# Boeing Alert Requirements Bulletin 777-28A0098 RB: No revision named, part 3 of 3 - Rights: © The Boeing Company. Filed by the FAA in regulations.gov docket FAA-2025-2546; AD 2026-15-02 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication. - Document: [Boeing Alert Requirements Bulletin 777-28A0098 RB](https://openairdocs.org/service-documents/boeing/777-28a0098-rb.md) - Title as filed: 777-28A0098 RB - Part3 - Pages: 8 - PDF: https://openairdocs.org/files/sha256/b9/cd/b9cda048dec572f0744f49bf52b5e0798581748c549995f5c5b4e8e3b8672636 - Page: https://openairdocs.org/service-documents/boeing/777-28a0098-rb/file/b9cda048dec5 ## Text This text is 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 (OCR) REQUIREMENTS BULLETIN 777-28A0098 ALERT ALERT 4. SECOND FILLET APPLICATION a. APPLY A SECOND FILLET OF BMS5-45, CLASS B-2 SEALANT BY LAYERING OR STACKING BEADS OF SEALANT ON TOP OF EACH OTHER STARTING FROM THE SPAR WALL TO THE TUBE WALL. EXTEND SEALANT A MINIMUM OF 0.25 INCH FROM THE COUPLING UP THE TUBE. EXTEND SEALANT A MINIMUM OF 0.25 INCH BEYOND THE MAXIMUM DIAMETER OF THE BULKHEAD FITTING HEX NUT ON THE FRONT SPAR BULKHEAD. REFER TO SOPM 20-50-19 AS AN ACCEPTED PROCEDURE. b. MAKE SURE SEALANT BEADS ARE LAYERED OR STACKED TO ONE ANOTHER AVOIDING ANY AIR ENTRAPMENT. IT IS ACCEPTABLE TO HAVE AN AIR GAP BETWEEN THE TUBE AND THE COUPLING. c. MAKE SURE THE BMS5-45, CLASS A SEALANT IS VISIBLE BEYOND THE BMS5-45 CLASS B SEALANT ON THE FRONT SPAR BULKHEAD. 3088738 APPENDIX G: AFT SIDE FRONT SPAR BULKHEAD FITTING SEALANT APPLICATION (SHEET 5 OF 11) Original Issue: August 15, 2025 Export Controlled ECCN: 9E991 777-28A0098 RB See page 1 for details 224 of 231 ### Page 2 (OCR) REQUIREMENTS BULLETIN 777-28A0098 ALERT ALERT 5. SMOOTH/BLEND SEALANT ENCAPSULATION a. USE A TOOL SUCH AS A SEALANT SPATULA TO SMOOTH AND BLEND SEALANT BEADS INTO A SINGLE ENCAPSULATION. - TOOLS MUST MEET THE REQUIREMENTS DEFINED IN THE SECTION 9. "TOOLS" OF THIS - SMOOTH IS DEFINED AS AN EQUAL AND CONSTANT SURFACE. SMOOTH DOES NOT MEAN FLAT OR WITHOUT SURFACE FEATURES. BRUSH MARKS ARE ACCEPTABLE IF 0.12 MINIMUM THICKNESS IS MET. b. BLEND THE BASE OF THE SEALANT TO THE STRUCTURE. C. CONTINUE SMOOTHING THE REMAINDER OF THE SEALANT TO FULLY ENCAPSULATE THE COUPLER AND ONTO THE FUEL TUBE. d. TAKE CARE DURING THE SMOOTHING PROCESS TO AVOID THE ENTRAPMENT OF AIR BUBBLES. 