{"id":"F2006B08836","name":"AD/DC4/3 - Main Fuel Line, Support Brackets in Wing - Replacement","slug":"ad-dc4-3-main-fuel-line-support-brackets-in-wing-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52305,"registerId":"commonwealth-F2006B08836-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DC4/3 - Main Fuel Line, Support Brackets in Wing - Replacement","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)  Douglas DC4 Series Aeroplanes\n\n \n\nAD/DC4/3 Main Fuel Line, Support Brackets NK\n\nin Wing - Replacement\n\nDocument: 1. Douglas SB (DC4) No. 5 dated 3 July 1946; or\n\n \n\n2. FAA AD 46-39-5; or\n\n \n\n3. ANO 105.1.16.2.5.2.\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":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The AD restates a requirement to replace the main fuel line support brackets in the wing for Douglas DC‑4 series aeroplanes and directs compliance to one of three listed documents (Douglas SB No.5 (3 July 1946); FAA AD 46-39-5; ANO 105.1.16.2.5.2). The supplied text does not itself broaden or narrow the technical scope compared with those source documents; rather, it makes the replacement requirement enforceable under the Commonwealth Schedule of Airworthiness Directives (Part 39 - 105). (AD/DC4/3, Document list; Header: Part 39 - 105)"},"complexity_factors":["Dependency on three external documents (Douglas SB No.5 (1946); FAA AD 46-39-5; ANO 105.1.16.2.5.2) to supply the technical steps rather than including them in the AD itself (AD/DC4/3, Document list).","Age of referenced material (Douglas SB dated 3 July 1946 and FAA AD from 1946), which may create interpretation issues and parts‑availability problems for implementers (Document list).","Limited text in the AD: absence of explicit compliance timeframes, definitions, or alternative‑means‑of‑compliance procedures in the supplied excerpt increases administrative and legal uncertainty (AD/DC4/3 text).","Regulatory enforcement resides under Part 39 (Civil Aviation Regulations 1998), requiring coordination between operators, approved maintenance organisations and the regulator (Header: Part 39 - 105).","Potential need for certified maintenance and recordkeeping, creating operational downtime and administrative burden for owners/operators (implied by mandatory replacement in AD/DC4/3)."],"plain_english_summary":"## What this instrument does\n\nThis is an airworthiness directive titled AD/DC4/3 that addresses the main fuel line support brackets in the wing of Douglas DC‑4 series aeroplanes. Mechanically, the directive requires replacement of those support brackets by carrying out the work set out in one of the three documents listed by the directive: Douglas Service Bulletin (DC4) No. 5 dated 3 July 1946; FAA AD 46-39-5; or ANO 105.1.16.2.5.2 (see \"Document\" list in the AD). (AD/DC4/3, Document list)\n\n## Who it affects\n\n- Owners and operators of Douglas DC‑4 series aeroplanes. (AD/DC4/3 title)\n- Maintenance organisations and certificated engineers who perform required work and certify aircraft as airworthy after the work. (Part 39 enforcement context)\n\n## How it works, step by step (mechanical effect)\n\n- The directive identifies the component to be changed: the main fuel line support brackets in the wing. (AD/DC4/3 title)\n- Compliance is achieved by carrying out the replacement procedure described in one of the three referenced documents. The AD points aircraft maintainers to those documents for the technical steps. (AD/DC4/3, Document list)\n- After replacement, the aircraft must be operated and certificated in line with the Civil Aviation Regulations (Part 39) and any recordkeeping required by those regulations. (Header: Civil Aviation Regulations 1998, Part 39)\n\n## Who pays and who decides\n\n- Owners/operators pay for parts, labour, and aircraft downtime required to replace the brackets; the AD itself does not fund those costs. (AD/DC4/3, Document list)\n- The Civil Aviation Safety Authority enforces compliance under the Schedule of Airworthiness Directives (Part 39 - 105). Approved maintenance organisations and certificated personnel decide how to implement the replacement in practice, subject to the referenced documents and regulatory approval. (Header: Commonwealth of Australia (Civil Aviation Regulations 1998), Part 39 - 105)\n\n## Incentives, costs and trade-offs\n\n- Incentives: Operators are required to comply to retain legal airworthiness and the ability to operate the aircraft; failure to comply risks regulatory enforcement. (Part 39 enforcement context)\n- Direct costs: purchase of replacement brackets (or fabrication