{"id":"F2006B09120","name":"AD/DHC-6/32 - Fuel Vent System - Modification","slug":"ad-dhc-6-32-fuel-vent-system-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115673,"registerId":"commonwealth-F2006B09120-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-6/32 - Fuel Vent System - 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-6/32 Fuel Vent System - Modification 11/71\n\nApplicability: All models with S/Nos. 6 to 310.\n\n \n\nDocument: De Havilland of Canada SB 6/211, Revision A. Compliance: Before 30 June 1972.\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 focused specifically on fuel vent system modifications for a defined aircraft subset. It has not expanded beyond its original technical safety purpose."},"complexity_factors":["Very short document (under 150 words)","Only 4 defined elements: applicability (serial number range), document reference, compliance deadline, and aircraft type","No cross-references to other legislation or regulations beyond the parent Civil Aviation Regulations 1998","Single unconditional requirement with clear deadline","No nested exceptions or conditional logic"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority for **De Havilland DHC-6 Twin Otter aircraft**.\n\n**What it does:**\n- Requires owners and operators of specific Twin Otter planes (serial numbers 6 through 310) to **modify the fuel vent system**\n- The modification must follow the manufacturer's Service Bulletin 6/211, Revision A\n\n**Who it affects:**\n- Owners and operators of early-model DHC-6 Twin Otter aircraft (serial numbers 6–310)\n- Maintenance organisations servicing these aircraft\n\n**Why it matters:**\n- Fuel vent system defects can cause dangerous pressure imbalances, fuel leaks, or engine failures\n- This directive mandates a fix to prevent potential accidents\n- **Compliance deadline:** Before 30 June 1972 (now historical, but would have been legally binding at the time)\n\n**Key point:** This is a **mandatory safety modification** — operators cannot legally fly these aircraft without completing this work by the deadline."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The supplied text prescribes a modification for aircraft with serial numbers 6–310 and sets a deadline and the service bulletin to follow. The document contains no indication that it alters or expands an earlier scope; it simply sets the requirement for the identified serial numbers. The text does not state any change from prior instruments."},"complexity_factors":["Narrow, specific applicability limited to DHC-6 serial numbers 6–310 (Applicability)","Single technical action required: modification of the fuel vent system per a named service bulletin (Document)","Fixed, short compliance deadline (before 30 June 1972) increases time pressure but simplifies scheduling (Compliance)","Dependence on an external technical document for implementation details (Document)","Minimal procedural detail in the text: no allocation of costs, no enforcement or approval process described (absence in supplied text)"],"plain_english_summary":"This Commonwealth/CASA airworthiness directive requires specified De Havilland DHC‑6 (Twin Otter) aeroplanes, serial numbers 6–310, to have their fuel vent system modified in accordance with De Havilland Service Bulletin 6/211 Revision A. The modification must be completed by 30 June 1972. The instrument sets the technical requirement and deadline but gives no details on costs, enforcement, or who performs or pays for the work."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-6-32-fuel-vent-system-modification","history":"/api/acts/ad-dhc-6-32-fuel-vent-system-modification/history","analysis":"/api/acts/ad-dhc-6-32-fuel-vent-system-modification/analysis","conflicts":"/api/acts/ad-dhc-6-32-fuel-vent-system-modification/conflicts","importantCases":"/api/acts/ad-dhc-6-32-fuel-vent-system-modification/important-cases","documents":"/api/acts/ad-dhc-6-32-fuel-vent-system-modification/documents"}}