{"id":"F2006B04660","name":"AD/BELL 412/25 - Main Rotor Flight Control System Bolts","slug":"ad-bell-412-25-main-rotor-flight-control-system-bolts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44412,"registerId":"commonwealth-F2006B04660-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 412/25 - Main Rotor Flight Control System Bolts","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 412/25 Main Rotor Flight Control System Bolts 10/89\n\nDM\n\n \n\nApplicability: All model 412 series.\n\nRequirement: Action in accordance with Bell Alert Service Bulletin No 412-89-45. Compliance:  At next scheduled inspection for issue of a Maintenance Release after 20 August\n\n1989, or by 20 October 1989, whichever occurs first. Thereafter, reinspect at intervals not exceeding 24 months calendar time.\n\n \n\nBackground: Bell have advised that some of the rotating control bolts have been found corroded, fretting and/or with excessive wear on the bolt shank.\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":1632},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive remains tightly focused on its original purpose: addressing a specific safety defect (corroded/worn bolts) in the main rotor flight control system of Bell 412 helicopters. No expansion of scope beyond this specific mechanical issue is evident."},"complexity_factors":["Single, short requirement spanning just a few paragraphs","Only one external reference to a manufacturer service bulletin","Simple compliance date calculation (whichever of two dates occurs first)","No defined terms, interpretation sections, or nested conditions"],"plain_english_summary":"This is a mandatory safety directive (called an **Airworthiness Directive**) for owners and operators of **Bell 412 series helicopters**.\n\n**What it does:**\nIt requires inspection of the bolts in the main rotor flight control system — the critical components that connect the rotating controls allowing the pilot to steer the helicopter.\n\n**Why it matters:**\nThe manufacturer found some of these bolts were corroded, worn down, or damaged from rubbing (called \"fretting\"). If these bolts fail, the pilot could lose control of the main rotor, creating a serious risk of crash.\n\n**What must be done:**\nOperators must follow the instructions in **Bell Alert Service Bulletin No 412-89-45** to inspect these bolts. This inspection must happen at the next scheduled maintenance check after 20 August 1989, or by 20 October 1989 at the latest — whichever comes first. After that, the bolts must be reinspected every 24 months (2 years)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-412-25-main-rotor-flight-control-system-bolts","history":"/api/acts/ad-bell-412-25-main-rotor-flight-control-system-bolts/history","analysis":"/api/acts/ad-bell-412-25-main-rotor-flight-control-system-bolts/analysis","conflicts":"/api/acts/ad-bell-412-25-main-rotor-flight-control-system-bolts/conflicts","importantCases":"/api/acts/ad-bell-412-25-main-rotor-flight-control-system-bolts/important-cases","documents":"/api/acts/ad-bell-412-25-main-rotor-flight-control-system-bolts/documents"}}