if originals are unavailable), labour, and aircraft downtime. (Implied by requirement to replace per AD/DC4/3)\n- Opportunity costs: aircraft out of service while the work is performed; resources diverted from other maintenance or operations. (Practical implication of mandatory replacement)\n- Trade-offs: the operator replaces or repairs a historically specified component now, which imposes immediate expense in exchange for meeting the AD requirement. (Mechanics of replacement requirement)\n\n## Implementation risks and compliance burden\n\n- The AD points to three external documents (one a 1946 Douglas service bulletin and an FAA AD), so implementers must obtain and interpret historic technical material to do the work. That creates a risk of ambiguity or interpretation differences if the documents are incomplete or obsolete. (AD/DC4/3, Document list)\n- Parts availability may be limited for older aircraft (Douglas DC‑4), which can increase cost or delay compliance; the AD itself does not address parts-supply or alternative means of compliance. (AD/DC4/3 title and Document list)\n- Compliance requires certified maintenance activity and appropriate recordkeeping under Part 39; this is a recurrent administrative burden for operators of affected aircraft. (Header: Civil Aviation Regulations 1998, Part 39)\n\n## Bureaucratic discretion and legal point of control\n\n- The legal requirement is set by the airworthiness directive; the CASA schedule and Part 39 provide the enforcement framework. Maintenance providers and CASA exercise judgment about acceptable means of compliance only to the extent permitted by regulation and any formally approved alternative methods. (Header: Part 39 - 105)\n\nNotes on the source text\n\n- The AD text supplied is concise and primarily lists the requirement and three documents to be followed; it does not reproduce step‑by‑step replacement instructions, compliance timeframes, or cost estimates. (AD/DC4/3, Document list)\n- The AD title includes the letters \"NK\" immediately after the subject line; the supplied text does not define what \"NK\" signifies. (AD/DC4/3 title)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted airworthiness directive addressing a specific mechanical defect in a particular aircraft type. It has not expanded beyond its original purpose of ensuring fuel line integrity in DC-4 aircraft."},"complexity_factors":["Extremely short document (under 200 words)","Single, specific mechanical requirement (replace support brackets)","Only 3 external references (all historical documents from 1946)","No defined terms section","No conditional logic or exceptions","No cross-references to other legislation beyond the parent Civil Aviation Regulations 1998","Straightforward compliance pathway: replace the brackets per the referenced documents"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** issued by Australia's Civil Aviation Safety Authority (CASA) for **Douglas DC-4 series aircraft**.\n\n**What it does:**\n- Requires the **replacement of main fuel line support brackets located inside the aircraft's wing**\n- These brackets hold the fuel lines in place; if they fail, fuel leaks or fires could occur\n\n**Who it affects:**\n- Owners and operators of Douglas DC-4 aeroplanes (a vintage four-engine propeller aircraft from the 1940s)\n- Maintenance organisations servicing these aircraft\n\n**Why it matters:**\n- **Safety critical:** Faulty fuel line supports could lead to fuel starvation, engine failure, or fire\n- **Compliance mandatory:** This AD makes the replacement compulsory, not optional\n- **Based on overseas data:** The directive references three source documents—a 1946 Douglas service bulletin, a 1946 US Federal Aviation Administration (FAA) directive, and an old Australian National Order—showing this addresses a known historical defect\n\n**Key point:** Even though the DC-4 is an elderly aircraft design, this directive remains active to ensure any still-flying examples in Australia meet safety standards."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dc4-3-main-fuel-line-support-brackets-in-wing-replacement","history":"/api/acts/ad-dc4-3-main-fuel-line-support-brackets-in-wing-replacement/history","analysis":"/api/acts/ad-dc4-3-main-fuel-line-support-brackets-in-wing-replacement/analysis","conflicts":"/api/acts/ad-dc4-3-main-fuel-line-support-brackets-in-wing-replacement/conflicts","importantCases":"/api/acts/ad-dc4-3-main-fuel-line-support-brackets-in-wing-replacement/important-cases","documents":"/api/acts/ad-dc4-3-main-fuel-line-support-brackets-in-wing-replacement/documents"}}