3088739 APPENDIX G: AFT SIDE FRONT SPAR BULKHEAD FITTING SEALANT APPLICATION (SHEET 6 OF 11) Original Issue: August 15, 2025 Export Controlled ECCN: 9E991 777-28A0098 RB See page 1 for details 225 of 231 ### Page 3 (OCR) REQUIREMENTS BULLETIN 777-28A0098 ALERT ALERT 6. APPLYING ADDITIONAL SEALANT TO CORNER a. TO MAKE SURE 0.12 INCH MINIMUM SEALANT THICKNESS IS MET AT THE CORNER OF THE FITTING AND TUBE. APPLY A THIRD BEAD OF BMS5-45, CLASS B-2 SEALANT AT THE CORNER OF THE FITTING OVER THE PREVIOUSLY SMOOTHED SEALANT ENCAPSULATION AT THE EDGE OF THE COUPLER TO THE TUBE. 3088740 APPENDIX G: AFT SIDE FRONT SPAR BULKHEAD FITTING SEALANT APPLICATION (SHEET 7 OF 11) Original Issue: August 15, 2025 Export Controlled ECCN: 9E991 777-28A0098 RB See page 1 for details 226 of 231 ### Page 4 (OCR) REQUIREMENTS BULLETIN 777-28A0098 ALERT ALERT 7. SMOOTH/BLEND THIRD SEALANT BEAD a. USE A TOOL SUCH AS A SEALANT SPATULA TO SMOOTH AND BLEND THE BEAD INTO THE PREVIOUSLY SMOOTHED SEALANT ENCAPSULATION. - TOOLS MUST MEET THE REQUIREMENTS DEFINED IN SECTION 9. "TOOLS" OF THIS - SMOOTH IS DEFINED AS AN EQUAL AND CONSTANT SURFACE. SMOOTH DOES NOT MEAN FLAT OR WITHOUT SURFACE FEATURES. BRUSH MARKS ARE ACCEPTABLE IF 0.12 MINIMUM THICKNESS IS MET. b. MAKE SURE THE THIRD BEAD OF SEALANT IS BLENDED TO THE PREVIOUSLY APPLIED SEALANT AND TUBE. 3088742 APPENDIX G: AFT SIDE FRONT SPAR BULKHEAD FITTING SEALANT APPLICATION (SHEET 8 OF 11) Original Issue: August 15, 2025 Export Controlled ECCN: 9E991 777-28A0098 RB See page 1 for details 227 of 231 ### Page 5 (OCR) REQUIREMENTS BULLETIN 777-28A0098 ALERT ALERT 8. SEALANT INSPECTION AND ERASER TEST a) DO A DETAILED INSPECTION (DET) OF THE SEALANT TO MAKE SURE: - SEALS ARE CONTINUOUS - SEALS HAVE THE CORRECT DIMENSIONS - NO EMBEDDED DEBRIS - NO VISIBLE BUBBLES, CRACKS, HOLES OR VOIDS b) AFTER SEALANT IS CURED, DO AN ERASER TEST TO CHECK SEALANT ADHESION: - CURED SEALANT CANNOT BE REMOVED BY RUBBING AN EDGE OF THE SEAL WITH A FRIXION ERASER 1. DO AN ADHESION TEST OF EACH SEALANT INTERFACE USING A FRIXION ERASER. - IT IS NOT NECESSARY TO TEST THE ADHESION BETWEEN THE FIRST FILLET AND THE BRUSHCOAT. - IT IS NOT NECESSARY TO TEST THE ADHESION BETWEEN THE SECOND FILLET AND THE FIRST FILLET - BMS5-45, CLASS A BRUSHCOAT SEALANT PEELING IS NOT CONSIDERED A FAIL IF THE PEELING STOPS BEFORE THE BMS5-45, CLASS B SEALANT. 2. START WITH THE INTERFACE BETWEEN THE PART SURFACE AND FIRST LAYER OF SEALANT. THE ADHESION TEST CAN BE DONE ON SEVERAL INTERFACES AT THE SAME 3. RUB EACH TEST LOCATION ON EACH SEALANT INTERFACE BETWEEN 7 AND 10 TIMES TO GIVE THE MOST ACCURATE RESULT. WHEN POSSIBLE, RUB THE ERASER IN A DIRECTION THAT IS APPROXIMATELY PERPENDICULAR TO THE INTERFACE AS SHOWN BELOW. 