{"id":"F2006B04887","name":"AD/CASA/7 - Rudder Control System - Modification","slug":"ad-casa-7-rudder-control-system-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44694,"registerId":"commonwealth-F2006B04887-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CASA/7 - Rudder Control System - 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)  Casa 212 Series Aeroplanes\n\n \n\nAD/CASA/7 Rudder Control System - Modification 1/84\n\nApplicability: All model CASA-212 with S/Nos referenced in the requirement document. Document:               Construcciones Aeronauticas SB 212-27-17R1.\n\nCompliance: Within 100 hours time in service after 31 January 1984 unless previously accomplished, or at the next scheduled inspection for maintenance release issue after 31 January 1984, whichever is the later.\n\n \n\nBackground:  Relocation of rudder control cables and replacement of pulley bracket at nose frame 7 will reduce cable wear and improve the Rudder Control System.\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":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive specifies a particular modification (relocation of rudder control cables and replacement of a pulley bracket) and prescribes a compliance window and a referenced service bulletin. The text does not indicate any expansion or narrowing of scope beyond mandating that modification for the listed CASA-212 serial numbers; there is no evidence in the provided text that the scope has changed from its stated purpose of reducing cable wear and improving the rudder control system. (Applicability, Document, Compliance, Background)"},"complexity_factors":["Technical nature of the modification (rudder cable routing and pulley bracket replacement). (Background)","Reference to an external technical document (Construcciones Aeronauticas SB 212-27-17R1) for the method of compliance. (Document)","Narrow applicability limited to specific CASA-212 serial numbers, requiring cross-checking of fleet records. (Applicability)","Fixed compliance timing (100 hours TIS after 31 Jan 1984 or next scheduled inspection), which requires scheduling against operational timetables. (Compliance)","Low regulatory ambiguity in the directive text (the requirement and timeline are stated clearly), reducing interpretive complexity."],"plain_english_summary":"What this directive does, mechanically\n\n- It requires a physical modification to the rudder control system on certain CASA-212 aeroplanes: the rudder control cables must be relocated and the pulley bracket at nose frame 7 must be replaced, following the instructions in Construcciones Aeronauticas Service Bulletin SB 212-27-17R1 (Document). (Document)\n\nWho it affects and when it must be done\n\n- Affected parties: owners/operators of the CASA-212 models whose serial numbers are listed in the referenced service document. (Applicability)\n- Timing: the work must be completed within 100 hours time-in-service after 31 January 1984 unless already done, or at the next scheduled inspection for maintenance release after 31 January 1984, whichever is later. (Compliance)\n\nWhy it is required (official claim)\n\n- The background statement in the directive says relocating the cables and replacing the pulley bracket \"will reduce cable wear and improve the Rudder Control System.\" That is the stated technical rationale for mandating the modification. (Background)\n\nPractical effects, who pays, who decides, and behaviour changes\n\n- Who pays: aircraft owners/operators will bear the direct costs for parts, labour and any associated downtime to perform the modification (the directive requires operators to have it done). (Applicability, Compliance)\n- Who decides/how to comply: compliance must follow the referenced service bulletin (Construcciones Aeronauticas SB 212-27-17R1). The regulator prescribes the required outcome and points to a specific technical document for the method. (Document)\n- Behaviour changes: operators must schedule the modification within the stated compliance window; maintenance providers will need to allocate labour and parts; operators may change inspection and maintenance scheduling to accommodate the requirement. (Compliance)\n\nCosts, incentives and trade-offs\n\n- Immediate costs: one-off expenditure on parts, installation labour and aircraft downtime while the modification is performed. (Applicability, Compliance)\n- Potential offsetting benefit: the stated aim is to reduce cable wear, which could lower future maintenance or replacement costs and possibly reduce risk of cable-related faults; this is presented as the rationale but is not quantified in the directive. (Background)\n- Incentives for operators: operators must weigh short-term outlay and operational disruption against prospective reductions in wear and future maintenance needs. (Compliance, Background)\n\nImplementation risk, compliance burden and discretion\n\n- Compliance burden: follows a prescriptive technical instruction (the referenced service bulletin). Operators and maintenance organisations must have access to and follow that document. (Document)\n- Implementation risk: the quality of the outcome depends on correct execution to the service bulletin; the directive does not set alternative compliance methods in the text provided. (Document)\n- Bureaucratic discretion: the directive mandates the modification and points to a specific service document; the regulator’s role is to require compliance rather than to choose technical details beyond referencing the service bulletin. (Document)\n\nMarket effects and effects on independent businesses\n\n- Demand for parts and skilled maintenance increases for the affected fleet, which creates work for approved independent maintenance providers and parts suppliers able to supply and install the specified modification. (Document, Applicability)\n- The requirement constrains operators’ choice in method (it prescribes the service bulletin) but does not in the text distinguish between authorised maintenance providers; in practice, operators may use any qualified maintenance organisation capable of performing the work to the specified standard. (Document)\n\nNet mechanical summary\n\n- Mechanically, the directive compels relocation of rudder cables and replacement of a pulley bracket at nose frame 7 on specified CASA-212 aircraft per a named service bulletin, within a short, specified compliance window. The stated purpose is to reduce cable wear and improve the rudder control system. (Document, Compliance, Background)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound airworthiness directive from 1984 addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original narrow safety purpose."},"complexity_factors":["Single, discrete mechanical modification with clear physical description","Only one defined applicability criterion (aircraft model and serial numbers)","Simple temporal compliance trigger (100 hours time-in-service or next inspection)","No nested exceptions, conditional logic, or cross-references to other legislation","Short document (approximately 150 words of substantive content)","Single external reference to manufacturer service bulletin"],"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) that requires specific repairs or modifications to aircraft.\n\n**What it does:** It orders owners and operators of **CASA-212 series aeroplanes** (a type of twin-turboprop aircraft) to modify the rudder control system. Specifically, they must:\n- Relocate the rudder control cables\n- Replace a pulley bracket at \"nose frame 7\" (a structural point near the front of the aircraft)\n\n**Why:** These changes reduce wear on the cables and improve the reliability of the rudder — the movable surface that steers the aircraft left and right. Worn cables or faulty brackets could lead to loss of rudder control, which is a serious safety risk.\n\n**Who must comply:** Anyone operating a CASA-212 aircraft with a serial number listed in the referenced service bulletin (Construcciones Aeronauticas SB 212-27-17R1).\n\n**When:** The work must be done within **100 hours of flying time** after 31 January 1984, or at the next scheduled inspection for issuing a maintenance release — whichever comes later.\n\n**Why it matters:** This is a **safety-critical mandate**. Non-compliance means the aircraft cannot legally fly in Australian airspace. It reflects the regulator's power to enforce manufacturer service bulletins as binding legal requirements."}},"importantCases":[],"_links":{"self":"/api/acts/ad-casa-7-rudder-control-system-modification","history":"/api/acts/ad-casa-7-rudder-control-system-modification/history","analysis":"/api/acts/ad-casa-7-rudder-control-system-modification/analysis","conflicts":"/api/acts/ad-casa-7-rudder-control-system-modification/conflicts","importantCases":"/api/acts/ad-casa-7-rudder-control-system-modification/important-cases","documents":"/api/acts/ad-casa-7-rudder-control-system-modification/documents"}}