{"id":"F2006B04500","name":"AD/BELL 206/44 - Rotor Brake Disc Assembly P/N 4000071 - Inspection and Modification","slug":"ad-bell-206-44-rotor-brake-disc-assembly-p-n-4000071-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114196,"registerId":"commonwealth-F2006B04500-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 206/44 - Rotor Brake Disc Assembly P/N 4000071 - Inspection and Modification","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\n# AD/BELL 206/44 Rotor Brake Disc Assembly\n\nP/N 4000071 - Inspection and Modification\n\nApplicability: All models fitted with rotor brake kit P/N 206-706-032-1. Document:  Bell SB No. 206-50-73-2.\n\n# 5/73\n\nCompliance: 1. For Part 1 of SB 206-50-73-2 For helicopters estimated to have had 300 or more rotor brake stops - within the next 25 rotor brake applications after 19 April 1973. For helicopters estimated to have had less than 300 rotor brake stops - prior to 325 rotor brake stops.\n\n \n\n2. For Part 2 of SB 206-50-73-2: At intervals not exceeding 300 hours time in service.\n\n \n\nBackground: AD/Agusta 206/33 equivalent.\n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The text sets a clear, narrow scope: it applies only to 206-series helicopters fitted with rotor brake kit P/N 206-706-032-1 and imposes inspections/modifications as described in Bell SB No. 206-50-73-2 (Applicability; Document; Compliance). The instrument itself contains no material indicating the scope was broadened or narrowed relative to an earlier version; therefore there is no evidence in the provided text that the scope has changed from any prior intent."},"complexity_factors":["Reliance on an external manufacturer service bulletin (Bell SB No. 206-50-73-2) for the technical steps (Document).","Two distinct compliance triggers: a historical/usage-based trigger using rotor brake application counts (with an explicit estimation element) and a recurring hours-in-service interval (Compliance: 1–2).","The need to estimate historical rotor brake stops where records are lacking ('estimated to have had 300 or more rotor brake stops') creates interpretive and recordkeeping uncertainty (Compliance: 1).","A vintage date-based immediate compliance window (actions within 25 rotor brake applications after 19 April 1973) introduces an unusual temporal compliance rule (Compliance: 1).","Narrow applicability keyed to a specific kit part number requires operators to identify configuration status precisely (Applicability)."],"plain_english_summary":"- What this instrument does mechanically\n  - It requires inspection and, where the Bell service bulletin prescribes it, modification of the rotor brake disc assembly part number (P/N) 4000071 on affected helicopters. The mandatory procedures are those set out in Bell Service Bulletin No. 206-50-73-2 (referred to in the AD) (Applicability; Document).\n  - It applies to every Bell/Agusta Bell 206 series helicopter that is fitted with rotor brake kit P/N 206-706-032-1 (Applicability).\n\n- When and how often the required work must be done\n  - Part 1 of the service bulletin: for helicopters estimated to have had 300 or more rotor brake stops, the inspection/modification must be done within the next 25 rotor brake applications after 19 April 1973. For helicopters estimated to have had fewer than 300 rotor brake stops, the work must be done before the helicopter reaches 325 rotor brake stops (Compliance: 1).\n  - Part 2 of the service bulletin: inspections (and any work that part requires) must be repeated at intervals not exceeding 300 hours time in service (Compliance: 2).\n\n- Source-stated background and authority\n  - This airworthiness directive is listed under the Civil Aviation Safety Authority schedule of Airworthiness Directives and cites an equivalent AD for Agusta (Background).\n\n- Who is directly affected and who must act\n  - The specified owners/operators/maintenance organisations of any 206-series helicopter fitted with rotor brake kit P/N 206-706-032-1 must follow the Bell service bulletin and meet the timing requirements set out above (Applicability; Compliance).\n  - The detailed technical steps to be followed are in Bell SB No. 206-50-73-2 (Document).\n\n- Implementation, incentives and practical trade-offs (source-grounded observations)\n  - The AD creates mandatory timing obligations tied to two different accounting methods: counting rotor brake applications (including an historical estimate threshold of 300 stops) and tracking hours-in-service (Compliance: 1–2). Operators therefore need accurate records or an estimation method to establish which compliance path applies.