# Boeing Alert Service Bulletin 747-53A2688: Revision 2 - Rights: © The Boeing Company. Filed by the FAA in regulations.gov docket FAA-2015-2464; AD 2016-07-31 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication. - Document: [Boeing Alert Service Bulletin 747-53A2688](https://openairdocs.org/service-documents/boeing/747-53a2688.md) - Title as filed: U.S. DOT/FAA - SB-747-53A2688-02 - Pages: 177 - PDF: https://openairdocs.org/files/sha256/07/aa/07aab96f4b6dc4f80f8a8b872ca4edd5ed6a2ee8a78fefe86b068eede2f67fb4 - Page: https://openairdocs.org/service-documents/boeing/747-53a2688/file/07aab96f4b6d ## 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: 747-53A2688 Original Issue: August 21, 2008 Revision 2: August 21, 2014 ATA System: 5321 SUBJECT: FUSELAGE - Floors - Section 41 and Section 44 Upper Deck Floor Beam Upper Chord Inspection and Repair at Floor Panel Attachment Fastener Holes Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15 CFR 300-774). An export license may be required before it is used for development, production or use by foreign persons from specific countries. The controller of this data has the individual responsibility to abide by all export laws. 9E991ECCN: BOEING PROPRIETARY, CONFIDENTIAL AND/OR TRADE SECRET Copyright © 2008 Boeing. Unpublished Work. All Rights Reserved. Treatment of this document and its content is governed by contract with Boeing. Rights to use this document are licensed on a per aircraft basis and such rights may not be transferable. For more information, contact The Boeing Company. Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner, BBJ, DC-8, DC-9, DC-10, KC-10, KC-46, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8, Poseidon and Boeing liveries are all trademarks owned by The Boeing Company; and no trademark license is granted in connection with this document unless provided in writing by Boeing. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 1 of 177 6.0 ### Page 2 Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 2 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT BLANK PAGE ### Page 3 Table of Contents Revision Transmittal Sheet ............................................ 5 Summary ...................................................... 7 1. PLANNING INFORMATION ........................................ 1 3 A. Effectivity ............................................... 1 3 1. Airplanes ............................................ 1 3 2. Spares Affected ........................................ 1 7 B. Concurrent Requirements ...................................... 1 7 C. Reason ................................................ 1 8 D. Description .............................................. 1 9 E. Compliance .............................................. 2 1 F. Approval ............................................... 2 7 G. Manpower .............................................. 2 8 H. Weight and Balance Changes .................................... 3 1 I. Electrical Load Data ......................................... 3 1 J. References .............................................. 3 1 1. Existing Data: ......................................... 3 1 2. Data Supplied with this Service Bulletin: ........................... 3 1 3. Installation Drawings Used in the Preparation of this Service Bulletin: ........... 3 2 K. Publications Affected ........................................ 3 2 L. Interchangeability and Intermixability of Parts ........................... 3 2 M. Software Accomplishment Summary ................................ 3 2 2. MATERIAL INFORMATION ........................................ 3 3 A. Material - Price and Availability ................................... 3 3 B. Industry Support Information .................................... 3 3 C. Parts Necessary for Each Airplane ................................. 3 3 1. Kits/Parts: ........................................... 3 3 2. Parts and Materials Supplied by the Operator: ........................ 3 3 3. Parts Modified and Reidentified: ............................... 3 7 4. Parts Removed and Not Replaced: .............................. 3 7 D. Parts Necessary to Change Spares ................................. 3 7 E. Special Tooling - Price and Availability ............................... 3 7 F. Special Tooling Necessary to do this Service Bulletin ....................... 3 7 3. ACCOMPLISHMENT INSTRUCTIONS .................................. 3 9 A. GENERAL INFORMATION ..................................... 3 9 B. WORK INSTRUCTIONS ....................................... 4 0 FIGURE 1: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA [Group 1] ....... 5 3 FIGURE 2: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA [Group 2] ....... 5 4 FIGURE 3: SECTION 41 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER LOCATIONS .......................................... 5 5 FIGURE 4: SECTION 41 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION ..... 5 8 FIGURE 5: SECTION 41 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION .......... 6 2 FIGURE 6: SECTION 41 - HOLE MEASUREMENTS AFTER CRACK REMOVAL ........... 6 5 FIGURE 7: SECTION 41 - REPAIR STRAP INSTALLATION ....................... 6 8 FIGURE 8: SECTION 41 - UPPER CHORD TRIM ............................ 7 2 FIGURE 9: SECTION 41 - UPPER CHORD REPAIR WITH STRAP ................... 7 5 Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 3 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 4 FIGURE 10: SECTION 41 - UPPER CHORD REPAIR WITH STRAP AND CLIP ............. 7 9 FIGURE 11: SECTION 41 - AFTER-REPAIR INSPECTION FOR LOCATIONS WITH THE STRAP REPAIR .................................................. 8 4 FIGURE 12: SECTION 41 - AFTER-REPAIR INSPECTIONS FOR LOCATIONS WITH UPPER CHORD TRIM REPAIR WITH STRAP OR ANGLE .............................. 8 7 FIGURE 13: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8) . . 90 FIGURE 14: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9) . . 95 FIGURE 15: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11) . . 100 FIGURE 16: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12) . . 105 FIGURE 17: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA [Group 3] ...... 1 1 0 FIGURE 18: SECTION 44 - UPPER DECK FLOOR BEAM INSPECTION AREA [Group 1] ...... 1 1 1 FIGURE 19: SECTION 44 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER LOCATIONS [Group 1] .................................... 1 1 2 FIGURE 20: SECTION 44 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION [Group 1] . 115 FIGURE 21: SECTION 44 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION [Group 1] .... 1 1 9 FIGURE 22: SECTION 44 - HOLE MEASUREMENTS AFTER CRACK REMOVAL [Group 1] ..... 1 2 2 FIGURE 23: SECTION 44 - REPAIR STRAP INSTALLATION [Group 1] ................ 1 2 5 FIGURE 24: SECTION 44 - UPPER CHORD TRIM [Group 1] ...................... 1 2 9 FIGURE 25: SECTION 44 - UPPER CHORD REPAIR WITH STRAP [Group 1] ............ 1 3 2 FIGURE 26: SECTION 44 - UPPER CHORD REPAIR WITH STRAP AND CLIP [Group 1] ...... 1 3 6 FIGURE 27: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8) [Group 1 ] ................................................ 1 4 1 FIGURE 28: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9) [Group 1 ] ................................................ 1 4 6 FIGURE 29: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11) [Group 1] ................................................. 1 5 1 FIGURE 30: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12) [Group 1] ................................................. 1 5 6 FIGURE 31: SECTION 44 - AFTER-REPAIR INSPECTION FOR LOCATIONS WITH THE STRAP REPAIR [Group 1] ............................................ 1 6 1 FIGURE 32: SECTION 44 - AFTER-REPAIR INSPECTIONS FOR LOCATIONS WITH UPPER CHORD TRIM REPAIR WITH STRAP OR ANGLE [Group 1] ........................ 1 6 4 FIGURE 33: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA [Group 4] ...... 1 6 7 FIGURE 34: SECTION 41 - HFEC INSPECTION OF UPPER CHORD AT PLUGGED OR RE-USED FLOOR PANEL ATTACHMENT HOLES [Group 2] .......................... 1 6 8 Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 4 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 5 Commercial Airplanes 747 Service Bulletin ALERT Revision Transmittal SheetNumber: 747-53A2688Original Issue: August 21, 2008 Revision 2: August 21, 2014 ATA System: 5321 SUBJECT: FUSELAGE - Floors - Section 41 and Section 44 Upper Deck Floor Beam Upper Chord Inspection and Repair at Floor Panel Attachment Fastener Holes This revision includes all pages of the service bulletin. COMPLIANCE INFORMATION RELATED TO THIS REVISION Federal Aviation Administration (FAA) Airworthiness Directives AD 2013-22-11 and AD 2004-07-22 R1 are related to this service bulletin. AD 2013-22-11 superseded AD 2009-10-06. Group 1, 3-4: No more work is necessary on the airplane(s) changed or inspected in accordance with Revision 1 of this service bulletin. Group 2: More work is necessary on the airplane(s) changed or inspected in accordance with Revision 1 of this service bulletin. Do a High Frequency Eddy Current (HFEC) inspection for any cracks in the upper deck floor beam upper chords and a detailed visual inspection of the upper deck floor beam vertical flanges. REASON FOR REVISION This revision is sent to add a High Frequency Eddy Current (HFEC) inspection for cracks in the upper deck floor beam upper chords, at floor panel and floor structure attachment holes, that were plugged or re-used during the conversion to Boeing Converted Freighter (BCF). These sections were changed: 1. Background and Reason Sections in the Summary have been updated to describe the reason for the new revision. 2. Action and Description Sections in the Summary, updated to include additional work and new groups. 3. Updated the Summary illustration to include new work. 4. In Paragraph 1.C Reason, added new work and updated the information to include the reason for the new revision. 5. In Paragraph 1.D Description, added new Group 4 and revised work summaries. 6. In Paragraph 1.E Compliance, revised tables to include new work and groups. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 5 of 177 ### Page 6 7. In Paragraph 1.F Approval, included alternative method of compliance (AMOC) paragraphs. 8. In Paragraph 1.G Manpower, revised to include new work and groups. 9. In Paragraph 1.J References, added new SRP reference. 10. In Paragraph 3.A., General Information, revised and added general notes. 11. In Paragraph 3.B., Work Instructions, Part 7 updated to include new work. 12. In Paragraph 3.B., Work Instructions, Part 8 added to include new work. 13. Figure 2, changed group information. 14. Figure 3, changed note for revised STA information. 15. Added Figure 33 and Figure 34 to include additional work for the new revision. Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity and format changes, to show the location of all content changes. Pages with no vertical lines have no changes. REVISION HISTORY August 21, 2008Original Issue: September 19, 2012Revision 1: August 21, 2014Revision 2: Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 6 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 7 Commercial Airplanes 747 Service Bulletin ALERT SummaryNumber: 747-53A2688Original Issue: August 21, 2008 Revision 2: August 21, 2014 ATA System: 5321 SUBJECT: FUSELAGE - Floors - Section 41 and Section 44 Upper Deck Floor Beam Upper Chord Inspection and Repair at Floor Panel Attachment Fastener Holes 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 This SB gives instructions to do inspections for fatigue cracks of the upper deck floor beam upper chords at the floor panel attachment holes. Also, additional inspections are provided at the floor panel attachment holes that have been plugged or re-used during the BCF modification in Section 41. Cracks in these chords that are not found and repaired could become large and cause the floor beam to become severed. This can lead to large deflection or deformation of the floor and of the body skin, frames, and stringers. This deflection or deformation could result in damage to wire bundles and unintended inputs to the flight control cables which could affect airplane controllability. Multiple adjacent severed floor beams could result in rapid decompression of the airplane. Flight critical wire bundles and control cables are routed through cutouts in the upper deck floor beams. Cracks have been found at open floor panel attach fastener holes in the upper chord of two Section 41 upper deck floor beam on three different 747-400D airplanes, which had flown 24,053, 24,783, and 25,631 flight-cycles. Boeing believes that these 747-400D airplanes were operated at reduced cabin differential pressures. Similar cracks were also found on the 747-400 Fatigue Test airplane. Accomplishment of the inspections given in this service bulletin will ensure the structural integrity of the upper chords of the Section 41 upper deck floor beams. A structural reassessment of the 747 airplane was conducted under the requirements of Federal Aviation Administration (FAA) Advisory Circular 91-56, in accordance with Federal Aviation Regulation (FAR) 25.571 as amended in 1978, to ensure safe operation of 747 airplanes throughout their operational life. From this requirement, the Section 41 upper deck floor beam upper chords were determined to be significant, in that they are critical to airplane structural integrity. Therefore, a flight safety inspection program which will continue throughout the operational life of the airplane is specified in this service bulletin. