{"id":"F2006B02633","name":"AD/B727/11 - Wing Rib Doubler Replacement at Wing Buttock Line 3480","slug":"ad-b727-11-wing-rib-doubler-replacement-at-wing-buttock-line-3480","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41949,"registerId":"commonwealth-F2006B02633-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/11 - Wing Rib Doubler Replacement at Wing Buttock Line 3480","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Boeing 727 Series Aeroplanes\n\n \n\nAD/B727/11 Wing Rib Doubler Replacement at Wing Buttock Line 3480\n\n\n11/65\n\n \n\nApplicability: All models. Document: Boeing SB No. 57-45.\n\nCompliance: Before 20000 hours total time in service.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive from 1965 addressing a specific structural fatigue concern in Boeing 727 wings. It has not expanded beyond its original purpose of mandating a particular structural repair/replacement."},"complexity_factors":["Extremely short document — only 4 substantive lines of regulatory text","No defined terms section — relies entirely on external technical references (Boeing Service Bulletin)","Single, unambiguous compliance requirement (time-based deadline only)","No conditional logic, exceptions, or nested provisions","Cross-reference to only one external document (Boeing SB 57-45)","Applicability is absolute ('All models') with no exclusions or carve-outs"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998.\n\n**What it does:**\nIt requires owners and operators of **Boeing 727 aircraft** to replace a specific structural part called a \"wing rib doubler\" located at a precise position on the wing (called \"Wing Buttock Line 3480\" — essentially a measurement point along the wing's structure).\n\n**Who it affects:**\n- Anyone who owns or operates a Boeing 727 series aircraft in Australia\n- Maintenance organisations servicing these aircraft\n\n**Why it matters:**\nAirworthiness Directives are legally binding safety instructions. They are issued when a safety problem is discovered that could affect the structural integrity or airworthiness of an aircraft. Failing to comply means the aircraft cannot legally fly.\n\n**The specific requirement:**\n- **What:** Replace the wing rib doubler (a reinforcement plate) at a specific location\n- **When:** Before the aircraft reaches 20,000 total flight hours\n- **How:** Follow Boeing Service Bulletin No. 57-45 (the manufacturer's official repair instructions)\n\nThis directive dates back to 1965 (noted as \"11/65\"), indicating it addresses a known fatigue or stress issue in the wing structure that was identified decades ago but remains relevant for any remaining Boeing 727s still in service."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD as presented sets a single, specific mandatory action (wing rib doubler replacement at buttock line 3480) applied to all Boeing 727 models with a fixed compliance threshold (before 20,000 hours). The text contains no indication that the scope has been altered from an earlier version; there is no information in the supplied document that suggests a change in scope or applicability."},"complexity_factors":["Single, narrowly defined technical action (replace wing rib doubler at buttock line 3480) reduces procedural complexity.","Fixed compliance deadline (before 20,000 hours total time-in-service) provides a clear timing requirement.","Universal applicability to all Boeing 727 models simplifies scope but increases the number of affected operators (Applicability: All models).","Reliance on an external technical document (Boeing SB No. 57-45) shifts procedural detail outside the AD and requires access to that bulletin (Document: Boeing SB No. 57-45).","AD text does not include procedural, cost, or justification details, requiring operators to consult the service bulletin and possibly the regulator for implementation specifics.","Regulatory enforceability is implicit from AD format and agency header, so compliance is mandatory despite the AD's brevity."],"plain_english_summary":"### What this directive requires\n\nThis airworthiness directive (AD/B727/11) requires the replacement of the wing rib doubler at wing buttock line 3480 on Boeing 727 series aeroplanes. The work must be carried out in accordance with Boeing Service Bulletin No. 57-45 (Document: Boeing SB No. 57-45) and completed before the aircraft reaches 20,000 hours total time in service (Compliance: Before 20000 hours total time in service). The directive is stated to apply to all Boeing 727 models (Applicability: All models).\n\n### Who this affects\n\n- Owners and operators of Boeing 727 series aeroplanes (Applicability: All models). They are the parties responsible for arranging and paying for the replacement and any associated maintenance downtime (Compliance: Before 20000 hours total time in service).\n- Maintenance organisations and engineers who will perform the work in accordance with Boeing SB No. 57-45 (Document: Boeing SB No. 57-45).\n- The Civil Aviation Safety Authority is the issuing regulator recorded on the document header.\n\n### How it works mechanically\n\n- The AD mandates that the specific structural part (the wing rib doubler at buttock line 3480) be replaced. The AD refers operators to Boeing Service Bulletin No. 57-45 for the technical procedure (Document: Boeing SB No. 57-45).\n- The replacement must be completed prior to the airframe accumulating 20,000 hours total time in service. The AD does not itself include the step-by-step technical instructions; it incorporates Boeing SB No. 57-45 by reference (Document: Boeing SB No. 57-45).\n\n### Why this matters and practical implications\n\n- The directive creates an enforceable maintenance requirement: operators must schedule and complete a discrete structural replacement before a defined flight-hour threshold (Compliance: Before 20000 hours total time in service). That obligation shifts immediate direct cost and downtime to operators; the AD text does not specify funding, compensation, or any exemptions.\n- The AD relies on an external manufacturer document for technical details (Document: Boeing SB No. 57-45). That means compliance requires access to and reliance on the service bulletin for parts, tooling and procedures; the AD itself does not set those technical specifications.\n- The AD applies broadly to all Boeing 727 models (Applicability: All models), so every operator of those models must follow the same requirement.\n\n### What the source does not state\n\n- The document as supplied does not include an explicit statement of the safety rationale, estimated costs, or implementation schedule beyond the 20,000-hour deadline. It also does not provide detail about parts provisioning, inspection intervals, or post-replacement verification in the text provided.\n\n(References in parentheses refer to the corresponding lines in the AD: AD number and title; Applicability: All models; Document: Boeing SB No. 57-45; Compliance: Before 20000 hours total time in service.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-11-wing-rib-doubler-replacement-at-wing-buttock-line-3480","history":"/api/acts/ad-b727-11-wing-rib-doubler-replacement-at-wing-buttock-line-3480/history","analysis":"/api/acts/ad-b727-11-wing-rib-doubler-replacement-at-wing-buttock-line-3480/analysis","conflicts":"/api/acts/ad-b727-11-wing-rib-doubler-replacement-at-wing-buttock-line-3480/conflicts","importantCases":"/api/acts/ad-b727-11-wing-rib-doubler-replacement-at-wing-buttock-line-3480/important-cases","documents":"/api/acts/ad-b727-11-wing-rib-doubler-replacement-at-wing-buttock-line-3480/documents"}}