{"id":"F2006B09147","name":"AD/DHC-6/6 - Tailplane Attachment Bolts - Modification","slug":"ad-dhc-6-6-tailplane-attachment-bolts-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115712,"registerId":"commonwealth-F2006B09147-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-6/6 - Tailplane Attachment Bolts - 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-6/6 Tailplane Attachment Bolts - Modification 10/67\n\nApplicability: All models with S/Nos. 1 to 63.\n\n \n\nDocument:  De Havilland of Canada Mod. Bulletin 6/1114. Compliance: Before 1 January 1968.\n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2138},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive remains tightly focused on its original purpose: correcting a specific structural defect in early-production DHC-6 aircraft. There is no expansion beyond the initial safety imperative."},"complexity_factors":["Single, unambiguous compliance action (modify specific bolts)","No defined terms or interpretation sections","Clear applicability limited to specific serial number range (S/Nos. 1-63)","External technical reference to manufacturer bulletin (6/1114) required for implementation details"],"plain_english_summary":"This is an **Airworthiness Directive** (AD) — a mandatory safety order issued under aviation law requiring specific action to fix an unsafe condition in aircraft.\n\n**What it does:**\n- Requires owners and operators of early-model De Havilland DHC-6 Twin Otter aircraft (serial numbers 1 to 63) to modify the bolts that attach the tailplane (the horizontal wing at the back of the plane).\n- The work must be done exactly as described in De Havilland of Canada Modification Bulletin 6/1114.\n- **Deadline:** The modification had to be completed before 1 January 1968.\n\n**Why it matters:**\nThe tailplane attachment bolts are critical structural components. If they fail, the tailplane could separate from the aircraft, causing catastrophic loss of control. This directive ensures a known defect in early-production aircraft is physically corrected before the plane can fly."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-6-6-tailplane-attachment-bolts-modification","history":"/api/acts/ad-dhc-6-6-tailplane-attachment-bolts-modification/history","analysis":"/api/acts/ad-dhc-6-6-tailplane-attachment-bolts-modification/analysis","conflicts":"/api/acts/ad-dhc-6-6-tailplane-attachment-bolts-modification/conflicts","importantCases":"/api/acts/ad-dhc-6-6-tailplane-attachment-bolts-modification/important-cases","documents":"/api/acts/ad-dhc-6-6-tailplane-attachment-bolts-modification/documents"}}