{"id":"F2006B04497","name":"AD/BELL 206/41 - Vertical Fin - Inspection","slug":"ad-bell-206-41-vertical-fin-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114191,"registerId":"commonwealth-F2006B04497-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 206/41 - Vertical Fin - Inspection","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 Canada (BHTC) 206 and Agusta Bell 206 Series Helicopters\n\n \n\nAD/BELL 206/41 Vertical Fin - Inspection 2/73\n\nApplicability: All models with S/Nos. detailed in requirement documents with vertical fin P/N 206-020-113-5, -7 or -9.\n\n \n\nDocument: Bell SB No. 206-01-73-1, or Agusta SB No. BT206-57.\n\n \n\nCompliance: Within 25 hours time in service after 8 January 1973, and thereafter at intervals not exceeding 25 hours time in service until incorporation of Bell SL No. 206-203.\n\n \n\nBackground: AD/Agusta 206/29 equivalent.\n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive applies to the specified helicopters and part numbers as set out in the requirement documents and prescribes inspections at 25-hour intervals until incorporation of Bell SL No. 206-203 (Applicability; Compliance). The document states it is equivalent to a prior Agusta AD (Background), and the directive itself does not indicate a change in scope from that prior action."},"complexity_factors":["Narrow, well-specified applicability (serial numbers listed in requirement documents and specific vertical fin part numbers) reduces ambiguity (Applicability).","Mandatory short inspection interval (25 hours time-in-service) creates operational frequency and scheduling complexity (Compliance).","Compliance is dependent on following external technical documents (Bell SB 206-01-73-1 or Agusta SB BT206-57), adding a cross-reference complexity (Document).","A single terminating action (incorporation of Bell SL No. 206-203) changes the compliance regime, requiring tracking of modification status (Compliance).","Reference to an equivalent earlier directive (AD/Agusta 206/29) requires understanding of continuity but does not itself add procedural complexity (Background)."],"plain_english_summary":"# What this directive requires, in plain terms\n\n- Mechanically, this airworthiness directive orders regular inspections of the vertical fin on certain Bell/Agusta Bell 206 series helicopters. It applies only to helicopters whose serial numbers are listed in the requirement documents and which have vertical fin part number 206-020-113-5, -7 or -9 (Applicability). \n\n- The inspection procedure to be used is set out in either Bell Service Bulletin No. 206-01-73-1 or Agusta Service Bulletin No. BT206-57 (Document). \n\n- The inspections must start within 25 hours time-in-service after 8 January 1973 and must be repeated at intervals not exceeding 25 hours time-in-service, until the operator has incorporated Bell Service Letter No. 206-203, after which these repeated inspections are no longer required (Compliance). \n\n- The directive notes that it is equivalent to a prior Agusta directive (Background: \"AD/Agusta 206/29 equivalent\").\n\nWho is affected and who decides\n\n- Affected parties: Owners and operators of the specified Bell/Agusta Bell 206 helicopters that have the listed vertical fin part numbers and are listed by serial number in the requirement documents (Applicability). \n\n- Decision-making and authority: The Civil Aviation Safety Authority (as issuer of the Schedule of Airworthiness Directives under the Civil Aviation Regulations) sets the compliance requirement; the technical steps to comply are set out in the referenced service bulletins (Document). \n\nWho pays and what behaviour changes\n\n- Payment: Owners/operators pay the costs of performing the inspections and any repair or replacement work discovered by those inspections (Compliance). \n\n- Behaviour change required: Operators must schedule and perform a recurring inspection every 25 hours time-in-service until they incorporate Bell SL No. 206-203. Incorporating Bell SL No. 206-203 is the one specified action that ends the recurring-inspection requirement (Compliance). \n\nWhy the directive exists (official claim) and how that interacts with costs and incentives\n\n- Official claim in the document: the directive references an equivalent prior AD (Background), which implies the measure aligns with or continues an earlier airworthiness action.\n\n- Costs and incentives: Requiring inspections every 25 flight hours imposes recurring labour and downtime costs on operators; those costs create an incentive for operators to adopt the terminating action (incorporate Bell SL No. 206-203) if that action is practicable and less costly over time (Compliance). The directive concentrates direct costs on the helicopter owners/operators and concentrates the procedural authority (what must be done and when) in the issuing authority and the referenced service bulletins (Applicability; Document; Compliance).\n\nCompliance burden, discretion and implementation risk\n\n- Compliance burden: Frequent inspections at a 25-hour interval can reduce availability of affected aircraft and increase maintenance workload and parts/repair costs for owners/operators (Compliance).\n\n- Discretion: The directive specifies the inspection time interval and the service documents to follow; it leaves operational discretion to owners/operators only in how they schedule and perform the mandated inspections and whether/when to incorporate Bell SL No. 206-203 to terminate the recurring inspections (Document; Compliance). \n\n- Implementation risk and trade-offs: The main operational trade-off is between allocating recurring resources to inspections versus taking the terminating action. There is an opportunity cost in aircraft downtime and maintenance resources while inspections continue. The directive references an equivalent prior AD (Background), indicating continuity with earlier requirements rather than a change in underlying technical approach.\n\nKey references from the directive: Applicability (which aircraft/parts are in scope); Document (which service bulletins to use); Compliance (timing, intervals and terminating action); Background (relationship to prior AD)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a vintage 1973 Airworthiness Directive that has remained focused on its original narrow purpose: inspecting specific vertical fin part numbers on Bell 206 helicopters. There is no evidence of scope creep; it addresses exactly one safety issue with precise applicability criteria."},"complexity_factors":["Single, specific maintenance task (visual inspection of one component)","Only 3 part numbers in applicability clause","Simple compliance timeline: 25 hours initial, then 25-hour recurring intervals","Clear termination condition (incorporation of Bell SL 206-203)","No nested exceptions, conditional logic, or cross-references to other legislation","References only 2 technical documents (service bulletins)","Extremely short text (under 150 words of substantive content)"],"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) under the Civil Aviation Regulations 1998.\n\n**What it does:** It requires owners and operators of specific Bell 206 series helicopters to **inspect the vertical fin** (the tall tail section that stabilises the helicopter) for defects.\n\n**Who it affects:** All Bell Helicopter Textron Canada (BHTC) 206 and Agusta Bell 206 helicopters with specific serial numbers and vertical fin part numbers ending in -113-5, -7, or -9.\n\n**What must be done:**\n- **First inspection:** Within 25 hours of flying time after 8 January 1973\n- **Repeat inspections:** Every 25 hours of flying time thereafter\n- **When it stops:** Once a specific service letter (Bell SL No. 206-203) is incorporated into the aircraft\n\n**Why it matters:** This AD addresses a safety-critical structural issue. The vertical fin is essential for helicopter stability and control. Repeated inspections ensure cracks or defects are caught before they cause catastrophic failure.\n\n**Key documents referenced:** Operators must follow the procedures in Bell Service Bulletin 206-01-73-1 or Agusta Service Bulletin BT206-57."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-206-41-vertical-fin-inspection","history":"/api/acts/ad-bell-206-41-vertical-fin-inspection/history","analysis":"/api/acts/ad-bell-206-41-vertical-fin-inspection/analysis","conflicts":"/api/acts/ad-bell-206-41-vertical-fin-inspection/conflicts","importantCases":"/api/acts/ad-bell-206-41-vertical-fin-inspection/important-cases","documents":"/api/acts/ad-bell-206-41-vertical-fin-inspection/documents"}}