{"id":"F2007L01071","name":"AD/B737/276 Amdt 1 - Nacelle Support Fitting Attachment Fasteners","slug":"ad-b737-276-amdt-1-nacelle-support-fitting-attachment-fasteners","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":65042,"registerId":"commonwealth-F2007L01071-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 737 Series Aeroplanes","sectionType":"division","heading":"Boeing 737 Series Aeroplanes","content":"### Boeing 737 Series Aeroplanes\n\n| AD/B737/276 Amdt 1 | Nacelle Support Fitting Attachment Fasteners | 5/2007 |\n| ------------------ | -------------------------------------------- | ------ |\n\n| Applicability: | Model 737-600, -700, -700C, and -800 series aircraft, line numbers 1 through 761; except for line numbers 596, 683, 742, 749, 750, 751, 754, 755, 759, and 760.                                                                                                                                                                                                                                                                                                                                                                                                        |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with the technical requirements of FAA AD 2005-24-03 R1Amdt 39-14955.Note: Boeing Service Bulletin 737-57-1275 Revision 3, or later FAA approved revision, refers.                                                                                                                                                                                                                                                                                                                                                                                |\n| Compliance:    | As specified in the Requirement document, with a revised effective date of10 May 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |\n|                | This Amendment becomes effective on 10 May 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |\n| Background:    | The FAA received a report from the manufacturer that in production, during the installation of certain attachment fasteners for the nacelle support fittings, only one washer was installed instead of two. Inadequate fastener clamp-up could result in cracking of the fastener holes, cracking along the lower wing skin panels, fuel leaking from the wing fuel tanks onto the engines, and possible fire.Amendment 1 is issued in response to a revision of the Requirement document, which introduces Revision 3 of related Boeing Service Bulletin 737-57-1275. |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n28 March 2007","sortOrder":0},{"sectionNumber":"AD/B737/276 Amdt 1","sectionType":"part","heading":"AD/B737/276 Amdt 1","content":"## AD/B737/276 Amdt 1","sortOrder":1},{"sectionNumber":"Nacelle Support Fitting Attachment Faste","sectionType":"part","heading":"Nacelle Support Fitting Attachment Fasteners","content":"## Nacelle Support Fitting Attachment Fasteners","sortOrder":2},{"sectionNumber":"5/2007","sectionType":"part","heading":"5/2007","content":"## 5/2007","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Amendment 1 updates the Requirement document to incorporate Boeing Service Bulletin 737-57-1275 Revision 3 and sets a revised effective date (10 May 2007). It does not expand the set of affected aircraft beyond the Applicability list nor add new types of obligations; it modifies the source document that contains the technical instructions. Therefore the Amendment does not materially change the original scope or purpose, it updates the technical reference and compliance timing."},"complexity_factors":["Short instrument with limited parts (Applicability, Requirement, Compliance, Background).","Single external technical reference: FAA AD 2005-24-03 R1 and Boeing Service Bulletin 737-57-1275 Rev 3 (or later FAA-approved revision).","List of 10 excluded line numbers creates a discrete exception within a compact applicability range (line numbers 1–761).","Conditional language permitting “later FAA approved revision” introduces dependence on external future approvals.","Technical content deferred to external documents rather than embedded, requiring cross-reference to operationalise the obligation."],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- It is an airworthiness directive that requires operators of certain Boeing 737 aeroplanes to carry out the actions specified in FAA Airworthiness Directive (AD) 2005-24-03 R1 (as amended) and the related Boeing Service Bulletin 737-57-1275 Revision 3 (or any later FAA‑approved revision). (Requirement)\n- The Directive applies to Model 737-600, -700, -700C and -800 series aircraft with line numbers 1–761, except for ten specific line numbers listed in the