{"id":"F2006B03497","name":"AD/BAe 146/46 Amdt 1 - Generator Control Unit","slug":"ad-bae-146-46-amdt-1-generator-control-unit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43051,"registerId":"commonwealth-F2006B03497-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BAe 146/46 Amdt 1 - 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 146/46\n\nAmdt 1\n\n  \nGenerator Control Unit 6/93\n\nApplicability: BAe 146 Series 100/100A, 200/200A and 300/300A aircraft identified in British Aerospace Regional Aircraft Limited Service Bulletin SB.24-91-70488B&C dated 28 January 1993.\n\nRequirement: Action in accordance with British Aerospace Regional Aircraft Limited Mandatory Service Bulletin SB.24-91-70488B&C dated 28 January 1993.\n\nNote: CAA(UK) AD 023-01-93 refers.\n\nCompliance: Prior to 1 March 1996.\n\nBackground: The aircraft manufacturer has established that a single phase fault current between 175 amps and 270 amps can activate the GCU undervoltage protection circuit rather than the overcurrent protection circuit resulting in the sequential loss of each main generator since the auto transfer circuit is not inhibited on undervoltage. Compliance with this Directive will decrease the probability of sequential generator loss.\n\nThis amendment aligns the requirements with those of the country of origin’s Airworthiness Directive.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment maintains the original scope — ensuring electrical system safety in BAe 146 aircraft. The amendment merely aligns Australian requirements with the UK country-of-origin directive without expanding the aircraft types affected, the nature of the defect addressed, or the required corrective action."},"complexity_factors":["Very short document (under 300 words)","Only 1 defined term implicitly referenced (the Service Bulletin)","No nested conditional logic — single straightforward compliance requirement","Single cross-reference to UK aviation authority (CAA(UK) AD 023-01-93)","Clear, unambiguous applicability criteria (specific aircraft series and specific service bulletin)","Single compliance deadline with no exceptions or alternative methods of compliance stated"],"plain_english_summary":"This CASA Airworthiness Directive orders owners/operators of BAe 146 Series 100/200/300 aircraft (per the Jan 1993 British Aerospace service bulletin) to repair a Generator Control Unit fault that can misinterpret 175–270 A overcurrent as low-voltage, causing sequential loss of main generators and potential total electrical failure. \n\nWork must follow SB.24-91-70488B&C before 1 March 1996. Amendment 1 aligns requirements with the UK regulator."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment aligns the Australian requirements with the United Kingdom Airworthiness Directive but does not expand the set of affected aircraft or add obligations beyond requiring compliance with the referenced Mandatory Service Bulletin by the stated deadline. The core requirement remains: perform the SB actions to address the specified GCU fault behaviour."},"complexity_factors":["Narrow applicability tied to specified BAe 146 Series aircraft identified in Mandatory Service Bulletin SB.24‑91‑70488B&C — operators must determine affected airframes.","Technical remedy affecting the Generator Control Unit to change protection behaviour (addresses single‑phase fault currents between 175 A and 270 A).","Mandated compliance with a manufacturer’s Mandatory Service Bulletin — requires certified maintenance action and possible parts or adjustments.","Hard compliance deadline (prior to 1 March 1996) imposing scheduling and operational constraints.","Cross‑jurisdictional alignment with the country of origin’s AD (CAA(UK) AD 023‑01‑93), requiring harmonisation of recordkeeping and compliance evidence."],"plain_english_summary":"This directive requires operators of certain BAe 146 Series 100/200/300 aircraft to carry out the generator control unit work described in British Aerospace Mandatory Service Bulletin SB.24‑91‑70488B&C. The work must be completed before 1 March 1996. It is intended to stop specific single‑phase fault currents (175–270 A) from causing the GCU’s undervoltage protection to disable generators sequentially. Aircraft operators and their maintenance organisations must arrange and pay for the mandated actions."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-46-amdt-1-generator-control-unit","history":"/api/acts/ad-bae-146-46-amdt-1-generator-control-unit/history","analysis":"/api/acts/ad-bae-146-46-amdt-1-generator-control-unit/analysis","conflicts":"/api/acts/ad-bae-146-46-amdt-1-generator-control-unit/conflicts","importantCases":"/api/acts/ad-bae-146-46-amdt-1-generator-control-unit/important-cases","documents":"/api/acts/ad-bae-146-46-amdt-1-generator-control-unit/documents"}}