{"id":"F2006B04653","name":"AD/BELL 412/19 - Emergency DC Bus Number One Feeder Circuit","slug":"ad-bell-412-19-emergency-dc-bus-number-one-feeder-circuit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44405,"registerId":"commonwealth-F2006B04653-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 412/19 - Emergency DC Bus Number One Feeder Circuit","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)  Bell Helicopter Textron 412 Series Helicopters\n\n \n\nAD/BELL 412/19 Emergency DC Bus Number One Feeder Circuit 3/88\n\nApplicability: All model Bell 412 and 412NB helicopters S/No 33108 to 33139 inclusive, and 33150 to 33154 inclusive.\n\n \n\nRequirement: Action in accordance with Bell ASB 412-87-33 dated 1 December 1987.\n\n \n\nCompliance: Within 100 hours time in service after 24 March 1988, or at the next scheduled inspection for Maintenance Release issue after 24 March 1988 whichever is the latter.\n\n \n\nBackground:  Bell have advised that Model 412 emergency and essential buses are configured such that a short circuit on essential bus number 2 will cause both emergency bus 50 amp feeder circuit breakers to open thus removing all power from the emergency bus.\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":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1886},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This airworthiness directive maintains its original narrow technical scope as a targeted safety intervention for a specific electrical fault. It has not expanded beyond its original purpose of mandating corrective action for the identified emergency DC bus feeder circuit defect in the specified helicopter models."},"complexity_factors":["Single operative requirement referencing one external technical standard (Bell ASB 412-87-33)","Narrow applicability restricted to specific aircraft serial number ranges","No definitions section, conditional logic, or nested exceptions","Linear structure with clear, unambiguous compliance deadline"],"plain_english_summary":"This Airworthiness Directive mandates owners/operators of Bell 412 and 412NB helicopters (S/N 33108–33139 and 33150–33154) to inspect/repair a wiring defect that can cause a short in essential bus No.2 and trip both emergency circuit breakers, cutting all emergency power. Compliance must follow Bell ASB 412-87-33 and be done within 100 flight hours after 24 Mar 1988 or at the next scheduled inspection, whichever is later."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-412-19-emergency-dc-bus-number-one-feeder-circuit","history":"/api/acts/ad-bell-412-19-emergency-dc-bus-number-one-feeder-circuit/history","analysis":"/api/acts/ad-bell-412-19-emergency-dc-bus-number-one-feeder-circuit/analysis","conflicts":"/api/acts/ad-bell-412-19-emergency-dc-bus-number-one-feeder-circuit/conflicts","importantCases":"/api/acts/ad-bell-412-19-emergency-dc-bus-number-one-feeder-circuit/important-cases","documents":"/api/acts/ad-bell-412-19-emergency-dc-bus-number-one-feeder-circuit/documents"}}