximum allowed trim out area, contact Boeing for repair data and do the repair. PART 5: RESTORATION 1. Close all access doors that were opened for access to the STA 2598 bulkhead. 2. Put the airplane back to a serviceable condition. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6: July 14, 2011 46 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 47 (OCR) BOEING SERVICE BULLETIN 747-53A2427 ALERT ALERT THIS FIGURE IS DELETED. INFORMATION IS NOW CONTAINED IN PARAGRAPH 1.E., COMPLIANCE. 1423714 FIGURE 1: DELETED (SHEET 1 OF 1) riginal Issue: December 11, 100 evision 6 July 14, 201 747-53A2427 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 47 of 118 ### Page 48 (OCR) BOEING SERVICE BULLETIN 747-53A2427 ALERT ALERT STA 2598 FORWARD SIDE INSPECTION STA SEE A 2598 AFT SIDE INSPECTION SEE HORIZONTAL STABILIZER FRAME SUPPORT LOWER WEB INSPECTION SEE O AFT INNER CHORD UP → FWD S64517 FIGURE 2: INSPECTION (SHEET 1 OF 7) Original Issue: December 17, 1998 Revision 6 July 14, 2011 LEAVES LAL BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 48 of 118 ### Page 49 (OCR) BOEING SERVICE BULLETIN 747-53A2427 ALERT ALERT FORWARD BULKHEAD FORWARD INNER CHORD WEB INNER BULKHEAD WEB CHORD INSPECTION AREA SPLICE TYPICAL FITTING CRACK TYPICAL • SHEAR CRACK AFT INNER DECK UP CHORD SPLICE FITTING UP FWD< SEE ® DECK SHEAR FRONT VIEW A-A INBD ' FWD (LEFT SIDE SHOWN SHEAR FRAME RIGHT SIDE OPPOSITE) DECK SUPPORT INSPECTION AREA (4) SPLICE FITTING STA 2598 FORWARD INNER CHORD SHEAR DECK UP TYPICAL FRAME > FWD SUPPORT CRACK FWD SPLICE FRONT VIEW FITTING (LEFT SIDE SHOWN RIGHT SIDE OPPOSITE) B—B FRAME SUPPORT S64578 FIGURE 2: INSPECTION (SHEET 2 OF 7) Original Issue: December 17, 1998 Revision 6 July 14, 2011 BOEING PROPRIETARY - 747-53A2427 Copyright © Unpublished Work - See page 1 for details. 49 of 118 ### Page 50 (OCR) BOEING SERVICE BULLETIN 747-53A2427 ALERT ALERT FORWARD INNER CHORD •AFT INNER CHORD BULKHEAD UPPER WEB • BULKHEAD UPPER WEB 1/8/13/14 3.8 FLOOR SUPPORT 2.00 14 SPLICE FITTING TYPICAL WEB CRACK 191314 AFT CHORD INSPECTION INNER S AREA CHORD UP 7 WEB INSPECTION AREA INBD 1 (AFT SIDE) FRAME REAR VIEW SUPPORT (LEFT SIDE SHOWN WEB INSPECTION AREA (FORWARD SIDE) AND RIGHT SIDE OPPOSITE) CHORD INSPECTION (AFT SIDE) 1474320 FIGURE 2: INSPECTION (SHEET 3 OF 7) Original Issue: December 17, 1998 Revision 6 July 14, 2011 BOEING PROPRIETARY - 747-53A2427 Copyright © Unpublished Work - See page 1 for details. 50 of 118 ### Page 51 (OCR) BOEING SERVICE BULLETIN 747-53A2427 ALERT ALERT AFT INNER TYPICAL CRACK CHORD 10BL 13) 14 STA 2598 BULKHEAD SPLICE FITTING 2D MINIMUM (TYPICAL) BULKHEAD THIS WORK APPLICABLE LOWER WEB → INBD LEFT SIDE ONLY WEB INSPECTION 2017960 AREA FIGURE 2: INSPECTION (SHEET 4 OF 7) Original Issue: December 17, 1998 Revision 6 July 14, 2011 747-53A2427 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 51 of 118 ### Page 52 The step numbers shown below agree with the numbers shown in the circle symbols in the figure. MORE DATAQTYIDENTIFICATIONNAMETASKSTEP -10-FastenersRemove1 (a)--Forward Inner ChordInspect2 (a)--Aft Inner ChordInspect3 (a)--Splice FittingInspect4 (a)--Frame SupportInspect5 (a) (c)--Aft Inner ChordInspect6 (a) (d)--Web (aft side)Inspect7 --Web (forward side)Inspect (b) (c) (e)--Aft Inner ChordInspect8 Forward Inner Chord Splice Fitting (b) (e)--Aft Inner ChordInspect9 Frame Support Splice Fitting FIGURE 2: INSPECTION (SHEET 5 OF 7) BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6 July 14, 2011 52 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 53 MORE DATAQTYIDENTIFICATIONNAMETASKSTEP (b) (c) (e)--Aft Inner ChordInspect10 Web Floor Support (b) (e)--Aft Inner ChordInspect11 Web Forward Inner Chord Splice Fitting (b) (d) (e)--Aft Inner ChordInspect12 Web and Doubler Floor Support (g) See fastener code table for hole sizes. 10 (g)-Fastener HoleDrill/Ream13 (f) -10 (g)FastenerInstall14 (a) Do a surface high frequency eddy current (HFEC) inspection for cracks in accordance with 747 NDT, Part 6, 51-00-00 Figure 4 or 23. The inspection area is shown shaded in the figure. (b) Do an open hole high frequency eddy current (HFEC) inspection for cracks at the identified fastener hole in accordance with 747 NDT, Part 6, 51-00-00 Figure 1, 11 or 16. (c) The inspection given in this step has a compliance time related to the date on Revision 4 of this service bulletin. (d) The inspection given in this step has a compliance time related to the date on Revision 6 of this service bulletin. (e) If a crack is indicated, the hole diameter can be increased up to a maximum 1/32 inch oversize to remove the crack. After the hole diameter is increased, repeat the open hole HFEC inspec- tion (in accordance with 747 NDT, Part 6, 51-00-00 Figure 1, 11 or 16). If a crack indication remains after a 1/32 oversize, more repair work is necessary. Do not install fasteners. (f) The work given in this step is to be done one time only with the initial open hole inspection. This work will make it easier to remove the fasteners for repeat inspections. If this work has been accomplished, this step is not applicable. (g) Do not drill/ream and install fasteners at the three fastener holes common to the inboard leg of the aft inner chord and the upper web in this step if the interim-modification is to be accom- plished before the next flight. Fasteners will be installed with the interim modification parts at these locations. The codes shown below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. The QTY numbers shown below are the number of fasteners necessary for this figure. If the grip length shown is not available, fasteners may be one grip length longer than indicated. Also, if any of the fastener part numbers are not available or have been superseded, Boeing Document D590 and Boeing drawing 012W6100 may be used to determine the part numbers used as substitutes. FIGURE 2: INSPECTION (SHEET 6 OF 7) BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6 July 14, 2011 53 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 54 MORE DATAHOLE DIAQTYIDENTIFICA- TION NAMECODE (a) (b) (d) (e) (f)Close Ream 0.2495/0.2505 6BACB30MY8K( )BOLTJ 6BACC30M8COLLAR (a) (c) (g) (h) (i)Close Ream 0.3120/0.3130 4BACB30MY10K12BOLTK 4BACC30M10COLLAR (a) Close ream holes are specified to facilitate subsequent open hole HFEC inspections and prevent contin- uous oversizing. (b) If necessary, up to 1/32 oversize is allowed. For 1/64 oversize use