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 7 of 177 ### Page 8 Between the original issue and Revision 1 of this service bulletin, Boeing has received two reports of cracking in upper deck floor beam upper chords in Section 44. The cracks were at STA 1000 and STA 1100. Due to these crack reports Boeing has determined that inspection of all upper deck floor beam upper chords in Section 44 (from STA 1000 to STA 1100) is required. Since the release of Revision 1 of this service bulletin, Boeing has found that certain fastener holes in the upper deck floor beam upper chords in Section 41, that were plugged or re-used during the conversion to BCF may not have been inspected in accordance with the instructions provided in Revision 1 of this service bulletin, because these locations may be hidden and not recognized as inspection locations. Boeing has determined that inspection of the upper deck floor beam upper chords in all locations containing plugged or re-used fastener holes is required. Boeing Service Related Problem (SRP) 747-SRP-53-0293, 747-SRP-53-0353 and 747-SRP-53-0428 are related to this service bulletin. The upper deck floor beam upper chords have been determined to be structure that is susceptible to Widespread Fatigue Damage (WFD). For more information about WFD, refer to Boeing Service Letter 747-SL-53-088A. This table is provided to operators for planning purposes only. Refer to the applicable sections for more information. ReferenceAffectedPlanning Data Paragraph 1.A.2., Spares AffectedNoSpares Affected Paragraph 1.E., ComplianceYesAD Related Paragraph 1.H., Weight and Balance ChangesYesWeight and Balance Change Paragraph 1.I., Electrical Load DataNoElectrical Load Changed Paragraph 1.K., Publications AffectedNoPublications Affected Paragraph 1.K., Publications AffectedNoAirplane Flight Operations Affected (Flight Crew Operations Manual and/or FAA Approved Air- plane Flight Manual) Paragraph 2.C.1., Kits/PartsNoKits/Parts Required Paragraph 2.C.2., Parts and Materials Supplied by the Operator YesOperator Supplied Material Paragraph 2.F., Special Tooling Necessary to do this Service Bulletin NoSpecial Tooling Required ACTION Group 1: Get access from above or below to the upper chords of the Section 41 upper deck floor beams from Station (STA) 340 to STA 520 and to the upper chords of the Section 44 upper deck floor beams from STA 1000 to STA 1100. Group 2: Get access from above or below to the upper chords of the Section 41 upper deck floor beams from STA 340 to STA 440. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 8 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 9 NOTE: On Group 2 airplanes, upper deck floor beams from STA 460 to STA 520 do not require inspection as given in this service bulletin because they were replaced with new floor beams during modification to Boeing Converted Freighter (BCF). The new floor beams have floor panel attachment fastener holes that have been cold-worked. Also, on Group 2 airplanes, inspection as given in this service bulletin are not necessary in Section 44 because all floor beams in Section 44 were replaced with tension ties during modification to BCF. Group 3: Get access from above or below to the upper chords of the Section 41 upper deck floor beams from STA 340 to STA 380. NOTE: On Group 3 airplanes, upper deck floor beams from STA 400 to STA 500 do not require inspection as given in this service bulletin because they were replaced with new floor beams during modification to Large Cargo Freighter (LCF). The new floor beams have floor panel attachment fastener holes that have been cold-worked. Group 4: Get access from above or below to the upper chords of the Section 41 upper deck floor beams from STA 340 to STA 420. NOTE: On Group 4 airplanes, upper deck floor beams from STA 440 to STA 500 do not require inspection as given in this service bulletin because they were replaced with new floor beams, or modified, during conversion to Large Cargo Freighter (LCF). The new floor beams have floor panel attachment fastener holes that have been cold-worked. If access was gained from above, do open hole HFEC inspections of the floor panel attachment fastener holes in the upper chords for cracks. If access was gained from below, modify the clipnuts for the floor panel attachment fasteners as given in this service bulletin. Do surface HFEC inspections of the forward and aft horizontal flanges of the upper chord at floor panel attachment fastener holes. If cracks are found, repair before any more flights. Repair as given in this service bulletin, or ask Boeing for repair data. For areas repaired as given in this service bulletin, start to do repeat inspections at repaired locations as given in this service bulletin at the times given in Paragraph 1.E., Compliance. For any locations that have a repair that is different from those shown in this service bulletin, contact Boeing for an after-repair inspection plan. If no cracks are found, do the inspection again at the time given in Paragraph 1.E., Compliance. Group 2: Do edge or surface HFEC inspections of the forward and aft horizontal flanges of the upper chord and a detailed inspection of the vertical flanges of the upper chord at all plugged or re-used floor panel attachment holes. If cracks are found in any plugged holes, contact Boeing for repair instructions and do the repair. If no cracks are found, do the inspection again at the time given in Paragraph 1.E., Compliance. Group 3-4: Replace all affected upper deck floor beam upper chords at the time given in Paragraph 1.E., Compliance. EFFECTIVITY All 747-400 and 747-400D airplanes. Refer to Paragraph 1.A.1., Airplanes for the list of affected airplanes. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 9 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 10 COMPLIANCE Federal Aviation Administration (FAA) Airworthiness Directives AD 2013-22-11 and AD 2004-07-22 R1 are related to this service bulletin. Refer to Paragraph 1.E., Compliance. INDUSTRY SUPPORT INFORMATION Boeing warranty remedies are not available for the inspection and repair procedures given in this service bulletin. MANPOWER Section 41 Inspections Elapsed Time (Hours) Total Man- Hours Airplanes 77.25259Passenger 72.25241Boeing Converted Freighter 36120Large Cargo Freighter Section 44 Inspections Elapsed Time (Hours) Total Man- Hours Airplanes 24.0066.00Passenger MATERIAL INFORMATION None. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 10 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 11 (OCR) BOEING SERVICE BULLETIN 747-53A2688 ALERT ALERT STA STA 1100 SECTION 44 1000 INSPECTION AREA SECTION 41 INSPECTION AREA STA 340 STA 360 STA STA STA 520 380 340 STA 400 STA 420 SECTION 41 INSPECTION STA 440 AREA SHOWN, SECTION 44 INSPECTION STA AREA SIMILAR 460 B • STA 480 _ STA 500 FLOOR PANEL ATTACH STA FASTENER HOLE 520 A-A FWD UPPER CHORD TYPICAL SECTION 41 INSPECTION AREA WEB OR STRAP FLOOR PANEL DO OPEN-HOLE OR SURFACE HFEC INSPECTIONS AT ALL FLOOR PANEL ATTACH FASTENER HOLES. ON BCF AIRPLANES ALSO INSPECT ALL PLUGGED OR > FWD B-B REUSED FLOOR PANEL ATTACH FASTENER HOLES, COMMON TO THE UPPER DECK FLOOR BEAM. 1454601 (TYPICAL) Original Issue: August 21, 2008 Revision 2: August 21, 2014 Export Controlled ECCN: 9E991 - BOEING 747-53A2688 PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 11 of 177 ### Page 12 Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 12 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT BLANK PAGE ### Page 13 Commercial Airplanes 747 Service Bulletin ALERT Number: 747-53A2688 Original Issue: August 21, 2008 Revision 2: August 21, 2014 ATA System: 5321 SUBJECT: FUSELAGE - Floors - Section 41 and Section 44 Upper Deck Floor Beam Upper Chord Inspection and Repair at Floor Panel Attachment Fastener Holes 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 Refer to Service Bulletin Index Document D6-30300, Part 3 for Airplane Variable Number, Line Number, and Serial Number data. This service bulletin is applicable to 747-400 and 747-400D airplanes, line number 696 through 1358, in 4 Groups. The Variable Numbers and Group Information for the applicable airplanes is given below. DESCRIPTIONCONFIGURATIONGROUP 747-400 and 747-400D airplanes, except those modified to the Boeing Converted Freighter (BCF) and Large Cargo Freighter (LCF) configurations. -1 747-400 and 747-400D airplanes that have been modified to the Boeing Converted Freighter (BCF) configuration. -2 747-400 airplane, variable number RT743, that has been modified to the Large Cargo Freighter (LCF) configuration. -3 747-400 airplanes, variable numbers RT631, RT632 and RT876, that have been modified to the Large Cargo Freighter (LCF) configuration. -4 Airplane Models: 747-400, 747-400D Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 13 of 177 ### Page 14 GroupVariable Number 1RF001 - RF006 1RM001 - RM007 1RM010 - RM013 1RM021 - RM024 1RM026 - RM030 1RM036 - RM045 1RM051 - RM053 1RM071 1RM081 - RM084 1RM091 1RM096 - RM097 1RM116 - RM117 1RM126 - RM127 2RM128 1RM129 - RM132 1RM136 - RM147 1RM156 - RM158 1RM166 - RM177 1RM191 - RM192 1RM231 - RM233 1RM241 - RM246 1RM261 - RM264 1RM316 - RM318 1RM331 - RM333 1RM341 1RM351 - RM355 1RM366 - RM367 1RM401 - RM403 1RM426 1RM431 1RM441 - RM443 1RM445 Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 14 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 15 GroupVariable Number 1RM801 - RM803 1RM811 - RM813 1RT001 - RT014 2RT021 - RT022 2RT031 - RT033 1RT034 - RT035 1RT041 - RT047 2RT061 2RT071 - RT072 1RT073 - RT074 2RT075 1RT101 - RT103 1RT121 1RT131 - RT137 1RT151 - RT152 2RT161 1RT162 - RT163 2RT164 1RT165 - RT168 1RT401 - RT412 1RT431 - RT447 1RT451 - RT455 2RT456 1RT457 - RT460 2RT461 1RT462 - RT469 1RT471 - RT499 2RT501 1RT502 - RT505 2RT506 - RT510 1RT511 - RT512 2RT513 1RT514 - RT515 Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 15 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 16 GroupVariable Number 2RT516 1RT517 2RT518 - RT520 1RT521 - RT523 2RT524 1RT525 2RT526 1RT527 2RT528 1RT529 2RT530 1RT531 - RT535 1RT551 - RT568 1RT571 2RT572 - RT579 1RT580 - RT591 1RT601 - RT630 4RT631 - RT632 1RT633 - RT641 2RT642 1RT643 - RT653 2RT654 - RT657 1RT671 - RT673 1RT681 - RT682 2RT691 - RT692 1RT693 - RT699 1RT701 - RT704 1RT711 - RT717 1RT741 - RT742 3RT743 1RT744 - RT750 2RT751 - RT752 1RT753 - RT757 Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 16 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 17 GroupVariable Number 1RT776 - RT777 2RT781 - RT782 1RT783 - RT784 1RT801 - RT803 1RT811 - RT814 1RT831 - RT836 2RT837 1RT861 - RT864 4RT876 1RT877 - RT880 1RT931 - RT932 1RT945 - RT949 1RT951 - RT955 1RT966 2RT967 1RU001 - RU006 1RU016 - RU017 1RU031 - RU032 1RU051 - RU052 1RU059 - RU062 1RU081 - RU083 1RU101 - RU102 1RU121 - RU132 1RU801 - RU809 1RU831 - RU841 2. Spares Affected None. B. Concurrent Requirements None. