{"id":"F2006B02202","name":"AD/AC-SNOW/11 - Carburettor Air Selector Valve Assembly - Inspection","slug":"ad-ac-snow-11-carburettor-air-selector-valve-assembly-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41432,"registerId":"commonwealth-F2006B02202-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AC-SNOW/11 - Carburettor Air Selector Valve Assembly - Inspection","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-description: CASA Airworthiness Directive\nmeta-generator: Aspose.Words for .NET 22.10.0\nmeta-keywords: Issue 3/1978,Aircraft below 5700 kg,Ayres Thrush (Snow) Commander Series Aeroplanes,Carburettor Air Selector Valve Assembly - Inspection,11\ntitle: Airworthiness Directive - AD/AC-SNOW/11 - Carburettor Air Selector Valve Assembly - Inspection\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)  Ayres Thrush (Snow) Commander Series Aeroplanes\n\n \n\n# AD/AC-SNOW/11 Carburettor Air Selector Valve Assembly - Inspection\n\nApplicability: Model S-2R with S/Nos. 5000 and up. Document:  Rockwell International SB No. SB-AG-8.\n\n# 3/78\n\nCompliance: Within 50 hours’ time in service after 30 April 1978 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","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD's scope is limited and specific: it requires inspection of the carburettor air selector valve assembly on Model S-2R aircraft with serial numbers 5000 and up, following the schedule given (first within 50 hours after 30 April 1978 and every 50 hours thereafter) and using Rockwell SB-AG-8. The text supplied shows no change or expansion from that narrowly defined scope."},"complexity_factors":["Narrow applicability: single aircraft model and limited serial-number range (Applicability)","Recurring inspection obligation with a short interval (50 hours) and a historic start date (Compliance)","Dependence on an external service bulletin for the inspection method (Document: Rockwell International SB No. SB-AG-8)","Statutory authority and enforceability referenced under Civil Aviation Regulations Part 39 - 105 (Header)","No alternative compliance paths or detailed procedural text included in the AD itself (AD text lacks procedural detail beyond the SB reference)"],"plain_english_summary":"This airworthiness directive mandates repetitive inspections of the carburettor air selector valve assembly on Ayres Thrush (Snow) Commander Model S‑2R aircraft, S/N 5000 and up, to be carried out per Rockwell Service Bulletin SB‑AG‑8. The first check is due within 50 flight hours after 30 April 1978 and then every 50 hours. CASA issues and enforces the requirement; affected operators/owners must arrange and pay for inspections and any repairs."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted airworthiness directive addressing a specific mechanical issue on a specific aircraft model. It has not expanded beyond its original purpose of mandating inspections for the carburettor air selector valve assembly. The scope remains precisely limited to the Ayres Thrush Commander S-2R series (serial numbers 5000 and up) and the specified maintenance action."},"complexity_factors":["Extremely short document (approximately 150 words)","Only 1 defined term implicitly referenced (the manufacturer's service bulletin)","No cross-references to other legislation beyond the enabling regulation (Civil Aviation Regulations 1998, Part 39)","Simple conditional logic: single applicability criterion (Model S-2R, S/N 5000+)","Straightforward compliance requirement with clear deadline and recurring interval","Single technical reference to external document (Rockwell International SB No. SB-AG-8)"],"plain_english_summary":"This is a **safety instruction** (called an \"Airworthiness Directive\") issued by Australia's Civil Aviation Safety Authority (CASA) for a specific type of agricultural aircraft: the **Ayres Thrush (Snow) Commander** series.\n\n**What it does:**\nIt requires owners and operators of certain Thrush Commander planes (specifically Model S-2R with serial numbers 5000 and up) to **inspect the carburettor air selector valve assembly** — a part that controls airflow to the engine's carburettor.\n\n**Who it affects:**\n- Owners and operators of affected Ayres Thrush Commander agricultural aircraft\n- Maintenance engineers working on these planes\n\n**When they must comply:**\n- **First inspection:** Within 50 hours of flying time after 30 April 1978\n- **Ongoing:** Every 50 hours of flying time thereafter\n\n**Why it matters:**\nThis directive was issued because of a safety concern identified by the manufacturer (Rockwell International) in Service Bulletin SB-AG-8. The carburettor air selector valve is critical for proper engine operation — if it fails, the engine could lose power or stop working entirely, which is obviously dangerous when flying. The recurring 50-hour inspection interval suggests this was considered a serious, ongoing maintenance issue requiring regular monitoring rather than a one-off fix."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ac-snow-11-carburettor-air-selector-valve-assembly-inspection","history":"/api/acts/ad-ac-snow-11-carburettor-air-selector-valve-assembly-inspection/history","analysis":"/api/acts/ad-ac-snow-11-carburettor-air-selector-valve-assembly-inspection/analysis","conflicts":"/api/acts/ad-ac-snow-11-carburettor-air-selector-valve-assembly-inspection/conflicts","importantCases":"/api/acts/ad-ac-snow-11-carburettor-air-selector-valve-assembly-inspection/important-cases","documents":"/api/acts/ad-ac-snow-11-carburettor-air-selector-valve-assembly-inspection/documents"}}