BACB30MY8K( )X and BACC30M8 in 0.2661/0.2651 close diameter hole. For 1/32 oversize use BACB30MY8K( )Y and BACC30R8 in 0.2817/0.2807 diameter hole. (c) If necessary, up to 1/32 oversize is allowed. For 1/64 oversize use BACB30MY10K( )X and BACC30M10 in 0.3286/0.3276 close diameter hole, and 1/32 oversize use BACB30MY10K( )Y and BACC30R10 in 0.3442/0.3432 diameter hole. (d) Alternate fastener: For standard size use BACB30NT4K( ) BOLT, BACW10BP4CD WASHER under head, BACW10BP4DP WASHER under nut and BACN10JC4CD NUT. Torque nut 63 - 67 inch/pounds. (e) Alternate fastener: For 1/64 oversize use BACB30LK4K( )X BOLT, BACW10BP41CD WASHER under head, BACW10BP41DP WASHER under nut and BACN10JC4CD NUT. Torque nut 63 - 67 inch/pounds. (f) Alternate fastener: For 1/32 oversize use BACB30LK4K( )Y BOLT, BACW10BP42CD WASHER under head, BACW10BP42DP WASHER under nut and BACN10JC4CD NUT. Torque nut 63 - 67 inch/pounds. (g) Alternate fastener: For standard size use BACB30NT5K( ) BOLT, BACW10BP5CD WASHER under head, BACW10BP5DP WASHER under nut and BACN10JC5CD NUT. Torque nut 120 - 130 inch/pounds (target is 125). (h) Alternate fastener: For 1/64 oversize use BACB30LK5K( )X BOLT, BACW10BP51CD WASHER under head, BACW10BP51DP WASHER under nut and BACN10JC5CD NUT. Torque nut 120 - 130 inch/pounds (target is 125). (i) Alternate fastener: For 1/32 oversize use BACB30LK5K( )Y BOLT, BACW10BP52CD WASHER under head, BACW10BP52DP WASHER under nut and BACN10JC5CD NUT. Torque nut 120 - 130 inch/pounds (target is 125). FIGURE 2: INSPECTION (SHEET 7 OF 7) BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6 July 14, 2011 54 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 55 (OCR) BOEING SERVICE BULLETIN 747-53A2427 ALERT ALERT THIS FIGURE IS DELETED. INFORMATION IS NOW CONTAINED IN PARAGRAPH 1.E., COMPLIANCE. 1423730 FIGURE 3: DELETED (SHEET 1 OF 1) riginal Issue: December 11, 100 evision 6 July 14, 201 747-53A2427 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 55 of 118 ### Page 56 (OCR) BOEING SERVICE BULLETIN 747-53A2427 ALERT ALERT STA 2598 STA 2598 SEE A HORIZONTAL STABILIZER 1 10 ›FWD 1474137 FIGURE 4: WEB CRACK REMOVAL (SHEET 1 OF 3) Original Issue: December 17, 1998 Revision 6 July 14, 2011 LEAVES LAL BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 811099 ### Page 57 (OCR) BOEING SERVICE BULLETIN 747-53A2427 ALERT ALERT FORWARD INNER CHORD STA 2598 BULKHEAD BULKHEAD UPPER WEB FLOOR -REFERENCE SUPPORT EDGE OF REMOVED TYPICAL CRACK CHORD TYPICAL TRIM OUT LINE 1.7D MINIMUM 1.7D MINIMUM (IF APPLICABLE) MAXIMUM TRIM-OUT AREA AND WEB INSPECTION AREA LOCATION WHERE FASTENER COMMON TO THE INNER CHORD WILL BE INSTALLED LATER WITH THE REPAIR PARTS. SPLICE REAR VIEW FITTING UP LEFT SIDE SHOWN → INBD 1474141 RIGHT SIDE OPPOSITE The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for a web crack repair on one side of the bulkhead. FIGURE 4: WEB CRACK REMOVAL (SHEET 2 OF 3) Original Issue: December 17, 1998 Revision 6 July 14, 2011 BOEING PROPRIETARY - 747-53A2427 Copyright © Unpublished Work - See page 1 for details. 