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 17 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 18 C. Reason This SB gives instructions to do inspections for fatigue cracks of the upper deck floor beam upper chords at the floor panel attachment holes. Also, additional inspections are provided at the floor panel attachment holes that have been plugged or re-used during the BCF modification in Section 41. Cracks in these chords that are not found and repaired could become large and cause the floor beam to become severed. This can lead to large deflection or deformation of the floor and of the body skin, frames, and stringers. This deflection or deformation could result in damage to wire bundles and unintended inputs to the flight control cables which could affect airplane controllability. Multiple adjacent severed floor beams could result in rapid decompression of the airplane. Flight critical wire bundles and control cables are routed through cutouts in the upper deck floor beams. Cracks have been found at open floor panel attach fastener holes in the upper chord of two Section 41 upper deck floor beam on three different 747-400D airplanes, which had flown 24,053, 24,783, and 25,631 flight-cycles. Boeing believes that these 747-400D airplanes were operated at reduced cabin differential pressures. Similar cracks were also found on the 747-400 Fatigue Test airplane. Accomplishment of the inspections given in this service bulletin will ensure the structural integrity of the upper chords of the Section 41 upper deck floor beams. A structural reassessment of the 747 airplane was conducted under the requirements of Federal Aviation Administration (FAA) Advisory Circular 91-56, in accordance with Federal Aviation Regulation (FAR) 25.571 as amended in 1978, to ensure safe operation of 747 airplanes throughout their operational life. From this requirement, the Section 41 upper deck floor beam upper chords were determined to be significant, in that they are critical to airplane structural integrity. Therefore, a flight safety inspection program which will continue throughout the operational life of the airplane is specified in this service bulletin. Between the original issue and Revision 1 of this service bulletin, the following cracks at upper deck floor beam fastener hole locations have been reported: Crack lengthCrack locationFlight hours/cycles unknownSTA 340,RBL 6037,561 / 29,013 not reportedSTA 440, BL 032,855 / 24,783 1 inch (corrosion)STA 440, RBL 5849,403 / 5,581 0.03 inchSTA 1000, LBL 5037,561 / 29,013 0.4 inchSTA 1100, RBL 5337,283 / 29,425 The cracks at STA 1000 and STA 1100 are at locations that are not common to the inspection area given in the original issue of this service bulletin. Due to these crack reports Boeing has determined that inspection of all upper deck floor beam upper chords in Section 44 (from STA 1000 to STA 1100) is required. Revision 1 is sent to add inspections and repair of the Section 44 upper deck floor beam upper chords from STA 1000 to STA 1100. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 18 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 19 NOTE: Inspections of Section 42 upper deck floor beam upper chords from STA 540 to STA 980 are not added to this service bulletin because the floor panel attachment holes in this area were cold worked in production. Boeing Service Related Problem (SRP) 747-SRP-53-0293, 747-SRP-53-0353 and 747-SRP-53-0428 are related to this service bulletin. The upper deck floor beam upper chords have been determined to be structure that is susceptible to Widespread Fatigue Damage (WFD). For more information about WFD, refer to Boeing Service Letter 747-SL-53-088A. Since the release of Revision 1 of this service bulletin, Boeing has found that certain fastener holes in the upper deck floor beam upper chords in Section 41, that were plugged or re-used during the conversion to BCF may not have been inspected in accordance with the instructions provided in Revision 1 of this service bulletin, because these locations may be hidden and not recognized as inspection locations. Boeing has determined that inspection of the upper deck floor beam upper chords in all locations containing plugged or re-used fastener holes is required. This revision is sent to add a High Frequency Eddy Current (HFEC) inspection for cracks in the upper deck floor beam upper chords, at the floor panel attachment, that were plugged or re-used during the conversion to Boeing Converted Freighter (BCF) and to add instructions to inspect and replace additional section 41 upper deck floor beam upper chords for Large Cargo Freighter (LCF) airplanes. D. Description Group 1: Get access from above or below to the upper chords of the Section 41 upper deck floor beams from Station (STA) 340 to STA 520 and to the upper chords of the Section 44 upper deck floor beams from STA 1000 to STA 1100. Group 2: Get access from above or below to the upper chords of the Section 41 upper deck floor beams from STA 340 to STA 440. NOTE: On Group 2 airplanes, upper deck floor beams from STA 460 to STA 520 do not require inspection as given in this service bulletin because they were replaced with new floor beams during modification to Boeing Converted Freighter (BCF). The new floor beams have floor panel attachment fastener holes that have been cold-worked. Also, on Group 2 airplanes, inspection as given in this service bulletin are not necessary in Section 44 because all floor beams in Section 44 were replaced with tension ties during modification to BCF. Group 3: Get access from above or below to the upper chords of the Section 41 upper deck floor beams from STA 340 to STA 420. NOTE: On Group 3 airplanes, upper deck floor beams from STA 400 to STA 500 do not require inspection as given in this service bulletin because they were replaced with new floor beams during modification to Large Cargo Freighter (LCF). The new floor beams have floor panel attachment fastener holes that have been cold-worked. Group 4: Get access from above or below to the upper chords of the Section 41 upper deck floor beams from STA 340 to STA 420. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 19 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 20 NOTE: On Group 4 airplanes, upper deck floor beams from STA 440 to STA 500 do not require inspection as given in this service bulletin because they were replaced with new floor beams, or modified, during conversion to Large Cargo Freighter (LCF). The new floor beams have floor panel attachment fastener holes that have been cold-worked. If access was gained from above, do open hole HFEC inspections of the floor panel attachment fastener holes in the upper chords for cracks. If access was gained from below, modify the clipnuts for the floor panel attachment fasteners as given in this service bulletin. Do surface HFEC inspections of the forward and aft horizontal flanges of the upper chord at floor panel attachment fastener holes. If cracks are found, repair before any more flights. Repair as given in this service bulletin, or ask Boeing for repair data. For areas repaired as given in this service bulletin, start to do repeat inspections at repaired locations as given in this service bulletin at the times given in Paragraph 1.E., Compliance. For any locations that have a repair that is different from those shown in this service bulletin, contact Boeing for an after-repair inspection plan. If no cracks are found, do the inspection again at the time given in Paragraph 1.E., Compliance. Group 2: Do edge or surface HFEC inspections of the forward and aft horizontal flanges of the upper chord and a detailed inspection of the vertical flanges of the upper chord at all plugged or re-used floor panel attachment holes. If cracks are found in any plugged holes, contact Boeing for repair instructions and do the repair. If no cracks are found, do the inspection again at the time given in Paragraph 1.E., Compliance. Group 3-4: Replace all affected upper deck floor beam upper chords at the time given in Paragraph 1.E., Compliance. Group 1, 3-4: No more work is necessary on the airplane(s) changed or inspected in accordance with the original issue of this service bulletin. No more work is necessary on the airplane(s) changed or inspected in accordance with Revision 1 of this service bulletin. Group 2: More work is necessary on the airplane(s) changed or inspected in accordance with the original issue of this service bulletin. More work is necessary on the airplane(s) changed or inspected in accordance with Revision 1 of this service bulletin. Do a High Frequency Eddy Current (HFEC) inspection for any cracks in the upper deck floor beam upper chords and a detailed visual inspection of the upper deck floor beam vertical flanges. The work in this service bulletin is done in the maintenance zone(s) given below. Group 1: Affected Maintenance Zones ZoneModel 211, 212, 221, 222, 223, 224, 225, 226, 231, 232, 241, 242 747-400, 747-400D Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 20 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 21 Group 2-4: Affected Maintenance Zones ZoneModel 211, 212, 221, 222, 223, 224, 231, 232747-400 E. Compliance Federal Aviation Administration (FAA) Airworthiness Directives AD 2013-22-11 and AD 2004-07-22 R1 are related to this service bulletin. The effective date of AD 2013-22-11 is December 10, 2013. The effective date of AD 2004-07-22 R1 is January 22, 2008. AD 2013-22-11 superseded AD 2009-10-06. The effective date of AD 2009-10-06 was June 17, 2009. Table 1 - Section 41 Compliance Times for Upper Deck Floor Beam Upper Chord Initial and Repeat In- spections Repeat Interval (Not to Exceed) Compliance Time (Whichever Occurs Last)ActionCondition -Within 2,000 flight-cycles of the last SSID in- spection, if sur- face HFEC was used in that in- spection. Within 6,000 flight-cy- cles of the last SSID inspection, if open hole HFEC was used in that inspec- tion. (a) Within 1,000 flight-cycles after June 17, 2009. Before 20,000 total flight-cycles. Do open hole or sur- face HFEC inspection of the floor panel attach- ment fastener holes in the upper deck floor beam upper chords for cracks in accordance with Paragraph 3.B., PART 1. All airplanes. -Before further flight.Do the applicable repair procedures in accor- dance with Paragraph 3.B., PART 2, or con- tact Boeing for repair instructions and do the repair. Any crack found in the floor panel at- tachment fastener holes. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 21 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 22 Table 1 - Section 41 Compliance Times for Upper Deck Floor Beam Upper Chord Initial and Repeat In- spections Repeat Interval (Not to Exceed) Compliance Time (Whichever Occurs Last)ActionCondition 2,000 flight-cycles if surface HFEC inspection was used; 6,000 flight- cycles if open hole HFEC in- spection was used. Within 2,000 flight-cycles if surface HFEC in- spection was used, or within 6,000 flight-cycles if open hole HFEC inspection was used. Repeat open hole or surface HFEC inspec- tion of the floor panel attachment fastener holes in the upper deck floor beam upper chords for cracks in ac- cordance with Para- graph 3.B., PART 1. No crack found in the floor panel at- tachment fastener holes. -Before further flight.As an option, do the hole modification proce- dure in accordance with FIGURE 5. -Before further flight.As an option, do one of the repair procedures as a hole modification in accordance with Paragraph 3.B., PART 2. Refer to Table 2 in Paragraph 1.E., Compliance. Refer to Table 2 in Paragraph 1.E., Compli- ance. Refer to Table 2 in Paragraph 1.E., Compli- ance. Location(s) modi- fied or repaired in accordance with FIGURE 5 or Paragraph 3.B., PART 2. -Before further flight.Do a repair. Contact Boeing for repair instruc- tions and do the repair. Any crack found in the repaired or modified loca- tion(s). (a) Applicable only to airplanes that have been previously inspected in accordance with SSID SSI's F-19B, F-19G, or F-19K. Table 2 - Section 41 Compliance Times for Inspection of Location(s) Repaired or Modified Repeat Interval (Not to Exceed) Compliance TimeActionCondition 2,000 flight-cycles if sur- face HFEC inspection was used; 6,000 flight- cycles if open hole HFEC inspection was used. Within 15,000 flight-cy- cles after the modification was accomplished. Do open hole or surface HFEC inspection for cracks in accordance with Paragraph 3.B., PART 1. Location(s) modified in accor- dance with FIGURE 5 where edge margin after modification is 2.0D or more. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 22 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 23 Table 2 - Section 41 Compliance Times for Inspection of Location(s) Repaired or Modified Repeat Interval (Not to Exceed) Compliance TimeActionCondition 2,000 flight-cycles if sur- face HFEC inspection was used; 6,000 flight- cycles if open hole HFEC inspection was used. Within 10,000 flight-cy- cles after the modification was accomplished. Do open hole or surface HFEC inspection for cracks in accordance with Paragraph 3.B., PART 1. Location(s) modified in accor- dance with FIGURE 5 where edge margin after modification is 1.3D or more and less than 2.0D. 2,000 flight-cycles if sur- face HFEC inspection was used; 6,000 flight- cycles if open hole HFEC inspection was used. Within 15,000 flight-cy- cles after the repair was accomplished. Do open hole or surface HFEC inspection for cracks in accordance with Paragraph 3.B., PART 1. Location(s) where repair #1 was done in accordance with Para- graph 3.B., PART 2 of this ser- vice bulletin. (a) 2,000 flight-cycles if sur- face HFEC inspection was used; 6,000 flight- cycles if open hole HFEC inspection was used. Within 10,000 flight-cy- cles after the repair was accomplished. Do open hole or surface HFEC inspection for cracks in accordance with Paragraph 3.B., PART 1. Location(s) where repair #2 was done in accordance with Para- graph 3.B., PART 2 of this ser- vice bulletin. (a) 3,000 flight-cycles.Within 10,000 flight-cy- cles after the repair was accomplished. Do open hole HFEC in- spection for cracks in ac- cordance with Paragraph 3.B., PART 3. Location(s) where repair #3 was done in accordance with Para- graph 3.B., PART 2 of this ser- vice bulletin. (a) 3,000 flight-cycles.Within 5,000 flight-cycles after the repair was ac- complished. Do open hole HFEC in- spection for cracks in ac- cordance with Paragraph 3.B., PART 1. Location(s) where repair #4 was done in accordance with Para- graph 3.B., PART 2 of this ser- vice bulletin. (a) 3,000 flight-cycles.Within 5,000 flight-cycles after the repair was ac- complished. Do open hole HFEC in- spection for cracks in ac- cordance with Paragraph 3.B., PART 3. Location(s) where repair #5 was done in accordance with Para- graph 3.B., PART 2 of this ser- vice bulletin. (a) 6,000 flight-cycles.Within 10,000 flight-cy- cles after the repair was accomplished. Do open hole and sur- face HFEC inspections for cracks in accordance with Paragraph 3.B., PART 3. Location(s) where repair #6, #7, #8, #9, #11 or #12 was done in accordance with Paragraph 3.B., PART 2 of this service bulletin. (a) Contact Boeing for after-repair inspection instructions and do the inspections at the compliance times specified by Boeing. Location(s) where repair #10 or #13 was done in accordance with Paragraph 3.B., PART 2 of this service bulletin. (a) -Before further flight.Do a repair. Contact Boeing for repair instruc- tions and do the repair. Any crack found in the repaired or modified location(s). (a) Refer to Paragraph 3.B., Work Instructions, PART 2, Tables 1 and 2 for corresponding repair procedures. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 23 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 24 Group 1: Table 3 - Section 44 Compliance Times for Upper Deck Floor Beam Upper Chord Initial and Repeat In- spections Repeat Interval (Not to Exceed) Compliance Time (Whichever Occurs Last)ActionCondition -Within 2,000 flight-cycles of the last SSID in- spection, if sur- face HFEC was used in that in- spection. Within 6,000 flight-cy- cles of the last SSID inspection, if open hole HFEC was used in that inspec- tion. (a) Within 1,000 flight-cycles after the Revi- sion 1 date of this service bulletin. Before 20,000 total flight-cycles. Do open hole or sur- face HFEC inspection of the floor panel attach- ment fastener holes in the upper deck floor beam upper chords for cracks in accordance with Paragraph 3.B., PART 4. All airplanes. -Before further flight.Do the applicable repair procedures in accor- dance with Paragraph 3.B., PART 5, or con- tact Boeing for repair data. Any crack found in the floor panel at- tachment fastener holes. 2,000 flight-cycles if surface HFEC inspection was used; 6,000 flight- cycles if open hole HFEC in- spection was used. Within 2,000 flight-cycles if surface HFEC in- spection was used, or within 6,000 flight-cycles if open hole HFEC inspection was used. Repeat open hole or surface HFEC inspec- tion of the floor panel attachment fastener holes in the upper deck floor beam upper chords for cracks in ac- cordance with Para- graph 3.B., PART 4. No crack found in the floor panel at- tachment fastener holes. -Before further flight.As an option, do the hole modification proce- dure in accordance with FIGURE 21. -Before further flight.As an option, do one of the repair procedures as a hole modification in accordance with Paragraph 3.B., PART 5. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 24 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 25 Group 1: Table 3 - Section 44 Compliance Times for Upper Deck Floor Beam Upper Chord Initial and Repeat In- spections Repeat Interval (Not to Exceed) Compliance Time (Whichever Occurs Last)ActionCondition Refer to Table 4 in Paragraph 1.E., Compliance. Refer to Table 4 in Paragraph 1.E., Compli- ance. Refer to Table 4 in Paragraph 1.E., Compli- ance. Location(s) modi- fied or repaired in accordance with FIGURE 21 or Paragraph 3.B., PART 5. -Before further flight.Do a repair. Contact Boeing for repair instruc- tions and do the repair. Any crack found in the repaired or modified loca- tion(s). (a) Applicable only to airplanes that have been previously inspected in accordance with SSID SSI's F-19B, F-19G, or F-19K. Group 1: Table 4 - Section 44 Compliance Times for Inspection of Location(s) Repaired or Modified Repeat Interval (Not to Exceed) Compliance TimeActionCondition 2,000 flight-cycles if sur- face HFEC inspection was used; 6,000 flight- cycles if open hole HFEC inspection was used. Within 15,000 flight-cy- cles after the modification was accomplished. Do open hole or surface HFEC inspection for cracks in accordance with Paragraph 3.B., PART 4. Location(s) modified in accor- dance with FIGURE 21 where edge margin after modification is 2.0D or more. 2,000 flight-cycles if sur- face HFEC inspection was used; 6,000 flight- cycles if open hole HFEC inspection was used. Within 10,000 flight-cy- cles after the modification was accomplished. Do open hole or surface HFEC inspection for cracks in accordance with Paragraph 3.B., PART 4. Location(s) modified in accor- dance with FIGURE 21 where edge margin after modification 1.3D or more and less than 2.0D. 2,000 flight-cycles if sur- face HFEC inspection was used; 6,000 flight- cycles if open hole HFEC inspection was used. Within 15,000 flight-cy- cles after the repair was accomplished. Do open hole or surface HFEC inspection for cracks in accordance with Paragraph 3.B., PART 4. Location(s) where repair #1 was done in accordance with Para- graph 3.B., PART 5 of this ser- vice bulletin. (a) 2,000 flight-cycles if sur- face HFEC inspection was used; 6,000 flight- cycles if open hole HFEC inspection was used. Within 10,000 flight-cy- cles after the repair was accomplished. Do open hole or surface HFEC inspection for cracks in accordance with Paragraph 3.B., PART 4. Location(s) where repair #2 was done in accordance with Para- graph 3.B., PART 5 of this ser- vice bulletin. (a) Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 25 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 26 Group 1: Table 4 - Section 44 Compliance Times for Inspection of Location(s) Repaired or Modified Repeat Interval (Not to Exceed) Compliance TimeActionCondition 3,000 flight-cycles.Within 10,000 flight-cy- cles after the repair was accomplished. Do open hole HFEC in- spection for cracks in ac- cordance with Paragraph 3.B., PART 6. Location(s) where repair #3 was done in accordance with Para- graph 3.B., PART 5 of this ser- vice bulletin. (a) 3,000 flight-cycles.Within 5,000 flight-cycles after the repair was ac- complished. Do open hole HFEC in- spection for cracks in ac- cordance with Paragraph 3.B., PART 4. Location(s) where repair #4 was done in accordance with Para- graph 3.B., PART 5 of this ser- vice bulletin. (a) 3,000 flight-cycles.Within 5,000 flight-cycles after the repair was ac- complished. Do open hole HFEC in- spection for cracks in ac- cordance with Paragraph 3.B., PART 6. Location(s) where repair #5 was done in accordance with Para- graph 3.B., PART 5 of this ser- vice bulletin. (a) 6,000 flight-cycles.Within 10,000 flight-cy- cles after the repair was accomplished. Do open hole and sur- face HFEC inspections for cracks in accordance with Paragraph 3.B., PART 6. Location(s) where repair #6, #7, #8, #9, #11 or #12 was done in accordance with Paragraph 3.B., PART 5 of this service bulletin. (a) Contact Boeing for after-repair inspection instructions and do the inspections at the compliance times specified by Boeing. Location(s) where repair #10 or #13 was done in accordance with Paragraph 3.B., PART 5 of this service bulletin. (a) -Before further flight.Do a repair. Contact Boeing for repair instruc- tions and do the repair. Any crack found in the repaired or modified location(s). (a) Refer to Paragraph 3.B., Work Instructions, PART 5, Tables 3 and 4 for corresponding repair procedures. Table 5 - Section 41 and 44 Upper Deck Floor Beam Upper Chord Replacement Compliance TimeActionCondition After 15,000 total flight cycles and before 35,000 total flight cycles. (a) Replace upper deck floor beam upper chords in ac- cordance with Paragraph 3.B., PART 7. All airplanes (a) Due to the post-replacement requirements, and the possibility that it will be necessary to replace the upper chords again, Boeing does not recommend upper chord replacement prior to 15,000 total flight-cycles. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 26 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 27 Group 2: Table 6 - Section 41 Compliance Times for Upper Deck Floor Beam Upper Chord Initial and Repeat Inspections for Plugged or Re-used Floor Panel Attachment Holes Repeat Interval (Not to Exceed) Compliance Time (Whichever Occurs Last) ActionCondition -Within 2,000 flight-cycles after the Revision 2 date of this ser- vice bulletin. Before 20,000 total flight-cycles. Do a Surface High Fre- quency Eddy Current (HFEC) inspection of the upper deck floor beam upper chords and do a detailed visual in- spection of the upper deck floor beam vertical flanges for cracks in accordance with Para- graph 3.B., PART 8. All airplanes. -Before further flight.Contact Boeing for re- pair instructions and do the repair. Any crack found. 2,000 flight-cy- cles. -Repeat Surface High Frequency Eddy Cur- rent (HFEC) inspection of the upper deck floor beam upper chords and do a detailed visual in- spection of the upper deck floor beam vertical flanges for cracks in accordance with Para- graph 3.B., PART 8. No crack found. 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 Federal Aviation Administration (FAA). In addition, the Manager of the FAA Seattle Aircraft Certification Office (ACO) approves the accomplishment of the inspection and repair actions with corresponding compliance times specified in Tables 1, 2, 3, 4 and 6 under paragraph 1.E., "Compliance", of Service Bulletin 747-53A2688, Revision 2, as an alternative method of compliance (AMOC) to the accomplishment of the corresponding inspection and repair Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 27 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 28 requirements of paragraphs (h) and (i) of AD 2004-07-22 R1, for the inspection of Structural Significant Items (SSI) F-19B, F-19G, and F-19K of Supplemental Structural Inspection Document (SSID) D6-35022, Revision G, dated December 2000 and Revision TR-08-001, dated June 2006. This AMOC only applies to the areas where upper deck floor beam upper chords were inspected in accordance with this service bulletin. When this service bulletin specifies contacting Boeing for repair instructions, the repair instructions 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, including the initial inspection threshold per paragraph (i) of AD 2004-07-22 R1, remain fully applicable and must be complied with accordingly. In addition, the manager of the Seattle Aircraft Certification Office (ACO) approves the accomplishment of the Section 41 inspection and repair actions with corresponding compliance times specified in Tables 1, 2, and 6 under paragraph 1.E., "Compliance," of Service Bulletin 747-53A2688, Revision 2, as an AMOC to the accomplishment of the corresponding inspection and repair requirements of paragraphs (g), (i) and (k)(1) of AD 2013-22-11. This AMOC is only for upper deck floor beam upper chords that have been inspected and repaired in accordance with this service bulletin. When this service bulletin specifies contacting Boeing for repair instructions, the repair instructions must be approved by the FAA in accordance with paragraph (p) of AD 2013-22-11. All