{"id":"F2006B08350","name":"AD/CESSNA 400/65 - Exhaust System Coupling - Replacement","slug":"ad-cessna-400-65-exhaust-system-coupling-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115757,"registerId":"commonwealth-F2006B08350-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 400/65 - Exhaust System Coupling - Replacement","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 400 Series Aeroplanes\n\n \n\nAD/CESSNA 400/65 Exhaust System Coupling - Replacement 3/79\n\nApplicability: Model 404 with S/Nos. 404-0001 to 404-0220.\n\nModel 414A with S/Nos. 414A0001 to 414A0040.\n\n \n\nDocument: Cessna SL ME78-38.\n\n \n\nCompliance: Within 100 hours time in service after 31 March 1979.\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":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive. Airworthiness Directives are inherently narrow in scope — they address specific technical defects in specific aircraft. There is no indication of scope creep; the document precisely matches its original purpose of mandating a single safety modification."},"complexity_factors":["Extremely short document (under 150 words)","Only 2 aircraft models affected with explicit serial number ranges","Single, unambiguous compliance action (replacement of one component)","Clear deadline (100 hours time in service after fixed date)","No defined terms section, no cross-references to other legislation, no conditional logic or exceptions","References only one external technical document (Cessna Service Letter ME78-38)"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998.\n\n**What it requires:** Owners and operators of specific Cessna 400-series aircraft must **replace the exhaust system coupling** (a part that connects sections of the engine exhaust pipe). This is a safety-critical fix.\n\n**Who it affects:**\n- **Cessna Model 404** aircraft with serial numbers 404-0001 through 404-0220\n- **Cessna Model 414A** aircraft with serial numbers 414A0001 through 414A0040\n\n**When it must be done:** Within **100 hours of flying time** after 31 March 1979.\n\n**Why it matters:** Exhaust system failures can cause carbon monoxide leaks into the cabin (a deadly, odourless gas) or engine damage. This AD forces a specific repair to prevent accidents.\n\n**Key document reference:** Cessna Service Letter ME78-38 provides the technical instructions for the replacement."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive, as presented, applies only to the specified models and serial-number ranges and mandates one replacement action per the referenced service letter within a defined 100‑hour window after 31 March 1979. The supplied text does not show any expansion or narrowing of scope beyond those explicit limits (Applicability; Document; Compliance)."},"complexity_factors":["Single, discrete mandated action (replacement of exhaust coupling)","Narrow applicability limited to two models and specific serial‑number ranges (clear scope)","Fixed, short compliance window tied to an absolute date and hours in service (temporal constraint)","Dependence on an external manufacturer document (Cessna SL ME78‑38) for procedural detail","No alternative compliance paths or discretion described in the supplied text","Administrative tasks: verifying serial number applicability and recording compliance"],"plain_english_summary":"This airworthiness directive mandates replacement of the exhaust‑system coupling on specified Cessna 404 (s/n 404‑0001–404‑0220) and 414A (s/n 414A0001–414A0040) aircraft. Replacement must follow Cessna Service Letter ME78‑38 and be completed within 100 hours time‑in‑service after 31 March 1979.\n\nIt affects owners/operators of those aircraft and creates a compulsory maintenance obligation to meet the safety requirement within the fixed compliance window."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-400-65-exhaust-system-coupling-replacement","history":"/api/acts/ad-cessna-400-65-exhaust-system-coupling-replacement/history","analysis":"/api/acts/ad-cessna-400-65-exhaust-system-coupling-replacement/analysis","conflicts":"/api/acts/ad-cessna-400-65-exhaust-system-coupling-replacement/conflicts","importantCases":"/api/acts/ad-cessna-400-65-exhaust-system-coupling-replacement/important-cases","documents":"/api/acts/ad-cessna-400-65-exhaust-system-coupling-replacement/documents"}}