{"id":"F2006B04980","name":"AD/CESSNA 170/52 - Muffler","slug":"ad-cessna-170-52-muffler","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44873,"registerId":"commonwealth-F2006B04980-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 170/52 - Muffler","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 170/52 Muffler 3/86\n\nApplicability: Cessna aircraft S/N 172RG 1135 to 172RG 1187.\n\n \n\nRequirement: Inspect muffler core below each end plate attachment screw for damage in accordance with Cessna SB No SEB85-17.\n\n \n\nCompliance: Prior to issue of Certificate of Airworthiness.\n\n \n\nBackground: A possibility exists that holes may have been drilled through the muffler allowing exhaust gases into the cabin during cabin heat operation.\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 addressing a specific manufacturing defect in a limited production run of aircraft. It has not expanded beyond its original purpose of ensuring muffler integrity on affected Cessna models."},"complexity_factors":["Very short document (under 200 words)","Only 1 defined term implicitly referenced (Certificate of Airworthiness)","Single, straightforward requirement with no conditional logic or exceptions","No cross-references to other legislation beyond the parent Civil Aviation Regulations 1998","Clear, specific applicability (single serial number range)","Single compliance trigger (prior to Certificate of Airworthiness issue)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety notice for aircraft owners and operators. It applies to specific Cessna aircraft (serial numbers 172RG 1135 through 172RG 1187).\n\n**What it requires:** Before the aircraft can be issued a Certificate of Airworthiness (the official document saying it's safe to fly), the muffler (exhaust silencer) must be inspected. Specifically, someone needs to check the muffler core near where the end plates are screwed on, looking for damage.\n\n**Why this matters:** There's a risk that holes were accidentally drilled through the muffler during manufacturing. If exhaust gases leak through these holes into the cabin heating system, carbon monoxide could poison the pilot and passengers.\n\n**Who must follow this:** Anyone who owns or operates one of these specific Cessna aircraft, and anyone issuing Certificates of Airworthiness for them."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive's scope is narrowly and explicitly set by serial number and a single required inspection. There is no indication in the text that the instrument expands or narrows that scope compared with its stated intent: it applies only to the listed aircraft, requires inspection per the referenced service bulletin, and conditions Certificate of Airworthiness issuance on compliance. (Applicability; Requirement; Compliance; Background)"},"complexity_factors":["Very narrow applicability limited to specific serial numbers (172RG 1135–1187). (Applicability)","Single, clearly defined action required (inspect muffler core under each end-plate screw). (Requirement)","Compliance timing is straightforward (prior to issue of Certificate of Airworthiness), reducing sequencing complexity. (Compliance)","Requires following an external document (Cessna SB No SEB85-17), introducing dependency on service bulletin clarity and availability. (Requirement)","AD does not specify remedial actions or cost estimates, leaving implementation decisions and potential variability to maintenance providers. (Requirement)"],"plain_english_summary":"This directive requires a one‑time inspection of the muffler core beneath each end‑plate attachment screw on Cessna 170/172/175 family aircraft with serial numbers 172RG 1135–1187, performed per Cessna Service Bulletin SEB85‑17, as a precondition for issuing the Certificate of Airworthiness.\n\nOwners/operators must arrange and pay for the inspection and any repairs; maintenance providers carry out the work. The action addresses possible drilled holes that could admit exhaust gases to the cabin."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-170-52-muffler","history":"/api/acts/ad-cessna-170-52-muffler/history","analysis":"/api/acts/ad-cessna-170-52-muffler/analysis","conflicts":"/api/acts/ad-cessna-170-52-muffler/conflicts","importantCases":"/api/acts/ad-cessna-170-52-muffler/important-cases","documents":"/api/acts/ad-cessna-170-52-muffler/documents"}}