provisions of AD 2013-22-11 that are not specifically referenced in this paragraph remain fully applicable and must be complied with accordingly. In addition, the manager of the Seattle Aircraft Certification Office (ACO) approves the accomplishment of the Section 44 inspection and repair actions with corresponding compliance times specified in Tables 3 and 4 under paragraph 1.E., "Compliance," of Service Bulletin 747-53A2688, Revision 2, as an AMOC to the accomplishment of the corresponding inspection and repair requirements of paragraphs (j), (k)(2) and (l) of AD 2013-22-11. This AMOC is only for upper deck floor beam upper chords that have been inspected and repaired in accordance with this service bulletin. When this service bulletin specifies contacting Boeing for repair instructions, the repair instructions must be approved by the FAA in accordance with paragraph (p) of AD 2013-22-11. All provisions of AD 2013-22-11 that are not specifically referenced in this paragraph remain fully applicable and must be complied with accordingly. In addition, the manager of the Seattle Aircraft Certification Office (ACO) approves the accomplishment of the replacement actions with corresponding compliance times specified in Table 5 under paragraph 1.E., "Compliance," of Service Bulletin 747-53A2688, Revision 2, as an AMOC to the accomplishment of the replacement requirements of paragraph (m) of AD 2013-22-11. This AMOC is only for upper deck floor beam upper chords that have been modified in accordance with this service bulletin. When this service bulletin specifies contacting Boeing for repair instructions, the repair instructions must be approved by the FAA in accordance with paragraph (p) of AD 2013-22-11. All provisions of AD 2013-22-11 that are not specifically referenced in this paragraph remain fully applicable and must be complied with accordingly. G. Manpower The table below shows an estimate of the man-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 man-hour data if necessary. The estimate does not include lost time. These are some examples of lost time: — Time to adjust to the workplace — Time to schedule the work — Time to examine the work — Time to cure the materials — Time to make the parts — Time to find the tools. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 28 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 29 Group 1: Section 41 Inspections Elapsed HoursTask HoursNumber of Persons Task 24964Open Access 25502Inspect 28.251134Close Access 77.25259TOTAL FOR EACH AIRPLANE Group 2: Section 41 Inspections Elapsed HoursTask HoursNumber of Persons Task 22.50904Open Access 24482Inspect 25.751034Close Access 72.25241TOTAL FOR EACH AIRPLANE Group 3: Section 41 Inspections Elapsed HoursTask HoursNumber of Persons Task 11.25454Open Access 12242Inspect 12.75514Close Access 36120TOTAL FOR EACH AIRPLANE Group 4: Section 41 Inspections Elapsed HoursTask HoursNumber of Persons Task 22.5904Open Access 24482Inspect 25.751034Close Access 72.25241TOTAL FOR EACH AIRPLANE Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 29 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 30 Group 1: Section 44 Inspections Elapsed HoursTask HoursNumber of Persons Task 4.0016.004Open Access 15.0030.002Inspect 5.0020.004Close Access 24.0066.00TOTAL FOR EACH AIRPLANE Group 1: Upper Chord Replacement Elapsed HoursTask HoursNumber of Persons Task 24964Open Access 113.254534Modification 28.251134Close Access 165.5662TOTAL FOR EACH AIRPLANE Group 2: Upper Chord Replacement Elapsed HoursTask HoursNumber of Persons Task 22.5904Open Access 682724Modification 25.751034Close Access 116.5465TOTAL FOR EACH AIRPLANE Group 3: Upper Chord Replacement Elapsed HoursTask HoursNumber of Persons Task 11.25454Open Access 341364Modification 12.75514Close Access 58232TOTAL FOR EACH AIRPLANE Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 30 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 31 Group 4: Upper Chord Replacement Elapsed HoursTask HoursNumber of Persons Task 22.5904Open Access 682724Modification 25.751034Close Access 116.25465TOTAL FOR EACH AIRPLANE NOTE: More time will be necessary for repairs if cracks are found. H. Weight and Balance Changes The repairs in this service bulletin will affect the weight and balance of the airplane. However, because of the variation in weight, location and quantity of repairs, it is not possible to specify weight and balance changes in this service bulletin. It will be necessary for operators to calculate the weight and balance changes for each airplane based on the repairs that are accomplished. I. Electrical Load Data Not changed. J. References 1. Existing Data: a. Boeing Service Bulletin 747-53A2500 b. Boeing Service Letter 747-SL-53-088A c. Boeing Service Related Problem (SRP) 747-SRP-53-0353, 747-SRP-53-0428 d. Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2004-07-22 R1, 2009-10-06, 2013-22-11 e. 747 Non-Destructive Testing (NDT) Manual Part 6, 51-00-00, Part 6, 53-10-53, Part 6, 53-10-54 f. 747-400 Aircraft Maintenance Manual (AMM) 25-11-01, 25-11-03, 25-16-00, 25-19-03, 25-21-04, 25-22-01, 25-23-00, 25-24-18, 25-25-01, 25-27-05, 25-28-01, 25-28-02, 25-32-01, 25-40-03, 25-59-01, 25-59-05, 53-21-02 g. 747-400 Structural Repair Manual (SRM) 51-40-05 h. Supplemental Structural Inspection Document (SSID) D6-35022, Revision G 2. Data Supplied with this Service Bulletin: None. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 31 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 32 3. Installation Drawings Used in the Preparation of this Service Bulletin: None. K. Publications Affected 1. Publications: None. 2. Damage Tolerance Based Structural Inspections: Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the Maintenance Program. This service bulletin affects FCS. DTI requirements for the structure affected are contained in Paragraph 1.E., Compliance of this service bulletin. L. Interchangeability and Intermixability of Parts Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts. M. Software Accomplishment Summary Not affected. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 32 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 33 2. MATERIAL INFORMATION A. Material - Price and Availability None. B. Industry Support Information Boeing warranty remedies are not available for the inspection and repair procedures given in this service bulletin. C. Parts Necessary for Each Airplane 1. Kits/Parts: None. 2. Parts and Materials Supplied by the Operator: NOTE: The number in the QTY column in the tables that follow is the number of parts necessary to accomplish one repair. 1. 2. More than one repair may be necessary if cracks are found. 3. Refer to 747 Structural Repair Manual Chapter 51 for alternative fasteners. Table 1 - Section 41 or Section 44 Repair Strap Installation (Refer to Figure 7 or Figure 23) NamePart NumberQTY Repair StrapA (a)1 BoltBACB30NW6K410 CollarBACC30M610 NutplateBACN10JR3F(b) RivetBACR15CE3AD4(b) Pressure and Environmental Sealant - Chromate Type BMS 5-952 oz. (c) Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c) (a) Make in accordance with FIGURE 7 or FIGURE 23. (b) Dependent upon the number of floor panel attachment fastener holes affected by the repair. (c) Refer to the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data. Table 2 - Section 41 or Section 44 Upper Chord Strap Repair (Refer to Figure 9 or Figure 25) NamePart NumberQTY Repair StrapA (a)1 Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 33 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 34 Table 2 - Section 41 or Section 44 Upper Chord Strap Repair (Refer to Figure 9 or Figure 25) NamePart NumberQTY FillerB (a)1 BoltBACB30NW6K410 CollarBACC30M610 NutplateBACN10JR3F(b) RivetBACR15CE3AD4(b) Pressure and Environmental Sealant - Chromate Type BMS 5-952 oz. (c) Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c) (a) Make in accordance with FIGURE 9 or FIGURE 25. (b) Dependent upon the number of floor panel attachment fastener holes affected by the repair. (c) Refer to the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data. Table 3 - Section 41 or Section 44 Upper Chord Clip Repair (Refer to Figure 10 or Figure 26) NamePart NumberQTY Repair StrapA (a)1 FillerB (a)1 Repair ClipC (a)1 BoltBACB30MY6K7X3 BoltBACB30NW6K410 CollarBACC30M613 NutplateBACN10JR3F(b) RivetBACR15CE3AD4(b) Pressure and Environmental Sealant - Chromate Type BMS 5-952 oz. (c) Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c) (a) Make in accordance with FIGURE 10 or FIGURE 26. (b) Dependent upon the number of floor panel attachment fastener holes affected by the repair. (c) Refer to the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 34 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 35 Table 4 - Section 44 Upper Chord Clip Repair (Refer to Figure 13 or Figure 27) NamePart NumberQTY Repair StrapA (a)1 FillerB (a)1 Repair StrapC (a)1 BoltBACB30NW6K52 BoltBACB30NW6K712 CollarBACC30M614 NutplateBACN10JR3F(b) RivetBACR15CE3AD4(b) Pressure and Environmental Sealant - Chromate Type BMS 5-952 oz. (c) Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c) (a) Make in accordance with FIGURE 13 or FIGURE 27. (b) Dependent upon the number of floor panel attachment fastener holes affected by the repair. (c) Refer to the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data. Table 5 - Section 44 Upper Chord Clip Repair (Refer to Figure 14 or Figure 28) NamePart NumberQTY Repair AngleA (a)1 FillerB (a)1 Repair StrapC (a)1 BoltBACB30MY6K7X14 BoltBACB30NW6K52 BoltBACB30NW6K712 CollarBACC30M628 NutplateBACN10JR3F(b) RivetBACR15CE3AD3(b) Pressure and Environmental Sealant - Chromate Type BMS 5-952 oz. (c) Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c) (a) Make in accordance with FIGURE 14 or FIGURE 28. (b) Dependent upon the number of floor panel attachment fastener holes affected by the repair. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 35 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 36 Table 5 - Section 44 Upper Chord Clip Repair (Refer to Figure 14 or Figure 28) NamePart NumberQTY (c) Refer to the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data. Table 6 - Section 44 Upper Chord Clip Repair (Refer to Figure 15 or Figure 29) NamePart NumberQTY Repair StrapA (a)1 FillerB (a)1 BoltBACB30NW6K312 CollarBACC30M612 NutplateBACN10JR3F(b) RivetBACR15CE3AD3(b) Pressure and Environmental Sealant - Chromate Type BMS 5-952 oz. (c) Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c) (a) Make in accordance with FIGURE 15 or FIGURE 29. (b) Dependent upon the number of floor panel attachment fastener holes affected by the repair. (c) Refer to the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data. Table 7 - Section 44 Upper Chord Clip Repair (Refer to Figure 16 or Figure 30) NamePart NumberQTY Repair AngleA (a)1 FillerB (a)1 BoltBACB30MY6K512 BoltBACB30NW6K412 CollarBACC30M624 NutplateBACN10JR3F(b) RivetBACR15CE3AD3(b) Pressure and Environmental Sealant - Chromate Type BMS 5-952 oz. (c) Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c) (a) Make in accordance with FIGURE 16 or FIGURE 30. (b) Dependent upon the number of floor panel attachment fastener holes affected by the repair. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 36 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 37 Table 7 - Section 44 Upper Chord Clip Repair (Refer to Figure 16 or Figure 30) NamePart NumberQTY (c) Refer to the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data. 3. Parts Modified and Reidentified: None. 4. Parts Removed and Not Replaced: None. D. Parts Necessary to Change Spares None. E. Special Tooling - Price and Availability None. F. Special Tooling Necessary to do this Service Bulletin No special tools or equipment are necessary to do the change in this service bulletin. But, maintenance and overhaul tools in the manuals given in Paragraph 1.J., References, can be necessary. Examine operator tool supply to make sure all necessary tools are available. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 37 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 38 Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 38 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT BLANK PAGE ### Page 39 3. ACCOMPLISHMENT INSTRUCTIONS A. GENERAL INFORMATION CAUTION: KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED MATERIAL, METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES CAN CAUSE DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE SPARKS OR OTHER ELECTRICAL DAMAGE. NOTE: 1. