{"id":"F2006B03474","name":"AD/BAe 146/21 - Remote Controlled Circuit Breaker","slug":"ad-bae-146-21-remote-controlled-circuit-breaker","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43028,"registerId":"commonwealth-F2006B03474-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BAe 146/21 - Remote Controlled Circuit Breaker","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 146/21 Remote Controlled Circuit Breaker 9/90\n\nApplicability: All BAe 146 Series aeroplanes detailed in the Requirement document. Requirement: Action in accordance with BAe Service Bulletin 24-69-70484A.\n\nNote: Compliance with this Service Bulletin has been classified mandatory by the UK CAA.\n\n \n\nCompliance: Prior to 6 November 1990.\n\n \n\nBackground: An in service incident has occurred where an adjustment nut came loose within the AC hydraulic pump remote controlled circuit breaker resulting in one set of contacts remaining closed, thus disabling the over current protection.\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 safety directive addressing a specific mechanical defect. It has not expanded beyond its original purpose of mandating a single corrective action."},"complexity_factors":["Single, specific technical requirement referencing an external manufacturer document","No defined terms section — uses plain technical language","No conditional logic or exceptions","Extremely short (under 200 words)","Single 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 specific aircraft.\n\n**What it does:**\nOrders owners and operators of **British Aerospace BAe 146 series aircraft** to carry out a specific safety fix on the **remote controlled circuit breaker** for the AC hydraulic pump.\n\n**The problem:**\nAn adjustment nut inside this circuit breaker can come loose. If it does, the circuit breaker fails to trip when it should, meaning **overcurrent protection is disabled**. This creates a fire or electrical damage risk.\n\n**What must happen:**\nOperators must follow the instructions in **BAe Service Bulletin 24-69-70484A** — a technical repair notice from the manufacturer — before **6 November 1990**.\n\n**Who it affects:**\nAnyone operating BAe 146 aircraft in Australia (airlines, cargo operators, charter companies).\n\n**Why it matters:**\nCircuit breakers are safety devices that cut power when electrical systems overload. If they fail \"closed\" (stuck on), wiring can overheat and catch fire. This directive prevents that failure mode."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The source does not indicate any change in scope from the instrument’s original corrective intent. The AD addresses a specific in-service failure mode and mandates implementation of BAe Service Bulletin 24-69-70484A for the BAe 146 series aeroplanes listed in the Requirement document, with a defined compliance date. There is no text in the source suggesting an expansion or narrowing of that scope beyond the stated applicability and required action (Applicability; Requirement; Compliance; Background)."},"complexity_factors":["External technical detail is contained in a separate BAe Service Bulletin (24-69-70484A) that the AD mandates rather than reproducing—compliance requires consulting that external document (Requirement).","Applicability requires checking a Requirement document to confirm which individual aeroplanes are affected rather than the AD listing serial numbers directly (Applicability).","A firm compliance deadline is given, creating scheduling and operational constraints for maintenance planning (Compliance).","The directive responds to a specific hardware failure mode (adjustment nut loosening) that has safety implications; understanding the fix may require technical/engineering assessment (Background).","Reference to the UK CAA’s prior mandatory classification creates an international regulatory linkage that operators may need to reconcile administratively (Note)."],"plain_english_summary":"What this instrument does\n\n- It orders that all affected BAe 146 series aeroplanes be inspected and modified in line with a specific British Aerospace (BAe) Service Bulletin (24-69-70484A). (Requirement)\n- The work must be completed before 6 November 1990. (Compliance)\n\nWho it affects\n\n- Owners and operators of BAe 146 aircraft that are listed as applicable in the Requirement document. They are the parties responsible for carrying out the mandated action. (Applicability; Requirement)\n\nWhy it matters (mechanics and risks)\n\n- The directive responds to an in-service incident where an adjustment nut came loose inside the AC hydraulic pump remote-controlled circuit breaker, leaving a contact set closed and defeating over-current protection. The Service Bulletin specifies the technical fix intended to prevent that failure mode. (Background; Requirement)\n- The UK Civil Aviation Authority has classified compliance with the Service Bulletin as mandatory, which is noted in the instrument. (Note)\n\nHow it works in practice (who pays, who decides, and what changes)\n\n- Who decides: the Civil Aviation Safety Authority issued the airworthiness directive and references the BAe Service Bulletin as the required remedial action. The UK CAA’s prior mandatory classification of the Bulletin is recorded. (Requirement; Note)\n- Who pays: aircraft owners/operators must arrange and fund the inspection/rectification work set out in the Service Bulletin. (Applicability; Requirement)\n- Behaviour change required: operators must inspect/modify the remote-controlled circuit breaker per BAe Service Bulletin 24-69-70484A and complete that work by the stated compliance date. Non-compliance would leave the aircraft exposed to the identified failure mode. (Requirement; Compliance; Background)\n\nCosts, incentives and trade-offs (practical considerations)\n\n- Direct costs: operators incur maintenance labour, any parts cost and aircraft downtime to implement the Service Bulletin. (Applicability; Requirement)\n- Incentives: completing the mandated work removes or reduces the specific risk described (a hardware fault that can defeat over-current protection). The directive creates a regulatory obligation that compels action rather than leaving it to voluntary commercial judgment. (Background; Requirement)\n- Implementation risk and compliance burden: operators must determine whether their aircraft are listed as applicable (the Requirement document), schedule maintenance before the deadline, and ensure the work follows the specified Service Bulletin. If the Bulletin requires particular parts, tools or specialist labour, that could increase downtime or cost. (Applicability; Requirement; Compliance)\n- Regulatory linkage: the note that the UK CAA classified the Service Bulletin as mandatory adds an element of cross-jurisdictional regulatory alignment; the directive formally adopts the BAe remedy and the associated compliance timing. (Note; Requirement)\n\nTrade-offs and opportunity costs\n\n- The instrument replaces the operator’s choice about whether or when to adopt the BAe fix with an enforceable deadline. That reduces the operator’s freedom to defer or negotiate an alternative fix, while aiming to reduce a specific safety risk identified in service. The source document specifies the risk and the mandated remedy but does not quantify costs or alternative technical options. (Requirement; Background)\n\nImplementation summary\n\n- Operators should consult the Requirement document to confirm applicability, then implement BAe Service Bulletin 24-69-70484A and document compliance on or before 6 November 1990. The directive’s stated purpose is to prevent recurrence of the specific circuit-breaker failure described. (Applicability; Requirement; Compliance; Background)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-21-remote-controlled-circuit-breaker","history":"/api/acts/ad-bae-146-21-remote-controlled-circuit-breaker/history","analysis":"/api/acts/ad-bae-146-21-remote-controlled-circuit-breaker/analysis","conflicts":"/api/acts/ad-bae-146-21-remote-controlled-circuit-breaker/conflicts","importantCases":"/api/acts/ad-bae-146-21-remote-controlled-circuit-breaker/important-cases","documents":"/api/acts/ad-bae-146-21-remote-controlled-circuit-breaker/documents"}}