{"id":"F2006B05112","name":"AD/CESSNA 185/21 - Engine Air Inlet Duct","slug":"ad-cessna-185-21-engine-air-inlet-duct","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":45105,"registerId":"commonwealth-F2006B05112-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 185/21 - Engine Air Inlet Duct","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)  Cessna 185 Series Aeroplanes\n\n \n\nAD/CESSNA 185/21 Engine Air Inlet Duct 5/74\n\nApplicability: All model A185 with S/Nos. 18502008 to 18502650. Requirement:  Action in accordance with Cessna SL No. SE75-5.\n\nNote: FAA AD 75-09-06 refers.\n\n \n\nCompliance: Within 500 hours time in service after 12 May 1975.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \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 from 1975 addressing a specific technical defect in a limited aircraft population. It has not expanded beyond its original narrow scope of requiring inspection/modification of engine air inlet ducts on specific Cessna 185 aircraft."},"complexity_factors":["Extremely short document (approximately 100 words of substantive content)","Only 1 defined applicability criterion (specific serial number range)","Single cross-reference to external document (Cessna Service Letter SE75-5)","Single cross-reference to related FAA directive (AD 75-09-06)","Simple unconditional requirement with clear compliance deadline","No nested exceptions, conditional logic, or interpretive provisions"],"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 Cessna 185 aircraft.\n\n**What it does:**\n- Requires owners/operators of certain Cessna 185 model A185 aeroplanes (serial numbers 18502008 to 18502650) to take specific maintenance action regarding the **engine air inlet duct**.\n- The required action is detailed in **Cessna Service Letter No. SE75-5** (a manufacturer-issued technical bulletin).\n\n**Who it affects:**\n- Owners and operators of Cessna 185 model A185 aircraft with serial numbers between 18502008 and 18502650.\n\n**Why it matters:**\n- Engine air inlet ducts are critical for supplying clean air to the engine. A defect here could cause engine failure or power loss — a serious safety risk in flight.\n- This AD addresses a known safety issue identified by both the manufacturer (Cessna) and the US Federal Aviation Administration (FAA AD 75-09-06).\n\n**Compliance deadline:**\n- The work must be completed within **500 hours of flight time** after 12 May 1975.\n\n**Key point:** This is a **historical directive** from 1975. While it remains part of the regulatory record, any aircraft still flying today would have had to comply with this decades ago."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The provided text gives no indication that the scope has changed from the instrument's original stated coverage. The AD applies to the specified serial-number range, mandates action per Cessna SL No. SE75-5, and sets a 500-hour compliance window; there is no wording in the text suggesting a change in that scope."},"complexity_factors":["Narrow applicability limited to a specific serial-number range (Applicability)","Substantive technical steps are not detailed in the AD but delegated to an external manufacturer service letter (Requirement)","Fixed compliance window measured in hours-in-service rather than a calendar date (Compliance)","Cross-reference to an external FAA AD that may contain related information but is not incorporated (Note)"],"plain_english_summary":"This airworthiness directive mandates a maintenance action on the engine air inlet duct for Cessna A185 aircraft serial numbers 18502008–18502650, requiring operators to follow Cessna Service Letter SE75‑5 within 500 hours time-in-service after 12 May 1975. It affects owners/operators and their maintenance providers; failure to comply renders the affected aircraft non‑airworthy."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-185-21-engine-air-inlet-duct","history":"/api/acts/ad-cessna-185-21-engine-air-inlet-duct/history","analysis":"/api/acts/ad-cessna-185-21-engine-air-inlet-duct/analysis","conflicts":"/api/acts/ad-cessna-185-21-engine-air-inlet-duct/conflicts","importantCases":"/api/acts/ad-cessna-185-21-engine-air-inlet-duct/important-cases","documents":"/api/acts/ad-cessna-185-21-engine-air-inlet-duct/documents"}}