{"id":"F2006B10501","name":"AD/HS 125/61 - Electrical Power - Modification","slug":"ad-hs-125-61-electrical-power-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116265,"registerId":"commonwealth-F2006B10501-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HS 125/61 - Electrical Power - 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)  British Aerospace BAe 125 Series Aeroplanes\n\n \n\nAD/HS 125/61 Electrical Power - Modification 5/83\n\nApplicability: All models.\n\n \n\nRequirement: British Aerospace 125 Service Bulletin 24-239-(2885). Compliance:  Within 100 hours time in service after 31 May 1983.\n\nBackground:  To ensure that resetting a circuit breaker onto a system fault will not result in rupture of the ‘PE’ busbar feeder fuses.\n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The instrument specifies a targeted modification for BAe 125 series aeroplanes and a fixed compliance deadline. The text provided sets the original scope: applicability to all BAe 125 models, the specific Service Bulletin as the required action, and the 100-hour compliance window after 31 May 1983. There is no information in the source text that indicates the scope has been altered from that original statement."},"complexity_factors":["Single clear requirement: mandatory compliance with a specific manufacturer Service Bulletin (Requirement).","Narrow technical focus: addresses one electrical system risk (Background).","Single, fixed compliance timeframe (Compliance).","Applies to a single aircraft family and all models (Applicability).","Dependence on external technical document (Service Bulletin) for implementation details increases operational but not legal complexity (Requirement).","Regulatory mechanism is straightforward — an Airworthiness Directive issued by the aviation regulator (header)."],"plain_english_summary":"What this instrument does (mechanics)\n\n- It mandates a specific electrical power system modification for British Aerospace BAe 125 series aeroplanes. (Requirement)\n- The modification to be carried out is the one described in British Aerospace Service Bulletin 24-239-(2885). (Requirement)\n- The rule applies to all BAe 125 models. (Applicability)\n- Operators must complete the modification within 100 hours time in service after 31 May 1983. (Compliance)\n\nWho it affects\n\n- Aircraft owners/operators of any BAe 125 model are required to arrange and pay for the modification called up by the Service Bulletin. (Applicability; Requirement)\n- Maintenance organisations that perform the work will carry out the technical actions in the Service Bulletin. (Requirement)\n- The Civil Aviation Safety Authority (CASA), identified in the header as the issuing authority, is the regulator that issues and enforces the Airworthiness Directive. (COMMONWEALTH ... CIVIL AVIATION SAFETY AUTHORITY)\n\nWhy it matters (official rationale and practical implications)\n\n- The document states the modification is intended to ensure that resetting a circuit breaker onto a system fault will not result in rupture of the ‘PE’ busbar feeder fuses. This is presented as the safety rationale. (Background)\n\nTesting the official rationale against practical costs and incentives (source-grounded)\n\n- Who pays: The source requires operators to carry out the Service Bulletin modification, so operators incur the direct costs of parts, labour and aircraft downtime. (Requirement; Applicability)\n\n- Compliance burden and timing: The directive imposes a fixed compliance window — completion within 100 hours time in service after 31 May 1983 — which forces operators to schedule the work within that operational window. That creates potential short-term maintenance capacity and scheduling costs. (Compliance)\n\n- Technical and implementation risk: The AD specifies a manufacturer Service Bulletin as the required method. Effective implementation depends on availability of the Service Bulletin instructions and competent execution by maintenance personnel. The AD does not itself describe the technical steps, only references the Service Bulletin. (Requirement)\n\n- Choice and substitution effects: Because the AD requires the particular Service Bulletin action, operators are constrained to the prescribed modification unless an alternative is approved by the regulator; the text does not provide alternative compliance routes. (Requirement)\n\n- Benefits and who receives them: The stated benefit is reduced risk of PE busbar feeder fuse rupture when resetting a circuit breaker onto a fault. The benefit is concentrated on any aircraft that would otherwise experience that specific failure mode; the directive does not quantify the probability or magnitude of that risk. (Background)\n\n- Regulatory discretion and enforcement: The AD appears as part of the Civil Aviation Safety Authority’s Schedule of Airworthiness Directives, which is the vehicle the regulator uses to require modifications. The instrument itself sets the mandate and deadline; enforcement and any approvals of alternatives would be a regulator function. (COMMONWEALTH ... CIVIL AVIATION SAFETY AUTHORITY; Requirement)\n\nTrade-offs and opportunity costs (source-grounded)\n\n- The directive trades operator expenditure and maintenance effort (costs) for reduced risk of a specific electrical failure (safety outcome claimed by the Background). The text does not provide cost estimates, alternatives, or data on failure frequency, so operators must accept the mandated modification or seek regulator relief. (Requirement; Background)\n\nSummary statement\n\n- In plain terms: every BAe 125 must be modified according to British Aerospace Service Bulletin 24-239-(2885) within the stated 100-hour window after 31 May 1983 to address a risk that resetting circuit breakers onto a system fault could rupture PE busbar feeder fuses. Operators bear the cost and scheduling burden of the mandated work; the regulator issues and enforces the requirement. (Applicability; Requirement; Compliance; Background)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive issued in 1983 with a specific technical purpose. It has not expanded beyond its original scope of requiring a single electrical modification to prevent fuse rupture."},"complexity_factors":["Single, specific technical requirement referencing an external manufacturer document (Service Bulletin)","No defined terms section","Simple applicability clause ('All models')","Clear compliance deadline (100 hours time in service after fixed date)","No nested exceptions or conditional logic","Background explanation provided in plain language","Extremely short document (approximately 100 words of substantive content)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\nIt requires owners and operators of **British Aerospace BAe 125 series aeroplanes** (a type of business jet) to carry out a specific electrical system modification.\n\n**The specific requirement:**\nOperators must follow **Service Bulletin 24-239-(2885)** issued by British Aerospace. This is a manufacturer-issued instruction detailing a technical fix or inspection procedure.\n\n**The deadline:**\nThe modification must be completed **within 100 hours of flight time** after 31 May 1983.\n\n**Why it matters:**\nThe fix prevents a dangerous electrical fault. Without it, resetting a tripped circuit breaker while a system fault still exists could cause the 'PE' busbar feeder fuses to rupture (break/explode). This could lead to loss of electrical power, fire, or other serious safety hazards in flight.\n\n**Who it affects:**\nAnyone operating BAe 125 aircraft in Australia — including airlines, charter companies, and private owners."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hs-125-61-electrical-power-modification","history":"/api/acts/ad-hs-125-61-electrical-power-modification/history","analysis":"/api/acts/ad-hs-125-61-electrical-power-modification/analysis","conflicts":"/api/acts/ad-hs-125-61-electrical-power-modification/conflicts","importantCases":"/api/acts/ad-hs-125-61-electrical-power-modification/important-cases","documents":"/api/acts/ad-hs-125-61-electrical-power-modification/documents"}}