{"id":"F2006B04877","name":"AD/CASA/20 - Corrosion of Rudder Torsion Tube","slug":"ad-casa-20-corrosion-of-rudder-torsion-tube","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44684,"registerId":"commonwealth-F2006B04877-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CASA/20 - Corrosion of Rudder Torsion Tube","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)  Casa 212 Series Aeroplanes\n\n \n\nAD/CASA/20 Corrosion of Rudder Torsion Tube 9/96\n\nDM\n\n \n\nApplicability: All models.\n\n \n\nRequirement: Action in accordance with CASA SB 212-27-34.\n\n \n\nNote: Spanish DGAC AD 06/96 refers.\n\n \n\nCompliance: Before 30 August 1996.\n\n \n\nBackground:  Corrosion has been detected in the rudder lower shaft and support structure. This has been caused by water entry through the space between the upper bearing and the fuselage structure.\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, time-bound safety directive addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original purpose of mandating corrosion inspection/repair."},"complexity_factors":["Extremely short document (under 200 words)","Only 1 defined term implicitly referenced (CASA SB 212-27-34)","No nested conditional logic or exceptions","Single, unambiguous compliance requirement","No cross-references to other legislation beyond a service bulletin and a Spanish DGAC AD for reference","Straightforward applicability (all models)"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it as a \"recall notice\" for aircraft, but legally binding.\n\n**What it does:** It requires owners and operators of **CASA 212 series aeroplanes** (a type of twin-turboprop utility aircraft) to inspect and fix a specific safety problem: **corrosion in the rudder torsion tube** (the metal shaft that helps control the plane's steering).\n\n**The problem:** Water was getting into the gap between the upper bearing and the fuselage, causing the rudder's lower shaft and support structure to rust. Corrosion in flight controls is serious — it can lead to control failure.\n\n**What must be done:** Operators must follow the instructions in **CASA Service Bulletin 212-27-34** (a technical repair guide) to address the corrosion.\n\n**Who it affects:** Anyone who owns, operates, or maintains CASA 212 aircraft in Australia.\n\n**Deadline:** The work had to be completed **before 30 August 1996**.\n\n**Why it matters:** This directive prevents potential catastrophic failure of the rudder — essential for controlling the aircraft during flight. Ignoring an AD is illegal and dangerous."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The instrument addresses corrosion of the rudder torsion tube and related structure for all CASA 212 models and requires action per CASA SB 212-27-34 to be completed by a specified date. Based solely on the text provided, there is no indication the scope has changed from the original intent: it targets the identified corrosion mechanism (water entry between upper bearing and fuselage) and mandates corrective action for the affected fleet (Applicability, Requirement, Background, Compliance, Note)."},"complexity_factors":["Short, narrowly focused directive covering a single corrosion issue (Background).","Applicability is universal across the model series, so no complex applicability matrix (Applicability).","Technical actions are delegated to a referenced service bulletin rather than detailed in the AD, reducing procedural complexity in the AD but requiring cross-reference (Requirement).","Clear single compliance deadline simplifies timing (Compliance).","Reference to a foreign AD (Spanish DGAC) introduces minor cross-jurisdictional context but no added procedural steps (Note)."],"plain_english_summary":"The directive requires all CASA 212 series aeroplanes to comply with CASA Service Bulletin SB 212-27-34 to inspect and correct corrosion found in the rudder lower shaft and its support—caused by water ingress—by 30 August 1996. Operators must carry out and pay for the work, affecting aircraft availability and maintenance costs to preserve airworthiness."}},"importantCases":[],"_links":{"self":"/api/acts/ad-casa-20-corrosion-of-rudder-torsion-tube","history":"/api/acts/ad-casa-20-corrosion-of-rudder-torsion-tube/history","analysis":"/api/acts/ad-casa-20-corrosion-of-rudder-torsion-tube/analysis","conflicts":"/api/acts/ad-casa-20-corrosion-of-rudder-torsion-tube/conflicts","importantCases":"/api/acts/ad-casa-20-corrosion-of-rudder-torsion-tube/important-cases","documents":"/api/acts/ad-casa-20-corrosion-of-rudder-torsion-tube/documents"}}