{"id":"F2006B07055","name":"AD/SM-205/33 - Exhaust System Muffler Assembly - Inspection - Replacement","slug":"ad-sm-205-33-exhaust-system-muffler-assembly-inspection-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48787,"registerId":"commonwealth-F2006B07055-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SM-205/33 - Exhaust System Muffler Assembly - Inspection - 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)  SIAI Marchetti S205 and S208 Series Aeroplanes\n\n \n\nAD/SM-205/33  Exhaust System Muffler Assembly - Inspection - Replacement\n\n\n9/83\n\n \n\nApplicability: All S205-22R aircraft fitted with muffler assembly P/Ns. 870-8 or P/Ns. 870-9. Document:               SIAI Marchetti SB No. 205B56.\n\nCompliance: Within 100 hours time in service after 30th September 1983, or, when muffler assembly has accumulated 500 hours time in service, which- ever occurs later, after 30 September 1983. Thereafter, at intervals of 100 hours time in service.\n\n \n\nBackground: Instances of detachment of the muffler baffling have been reported by the manufacturer which can result in partial or complete loss of engine power.\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":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The source text presents a single, self-contained directive with defined applicability (S205-22R aircraft with muffler P/Ns 870-8 or 870-9), specified compliance intervals and a referenced service bulletin. There is no wording in the provided text indicating any amendment, narrowing or expansion of scope from an earlier or original version; therefore, based solely on the supplied instrument, the scope has not changed."},"complexity_factors":["Clear, limited applicability (specific aircraft model and two part numbers) reduces scope complexity (Applicability).","Fixed inspection intervals and an explicit initial compliance trigger simplify scheduling, but require precise tracking of hours-in-service for each muffler assembly (Compliance).","Technical inspection and repair procedures are not included in the AD itself but are delegated to a referenced service bulletin (SIAI Marchetti SB No. 205B56), creating dependency on an external document (Document).","The AD text is short and prescriptive; potential complexity arises in implementation (maintenance logistics, parts sourcing and downtime) rather than in legal interpretation (Compliance, Document).","The initial compliance condition uses a compound trigger (within 100 hours after a set date or when the muffler reaches 500 hours, whichever is later), which requires operators to compute and reconcile calendar and component-hour thresholds (Compliance)."],"plain_english_summary":"What this instrument does (mechanics)\n\n- This Airworthiness Directive (AD) requires regular inspection and, where necessary, replacement of the exhaust muffler assembly on certain SIAI Marchetti aeroplanes. It applies to all S205-22R aircraft fitted with muffler assembly part numbers 870-8 or 870-9. (Applicability)\n- The AD sets an initial compliance window: perform the required inspection within 100 hours time-in-service after 30 September 1983, or when the muffler assembly reaches 500 hours time-in-service, whichever is later. After that initial action, the inspection must be repeated every 100 hours time-in-service. (Compliance)\n- The technical method or details are referenced to the manufacturer’s service bulletin: SIAI Marchetti SB No. 205B56. (Document)\n\nWhy it exists (stated reason)\n\n- The manufacturer reported occurrences where muffler baffling became detached. The AD cites that detachment can lead to partial or complete loss of engine power. (Background)\n\nWho is directly affected and who pays\n\n- Aircraft owners/operators of S205-22R aeroplanes fitted with muffler P/N 870-8 or 870-9 must carry out the inspections and any necessary replacements. (Applicability, Compliance)\n- The owner/operator or their maintenance provider will bear the costs of inspection, replacement parts, labour and aircraft downtime. (Applicability, Compliance, Document)\n\nWhat behaviour changes and decisions are required\n\n- Owners/operators must schedule and record inspections at the specified intervals (initial window, then every 100 hours). (Compliance)\n- If an inspection identifies detached or failing baffling, the muffler assembly must be replaced or repaired in accordance with the referenced service bulletin. (Document)\n- Maintenance organisations will apply the inspection