{"id":"F2006B04718","name":"AD/BELL 47/97 - Main Rotor Flight Control System Bolts","slug":"ad-bell-47-97-main-rotor-flight-control-system-bolts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44482,"registerId":"commonwealth-F2006B04718-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 47/97 - 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 47 (All Variants) Series Helicopters\n\n \n\nAD/BELL 47/97 Main Rotor Flight Control System Bolts 2/90\n\nApplicability: All models.\n\n \n\nRequirement: Action in accordance with Bell Alert Service Bulletin No 47-89-16.\n\n \n\nCompliance: At the next scheduled inspection for issue of a Maintenance Release after 30 March 1990 or by 30 June 1990, 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\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-bound safety directive targeting a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original purpose of mandating bolt inspections."},"complexity_factors":["Very short document (under 200 words)","Only 4 operative paragraphs (Applicability, Requirement, Compliance, Background)","Zero defined terms or interpretation sections","Single cross-reference to external technical document (Bell Service Bulletin)","Simple conditional logic: 'whichever occurs first' date calculation","No nested exceptions or sub-paragraphs"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:** It requires owners and operators of **Bell 47 series helicopters** (all models) to inspect the bolts in the main rotor flight control system. These bolts are critical — they connect the pilot's control inputs to the spinning main rotor blades. If they fail, the pilot loses control of the helicopter.\n\n**Why it matters:** Bell (the manufacturer) discovered that some of these bolts were corroding, wearing down, or developing damage from rubbing (\"fretting\"). This could lead to bolt failure and catastrophic loss of control.\n\n**What must be done:**\n- **Initial inspection:** Must be completed by the earlier of either (a) the next scheduled maintenance check after 30 March 1990, or (b) 30 June 1990.\n- **Ongoing checks:** Re-inspect every 24 months thereafter.\n- **How:** Follow the specific procedures in Bell Alert Service Bulletin No. 47-89-16.\n\n**Who it affects:** Anyone who owns, operates, or maintains Bell 47 helicopters in Australia — including training schools, private owners, and commercial operators."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive does not change scope from its stated original intent in the text: it applies to all Bell 47 models and mandates inspections and reinspections to address identified corrosion, fretting and wear on rotating control bolts. The instrument delegates technical detail to Bell Alert Service Bulletin No 47-89-16 and establishes initial and recurring compliance timing (Applicability; Requirement; Compliance; Background)."},"complexity_factors":["Broad applicability to all Bell 47 variants increases the number of affected operators.","Mandates adherence to an external technical document (Bell Alert Service Bulletin No 47-89-16) rather than specifying procedures in the directive itself.","Compliance timing uses two conditional triggers (next scheduled Maintenance Release after 30 March 1990 OR by 30 June 1990) which requires operators to check their maintenance schedules.","Requires recurring inspections at fixed calendar intervals (every 24 months), creating ongoing obligations.","Implementation and enforcement rest on coordination between operators, maintenance providers and the regulator under the airworthiness directive regime."],"plain_english_summary":"This airworthiness directive requires operators of all Bell 47 helicopters to inspect main-rotor flight-control system bolts following Bell Alert Service Bulletin No. 47-89-16. Initial inspections are due at the next Maintenance Release after 30 March 1990 or by 30 June 1990 (whichever is earlier), then at intervals not exceeding 24 months.\n\nIt matters because corrosion, fretting or excessive wear has been found on rotating control bolts; operators/owners must arrange, fund and document inspections and any corrective work."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-47-97-main-rotor-flight-control-system-bolts","history":"/api/acts/ad-bell-47-97-main-rotor-flight-control-system-bolts/history","analysis":"/api/acts/ad-bell-47-97-main-rotor-flight-control-system-bolts/analysis","conflicts":"/api/acts/ad-bell-47-97-main-rotor-flight-control-system-bolts/conflicts","importantCases":"/api/acts/ad-bell-47-97-main-rotor-flight-control-system-bolts/important-cases","documents":"/api/acts/ad-bell-47-97-main-rotor-flight-control-system-bolts/documents"}}