{"id":"F2006B08827","name":"AD/DC4/21 - Control Surface Attachment - Modification","slug":"ad-dc4-21-control-surface-attachment-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52264,"registerId":"commonwealth-F2006B08827-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DC4/21 - Control Surface Attachment - Modification","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/DC4/21 Control Surface Attachment - Modification NK\n\nDocument: 1. Douglas SB (DC4) No. 83, dated 20 November 1947; or\n\n \n\n2. FAA AD 48-6-5; or\n\n \n\n3. ANO 105.1.16.2.5.20, Issue 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\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"Based on the text provided, there is no indication the AD changes scope from an original stated intent. The instrument applies to Douglas DC4 series aeroplanes and requires a control surface attachment modification, with compliance achieved by following one of three listed documents (\"Document: 1. Douglas SB (DC4) No. 83... or 2. FAA AD 48-6-5; or 3. ANO 105.1.16.2.5.20, Issue 2\"). The AD itself merely specifies the required action and acceptable compliance documents; it does not show an alteration of scope within the text supplied."},"complexity_factors":["Directive delegates technical detail to three external documents rather than containing instructions itself (see \"Document:\" list).","One acceptable compliance document is an older service bulletin dated 20 November 1947 (\"Douglas SB (DC4) No. 83, dated 20 November 1947\"), which may raise availability or interpretation issues.","Multiple alternative compliance paths (three listed documents) require operators to choose and justify a method of compliance.","The AD is specific to a legacy aircraft type (\"Douglas DC4 Series Aeroplanes\"), which may limit the number of qualified maintenance providers and spare parts (implied by aircraft specificity).","Enforcement and applicability are under Civil Aviation Regulations 1998, Part 39, which creates a regulatory compliance obligation enforced by CASA (header)."],"plain_english_summary":"This AD requires owners/operators of Douglas DC‑4 series aeroplanes to modify the control‑surface attachment and to comply by following one of three specified technical documents. Issued and enforced by CASA under Part 39, the directive delegates the technical detail to those referenced documents; operators must obtain the appropriate instructions, carry out the work and absorb the parts, labour and downtime costs."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive focused specifically on DC-4 control surface modifications. It has not expanded beyond its original safety purpose."},"complexity_factors":["Very short document (approximately 15 lines of substantive content)","No defined terms section — uses standard aviation terminology only","No conditional logic or exceptions — straightforward mandatory requirement","Simple structure: identifies aircraft type, describes required action, lists three alternative compliance documents","No cross-references to other legislation beyond the enabling Civil Aviation Regulations 1998"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\nThis directive requires owners and operators of **Douglas DC-4 series aeroplanes** to carry out a specific **modification to the control surface attachment** (the hardware that connects the moving flight controls — like ailerons, elevators, or rudders — to the aircraft structure).\n\n**Who it affects:**\n- Anyone who owns or operates a Douglas DC-4 aircraft in Australia\n- Maintenance organisations servicing these aircraft\n\n**Why it matters:**\nControl surface attachments are critical for flight safety. If they fail, the pilot could lose control of the aircraft. This AD mandates a fix based on manufacturer service bulletins and international safety notices to prevent potential accidents.\n\n**Compliance requirements:**\nOperators must follow one of three approved documents to make the modification:\n- Douglas Service Bulletin No. 83 (dated 20 November 1947)\n- FAA Airworthiness Directive 48-6-5 (American equivalent)\n- ANO 105.1.16.2.5.20, Issue 2 (an older Australian aviation order)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-dc4-21-control-surface-attachment-modification","history":"/api/acts/ad-dc4-21-control-surface-attachment-modification/history","analysis":"/api/acts/ad-dc4-21-control-surface-attachment-modification/analysis","conflicts":"/api/acts/ad-dc4-21-control-surface-attachment-modification/conflicts","importantCases":"/api/acts/ad-dc4-21-control-surface-attachment-modification/important-cases","documents":"/api/acts/ad-dc4-21-control-surface-attachment-modification/documents"}}