57 of 118 ### Page 58 NOTE: After the work given in this figure is accomplished, the web repair is to be completed in accordance with FIGURE 7 or FIGURE 9 (group 1 airplanes) or FIGURE 8 or FIGURE 10 (group 2, 3 airplanes). MORE DATAQTYIDENTIFICATIONNAMETASKSTEP 2-Strut AssemblyRemove/Keep1 2-Back-Up FittingRemove/Keep2 1-Aft Inner ChordRemove/Keep3 (a)10-FastenerRemove4 (b)--WebTrim5 (c)--WebInspect6 (d) (e)--FinishApply7 (f)1-Aft Inner ChordInstall/Kept8 -2-Back-Up FittingInstall/Kept9 -2-Strut AssemblyInstall/Kept10 (a) To permit separation of the web and the floor support, remove the fasteners common to these parts at the 10 locations shown in the figure. (b) Install a temporary/protective shim between the web and floor support, or use other means, to prevent damage to the floor support when the web is trimmed. Trim material from the web as necessary to remove crack damage. The inside radius on the trim out is to be not less than 0.50 inch, and the web surface finish is to be 125 micro-inches or better. The trim out can extend to the maximum limits shown if necessary to remove the crack. (c) Do a surface high frequency eddy current (HFEC) inspection of the web and all web trimmed edges for cracks in accordance with 747 NDT Part 6, 51-00-00 Figure 4 or 23 to make sure that there is no indication from a remaining crack. (d) Apply a chemical conversion coating to all bare aluminum surfaces. Refer to SOPM 20-43-03, Type 2, Class A. (e) Apply BMS 10-11, Type 1 primer. Refer to SOPM 20-41-02. (f) Do not install fasteners common to the aft inner chord at the locations identified in the figure. These fasteners will be installed later with the repair/modification parts. FIGURE 4: WEB CRACK REMOVAL (SHEET 3 OF 3) BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 17, 1998 747-53A2427Revision 6 July 14, 2011 58 of 118 BOEING SERVICE BULLETIN 747-53A2427 ALERTALERT ### Page 59 (OCR) BOEING SERVICE BULLETIN 747-53A2427 ALERT ALERT STA 2598 STA 2598 WHICHEVER SHOWS THE ACTUAL REPAIR OR MODIFICATION CONFIGURATION SEE TA HORIZONTAL STABILIZER FRAME SUPPORT AFT INNER CHORD → FWD LEFT SIDE SHOWN 1474285 RIGHT SIDE OPPOSITE FIGURE 5: INSPECTION - POST REPAIR / INTERIM MODIFICATION - REPAIRED/MODIFIED AREA (SHEET 1 OF 9) Original Issue: December 17, 1998 Revision 6 July 14, 2011 747-53A2427 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 59 of 118 ### Page 60 (OCR) BOEING SERVICE BULLETIN 747-53A2427 ALERT ALERT FORWARD INNER CHORD •AFT INNER CHORD BULKHEAD UPPER WEB FILLER 13 1514 BULKHEAD 10 - FLOOR (13) UPPER WEB (2) 14 SUPPORT SPLICE 1414 2.00 FITTING SEE FOR POST- CHORD REPAIR AFT INSPECTION INNER THIS AREA CHORD AFT SIDE FRAME INSPECTION SUPPORT OUTER AREA ANGLE FORWARD UP SIDE JINBD REAR VIEW INNER INSPECTION AREA ANGLE INTERIM MODIFICATION INSTALLED IN ACCORDANCE 2016911 WITH REVISION 4 OR 5 OF THIS SERVICE BULLETIN FIGURE 5: INSPECTION - POST REPAIR / INTERIM MODIFICATION - REPAIRED/MODIFIED AREA (SHEET 2 OF 9) Original Issue: December 17, 1998 Revision 6 July 14, 2011 BOEING PROPRIETARY - 747-53A2427 Copyright © Unpublished Work - See page 1 for details. 60 of 118 The text continues at https://openairdocs.org/service-documents/boeing/747-53a2427/file/d631c7ba0d9a.md?from=61 --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain, except the copies of manufacturers’ service documents, which belong to their rights holders.