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for definition of the acronyms. 2. Obey all of the warnings and cautions given in the specified manual sections. 3. Unless shown differently, these dimensions and tolerances are used: – Linear dimensions are in inches – Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus or minus 0.03 inch – Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch – Angular tolerance is plus or minus 2 degrees – Hole dimensions for standard solid rivets and fasteners are in Structural Repair Manual (SRM) Chapter 51 – Torque limits to tighten nuts and bolts are in SRM Chapter 51 4. Use the approved fastener and process material substitutions in accordance with SRM Chapter 51. 5. If the length of any fastener specified in this service bulletin does not meet installation standards given in SRM Chapter 51, then a fastener of the same specification, or an approved substitute, with a length which meets the installation standards given in SRM Chapter 51 may be used. In addition, washers may be installed for fastener grip length in accordance with SRM Chapter 51. 6. A Detailed Inspection is defined as: An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirrors magnifying lenses, etc. may be necessary. Surface cleaning and elaborate procedures may be required. 7. These work instructions refer to procedures included on 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. 8. For initial and repeat inspections of unrepaired and unmodified holes, either the open hole HFEC inspection method or the surface HFEC inspection method can be used. At hole locations where a repair or modification procedure has been done, do the type of inspection specified in paragraph 1.E., Compliance, depending on which repair was done. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 39 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 40 9. The affected areas are also visually inspected in accordance with Boeing Service Bulletin 747-53A2500, "FUSELAGE - Main Frame - Inspections Based on Fatigue Test Results". 10. If affected floor beams or floor beam upper chords have been previously replaced with new parts, the inspection threshold for the replaced part should be counted from the time of the replacement. 11. Fasteners may be oversized 1/64 or 1/32 inch in diameter as needed. Maintain 1.7D minimum edge margin on the upper chord and all adjacent parts. Edge margin is defined as the distance from the edge of the part to the center of the hole, and "D" is the hole diameter 12. Boeing Service Letter 747-SL-51-048, Damage Reporting and Repair Plan/Design Guidelines, is an acceptable procedure to request information from Boeing for additional structural repair instructions. The Service Letter describes what information must be provided to Boeing before a structural repair can be provided. 13. The instructions in Paragraph 3.B., Work Instructions and the figures can include operation of tools or test equipment. Boeing Engineering Tool Drawings, the Illustrated Tool and Equipment Manual, and the Special Tool and Ground Handling Drawing Index contain data on versions of the tools or test equipment that you can use. It is permitted to use replaced tools. It is not permitted to use superseded tools. 14. If it is necessary to remove more parts for access, you can remove those parts. If you can get access without removing identified parts, it is not necessary to remove all of the identified parts. Jacking and shoring limitations must be observed. 15. Where the work instructions include installation of a kept part, a new or serviceable part with the same part number can be installed as an alternative to the kept part. 16. Figures 9, 10, 25, and 26 are for upper chords that have forward and aft flanges of the same thickness. Figures 13, 14, 15, 16, 27, 28, 29, and 30 are for upper chords with forward and aft flanges with different thickness. All other figures are applicable to either configuration. 17. In Figures 13, 14, 15, 16, 27, 28, 29, and 30, the typical illustrations show the thick flange on the forward side of the floor beam. However, at STA 1000, the thick flange is on the aft side of the floor beam. B. WORK INSTRUCTIONS PART 1 -SECTION 41 - INITIAL INSPECTION, REPEAT INSPECTION and INSPECTION OF HOLES THAT HAVE ONLY BEEN REPAIRED OR MODIFIED BY OVERSIZING 1. Group 1: The area to be inspected is shown in FIGURE 1. 2. Group 2: The area to be inspected is shown in FIGURE 2. 3. Group 3: The area to be inspected is shown in FIGURE 17. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 40 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 41 4. Group 4: The area to be inspected is shown in FIGURE 33. 5. If the open hole High Frequency Eddy Current (HFEC) inspection method will be used at the floor panel attach fastener holes: a. Remove equipment from the upper deck in accordance with the table that follows for access to the affected upper deck floor beams from above: Refer to as an accepted procedure Equipment 747-400 AMM 25-16-00Flight Compartment Floor Covering 747-400 AMM 25-11-01Captain and First Officer Seat 747-400 AMM 25-11-03Observer's Seat 747-400 AMM 25-19-03Flight Deck Crew Rest Partitions 747-400 AMM 25-25-01Upper Deck Passenger Seat 747-400 AMM 25-27-05Upper Deck Floor Covering 747-400 AMM 25-40-03Upper Deck Lavatories 747-400 AMM 25-24-18Upper Deck Closets 747-400 AMM 25-32-01Upper Deck Galleys 747-400 AMM 53-21-02Upper Deck Floor Panels NOTE: All of the equipment listed above may not be installed on all affected airplanes. This list is only intended to show equipment typically installed in the upper deck cabin on a typical 747 airplane. b. At all floor panel attach hole locations in the affected floor beam upper chords, do open hole HFEC inspections for cracks in accordance with FIGURE 3. c. If no crack indications found at floor panel attach hole locations: (1) Option 1: Install the floor panels and equipment that were removed for access to the area. Do inspections again, in accordance with Paragraph 1.E., Compliance. (2) Option 2: A new inspection threshold can be obtained by doing one of the following: (a) Do the fastener hole modification in accordance with FIGURE 5. After the modification, do inspections again, in accordance with Paragraph 1.E., Compliance. (b) Do one of the repair procedures in accordance with PART 2 to modify the hole. After the modification, do inspections again, in accordance with Paragraph 1.E., Compliance. d. If crack indications are found at floor panel attach fastener holes, repair in accordance with PART 2 or ask Boeing for repair data. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 41 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 42 NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (in accordance with FIGURE 5 or in accordance with Paragraph 3.B., Part 2) and is not at least five fasteners away from the end of the repair strap is not considered a repaired hole. 6. If the surface HFEC inspection method will be used at the floor panel attach fastener holes: a. Get access to the affected upper deck floor beams from below as follows: Group 1: Refer to as an accepted procedure Equipment 747-400 AMM 25-21-04Ceiling Insulation 747-400 AMM 25-22-01Ceiling Access Panels 747-400 AMM 25-23-00Passenger Service Units 747-400 AMM 25-25-01Passenger Seats 747-400 AMM 25-28-02Center Overhead Stowage Compartments 747-400 AMM 25-28-01Side Overhead Stowage Compartments Group 1: NOTE: All of the equipment listed above may not be installed on all affected airplanes. This list is only intended to show equipment typically installed in the main deck on a typical 747 Passenger airplane. Group 2-4: Refer to as an accepted procedure Equipment 747-400 AMM 25-59-01Main Deck Cargo Compartment Ceiling Lining 747-400 AMM 25-59-05Main Deck Ceiling Insulation b. At all floor panel attach hole locations, modify the clipnuts and do surface HFEC inspections for cracks in accordance with FIGURE 4. c. If no crack indications are found, install the floor panels and equipment that were removed for access to the area. Do inspections again, in accordance with Paragraph 1.E., Compliance. d. If crack indications are found, repair in accordance with PART 2 or ask Boeing for repair data. NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (in accordance with FIGURE 5 or in accordance with Paragraph 3.B., Part 2) and is not at least five fasteners away from the end of the repair strap is not considered a repaired hole. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 42 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 43 PART 2 - SECTION 41 - REPAIR (Can also be accomplished as a modification) 1. If not already done, remove equipment and floor panels as necessary for access to the affected fastener hole from above. 2. For hole locations where this repair procedure is being accomplished as a modification (no crack has been found), make the fastener hole diameter 1/64 oversize, then go to step 4. 3. For hole locations where a crack indication was found during an inspection, do the following: NOTE: It is acceptable to skip this step at any fastener where the chord will be trimmed in accordance with FIGURE 8. For example, if the crack extends to the edge of the upper chord, or if you think that oversizing the crack will result in less edge margin less than 1.3D, then you can do a trim out in accordance with FIGURE 8 instead of doing this step. a. Make the affected fastener hole diameter 1/64 inch oversize. b. Do an open hole HFEC inspection of the hole in accordance with 747 NDT Part 6, 53-10-54 or 747 NDT Part 6, 51-00-00, Figure 1, 11, or 16 for cracks. c. If crack indications are found, repeat the hole oversize and open hole HFEC inspection until no crack indication is found. d. If no crack indication is found, continue to the next step. 4. Prior to any insurance cut, measure the edge margin and hole diameter in accordance with FIGURE 6. 5. Repair the hole in accordance with Table 1 - Hole Repair Instructions. NOTE: Before starting the repair, confirm that the damaged location meets all the repair requirements. Table 1 - Hole Repair Instructions Repair ProcedureEdge MarginCrack-Free Hole Diam- eter Repair # Make hole 1/16 inch oversize (Insurance Cut) (a) 2.5D or more (before insurance cut) 0.281 inch or less (be- fore insurance cut)1 Make hole 1/16 inch oversize (Insurance Cut) (a) 1.6D or more and less than 2.5D (before insur- ance cut) 0.281 inch or less (be- fore insurance cut)2 Make hole 1/16 inch oversize (Insurance Cut) and install strap in accordance with FIGURE 7. (a) 1.3D or more and less than 1.6D (before insur- ance cut) 0.281 inch or less (be- fore insurance cut)3 Trim the chord in accordance with FIGURE 8. Install the appropriate repair from Table 2 - Hole Trimout Repairs. Less than 1.3D0.281 inch or less(Refer to Table 2) None (b)1.3D or more0.282 - 0.343 inch4 Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 43 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 44 Table 1 - Hole Repair Instructions Repair ProcedureEdge MarginCrack-Free Hole Diam- eter Repair # Install strap in accordance with FIGURE 7. (b)1.1D or more and less than 1.3D 0.282 - 0.343 inch5 Trim the chord in accordance with FIGURE 8. Install the appropriate repair from Table 2 - Hole Trimout Repairs. Less than 1.1D0.282 - 0.343 inch(Refer to Table 2) Trim the chord in accordance with FIGURE 8. Install the appropriate repair from Table 2 - Hole Trimout Repairs. AnyMore than 0.343 inch(Refer to Table 2) (a) The hole diameter must not exceed 0.343 inch. (b) As an alternative it is acceptable to trim the chord in accordance with FIGURE 8 and then install the ap- propriate repair from Table 2 - Hole Trimout Repairs. Table 2 - Hole Trimout Repairs Repair in accordance with ConditionBody Station (STA)Repair # FIGURE 10Affected hole location is common to the fasteners that support any upper deck equipment support brackets. Affected floor beam locations where upper chord is not made from BAC1506-2441 extrusion 6 FIGURE 9Affected hole location is not com- mon to the fasteners that support any upper deck equipment support brackets. 7 FIGURE 13'f' is less than or equal to 0.75 inch. (a) Affected floor beam locations where upper chord is made from BAC1506- 2441 extrusion and cracking is locat- ed on the thick flange of the upper chord. 8 FIGURE 14'f' is more than 0.75 inch and less than or equal to 0.90 inch. (a)9 Contact Boeing (c)'f' is more than 0.90 inch. (a)10 FIGURE 15'a' is less than or equal to 0.60 inch. (b) Affected floor beam locations where upper chord is made from BAC1506- 2441 extrusion and cracking is locat- ed on the thin flange of the upper chord. 