{"id":"F2006B08416","name":"AD/CESSNA 550/11 - TKS Proportioning Unit Connections","slug":"ad-cessna-550-11-tks-proportioning-unit-connections","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115882,"registerId":"commonwealth-F2006B08416-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 550/11 - TKS Proportioning Unit Connections","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 550 (Citation II) Series Aeroplanes\n\n \n\nAD/CESSNA 550/11 TKS Proportioning Unit Connections 5/86\n\nApplicability: Model S550 unit numbers - 0001 through - 0048, -0051 through - 0075, and - 0077 and - 0079.\n\n \n\nRequirement: Action in accordance with Cessna Citation Alert Service Letter SLAS 550-30-05. Compliance:               Before issue of a certificate of airworthiness.\n\nBackground: The manufacturer has identified the possible incorrect installation of TKS proportioning unit plumbing.\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":1369},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive maintains its original targeted scope as a specific safety intervention addressing a known manufacturing defect in identified aircraft serial numbers, with no evidence of scope creep or expansion beyond the initial technical correction."},"complexity_factors":["Extremely short length with single operative requirement","Narrow applicability limited to specific aircraft serial number ranges","Reference to external technical document (Cessna Service Letter) for actual implementation details","Technical aviation terminology requiring specialized knowledge (TKS proportioning unit, certificate of airworthiness)"],"plain_english_summary":"This airworthiness directive mandates a safety fix for specific Cessna 550 Citation II business jets to correct potentially faulty plumbing in the ice protection system.\n\n**What it requires:**\n- Aircraft owners must inspect and correct the installation of pipes in the TKS (anti-icing fluid) proportioning unit according to manufacturer service letter SLAS 550-30-05\n- This must be done before the aircraft can be issued a certificate of airworthiness (the legal document allowing it to fly)\n\n**Who is affected:**\n- Owners and operators of Cessna 550 models with serial numbers S550-0001 through -0048, -0051 through -0075, and specifically -0077 and -0079\n\n**Why this matters:**\n- The TKS system prevents dangerous ice buildup on wings and flight surfaces\n- Incorrect plumbing could cause the system to fail in icing conditions, creating a serious flight safety hazard\n- This ensures the anti-ice system operates as designed before the aircraft returns to service"}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-550-11-tks-proportioning-unit-connections","history":"/api/acts/ad-cessna-550-11-tks-proportioning-unit-connections/history","analysis":"/api/acts/ad-cessna-550-11-tks-proportioning-unit-connections/analysis","conflicts":"/api/acts/ad-cessna-550-11-tks-proportioning-unit-connections/conflicts","importantCases":"/api/acts/ad-cessna-550-11-tks-proportioning-unit-connections/important-cases","documents":"/api/acts/ad-cessna-550-11-tks-proportioning-unit-connections/documents"}}