{"id":"F2006B09109","name":"AD/DHC-6/22 - Propeller Auto Feather System - Modification","slug":"ad-dhc-6-22-propeller-auto-feather-system-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115662,"registerId":"commonwealth-F2006B09109-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-6/22 - Propeller Auto Feather System -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-6/22 Propeller Auto Feather System - Modification 6/70\n\nApplicability: S/Nos. 210, 231, 232, 234-245, 247-250, 252-256, 259-261, 264, 265, 267, 269-273\n\nand 275 to 277.\n\n \n\nDocument: De Havilland of Canada SB No. 6/236. Compliance: Before 1 September 1970.\n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1646},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This directive maintains its original narrow technical scope requiring a specific safety modification to the propeller auto-feather system for affected aircraft. There is no evidence of scope creep beyond the original safety intent."},"complexity_factors":["Very short length with only one compliance requirement","Specific applicability limited to a discrete list of aircraft serial numbers","Single external cross-reference to a technical service bulletin rather than detailed internal technical instructions"],"plain_english_summary":"**What this is:** A mandatory safety order (called an \"Airworthiness Directive\") for specific DHC-6 \"Twin Otter\" aircraft.\n\n**Who it affects:** Owners and operators of Twin Otter planes with serial numbers 210, 231, 232, 234-245, 247-250, 252-256, 259-261, 264, 265, 267, 269-273, and 275 to 277.\n\n**What you must do:** Modify the **propeller auto-feather system** (a safety mechanism that automatically adjusts the propeller blades to reduce drag if an engine fails). The work must be done exactly as described in the manufacturer's technical bulletin \"De Havilland of Canada SB No. 6/236\".\n\n**Deadline:** The modification must be completed before 1 September 1970.\n\n**Why it matters:** This ensures the aircraft's safety system works correctly to prevent dangerous handling problems if an engine loses power during flight."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-6-22-propeller-auto-feather-system-modification","history":"/api/acts/ad-dhc-6-22-propeller-auto-feather-system-modification/history","analysis":"/api/acts/ad-dhc-6-22-propeller-auto-feather-system-modification/analysis","conflicts":"/api/acts/ad-dhc-6-22-propeller-auto-feather-system-modification/conflicts","importantCases":"/api/acts/ad-dhc-6-22-propeller-auto-feather-system-modification/important-cases","documents":"/api/acts/ad-dhc-6-22-propeller-auto-feather-system-modification/documents"}}