{"id":"F2006B02553","name":"AD/AT/4 - Rudder Hinges - Inspection","slug":"ad-at-4-rudder-hinges-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41809,"registerId":"commonwealth-F2006B02553-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AT/4 - Rudder Hinges - Inspection","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)  Airtractor AT-300, 400 and 500 Series Aeroplanes\n\n \n\n \n\n| AD/AT/4 | Rudder Hinges - Inspection | 7/83 |\n| --- | --- | --- |\n| Applicability: | All models AT-300, AT-301 and AT-302 with S/Nos. 0001 to 0260. |  |\n| Document: | Snow Engineering Co. Service Letter No. 48. |  |\n\n\n \n\nCompliance: Within 100 hours time in service after 31st July 1983 and thereafter at intervals not exceeding 1 year.\n\n \n\nBackground: The manufacturer reports a case of a rudder hinge failure due to corrosion of the rudder spar tube.\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":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":952},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This directive maintains its original, narrow scope: addressing a specific corrosion-related airworthiness concern in identified Air Tractor aircraft models. It has not expanded beyond the original safety issue of rudder hinge inspection."},"complexity_factors":["Single, specific technical requirement with clear deadline","Limited applicability to specific aircraft models and serial number range (0001-0260)","References external technical document (Snow Engineering Service Letter No. 48) without reproducing its contents","Uses aviation-specific terms ('time in service', 'rudder spar tube') but defines the safety issue clearly"],"plain_english_summary":"**What this is:** A mandatory safety inspection order (called an Airworthiness Directive) for specific agricultural aircraft.\n\n**Who it affects:** Owners and operators of Air Tractor AT-300, AT-301, and AT-302 aeroplanes with serial numbers 0001 through 0260.\n\n**What you must do:**\n- **Inspect the rudder hinges** for corrosion damage within 100 flight hours after 31 July 1983\n- **Repeat this inspection** at least once every year thereafter\n\n**Why this matters:** The aircraft manufacturer reported a case where a rudder hinge failed because the metal tube inside the rudder had corroded (rusted). If this happens in flight, the pilot could lose control of the aircraft's steering, potentially causing a crash. This rule forces operators to check for this hidden corrosion before it causes catastrophic failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-at-4-rudder-hinges-inspection","history":"/api/acts/ad-at-4-rudder-hinges-inspection/history","analysis":"/api/acts/ad-at-4-rudder-hinges-inspection/analysis","conflicts":"/api/acts/ad-at-4-rudder-hinges-inspection/conflicts","importantCases":"/api/acts/ad-at-4-rudder-hinges-inspection/important-cases","documents":"/api/acts/ad-at-4-rudder-hinges-inspection/documents"}}