\n  - The requirement to act “within the next 25 rotor brake applications” after a specified date for helicopters with an estimated ≥300 stops (Compliance: 1) introduces a practical need to estimate past rotor brake usage; that estimation is the explicit mechanism the AD uses to determine the immediate compliance window.\n  - The AD delegates the technical content of the inspection and modification to the manufacturer’s service bulletin (Document). Compliance therefore requires access to and implementation of the SB’s procedures.\n  - The AD establishes recurring inspection frequency for Part 2 of the SB (every 300 hours TIS) (Compliance: 2). This creates an ongoing maintenance scheduling obligation.\n\n- Compliance burden and discretion points (source-grounded)\n  - Operators must estimate past rotor brake stops where records are incomplete because the compliance trigger in Part 1 is phrased around an estimate of ‘‘300 or more rotor brake stops’’ (Compliance: 1). That phrasing creates potential variability in how operators determine the immediate compliance deadline.\n  - The directive refers to an external technical document (Bell SB No. 206-50-73-2) for the detailed procedures (Document). Determinations about parts, tooling, or whether a modification is required depend on the SB’s content, not the AD text itself; therefore compliance requires reliance on that SB.\n\n- Concentration of effects and likely distribution of burdens\n  - The AD targets a specific fitted configuration (rotor brake kit P/N 206-706-032-1). The population affected is therefore narrowly defined by that configuration (Applicability).\n  - The timing rules (immediate application window tied to past usage versus a repeating hours-based interval) concentrate an immediate compliance burden on helicopters that meet or are estimated to meet the 300-stop threshold (Compliance: 1).\n\n- Official rationale as stated in the instrument\n  - The document lists a related Agusta AD as equivalent in the background note (Background). The AD itself prescribes inspection/modification actions; the detailed reasons and technical justification for those actions are set out in the referenced service bulletin (Document).\n\n- Key citations to the instrument text\n  - Applicability: All models fitted with rotor brake kit P/N 206-706-032-1 (Applicability).\n  - Document specifying required procedures: Bell SB No. 206-50-73-2 (Document).\n  - Compliance timing: Part 1 (based on estimated rotor brake stops and a 19 April 1973 reference date) and Part 2 (every 300 hours TIS) (Compliance: 1–2).\n  - Background reference: AD/Agusta 206/33 equivalent (Background)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused on a specific mechanical component. It has not expanded beyond its original purpose of addressing a known defect in the rotor brake disc assembly."},"complexity_factors":["Very short document (under 300 words)","Only 1 defined term implicitly referenced (the part number)","Simple conditional logic based on estimated brake stop counts","No cross-references to other legislation beyond a single service bulletin","Clear, unambiguous compliance deadlines","Single applicability criterion (specific rotor brake kit part number)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It applies to specific **Bell 206 series helicopters** that have a particular rotor brake kit installed.\n\n**What it requires:**\n- **Inspection and modification** of a rotor brake disc assembly (part number 4000071) to prevent potential failures.\n- **Two-part compliance:**\n  1. **Immediate action:** Helicopters with heavy use (300+ brake stops) must be inspected within the next 25 brake applications after 19 April 1973. Those with lighter use must be inspected before reaching 325 total brake stops.\n  2. **Ongoing maintenance:** Repeat inspections every 300 hours of flight time.\n\n**Who it affects:**\n- Owners and operators of Bell 206 and Agusta Bell 206 helicopters fitted with rotor brake kit P/N 206-706-032-1.\n\n**Why it matters:**\nRotor brake failures can cause loss of braking control, creating serious safety risks during ground operations. This AD mandates specific maintenance to prevent accidents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-206-44-rotor-brake-disc-assembly-p-n-4000071-inspection-and-modification","history":"/api/acts/ad-bell-206-44-rotor-brake-disc-assembly-p-n-4000071-inspection-and-modification/history","analysis":"/api/acts/ad-bell-206-44-rotor-brake-disc-assembly-p-n-4000071-inspection-and-modification/analysis","conflicts":"/api/acts/ad-bell-206-44-rotor-brake-disc-assembly-p-n-4000071-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-bell-206-44-rotor-brake-disc-assembly-p-n-4000071-inspection-and-modification/important-cases","documents":"/api/acts/ad-bell-206-44-rotor-brake-disc-assembly-p-n-4000071-inspection-and-modification/documents"}}