{"id":"F2006B03488","name":"AD/BAe 146/38 - Generator Control Unit (GCU) Replacement","slug":"ad-bae-146-38-generator-control-unit-gcu-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43042,"registerId":"commonwealth-F2006B03488-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BAe 146/38 - Generator Control Unit (GCU) Replacement","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 146/38 Generator Control Unit (GCU) Replacement 1/92\n\nTX\n\n \n\nApplicability: As specified in the requirement document.\n\n \n\nRequirement: Action in accordance with BAe 146 Mandatory Alert Service Bulletin 24-A97. Compliance:              Prior to 17 November 1991.\n\nBackground: BAe have advised that failure of affected GCUs to detect a single phase feeder line open circuit may lead to inaccurate instrument readings.\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\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-limited safety directive focused on a specific technical defect in a specific aircraft type. It has not expanded beyond its original purpose of mandating GCU replacement to prevent instrument reading errors."},"complexity_factors":["Very short document (under 200 words)","Only 1 substantive requirement with a single compliance action","No defined terms section — relies entirely on external technical reference (Service Bulletin 24-A97)","No conditional logic, exceptions, or nested provisions","Single applicability criterion referencing an external document","Straightforward deadline-based compliance (fixed date, not flight hours or cycles)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially 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 replace certain **Generator Control Units (GCUs)** — the electronic boxes that manage electrical power from the aircraft's generators.\n\n**Why it matters:**\nThe manufacturer (BAe) discovered that some GCUs could fail to detect a specific electrical fault (a \"single phase feeder line open circuit\"). If this happens, the aircraft's instruments might display **inaccurate readings**, potentially misleading pilots about the plane's electrical or engine status. This creates a safety risk during flight.\n\n**Who must act:**\nAnyone operating BAe 146 aircraft covered by the referenced technical document (BAe 146 Mandatory Alert Service Bulletin 24-A97).\n\n**What they must do:**\nReplace the faulty GCUs **before 17 November 1991** (the compliance deadline has long passed, meaning this AD applied to historical operations)."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The text sets out a single, targeted requirement: replacement of affected GCUs according to BAe Mandatory Alert Service Bulletin 24-A97, with applicability defined in the requirement document and a fixed compliance date. Nothing in the AD text indicates a change of scope from that stated purpose (replacement to address failure to detect single phase feeder line open circuits) or an expansion beyond the manufacturer-identified affected units (Applicability; Requirement; Background; Compliance)."},"complexity_factors":["Single, discrete mandatory action (GCU replacement) with one compliance deadline (Compliance).","Applicability left to an external requirement document rather than fully specified in the AD (Applicability), requiring operators to consult additional material to determine if they are affected.","Technical method and details delegated to an external manufacturer’s Mandatory Alert Service Bulletin (Requirement), creating dependency on that document.","No alternative compliance routes or exemptions stated in the AD text; limited regulator discretion in the text (Requirement).","Short timeframe context (date already in past in this text) but deadline is explicit, simplifying enforcement (Compliance)."],"plain_english_summary":"This AD mandates replacement of certain Generator Control Units on affected BAe 146 series aircraft, to be carried out per BAe 146 Mandatory Alert Service Bulletin 24‑A97 and completed by 17 November 1991. It targets operators/owners of aircraft within the AD’s applicability because the GCUs may fail to detect a single‑phase feeder open circuit, risking inaccurate instrument readings. Compliance requires parts, maintenance time and associated downtime."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-38-generator-control-unit-gcu-replacement","history":"/api/acts/ad-bae-146-38-generator-control-unit-gcu-replacement/history","analysis":"/api/acts/ad-bae-146-38-generator-control-unit-gcu-replacement/analysis","conflicts":"/api/acts/ad-bae-146-38-generator-control-unit-gcu-replacement/conflicts","importantCases":"/api/acts/ad-bae-146-38-generator-control-unit-gcu-replacement/important-cases","documents":"/api/acts/ad-bae-146-38-generator-control-unit-gcu-replacement/documents"}}