{"id":"F2006B04954","name":"AD/CESSNA 170/21 - Control Systems","slug":"ad-cessna-170-21-control-systems","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44824,"registerId":"commonwealth-F2006B04954-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 170/21 - Control Systems","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 170, 172, F172, FR172 and 175 Series Aeroplanes\n\n \n\nAD/CESSNA 170/21 Control Systems 5/70\n\nApplicability: All models with S/Nos 17258161 to 17258844, F1720640 to F1720687, FR1720108 to FR1720175.\n\n \n\nRequirement: Action in accordance with Cessna SL SE 69-28. Compliance:  Within 100 hours time in service after 29 April 1970.\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":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2206},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-purpose safety directive from 1970 targeting specific control system issues in specific aircraft models. There is no evidence of scope expansion beyond the original safety intent."},"complexity_factors":["Very short document (approximately 100 words of substantive content)","Single external reference to manufacturer service letter (Cessna SL SE 69-28) without reproducing technical details","Specific serial number ranges require cross-checking against aircraft logs","No nested definitions or conditional clauses"],"plain_english_summary":"**What this is:** An Airworthiness Directive (AD) — a mandatory safety order issued by the Civil Aviation Safety Authority (CASA) that legally requires aircraft owners to fix specific defects.\n\n**What it does:** Requires owners of certain Cessna aircraft (models 170, 172, F172, FR172, and 175) with specific serial numbers to perform maintenance actions on the control systems. The exact repair instructions are contained in a Cessna Service Letter (SE 69-28), which this directive legally mandates.\n\n**Who it affects:** Owners and operators of Cessna planes with serial numbers between 17258161–17258844, F1720640–F1720687, and FR1720108–FR1720175.\n\n**Why it matters:** Control systems are critical to flight safety. This directive ensures potential defects in the control systems are addressed before the aircraft accumulates too much flight time.\n\n**Deadline:** The work must be completed within 100 hours of flight time (\"time in service\") after 29 April 1970."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-170-21-control-systems","history":"/api/acts/ad-cessna-170-21-control-systems/history","analysis":"/api/acts/ad-cessna-170-21-control-systems/analysis","conflicts":"/api/acts/ad-cessna-170-21-control-systems/conflicts","importantCases":"/api/acts/ad-cessna-170-21-control-systems/important-cases","documents":"/api/acts/ad-cessna-170-21-control-systems/documents"}}