{"id":"F2006B03476","name":"AD/BAe 146/25 - Freight Door Torque Shaft","slug":"ad-bae-146-25-freight-door-torque-shaft","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43030,"registerId":"commonwealth-F2006B03476-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BAe 146/25 - Freight Door Torque Shaft","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)  British Aerospace BAe 146 Series Aeroplanes\n\n \n\nAD/BAe 146/25 Freight Door Torque Shaft 3/91\n\nApplicability: Model 146 with Constructor’s numbers listed in BAe SB 52-81-56012A Rev 1. Requirement:               Action in accordance with BAe Mandatory SB 52-81-56012A Rev 1.\n\nCompliance: As specified in the Requirement Document with revised effective date 31 March 1991.\n\n \n\nBackground: This Directive is raised to introduce a modification that adds two spring struts to the torque shaft detents to provide additional locking torque. This will ensure that the vent door does not open under any circumstances other than normal freight door operation.\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":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Based on the source text, the directive sets a targeted scope: BAe 146 aircraft with constructor’s numbers listed in BAe SB 52-81-56012A Rev 1 must have the SB’s modification carried out. The document does not indicate any change to that scope beyond those identified aircraft or any expansion/narrowing of applicability. The AD delegates method and technical detail to the referenced Mandatory SB and fixes a compliance effective date (31 March 1991)."},"complexity_factors":["Reference to an external Mandatory Service Bulletin (BAe SB 52-81-56012A Rev 1) — technical and procedural details are contained outside the directive.","Applicability is limited to aircraft listed by constructor’s number in the SB — requires cross-checking serial/constructor numbers to determine applicability.","Mandatory compliance with a specified effective date (31 March 1991) — timing and scheduling considerations for operators.","Technical nature of the modification (adding two spring struts to torque shaft detents) requires maintenance facilities, parts and trained personnel.","The directive text is short and delegates substantive implementation detail to the SB, increasing dependence on the SB for cost and labour estimates."],"plain_english_summary":"### What this directive does (mechanical change)\n\n- The airworthiness directive requires operators of certain British Aerospace BAe 146 aircraft to carry out a specific modification described in BAe Mandatory Service Bulletin (SB) 52-81-56012A Rev 1. (Requirement)\n- The modification adds two spring struts to the torque shaft detents of the freight/vent door mechanism to provide additional locking torque. (Background)\n- The directive applies to BAe 146 aircraft whose constructor’s numbers are listed in the referenced SB. (Applicability)\n- Compliance must be completed as specified in the Requirement Document, with a revised effective date of 31 March 1991. (Compliance)\n\n### Stated purpose (regulatory rationale)\n\n- The directive states that the modification is intended to ensure the vent door does not open except during normal freight door operation by providing additional locking torque to the torque shaft detents. (Background)\n\n### Compliance and Economic Implications\n\n- Who decides and how: The Civil Aviation Safety Authority issued this airworthiness directive under Part 39; the actions required are set out by reference to BAe Mandatory SB 52-81-56012A Rev 1. (header; Requirement)\n- Who pays: The directive requires affected aircraft owners/operators to fund and execute the modification; the source does not describe cost-sharing or subsidy mechanisms. (Requirement)\n- Compliance burden: The directive mandates carrying out the SB’s modification steps for the listed constructor’s numbers and meeting the compliance timing shown in the Requirement Document (revised effective date 31 March 1991). The SB itself contains the technical instructions. (Applicability; Compliance; Requirement)\n- Technical dependency: The AD is brief and delegates technical detail to the referenced Mandatory SB; the SB will set out procedures, parts, and tooling needed to add the two spring struts. The AD does not list those technical or logistical details. (Requirement; Background)\n- Incentives created: The directive mandates compliance with the referenced SB; the source does not describe alternative compliance methods. (Requirement)\n- Effects on private choice: The directive requires a specific modification; operators do not have discretion to defer or substitute alternative methods under this text. It limits operator choice to implementing the modification as specified for the aircraft identified. (Requirement; Applicability)\n- Implementation risk and trade-offs: The source describes the intended mechanical change (addition of spring struts) but does not quantify costs, parts availability, labour time, or any operational downtime required. Those practical effects will depend on the SB’s technical content and how operators schedule the work. (Background; Requirement)\n\n### Practical snapshot: who acts and when\n\n- Actioning body: Aircraft owners/operators (to carry out the SB) following the technical instructions in BAe Mandatory SB 52-81-56012A Rev 1. (Requirement)\n- Effective timing: Compliance as specified in the Requirement Document with revised effective date 31 March 1991. (Compliance)\n\n(References: Applicability; Requirement; Compliance; Background.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive remains tightly scoped to its original safety purpose — addressing a specific mechanical defect in a specific aircraft type. There is no evidence of scope creep; it targets one technical modification to one component on one aircraft series."},"complexity_factors":["Single, specific technical requirement with no conditional logic or exceptions","Only one defined applicability criterion (specific constructor's numbers)","No cross-references to other legislation or regulations beyond the parent Civil Aviation Regulations 1998","Short document (approximately 150 words of substantive content)","Straightforward compliance deadline with no alternative methods or phased implementation"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\nOrders owners and operators of specific British Aerospace BAe 146 model aircraft to install a safety modification to the freight door mechanism. The fix adds two spring struts to the \"torque shaft detents\" (the locking parts that hold the door in place) to make them stronger.\n\n**Why it matters:**\nWithout this modification, there's a risk the vent door could accidentally open during flight — not through normal operation, but due to mechanical failure or stress. An unexpected door opening at altitude could cause rapid decompression, damage to the aircraft, or endanger crew and cargo.\n\n**Who must comply:**\nAnyone operating a BAe 146 aircraft with specific serial numbers listed in the referenced British Aerospace service bulletin (SB 52-81-56012A Rev 1).\n\n**What must be done:**\nFollow the exact instructions in British Aerospace Mandatory Service Bulletin 52-81-56012A Revision 1, with the work completed by 31 March 1991."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-25-freight-door-torque-shaft","history":"/api/acts/ad-bae-146-25-freight-door-torque-shaft/history","analysis":"/api/acts/ad-bae-146-25-freight-door-torque-shaft/analysis","conflicts":"/api/acts/ad-bae-146-25-freight-door-torque-shaft/conflicts","importantCases":"/api/acts/ad-bae-146-25-freight-door-torque-shaft/important-cases","documents":"/api/acts/ad-bae-146-25-freight-door-torque-shaft/documents"}}