{"id":"F2006B05299","name":"AD/CESSNA 207/4 - Exhaust Manifold Heat Exchanger","slug":"ad-cessna-207-4-exhaust-manifold-heat-exchanger","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":45709,"registerId":"commonwealth-F2006B05299-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 207/4 - Exhaust Manifold Heat Exchanger","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 207 Series Aeroplanes\n\n \n\nAD/CESSNA 207/4 Exhaust Manifold Heat Exchanger 6/71\n\nApplicability: All turbocharged models.\n\n \n\nRequirement: Action in accordance with Cessna SL No. SE71-11.\n\n \n\nCompliance: Within 50 hours time in service after 9 June 1971 and thereafter at intervals not exceeding 50 hours time in service.\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\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive from 1971 addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original purpose of ensuring exhaust system integrity in turbocharged Cessna 207 aircraft."},"complexity_factors":["Extremely short document (under 150 words)","No defined terms section","No cross-references to other legislation (only references a Cessna Service Letter)","Simple conditional structure: single applicability criterion ('All turbocharged models')","Single compliance requirement with clear time trigger","No exceptions, exemptions, or nested conditions"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:** It requires owners and operators of **Cessna 207 series aeroplanes with turbocharged engines** to inspect or replace the **exhaust manifold heat exchanger** (a component that uses hot exhaust gases to warm cabin air or for other systems). The work must follow specific instructions in **Cessna Service Letter SE71-11**.\n\n**Who it affects:** Anyone operating a turbocharged Cessna 207 aircraft in Australia — including private owners, charter operators, and flying schools.\n\n**When and how often:**\n- **First check:** Within 50 hours of flying time after 9 June 1971\n- **Ongoing:** Every 50 hours of flying time thereafter\n\n**Why it matters:** Exhaust manifold heat exchangers can crack or fail, potentially leaking exhaust gases (including deadly carbon monoxide) into the cabin heating system. This directive prevents accidents and protects pilots and passengers from poisoning or fire hazards.\n\n**Key point:** This is a recurring, time-based maintenance requirement — not a one-off fix. The 50-hour interval is relatively frequent, reflecting the serious safety risk."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The supplied AD text sets a clear, limited scope: it applies to all turbocharged Cessna 207 models and requires action in accordance with a specified Cessna service letter, to be done within 50 hours after 9 June 1971 and repeated every 50 hours (Applicability; Requirement; Compliance). The document does not indicate any change to that scope from an earlier or different intent within the supplied text."},"complexity_factors":["Narrow, clear applicability limited to \"All turbocharged models\" (Applicability) reduces scope complexity.","Dependency on an external document (Cessna SL No. SE71-11) for technical detail increases implementation complexity (Requirement).","Short, repeating compliance interval (every 50 hours after 9 June 1971) creates recurring operational and record‑keeping burden (Compliance).","The AD text omits allocation of costs and explicit enforcement or deviation procedures, leaving practical questions for operators and maintainers (Requirement; Compliance).","Potential ambiguity in how to interpret or apply the service letter if it is unavailable or unclear (Requirement)."],"plain_english_summary":"The Civil Aviation Safety Authority requires turbocharged Cessna 207 aeroplanes to have the exhaust‑manifold heat exchanger work performed exactly as described in Cessna SL No. SE71‑11. Compliance is mandatory within 50 hours time‑in‑service after 9 June 1971 and must be repeated at intervals not exceeding 50 hours. This converts the service letter task into a recurring regulatory obligation for owners, operators and maintenance organisations, creating ongoing maintenance and scheduling impacts."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-207-4-exhaust-manifold-heat-exchanger","history":"/api/acts/ad-cessna-207-4-exhaust-manifold-heat-exchanger/history","analysis":"/api/acts/ad-cessna-207-4-exhaust-manifold-heat-exchanger/analysis","conflicts":"/api/acts/ad-cessna-207-4-exhaust-manifold-heat-exchanger/conflicts","importantCases":"/api/acts/ad-cessna-207-4-exhaust-manifold-heat-exchanger/important-cases","documents":"/api/acts/ad-cessna-207-4-exhaust-manifold-heat-exchanger/documents"}}