11 FIGURE 16'a' is more than 0.60 inch and less than or equal to 0.80 inch. (b)12 Contact Boeing (c)'a' is more than 0.80 inch. (b)13 (a) 'f' is the depth of the trim from the edge of the thick flange of the upper chord. Refer to FIGURE 8. (b) 'a' is the depth of the trim from the edge of the thin flange of the upper chord. Refer to FIGURE 8. (c) Contact Boeing for repair instructions and do the repair instructed by Boeing. 6. Install all equipment that was removed for access to the repair area. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 44 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 45 7. Put the airplane back to a serviceable condition. Do inspections again, in accordance with Paragraph 1.E., Compliance. NOTE: 1. Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (in accordance with FIGURE 5 or in accordance with Paragraph 3.B., Part 2) and is not at least five fasteners away from the end of the repair strap is not considered a repaired hole. 2. For any locations that have a repair that is different from those shown in this service bulletin, contact Boeing for an after-repair inspection plan. PART 3 - SECTION 41 - INSPECTION OF HOLES REPAIRED OR MODIFIED WITH STRAP OR ANGLE 1. Remove the equipment that follows from the upper deck for access to the upper chords of the upper deck floor beams from above: Refer to as an accepted procedure Equipment 747-400 AMM 25-16-00Flight Compartment Floor Covering 747-400 AMM 25-11-01Captain and First Officer Seat 747-400 AMM 25-11-03Observer's Seat 747-400 AMM 25-19-03Flight Deck Crew Rest Partitions 747-400 AMM 25-25-01Upper Deck Passenger Seat 747-400 AMM 25-27-05Upper Deck Floor Covering 747-400 AMM 25-40-03Upper Deck Lavatories 747-400 AMM 25-24-18Upper Deck Closets 747-400 AMM 25-32-01Upper Deck Galleys 747-400 AMM 53-21-02Upper Deck Floor Panels NOTE: All of the equipment listed above may not be installed on all affected airplanes. This list is only intended to show equipment typically installed in the upper deck cabin on a typical 747 airplane. 2. Do inspections of repaired locations as follows: a. For locations where repair #3 or #5 was done, inspect in accordance with FIGURE 11. b. For locations where repair #6, #7, #8, #9, #11 or #12 was done, inspect in accordance with FIGURE 12. c. For locations where repair #10 or #13 was done, contact Boeing for inspection instructions and do the inspections. 3. If no crack indications are found, install the equipment that were removed for access and put the airplane back to a serviceable condition. Do inspections again, in accordance with Paragraph 1.E., Compliance. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 45 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 46 NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (as given in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at least five fasteners away from the end of the repair strap is not considered a repaired hole. 4. If crack indications are found, install a repair. Ask Boeing for repair data. 5. Put the airplane back to a serviceable condition. Do inspections again, in accordance with Paragraph 1.E., Compliance. NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (as given in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at least five fasteners away from the end of the repair strap is not considered a repaired hole. Group 1: PART 4 - SECTION 44 - INITIAL INSPECTION, REPEAT INSPECTION, and INSPECTION OF HOLES THAT HAVE ONLY BEEN REPAIRED OR MODIFIED BY OVERSIZING 1. The area to be inspected is shown in FIGURE 18. 2. If the open hole High Frequency Eddy Current (HFEC) inspection method will be used at the floor panel attach fastener holes: a. Remove equipment from the upper deck in accordance with the table that follows for access to the affected upper deck floor beams from above: Refer to as an accepted procedure Equipment 747-400 AMM 25-27-05Upper Deck Floor Covering 747-400 AMM 25-32-01Upper Deck Galleys 747-400 AMM 53-21-02Upper Deck Floor Panels NOTE: All of the equipment listed above may not be installed on all affected airplanes. This list is only intended to show equipment typically installed in the upper deck cabin on a typical 747 airplane. b. At all floor panel attach hole locations in the affected floor beam upper chords, do open hole HFEC inspections for cracks in accordance with FIGURE 19. c. If no crack indications found at floor panel attach hole locations: (1) Option 1: Install the floor panels and equipment that were removed for access to the area. Do inspections again, in accordance with Paragraph 1.E., Compliance. (2) Option 2: A new inspection threshold can be obtained by doing one of the following: (a) Do the fastener hole modification in accordance with FIGURE 21. After modification, do inspections again, in accordance with Paragraph 1.E., Compliance. (b) Do one of the repair procedures in accordance with PART 5. After repair, do inspections again, in accordance with Paragraph 1.E., Compliance. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 46 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 47 d. If crack indications are found at floor panel attach fastener holes, repair in accordance with PART 5 or ask Boeing for repair data. e. Put the airplane back to a serviceable condition. Do inspections again, in accordance with Paragraph 1.E., Compliance. NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (as given in FIGURE 21 or as given in Paragraph 3.B., Part 5) and is not at least five fasteners away from the end of the repair strap is not considered a repaired hole. 3. If the surface HFEC inspection method will be used at the floor panel attach fastener holes: a. Get access to the affected upper deck floor beams from below as follows: Refer to as an accepted procedure Equipment 747-400 AMM 25-21-04Ceiling Insulation 747-400 AMM 25-22-01Ceiling Access Panels 747-400 AMM 25-23-00Passenger Service Units 747-400 AMM 25-25-01Passenger Seats 747-400 AMM 25-28-02Center Overhead Stowage Compartments 747-400 AMM 25-28-01Side Overhead Stowage Compartments NOTE: All of the equipment listed above may not be installed on all affected airplanes. This list is only intended to show equipment typically installed in the main deck on a typical 747 Passenger airplane. b. At all floor panel attach hole locations, modify the clipnuts and do surface HFEC inspections for cracks as given in FIGURE 20. c. If no crack indications are found, install the floor panels and equipment that were removed for access to the area. Do inspections again, in accordance with Paragraph 1.E., Compliance. d. If crack indications are found, repair in accordance with PART 5 or ask Boeing for repair data. e. Put the airplane back to a serviceable condition. Do inspections again, in accordance with Paragraph 1.E., Compliance. NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (as given in FIGURE 21 or as given in Paragraph 3.B., Part 5) and is not at least five fasteners away from the end of the repair strap is not considered a repaired hole. Group 1: PART 5 - SECTION 44 - REPAIR (Can also be accomplished as a modification) 1. If not already done, remove equipment and floor panels as necessary for access to the affected fastener hole from above. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 47 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 48 2. For hole locations where this repair procedure is being accomplished as a modification (no crack has been found), make the fastener hole diameter 1/64 oversize, then go to step 4. 3. For hole locations where a crack indication was found during an inspection, do the following: NOTE: It is acceptable to skip this step at any fastener where the chord will be trimmed in accordance with FIGURE 24. For example, if the crack extends to the edge of the upper chord, or if you think that oversizing the crack will result in less edge margin less than 1.3D, then you can do a trim out in accordance with FIGURE 24 instead of doing this step. a. Make the affected fastener hole diameter 1/64 inch oversize. b. Do an open hole HFEC inspection of the hole in accordance with 747 NDT Part 6, 53-10-54 or 747 NDT Part 6, 51-00-00, Figure 1, 11, or 16 for cracks. c. If crack indications are found, repeat the hole oversize and open hole HFEC inspection until no crack indication is found. d. If no crack indication is found, continue to the next step. 4. Prior to any insurance cut, measure the edge margin and hole diameter in accordance with FIGURE 22. 5. Repair the hole in accordance with Table 3 - Hole Repair Instructions. NOTE: Before starting the repair, confirm that the damaged location meets all the repair requirements. Table 3 - Hole Repair Instructions Repair ProcedureEdge MarginCrack-Free Hole Diam- eter Repair # Make hole 1/16 inch oversize (Insurance Cut) (a) 2.5D or more (before insurance cut) 0.281 inch or less (be- fore insurance cut)1 Make hole 1/16 inch oversize (Insurance Cut) (a) 1.6D or more and less than 2.5D (before insur- ance cut) 0.281 inch or less (be- fore insurance cut)2 Make hole 1/16 inch oversize (Insurance Cut) and install strap in accordance with FIGURE 23. (a) 1.3D or more and less than 1.6D (before insur- ance cut) 0.281 inch or less (be- fore insurance cut)3 Trim the chord in accordance with FIGURE 24. Install the appropriate repair from Table 4 - Hole Trimout Repairs. Less than 1.3D0.281 inch or less(Refer to Table 4) None (b)1.3D or more0.282 - 0.343 inch4 Install strap in accordance with FIGURE 23. (b)1.1D or more and less than 1.3D 0.282 - 0.343 inch5 Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 48 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 49 Table 3 - Hole Repair Instructions Repair ProcedureEdge MarginCrack-Free Hole Diam- eter Repair # Trim the chord in accordance with FIGURE 24. Install the appropriate repair from Table 4 - Hole Trimout Repairs. Less than 1.1D0.282 - 0.343 inch(Refer to Table 4) Trim the chord in accordance with FIGURE 24. Install the appropriate repair from Table 4 - Hole Trimout Repairs. AnyMore than 0.343 inch(Refer to Table 4) (a) The hole diameter must not exceed 0.343 inch. (b) As an alternative it is acceptable to trim the chord in accordance with FIGURE 24 and then install the ap- propriate repair from Table 4 - Hole Trimout Repairs. Table 4 - Hole Trimout Repairs Repair as given inConditionLocationRepair # FIGURE 26Affected hole location is common to the fasteners that support any upper deck equipment support brackets. Affected floor beam locations where upper chord is not made from BAC1506-2441 extrusion. 6 FIGURE 25Affected hole location is not com- mon to the fasteners that support any upper deck equipment support brackets. 7 FIGURE 27'f' is less than or equal to 0.75 inch. (a) Affected floor beam locations where upper chord is made from BAC1506- 2441 extrusion and cracking is locat- ed on the thick flange of the upper chord. 8 FIGURE 28'f' is more than 0.75 inch and less than or equal to 0.90 inch. (a)9 Contact Boeing (c)'f' is more than 0.90 inch. (a)10 FIGURE 29'a' is less than or equal to 0.60 inch. (b) Affected floor beam locations where upper chord is made from BAC1506- 2441 extrusion and cracking is locat- ed on the thin flange of the upper chord. 11 FIGURE 30'a' is more than 0.60 inch and less than or equal to 0.80 inch. (b)12 Contact Boeing (c)'a' is more than 0.80 inch. (b)13 (a) 'f' is the depth of the trim from the forward edge of the thick flange of the upper chord. Refer to FIGURE 24. (b) 'a' is the depth of the trim from the aft edge of the thin flange of the upper chord. Refer to FIGURE 24. (c) Contact Boeing for repair instructions and do the repair instructed by Boeing. 6. Install all equipment that was removed for access to the repair area. 7. Put the airplane back to a serviceable condition. Do inspections again, in accordance with Paragraph 1.E., Compliance. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 49 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 50 NOTE: 1. Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (as given in FIGURE 21 or as given in Paragraph 3.B., Part 5) and is not at least five fasteners away from the end of the repair strap is not considered a repaired hole. 2. For any locations that have a repair that is different from those shown in this service bulletin, contact Boeing for an after-repair inspection plan. Group 1: PART 6 - SECTION 44 - INSPECTION OF HOLES REPAIRED OR MODIFIED WITH STRAP OR ANGLE 1. Remove the equipment that follows from the upper deck for access to the upper chords of the upper deck floor beams from above: Refer to as an accepted procedure Equipment 747-400 AMM 25-27-05Upper Deck Floor Covering 747-400 AMM 25-32-01Upper Deck Galleys 747-400 AMM 53-21-02Upper Deck Floor Panels NOTE: All of the equipment listed above may not be installed on all affected airplanes. This list is only intended to show equipment typically installed in the upper deck cabin on a typical 747 airplane. 