4. REMOVE AND REPLACE ENTIRE SEALANT ENCAPSULATION IF CLASS B MATERIAL FAILS. PEELING OF BRUSHCOAT IS NOT A FAILURE IF THE PEELING STOPS BEFORE THE CLASS B SEAL. c) IF THE BMS5-45 CLASS B SEALANT FAILS TO MEET THE REQUIREMENTS OF THE DET INSPECTION OR FAILS THE ADHESION TEST AFTER CURE, REMOVE ALL SEALANT AND APPLY AGAIN IN ACCORDANCE WITH THE STEPS ON SHEET 1, SECTION 1. "BRUSHCOAT APPLICATION." TEST AREA AND DIRECTION BRUSHCOAT FILLET 3093843 APPENDIX G: AFT SIDE FRONT SPAR BULKHEAD FITTING SEALANT APPLICATION (SHEET 9 OF 11) Original Issue: August 15, 2025 Export Controlled ECCN: 9E991 See page 1 for details 777-28A0098 RB 228 of 231 ### Page 6 (OCR) REQUIREMENTS BULLETIN 777-28A0098 ALERT ALERT 9. TOOLS BRUSHES, NON-METALLIC, WITH NATURAL OR SYNTHETIC BRISTLES: a. STENCIL BRUSH AS SHOWN IN BELOW, NATURAL BRISTLE, ROUND ALUMINUM FERRULE, UNFINISHED WOOD HANDLE, SIZE 6 OR OTHER SIZE, ALSO KNOWN AS MARSEL 311 OR DEMCO 311, THAT MEETS THE REQUIREMENTS LISTED ABOVE. STENCIL BRUSH 311-6 (SIZE 6), PART NUMBER 401794F610543, INDEUTSCH INDUSTRIES PRIVATE LIMITED, NOIDA, INDIA. STENCIL BRUSH 311-8 (SIZE 8), PART NUMBER 401794F610542, INDEUTSCH INDUSTRIES PRIVATE LIMITED, NOIDA, INDIA. b. OTHER BRUSHES THAT MEET THE REQUIREMENTS LISTED ABOVE ARE ALSO ACCEPTABLE. INDEUTSCH SERIES-311 STENCIL BRUSH (FOR REFERENCE ONLY) 3091909 APPENDIX G: AFT SIDE FRONT SPAR BULKHEAD FITTING SEALANT APPLICATION (SHEET 10 OF 11) Original Issue: August 15, 2025 Export Controlled ECCN: 9E991 777-28A0098 RB See page 1 for details 229 of 231 ### Page 7 (OCR) REQUIREMENTS BULLETIN 777-28A0098 ALERT ALERT 9. TOOLS (CONTINUED) SEALANT SMOOTHING TOOLS a. RECOMMENDED TOOL: PPG SEMCO SPATULA PART NUMBER: 231349. SHOWN BELOW. b. OTHER SIMILAR OR EQUIVALENT TOOLS TO THE RECOMMENDED TOOL THAT MEET THE TOOL REQUIREMENTS LISTED ABOVE CAN BE USED. RECOMMENDED TOOL EXAMPLE SEALANT SMOOTHING TOOLS REQUIREMENTS FOR TOOLS: a. MUST NOT CAUSE CONTAMINATION OF THE SEALANT APPLICATION AREA OR DECREASE SEALANT ADHESION. b. MUST NOT CAUSE CONTAMINATION OF THE SEALANT (FOR EXAMPLE: FIBERS, BRISTLES, LINT, OR CURED SEALANT). c. MUST NOT BE REUSED IF THE MATERIAL CAN DEGRADE AND TRANSFER CONTAMINATION TO THE SEALANT OR TO THE SURFACE. 3091910 APPENDIX G: AFT SIDE FRONT SPAR BULKHEAD FITTING SEALANT APPLICATION (SHEET 11 OF 11) Original Issue: August 15, 2025 777-28A0098 RB Export Controlled ECCN: 9E991 See page 1 for details 230 of 231 ### Page 8 (OCR) REQUIREMENTS BULLETIN 777-28A0098 ALERT ALERT C-CO ACCEPTABLE INSTALLATION BOTH BONDING JUMPERS INSTALLED ON THE NUT SIDE ACCEPTABLE INSTALLATION BONDING JUMPERS INSTALLED EITHER SIDE OF THE TUBE CLAMP LUG ACCEPTABLE INSTALLATION 3090594 BONDING JUMPERS INSTALLED ON THE FASTENER SIDE APPENDIX H: ACCEPTABLE BONDING JUMPER INSTALLATIONS (SHEET 1 OF 1) Original Issue: August 15, 2025 777-28A0098 RB Export Controlled ECCN: 9E991 See page 1 for details 231 of 231 --- 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.