{"id":"F2006B04822","name":"AD/CA21/3 - Rudder Actuator Horn","slug":"ad-ca21-3-rudder-actuator-horn","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44623,"registerId":"commonwealth-F2006B04822-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CA21/3 - Rudder Actuator Horn","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)  Skyfox Aviation (Calair/Hedaro) CA21 and CA22A Series Aeroplanes\n\n \n\nAD/CA21/3 Rudder Actuator Horn 1/96\n\nApplicability: CA21 aircraft, serial numbers CA21004 through CA21035.\n\n \n\nRequirement: Inspect the rudder actuator horn for drain hole in accordance with Skyfox Aviation Service Bulletin No.4.\n\n \n\nCompliance: At the next inspection for issue of a Maintenance Release or within 100 hours time in service, from 4 January 1996 whichever occurs first.\n\n \n\nBackground: Skyfox advise that a number of rudder actuator horns may not have had a drain hole installed at manufacture. This AD requires a drain hole to be drilled if not already fitted.\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 aircraft population. It has not expanded beyond its original purpose of ensuring drain holes exist in rudder actuator horns."},"complexity_factors":["Single, specific mechanical requirement (one inspection task)","Narrow applicability (only 32 specific aircraft by serial number)","No defined terms section or complex interpretive provisions","Simple conditional compliance deadline (whichever occurs first)","No cross-references to other legislation beyond the parent Civil Aviation Regulations 1998","Clear, single-step requirement with reference to manufacturer service bulletin"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) requiring specific aircraft owners to fix a manufacturing defect.\n\n**What it does:**\n- Requires owners of specific Skyfox CA21 aircraft (serial numbers CA21004 to CA21035) to inspect their plane's **rudder actuator horn** (a mechanical part that helps control the rudder) for a missing **drain hole** (a small hole that lets water escape).\n- If the drain hole is missing, it must be drilled according to the manufacturer's instructions.\n\n**Why it matters:**\n- Without a drain hole, water can collect inside the rudder actuator horn, potentially causing corrosion or freezing that could jam the rudder — a serious flight safety risk.\n\n**Who must comply:**\n- Owners/operators of the 32 affected CA21 aircraft (serials CA21004–CA21035).\n\n**When to do it:**\n- By the next scheduled maintenance check, or within 100 hours of flight time after 4 January 1996 — whichever comes first."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive’s scope is to require inspection and drilling (if needed) of the rudder actuator horn for CA21 aircraft serial numbers CA21004–CA21035. The instrument’s text is consistent with that targeted corrective action and does not indicate an expansion or narrowing of scope beyond those aircraft and the single remedial task."},"complexity_factors":["Very narrow applicability limited to specific serial numbers (Applicability).","Single, concrete technical action required: inspect and drill a drain hole if missing (Requirement).","Short, simple compliance timeframe tied to next Maintenance Release or 100 hours TIS (Compliance).","Procedure referenced externally (Skyfox Aviation Service Bulletin No.4) which requires maintenance personnel to follow technical steps.","Potential operational risk if technical steps are not followed correctly (Background)."],"plain_english_summary":"This AD requires inspection of the rudder actuator horn on Skyfox CA21 serials CA21004–CA21035 to confirm a drain hole; if absent, a drain hole must be drilled per Skyfox Aviation Service Bulletin No.4. Owners/operators must do this at the next Maintenance Release or within 100 flight hours from 4 January 1996 to address a manufacturing omission that could allow water retention."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ca21-3-rudder-actuator-horn","history":"/api/acts/ad-ca21-3-rudder-actuator-horn/history","analysis":"/api/acts/ad-ca21-3-rudder-actuator-horn/analysis","conflicts":"/api/acts/ad-ca21-3-rudder-actuator-horn/conflicts","importantCases":"/api/acts/ad-ca21-3-rudder-actuator-horn/important-cases","documents":"/api/acts/ad-ca21-3-rudder-actuator-horn/documents"}}