{"id":"F2006B03501","name":"AD/BAe 146/50 - Generator Control Unit","slug":"ad-bae-146-50-generator-control-unit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43055,"registerId":"commonwealth-F2006B03501-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BAe 146/50 - Generator Control Unit","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBritish Aerospace BAe 146 Series Aeroplanes\n\nAD/BAe 146/50 Generator Control Unit 8/94\n\nApplicability: All series BAe 146 aircraft.\n\nRequirement: Action in accordance with Avro International Aerospace Mandatory Inspection Service Bulletin S.B.24-103 dated 24 March 1994.\n\nNote: CAA(UK) AD 014-03-94 refers.\n\nCompliance: Prior to 30 November 1994.\n\nBackground: The CAA(UK) have advised that investigation of in-service generator control unit (GCU) failures has highlighted the possibility that GCUs repaired or rectified by workshops other than GEC-Marconi, may have the under-frequency trip level set too high. This Directive requires the one time inspection of GCUs for possible incorrect under-frequency trip level settings and, if necessary, adjustment of the settings. The CAA(UK) compliance time is extended by two calendar months.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-limited airworthiness directive with a narrow, specific safety purpose. It has not expanded beyond its original intent — it addresses a single identified defect in a specific aircraft component and requires a one-time inspection. The scope remains tightly constrained to BAe 146 GCUs with the identified repair history issue."},"complexity_factors":["Single, specific technical requirement referencing an external manufacturer bulletin","No defined terms section — uses plain technical language (GCU, under-frequency trip level)","No nested exceptions or conditional logic — straightforward applicability ('All series BAe 146 aircraft')","Single compliance date with simple extension note","Short document (approximately 150 words) with clear structure: Applicability, Requirement, Note, Compliance, Background"],"plain_english_summary":"This is an **airworthiness directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific maintenance action on certain aircraft.\n\n**What it does:**\n- Requires owners and operators of **British Aerospace BAe 146 series aircraft** to inspect their **generator control units (GCUs)** — the electronic systems that manage electrical power generation on the plane.\n- The inspection must follow a specific technical bulletin from the manufacturer (Avro International Aerospace Service Bulletin S.B.24-103).\n- If the inspection finds the under-frequency trip level is set incorrectly (too high), it must be adjusted.\n\n**Why it matters:**\n- The UK aviation authority discovered that GCUs repaired by unauthorised workshops (not GEC-Marconi) might have a safety-critical setting wrong. If the under-frequency trip level is too high, the generator might not shut down properly during an electrical fault, potentially causing power system failures or fire risks.\n- This directive prevents that risk by forcing a one-time inspection and correction.\n\n**Who must comply:**\n- All operators of BAe 146 aircraft in Australia.\n- **Deadline:** Before 30 November 1994 (Australia allowed two extra months compared to the UK's deadline).\n\n**Key point:** This is a **retrospective safety fix** — it applies to existing aircraft and repairs already done, not just new manufacturing."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive implements the original, stated intent: a one-time inspection and, if necessary, adjustment of GCU under-frequency trip settings on BAe 146 aircraft. Applicability (all BAe 146 series), the required action (follow Avro S.B.24-103), and the compliance deadline (prior to 30 November 1994) are consistent with the stated background concern about incorrect settings on units repaired by non-GEC-Marconi workshops; there is no indication in the text that the scope was broadened or narrowed from that intent (Applicability; Requirement; Compliance; Background)."},"complexity_factors":["Single, one-time technical action mandated (inspection and adjustment) rather than ongoing regulatory regime (Requirement).","Applicability to a defined fleet only (all BAe 146 series aircraft) keeps scope narrow (Applicability).","Reliance on an external technical document (Avro S.B.24-103) for procedural detail increases operational dependency on that bulletin (Requirement).","Fixed compliance date creates a time-pressure implementation constraint (Compliance).","Technical identification of affected units may require tracing prior repairs by third-party workshops, adding administrative effort (Background)."],"plain_english_summary":"Owners and operators of British Aerospace BAe 146 aircraft must arrange and pay for a one‑time inspection of generator control units (GCUs) and, if needed, adjust the under‑frequency trip setting per Avro International Aerospace Mandatory Inspection Service Bulletin S.B.24‑103. The measure, to be completed by 30 November 1994, responds to CAA findings that GCUs repaired by non‑GEC–Marconi workshops may have incorrect trip levels and aims to reduce related in‑service failures."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-50-generator-control-unit","history":"/api/acts/ad-bae-146-50-generator-control-unit/history","analysis":"/api/acts/ad-bae-146-50-generator-control-unit/analysis","conflicts":"/api/acts/ad-bae-146-50-generator-control-unit/conflicts","importantCases":"/api/acts/ad-bae-146-50-generator-control-unit/important-cases","documents":"/api/acts/ad-bae-146-50-generator-control-unit/documents"}}