{"id":"F2006B07564","name":"AD/VAT/30 - Exhaust System Muffler Shroud - Modification","slug":"ad-vat-30-exhaust-system-muffler-shroud-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":50159,"registerId":"commonwealth-F2006B07564-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/VAT/30 - Exhaust System Muffler Shroud - Modification","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)  Victa and A.E.S.L. Airtourer Series Aeroplanes\n\n \n\nAD/VAT/30 Exhaust System Muffler Shroud - Modification 1/68\n\nApplicability: Victa Airtourer 100.\n\n \n\nRequirement: Drill a 3/16 inch diameter drain hole just forward of the rear face bottom centre line of each exhaust system muffler shroud P/N 42124/1.\n\n \n\nCompliance: Within 100 hours time in service after 25 January 1968.\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-purpose safety directive from 1968. It has not expanded beyond its original narrow scope of requiring a specific exhaust modification on one aircraft type."},"complexity_factors":["Single, unambiguous mechanical instruction (drill one hole)","No defined terms requiring interpretation","No cross-references to other legislation or regulations","No conditional logic or exceptions","Extremely short (under 100 words of substantive content)","Clear applicability (single aircraft model) and compliance deadline"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It requires owners and operators of a specific light aircraft (the **Victa Airtourer 100**) to make a simple physical modification to the exhaust system.\n\n**What must be done:**\n- Drill a small drain hole (3/16 inch, or about 4.8mm) in a specific location on each exhaust muffler shroud\n- The part number affected is P/N 42124/1\n\n**Why it matters:**\n- Exhaust systems on aircraft can collect moisture, which causes corrosion and potential failure. A drain hole allows water to escape, preventing rust and maintaining safe operation.\n\n**Who must comply:**\n- Anyone operating a Victa Airtourer 100 aircraft\n\n**When:**\n- Within 100 hours of flight time after 25 January 1968 (this is a historical directive from 1968, so compliance would have been required decades ago for aircraft still in service at that time)"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The text of the directive as supplied sets out a single, specific modification for Victa Airtourer 100 aircraft and contains no language indicating an expansion or narrowing of scope from an earlier or different intent. There is no information in the provided text showing any change to scope or applicability."},"complexity_factors":["Narrow applicability: applies only to Victa Airtourer 100 aircraft (Applicability).","Single, prescriptive action: one hole of specified diameter and location must be drilled (Requirement).","Clear compliance window: fixed 100 hours time-in-service deadline after a specified date (Compliance).","Part-specific instruction: references a single part number P/N 42124/1, reducing ambiguity (Requirement).","Potential implementation risk: correct execution matters but the directive gives minimal procedural detail, which can create practical execution uncertainty (Requirement)."],"plain_english_summary":"This mandatory airworthiness directive (CASA) requires owners/operators of Victa Airtourer 100 aeroplanes to drill a 3/16\" drain hole in each exhaust muffler shroud P/N 42124/1 within 100 hours TIS after 25 January 1968. The operator bears the cost and compliance burden. The directive gives no rationale; a plausible inference is to allow drainage of fluids to reduce corrosion or liquid trapping."}},"importantCases":[],"_links":{"self":"/api/acts/ad-vat-30-exhaust-system-muffler-shroud-modification","history":"/api/acts/ad-vat-30-exhaust-system-muffler-shroud-modification/history","analysis":"/api/acts/ad-vat-30-exhaust-system-muffler-shroud-modification/analysis","conflicts":"/api/acts/ad-vat-30-exhaust-system-muffler-shroud-modification/conflicts","importantCases":"/api/acts/ad-vat-30-exhaust-system-muffler-shroud-modification/important-cases","documents":"/api/acts/ad-vat-30-exhaust-system-muffler-shroud-modification/documents"}}