Applicability table. (Applicability)\n- The Amendment sets a revised effective date of 10 May 2007 for compliance. (Compliance)\n\n**Why the directive was issued (technical problem)**\n\n- During production, some nacelle support fitting attachment fasteners were installed with only one washer instead of two. The missing washer can allow inadequate clamp-up of the fastener, which can lead to cracked fastener holes or wing skin, fuel leaking from wing tanks onto engines, and an increased risk of engine fire. (Background)\n\n**Who is affected and who must act**\n\n- Aircraft owners/operators of the listed Boeing 737 models must follow the inspection/repair/replacement procedures set out in the referenced FAA AD and Boeing service bulletin. That typically means maintenance organisations must inspect the affected attachment fasteners and fix any incorrect installations. (Applicability & Requirement)\n\n**Who decides what to do**\n\n- The Directive makes the FAA AD and the Boeing service bulletin the required technical standard; the Civil Aviation Safety Authority (CASA) adopts that requirement by amendment so Australian operators must comply. Maintenance organisations and operators decide how to schedule the required work, subject to the AD’s compliance times and any regulatory oversight.\n\n**Costs, incentives and trade-offs**\n\n- Direct costs fall on aircraft operators: labour, replacement parts (washers/fasteners if required), and aircraft downtime while inspections/repairs are done.\n- Benefit is reduced technical risk (cracked structure, fuel leaks, possible fire). This is a concentrated safety benefit for operators and passengers; the costs are concentrated on the affected operators and their maintenance providers.\n- The instrument relies on external technical documents (FAA AD and Boeing service bulletin). That reduces the Directive’s own technical detail but forces operators to obtain and follow those documents, which can add administrative burden and reliance on future FAA/Boeing revisions.\n- Implementation risk centres on correctly identifying affected line numbers and ensuring shops follow the latest FAA‑approved revision of the Boeing service bulletin.\n\n**Practical effects on private behaviour**\n\n- Operators must prioritise inspections/repairs on affected airframes, reallocate maintenance slots, and bear the cost of parts and labour.\n- Maintenance organisations must follow the specified service instructions and may need to demonstrate compliance to regulators. The Directive also creates a requirement to track which aircraft (by line number) are subject to the action.\n\n**Other notes on operation of the instrument**\n\n- Amendment 1 does not set new inspection technique details in the text itself; instead it adopts Revision 3 of Boeing Service Bulletin 737-57-1275 (or later FAA‑approved revision) as the mandatory technical source. (Requirement)\n- The Amendment’s effective date is 10 May 2007. (Compliance)\n\n(References in this summary: Applicability, Requirement, Compliance, Background sections of AD/B737/276 Amdt 1.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a narrow, technical safety directive focused on a specific mechanical defect in specific aircraft. It has not expanded beyond its original purpose of addressing the missing washer issue."},"complexity_factors":["Very short document (under 300 words)","Only 4 substantive sections: Applicability, Requirement, Compliance, and Background","Single technical requirement referencing an external FAA document","Limited conditional logic (only aircraft line number exclusions in applicability)","No defined terms section","No cross-references to other legislation"],"plain_english_summary":"This is an **airworthiness directive** (a mandatory safety order) for specific Boeing 737 aircraft. It requires airlines to inspect and fix a manufacturing defect where some planes were built with only one washer instead of two on certain bolts that attach engine housings (nacelles) to the wing. The missing washer could cause cracks, fuel leaks onto the engine, and potentially fires. Airlines must follow the technical instructions in a specific Boeing service bulletin to fix the problem."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-276-amdt-1-nacelle-support-fitting-attachment-fasteners","history":"/api/acts/ad-b737-276-amdt-1-nacelle-support-fitting-attachment-fasteners/history","analysis":"/api/acts/ad-b737-276-amdt-1-nacelle-support-fitting-attachment-fasteners/analysis","conflicts":"/api/acts/ad-b737-276-amdt-1-nacelle-support-fitting-attachment-fasteners/conflicts","importantCases":"/api/acts/ad-b737-276-amdt-1-nacelle-support-fitting-attachment-fasteners/important-cases","documents":"/api/acts/ad-b737-276-amdt-1-nacelle-support-fitting-attachment-fasteners/documents"}}