procedures and replacement instructions set out in SIAI Marchetti SB No. 205B56. The AD prescribes the interval but relies on the service bulletin for technical method. (Compliance, Document)\n\nIncentives, costs and trade-offs\n\n- Incentives: compliance reduces the risk of in-flight loss of engine power associated with muffler baffling detachment. (Background)\n- Direct costs: periodic inspections every 100 hours increase maintenance workload and parts/labour expense; replacements create additional parts and downtime costs for affected aircraft. (Compliance, Document)\n- Opportunity cost: time spent on mandated inspections reduces available aircraft utilisation. (Compliance)\n- The AD concentrates benefit (reduced risk of baffling detachment) for anyone operating the affected aircraft; the costs (inspection and replacement) fall on the aircraft owners/operators. (Applicability, Compliance)\n\nImplementation, compliance burden and discretion\n\n- The AD sets clear intervals but delegates technical inspection and repair procedures to the manufacturer’s service bulletin, giving maintenance providers responsibility to apply the detailed methods in SB No. 205B56. (Document)\n- Compliance requires recordkeeping of hours-in-service and inspection results to calculate the 100-hour intervals and the 500-hour trigger for initial compliance. (Compliance)\n- The AD does not set alternative intervals or offer waivers within its text; any departure would require formal approval under the regulatory framework that issues ADs. (Compliance)\n\nRisks and practical considerations\n\n- The AD addresses a safety hazard reported by the manufacturer (detachment of muffler baffling). The inspection interval and the 500-hour threshold create a predictable compliance schedule but require accurate time-in-service tracking for each muffler assembly. (Background, Compliance)\n- The reliance on the service bulletin for technical detail means the effectiveness of the AD depends on the adequacy of SB No. 205B56 and correct application by maintenance organisations. (Document)\n\nSource references: Applicability; Compliance; Document; Background."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific aircraft. It has not expanded beyond its original purpose of preventing muffler-related engine failures."},"complexity_factors":["Single, clearly defined applicability (one aircraft model, two specific part numbers)","Straightforward compliance timeline with only two conditions (100 hours post-date OR 500 hours total time)","No defined terms section or interpretation provisions","No cross-references to other legislation or regulations beyond the parent Civil Aviation Regulations 1998","Single background rationale with clear safety justification","Total length is approximately 150 words"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority for specific Italian-made aircraft.\n\n**What it does:**\n- Requires owners and operators of **SIAI Marchetti S205-22R aeroplanes** to inspect and replace the exhaust system muffler assembly on a strict schedule.\n\n**Who it affects:**\n- Owners and operators of these specific aircraft models fitted with muffler part numbers 870-8 or 870-9.\n\n**Why it matters:**\n- The manufacturer reported cases where internal muffler baffling (sound-dampening components inside the exhaust) broke loose. If this happens in flight, it can **block the exhaust and cause partial or complete engine failure** — a serious safety risk.\n\n**What must be done:**\n- **First inspection/replacement:** Within 100 flight hours after 30 September 1983, **OR** when the muffler reaches 500 total flight hours — whichever comes **later**.\n- **Ongoing:** Repeat the inspection every 100 flight hours after that.\n\n**Key document reference:**\n- Operators must follow the manufacturer's Service Bulletin 205B56 for the correct procedure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-sm-205-33-exhaust-system-muffler-assembly-inspection-replacement","history":"/api/acts/ad-sm-205-33-exhaust-system-muffler-assembly-inspection-replacement/history","analysis":"/api/acts/ad-sm-205-33-exhaust-system-muffler-assembly-inspection-replacement/analysis","conflicts":"/api/acts/ad-sm-205-33-exhaust-system-muffler-assembly-inspection-replacement/conflicts","importantCases":"/api/acts/ad-sm-205-33-exhaust-system-muffler-assembly-inspection-replacement/important-cases","documents":"/api/acts/ad-sm-205-33-exhaust-system-muffler-assembly-inspection-replacement/documents"}}