{"id":"F2006B10511","name":"AD/HS 125/70 - EFIS Power Supply","slug":"ad-hs-125-70-efis-power-supply","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116285,"registerId":"commonwealth-F2006B10511-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HS 125/70 - EFIS Power Supply","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 125/70 EFIS Power Supply 8/85\n\nApplicability: All BAe-125 series aeroplanes with the following S/Nos: Series 700B - 257208 to 257210, 257214 and 257215\n\nSeries 800A and B - 258001 to 258020, 258022 to 258024 and 258026.\n\n \n\nRequirement: Modify the EFIS power supply according to the requirements detailed in British Aerospace 125 S.B. 24-248-(3024).\n\n \n\nNote: United Kingdom CAA AD No. 004-04-85 Refers.\n\n \n\nCompliance: Prior to 31 October 1985.\n\n \n\nBackground: The aircraft manufacturer advises of an overheat of the heat sink diode assembly on a completed aircraft.\n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue safety directive from 1985 addressing a specific electrical defect in specific aircraft. It has not expanded beyond its original purpose of mandating a single hardware modification."},"complexity_factors":["Very short document (under 200 words)","Only 4 structural sections: Applicability, Requirement, Note, Compliance, and Background","No defined terms section — all terminology is standard aviation maintenance language","Single, unambiguous compliance action (modify per specific service bulletin)","No cross-references to other legislation or regulations beyond a single reference to a UK CAA AD","No conditional logic, exceptions, or alternative compliance methods","Applicability determined by simple serial number list rather than complex criteria"],"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 like a compulsory recall notice, but for aircraft rather than cars.\n\n**What it does:** It requires owners and operators of specific British Aerospace BAe 125 business jets to modify the **EFIS power supply** (the electrical system that powers the Electronic Flight Instrument System — basically the digital screens pilots use to see flight data). The fix must follow the manufacturer's Service Bulletin 24-248-(3024).\n\n**Who it affects:** Only specific serial numbers of BAe-125 aircraft:\n- **Series 700B:** Serial numbers 257208 to 257210, 257214 and 257215\n- **Series 800A and B:** Serial numbers 258001 to 258020, 258022 to 258024, and 258026\n\n**Why it matters:** The manufacturer discovered that the **heat sink diode assembly** (a component that prevents electrical overheating) could overheat on completed aircraft. This creates a fire risk or electrical failure hazard that could affect critical flight instruments. The directive makes the fix legally mandatory rather than optional.\n\n**Key deadline:** The modification had to be completed before **31 October 1985** (this is a historical directive from 1985)."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive’s scope, as set out in the text, is limited to the listed BAe-125 serial numbers and requires a particular modification per the manufacturer’s service bulletin to be completed by a stated deadline. The instrument does not expand applicability beyond those serial numbers, nor does it introduce additional obligations beyond the specified modification and deadline. Therefore there is no indication in the text that the scope has changed from its apparent original purpose of mandating this specific corrective action in response to the reported overheating. (Applicability; Requirement; Compliance; Background)"},"complexity_factors":["Narrow applicability limited to specific serial numbers (reduces scope complexity). (Applicability)","Technical execution is delegated to an external document (British Aerospace Service Bulletin 24-248-(3024)), which requires operators/maintenance providers to obtain and interpret that material. (Requirement)","Fixed compliance deadline creates scheduling and operational-planning complexity for affected operators. (Compliance)","Cross-reference to a foreign regulator’s AD (United Kingdom CAA) introduces an additional source to consult for context or parallel requirements. (Note)","The AD prescribes a single remedial route and does not set out alternatives or administrative exceptions within its text, so any deviation requires separate regulatory action. (Requirement; Compliance)"],"plain_english_summary":"This directive mandates that owners/operators of the specifically listed BAe‑125 series aeroplanes install the EFIS power‑supply modification exactly per British Aerospace Service Bulletin 24‑248‑(3024), to address a reported heat‑sink diode overheat. Work must be done and paid for by the owners before 31 October 1985; technical execution follows the manufacturer’s bulletin and alternatives require separate approval."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hs-125-70-efis-power-supply","history":"/api/acts/ad-hs-125-70-efis-power-supply/history","analysis":"/api/acts/ad-hs-125-70-efis-power-supply/analysis","conflicts":"/api/acts/ad-hs-125-70-efis-power-supply/conflicts","importantCases":"/api/acts/ad-hs-125-70-efis-power-supply/important-cases","documents":"/api/acts/ad-hs-125-70-efis-power-supply/documents"}}