2. Do inspections of repaired locations as follows: a. For locations where repair #3 or #5 was done, inspect in accordance with FIGURE 31. b. For locations where repair #6, #7, #8, #9, #11 or #12 was done, inspect in accordance with FIGURE 32. c. For locations where repair #10 or #13 was done, contact Boeing for inspection instructions and do the inspections. 3. If no crack indications are found, install the equipment that were removed for access and put the airplane back to a serviceable condition. Do inspections again, in accordance with Paragraph 1.E., Compliance. NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (in accordance with FIGURE 21 or as given in Paragraph 3.B., Part 5) and is not at least five fasteners away from the end of the repair strap is not considered a repaired hole. 4. If crack indications are found, install a repair. Ask Boeing for repair data. 5. Put the airplane back to a serviceable condition. Do inspections again, in accordance with Paragraph 1.E., Compliance. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 50 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 51 NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (as given in FIGURE 21 or as given in Paragraph 3.B., Part 5) and is not at least five fasteners away from the end of the repair strap is not considered a repaired hole. PART 7 - SECTION 41 AND SECTION 44 UPPER DECK FLOOR BEAM UPPER CHORD REPLACEMENT 1. Group 1: Replace all upper deck floor beam upper chords with identical parts and restore all structure to original drawing requirements in the areas shown in FIGURE 1 and FIGURE 18 at the time given in Paragraph 1.E., Compliance. 2. Group 2: Replace all upper deck floor beam upper chords with identical parts and restore all structure to original drawing requirements in the area shown in FIGURE 2 at the time given in Paragraph 1.E., Compliance. 3. Group 3: Replace all upper deck floor beam upper chords with identical parts and restore all structure to original drawing requirements in the area shown in FIGURE 17 at the time given in Paragraph 1.E., Compliance. 4. Group 4: Replace all upper deck floor beam upper chords with identical parts and restore all structure to original drawing requirements in the area shown in FIGURE 33 at the time given in Paragraph 1.E., Compliance. Group 2: PART 8 - SECTION 41 - INSPECTION OF UPPER CHORD AT PLUGGED OR RE-USED FLOOR PANEL ATTACHMENT HOLES (More Work on Group 2 Airplanes) 1. Inspection of upper chord at plugged or re-used floor panel attachment holes: a. Get access to the affected upper deck floor beams from above or below as follows: (1) For access to the affected upper deck floor beams from above, remove equipment from the upper deck in accordance with the table that follows: Refer to as an accepted procedure Equipment 747-400 AMM 25-16-00Flight Compartment Floor Covering 747-400 AMM 25-11-01Captain and First Officer Seat 747-400 AMM 25-11-03Observer's Seat 747-400 AMM 25-19-03Flight Deck Crew Rest Partitions 747-400 AMM 25-25-01Upper Deck Passenger Seat 747-400 AMM 25-27-05Upper Deck Floor Covering 747-400 AMM 25-40-03Upper Deck Lavatories 747-400 AMM 25-24-18Upper Deck Closets Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 51 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 52 Refer to as an accepted procedure Equipment 747-400 AMM 25-32-01Upper Deck Galleys 747-400 AMM 53-21-02Upper Deck Floor Panels NOTE: All of the equipment listed above may not be installed on all affected airplanes. This list is only intended to show equipment typically installed in the upper deck cabin on a typical 747 airplane. (2) For access to the affected upper deck floor beams from below, remove equipment from the upper deck in accordance with the table that follows: Refer to as an accepted procedure Equipment 747-400 AMM 25-59-01Main Deck Cargo Compartment Ceiling Lining 747-400 AMM 25-59-05Main Deck Ceiling Insulation b. At all plugged or re-used floor panel attachment holes in the affected floor beam upper chords, do a surface HFEC inspection of the upper deck floor beam upper chords and detailed inspection of the vertical flange in accordance with FIGURE 34 c. If no crack indications found at plugged floor panel fastener hole, or plugged floor structure fastener hole locations: (1) Install the floor panels and equipment that were removed for access to the area. Do inspections again, in accordance with Paragraph 1.E., Compliance. d. If crack indications are found at plugged floor panel fastener holes, or plugged floor structure fastener holes: (1) Contact Boeing for repair instructions and do the repair. Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2: August 21, 2014 52 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 53 (OCR) BOEING SERVICE BULLETIN 747-53A2688 ALERT ALERT This Figure applies only to: Group 1. 0000 0000000000 STA 520 STA 340 STA STA STA 360 400 500 520 STA 340 FWD A-A UPPER DECK FLOOR BEAM 1452156 INSPECTION LOCATIONS FIGURE 1: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA (SHEET 1 OF 1) Original Issue: August 21, 2008 Revision 2 August 21, 2014 Export Controlled ECCN: 9E991 - BOEING 747-53A2688 PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 53 of 177 ### Page 54 (OCR) BOEING SERVICE BULLETIN 747-53A2688 ALERT ALERT This Figure applies only to: Group 2. 000 0000 0000000 STA 520 STA 340 STA STA STA STA 360 380 400 440 STA 340 FWD A-A UPPER DECK FLOOR BEAM 1452158 INSPECTION LOCATIONS FIGURE 2: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA (SHEET 1 OF 1) Original Issue: August 21, 2008 Revision 2 August 21, 2014 Export Controlled ECCN: 9E991 - BOEING 747-53A2688 PROPRIETARY - Copyright @ Unpublished Work - See page 1 for details. 54 of 177 ### Page 55 (OCR) BOEING SERVICE BULLETIN 747-53A2688 ALERT ALERT > A doa 00000000000000 STA 520 STA 340 STA STA STA STA STA STA STA STA 360 380 400 460 480 500 520 STA 340 FWDY A-A TYPICAL INSPECTION 1452164 AREA FIGURE 3: SECTION 41 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER LOCATIONS (SHEET 1 OF 3) Original Issue: August 21, 2008 Revision 2 August 21, 2014 Export Controlled ECCN: 9E991 - BOEING 747-53A2688 PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 55 of 177 ### Page 56 (OCR) BOEING SERVICE BULLETIN 747-53A2688 ALERT ALERT T FLOOR PANEL ATTACH HOLE UPPER CHORD UP —→FWD B-B TYPICAL AFFECTED FLOOR BEAM UPPER CHORD 1 FLOOR PANEL ATTACH HOLE UPPER CHORD RADIUS FILLER UP > FWD B—B TYPICAL AFFECTED FLOOR BEAM UPPER CHORD WITH RADIUS FILLER 1452181 (ANGLE SIMILAR) FIGURE 3: SECTION 41 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER LOCATIONS (SHEET 2 OF 3) Original Issue: August 21, 2008 Revision 2 August 21, 2014 PROPRIETARY - Copyright © Unpublished Export Controlled ECCN: 9E991 - BOEING 747-53A2688 Work - See page 1 for details. 56 of 177 ### Page 57 The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each affected floor panel attachment fastener hole. NOTE: As shown in FIGURE 2, the STA 460 - 520 floor beams are not affected on Group 2 airplanes.1. 2. As shown in FIGURE 17, the STA 440 - STA 520 floor beam is not affected on Group 3 airplanes. 3. As shown in FIGURE 33, the STA 440 and STA 480 - 520 floor beams are not affected on Group 4 airplanes. 4. Inspect all floor panel attachment fastener holes in each affected floor beam. Both the forward and aft horizontal flanges of each floor beam upper chord, from the left body frame to the right body frame, are affected. 5. If clipnuts are installed, move or remove the clipnuts to accomplish this inspection. Reinstall the clipnuts after the inspection is complete. Prior to clipnut reinstallation, touch up any areas of damaged finish with chemical film treatment and one coat of BMS 10-11, Type 1 primer. MORE DATAQTYIDENTIFICATIONNAMETASKSTEP Open hole HFEC for cracks, in accordance with 747 NDT Part 6, 53- 10-54 or 747 NDT Part 6, 51-00-00 Figure 1, 11, or 16. (a) (b) --Fastener HoleInspect1 Surface HFEC for cracks, in accordance with 747 NDT Part 6, 53-10-53 or 747 NDT Part 6, 51-00-00 Figure 4 or 23. (a) (b) --Upper ChordInspect2 (a) Optional: As an alternative to open hole HFEC inspections, do surface HFEC inspections of the upper and lower surfaces of the horizontal flange of the upper chord at each affected floor panel attachment fastener hole. This option is NOT applicable if the floor panel attachment hole modification shown in Figure 5 is to be done. (b) On Group 2 airplanes, a portion of the STA 440 floor beam has a strap on the upper surface. However, this should not affect the inspection procedure. FIGURE 3: SECTION 41 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER LOCATIONS (SHEET 3 OF 3) Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2 August 21, 2014 57 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT ### Page 58 (OCR) BOEING SERVICE BULLETIN 747-53A2688 ALERT ALERT 00000000000000 STA 520 STA 340 STA STA STA STA STA STA STA STA STA 360 380 400 420 440 460 480 500 520 STA 340 SEE FWDS A-A TYPICAL INSPECTION 1452244 AREA FIGURE 4: SECTION 41 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION (SHEET 1 OF 4) Original Issue: August 21, 2008 Revision 2 August 21, 2014 Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished 747-53A2688 Work - See page 1 for details. 58 of 177 ### Page 59 (OCR) BOEING SERVICE BULLETIN 747-53A2688 ALERT ALERT CLIPNUT (TYPICAL) FLOOR PANEL UPPER CHORD * B UP WEB → FWD A—A TYPICAL CLIPNUT INSTALLATION 0.10 CUT LINE CUT LINE 3 - 0.10 0.12 - -0.10 B-B 1452247 TYPICAL CLIPNUT INSTALLATION FIGURE 4: SECTION 41 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION (SHEET 2 OF 4) Original Issue: August 21, 2008 Revision 2 August 21, 2014 PROPRIETARY - Copyright © Unpublished Export Controlled ECCN: 9E991 - BOEING 747-53A2688 Work - See page 1 for details. 59 of 177 ### Page 60 The step numbers shown below agree with the numbers shown in the circle symbols in the figure. NOTE: Inspect all floor panel attachment fastener holes in each affected floor beam. Both the forward and aft horizontal flanges of each floor beam upper chord, from the left body frame to the right body frame, are affected. 1. 2. Modify clipnuts in the affected area for access to the floor beam upper chord. This clipnut modification is only necessary the first time this inspection is done. 3. Steps 1 - 4 that follow give a suggested method for clipnut modification. Any clipnut modification procedure that allows access to the horizontal flange of the upper chord can be used, as long as the surface HFEC inspections in Steps 5 or 6, and in Step 7, can be accomplished. 4. Do the inspections in Steps 5, 6, and 7 in the area within 1 inch inboard and outboard of each floor panel attachment hole. CAUTION: WHEN CLIPNUTS ARE CUT, USE CAUTION TO AVOID DAMAGE TO THE FLOOR BEAM UPPER CHORD OR ITS FINISH. MORE WORK WILL BE NECESSARY FOR REPAIRS IF THE UPPER CHORD OR ITS FINISH IS DAMAGED. The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each affected fastener hole location.. MORE DATAQTYIDENTIFICATIONNAMETASKSTEP as close as possible to the top of the clipnut --ClipnutCut1 down to expose the edge of the upper chord --ClipnutBend2 On the clipnut lower flange --ClipnutCut3 ---Clipnut FlangeRemove / Discard4 Surface HFEC for cracks, in accordance with 747 NDT Part 6, 53-10-53 or 747 NDT Part 6, 51-00-00 Figure 4 or 23 (a) (c) -Vertical Edge of Upper Chord Inspect5 Surface HFEC for cracks, in accordance with 747 NDT Part 6, 53-10-53 or 747 NDT Part 6, 51-00-00 Figure 4 or 23 (b) (c) -Horizontal Edge of Upper Chord Inspect6 Surface HFEC for cracks, in accordance with 747 NDT Part 6, 53-10-53 or 747 NDT Part 6, 51-00-00 Figure 4 or 23 (c) -Upper ChordInspect7 FIGURE 4: SECTION 41 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION (SHEET 3 OF 4) Export Controlled ECCN: 9E991 - BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 21, 2008 747-53A2688Revision 2 August 21, 2014 60 of 177 BOEING SERVICE BULLETIN 747-53A2688 ALERTALERT The text continues at https://openairdocs.org/service-documents/boeing/747-53a2688/file/07aab96f4b6d.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.