{"id":"F2006B09127","name":"AD/DHC-6/39 - Electric Power Cable Below Cockpit - Modification","slug":"ad-dhc-6-39-electric-power-cable-below-cockpit-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115680,"registerId":"commonwealth-F2006B09127-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-6/39 - Electric Power Cable Below Cockpit - 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)  DHC-6 (Twin Otter) Series Aeroplanes\n\n \n\nAD/DHC-6/39 Electric Power Cable Below Cockpit - Modification\n\nApplicability: All models with S/Nos. 1 to 135.\n\n \n\nDocument: De Havilland of Canada SB No. 6/304 Rev. B.\n\n \n\nCompliance: Within the next 100 hours time in service after 30 August 1974.\n\n\n7/74\n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD text sets a single, narrow scope: mandate a modification for DHC-6 aeroplanes S/Nos. 1–135, to be carried out per the referenced Service Bulletin within the stated 100-hour window after 30 August 1974 (Applicability; Document; Compliance). Nothing in the supplied text indicates that the scope has been changed from its original formulation."},"complexity_factors":["Narrow and clear applicability by serial number range reduces scope complexity (Applicability).","Mandatory compliance with a fixed service-hour deadline creates scheduling and operational complexity for operators (Compliance).","Technical steps are not given in the AD itself but are delegated to an external Service Bulletin, requiring operators to obtain and interpret that document (Document).","No alternative compliance routes or exemptions are specified in the AD text, increasing operational inflexibility.","Historical timestamping (deadline tied to a date in 1974) could complicate record verification for ongoing continuing airworthiness records."],"plain_english_summary":"This airworthiness directive (AD/DHC-6/39) mandates a modification to the electric power cable below the cockpit on De Havilland DHC‑6 (Twin Otter) aeroplanes serial numbers 1–135, carried out per De Havilland SB No. 6/304 Revision B within 100 hours TIS after 30 August 1974.\n\nIt affects registered owners/operators, who must arrange and pay for the maintenance and record compliance so the aircraft meet continuing airworthiness requirements."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue safety directive from 1974 addressing a specific technical modification. It has not expanded beyond its original narrow scope of requiring a wiring modification on early-model Twin Otters."},"complexity_factors":["Very short document (approximately 100 words)","Only one defined applicability criterion (serial numbers 1-135)","Single compliance requirement with clear deadline","No cross-references to other legislation beyond the parent Civil Aviation Regulations 1998","No conditional logic or exceptions","Refers to external technical document (Service Bulletin) for actual modification details rather than including them in the text"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\n- Requires owners and operators of specific **De Havilland DHC-6 Twin Otter aircraft** (serial numbers 1 to 135) to modify the electric power cable located below the cockpit.\n- The modification must follow the instructions in **De Havilland Service Bulletin No. 6/304 Revision B**.\n\n**Who it affects:**\n- Anyone who owns or operates a DHC-6 Twin Otter with serial numbers 1 through 135.\n\n**Why it matters:**\n- Airworthiness Directives are legally binding safety requirements. If you don't comply, you cannot legally fly the aircraft. This particular directive addresses a specific electrical system issue that could affect flight safety.\n\n**Deadline:**\n- The work must be completed within **100 hours of flight time** after 30 August 1974."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-6-39-electric-power-cable-below-cockpit-modification","history":"/api/acts/ad-dhc-6-39-electric-power-cable-below-cockpit-modification/history","analysis":"/api/acts/ad-dhc-6-39-electric-power-cable-below-cockpit-modification/analysis","conflicts":"/api/acts/ad-dhc-6-39-electric-power-cable-below-cockpit-modification/conflicts","importantCases":"/api/acts/ad-dhc-6-39-electric-power-cable-below-cockpit-modification/important-cases","documents":"/api/acts/ad-dhc-6-39-electric-power-cable-below-cockpit-modification/documents"}}