{"id":"F2006B09066","name":"AD/DHC-3/18 - Wing Strut Spar","slug":"ad-dhc-3-18-wing-strut-spar","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52824,"registerId":"commonwealth-F2006B09066-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-3/18 - Wing Strut Spar","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-3 (Otter) Series Aeroplanes\n\n \n\nAD/DHC-3/18 Wing Strut Spar NK\n\nApplicability: All models prior to S/No 356.\n\n \n\nRequirement: Action in accordance with De H Canada EB “O” No 66. Compliance:  At intervals not exceeding 250 hours time in service.\n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused specifically on wing strut spar inspections for early-model DHC-3 Otter aircraft. It has not expanded beyond its original purpose of addressing a known structural concern in this specific aircraft type."},"complexity_factors":["Extremely short document — only 4 substantive lines","Single defined term implicitly understood ('time in service')","No cross-references to other legislation beyond the parent Civil Aviation Regulations 1998","No conditional logic or exceptions — applies to all listed serial numbers without variation","Relies entirely on external technical document (De Havilland Canada EB 'O' No 66) for actual procedural detail"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\n- Requires owners and operators of **De Havilland Canada DHC-3 (Otter) series aeroplanes** with **serial numbers below 356** to perform specific maintenance inspections on the **wing strut spar** (a critical structural component that helps hold the wing to the fuselage).\n\n**Who must follow it:**\n- Anyone operating or maintaining affected DHC-3 Otter aircraft in Australia.\n\n**What must be done:**\n- Follow the instructions in **De Havilland Canada Engineering Bulletin \"O\" No. 66** (the manufacturer's official technical guidance).\n- Repeat this inspection **every 250 hours of flight time** (\"time in service\" means actual flying hours, not just calendar time).\n\n**Why it matters:**\nWing strut spars bear enormous stress during flight. If they crack or fail, the wing could separate from the aircraft with catastrophic results. This AD ensures potential defects are caught before they become dangerous."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive applies to all DHC-3 models prior to serial number 356 and mandates repeated action per De H Canada EB \"O\" No 66 at intervals not exceeding 250 hours TIS. The text does not indicate any expansion or narrowing of that applicability or the required actions beyond those stated."},"complexity_factors":["Short text but delegates all technical detail to an external document (De H Canada EB \"O\" No 66), which operators must obtain and follow.","Applicability limited by serial-number cutoff (S/No 356), requiring accurate aircraft identification and record checks.","Recurring compliance interval (every ≤250 hours TIS) requires ongoing tracking of flight hours and scheduling of maintenance downtime.","AD is issued under Part 39 (regulatory enforcement context) but the directive itself does not describe enforcement, alternative compliance, or approval pathways.","Potential ambiguity in practical availability or specificity of the referenced Engineering Bulletin increases implementation uncertainty for operators and maintainers."],"plain_english_summary":"This Airworthiness Directive (Part 39) mandates recurring maintenance for De Havilland DHC‑3 (Otter) aircraft with serial numbers before 356: operators must perform the work specified in De Havilland Canada Engineering Bulletin \"O\" No 66 at intervals not exceeding 250 hours time‑in‑service. It’s compulsory under CASA; owners/operators pay for and arrange the inspections/repairs, and maintenance organisations must follow the referenced EB to demonstrate compliance."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-3-18-wing-strut-spar","history":"/api/acts/ad-dhc-3-18-wing-strut-spar/history","analysis":"/api/acts/ad-dhc-3-18-wing-strut-spar/analysis","conflicts":"/api/acts/ad-dhc-3-18-wing-strut-spar/conflicts","importantCases":"/api/acts/ad-dhc-3-18-wing-strut-spar/important-cases","documents":"/api/acts/ad-dhc-3-18-wing-strut-spar/documents"}}