{"id":"F2006B04397","name":"AD/BELL 205/60 - Tail Rotor Driveshaft Hangar Bearings","slug":"ad-bell-205-60-tail-rotor-driveshaft-hangar-bearings","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44222,"registerId":"commonwealth-F2006B04397-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 205/60 - Tail Rotor Driveshaft Hangar Bearings","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\nBell Helicopter Textron 205 Series Helicopters\n\n \n\nAD/BELL 205/60 Tail Rotor Driveshaft Hangar Bearings 1/92\n\nApplicability: All models 205A and 205A-1 fitted with tail rotor driveshaft bearings P/N 204-040- 623-003 with S/N prefixed with either “T” or “N” prior to N4000 and all -005 bearings with a S/N prefix “T” or “N”.\n\n \n\nRequirement: Action in accordance with Bell Alert Service Bulletin 205-91-43 Revision A.\n\n \n\nNote: FAA Priority Letter AD 91-24-16 refers.\n\n \n\nCompliance: Daily before first flight of the day after 12 January 1992.\n\n \n\nBackground: A daily inspection of the tail rotor driveshaft bearings has been found necessary following a fatal accident which revealed the possibility of a production batch problem with these bearings.\n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD sets a narrow, clearly described requirement: daily inspections of specified tail-rotor driveshaft bearings on certain Bell 205A/205A-1 helicopters. The available text does not indicate any change in the breadth of applicability or the mandated action from the instrument's original stated purpose; it remains focused on the identified bearing batches and prescribes the inspection regime and the Service Bulletin as the procedural source (Applicability; Requirement; Compliance; Background)."},"complexity_factors":["Narrow technical applicability defined by part number and specific serial-number prefixes (Applicability).","Mandated action refers to an external technical document (Bell Alert Service Bulletin 205-91-43 Revision A), requiring operators to obtain and follow another document to implement the AD (Requirement).","High-frequency compliance timing (daily, before first flight) creates recurring operational burden and scheduling impacts (Compliance).","Safety-critical context (issued after a fatal accident) increases enforcement and operational attention but the AD itself is procedurally simple (Background).","Cross-reference to FAA Priority Letter introduces additional external guidance to consider (Note)."],"plain_english_summary":"### What this directive does\n\nThis Airworthiness Directive (AD) requires daily inspections of specific tail-rotor driveshaft bearings on Bell 205A and 205A-1 helicopters. The directive applies only to helicopters fitted with part-number 204-040-623-003 bearings whose serial numbers are prefixed with \"T\" or \"N\" prior to N4000, and to all -005 bearings with a serial-number prefix \"T\" or \"N\". (Applicability)\n\nThe AD instructs owners/operators to carry out the specified action in Bell Alert Service Bulletin 205-91-43 Revision A. (Requirement)\n\nThe inspections must be done daily, before the first flight of the day, from 12 January 1992 onwards. (Compliance)\n\nA related FAA Priority Letter AD (91-24-16) is noted. (Note)\n\n### Why this was issued (as stated in the AD)\n\nThe AD says a fatal accident revealed a possible production-batch problem with these bearings, and a daily inspection regime was found necessary. (Background)\n\n### Who this affects and who decides\n\n- Affected: operators/owners of Bell 205A and 205A-1 helicopters that have the specified bearings. (Applicability)\n- Decision/issuer: the Civil Aviation Safety Authority under the Civil Aviation Regulations (header). The AD directs compliance by reference to Bell's Alert Service Bulletin. (header; Requirement)\n\n### Who pays and what behaviour changes\n\n- Who pays: the helicopter operators or owners will bear the cost of performing the daily inspections and any follow-up maintenance or replacement required by the Service Bulletin. (Requirement; Compliance)\n- Behaviour change: operators must add a daily pre-flight inspection step for the tail-rotor driveshaft bearings (more frequent checks than normal if not already performed) and must follow the procedures in Bell Alert Service Bulletin 205-91-43 Revision A. (Requirement; Compliance)\n\n### Practical implementation and compliance points\n\n- The AD cross-references an external technical document (Bell Alert Service Bulletin 205-91-43 Revision A). Operators need to obtain and follow that bulletin to know the exact inspection steps and any corrective actions. (Requirement)\n- Inspections are required every day before first flight, which creates a recurring operational task and may affect aircraft availability or scheduling. (Compliance)\n- The AD targets a narrow set of bearings identified by part number and serial-number prefixes; operators must confirm serial numbers to establish applicability. (Applicability)\n- The AD references an FAA Priority Letter, indicating related international guidance to consult. (Note)\n\n### Trade-offs, risks and costs (source-grounded)\n\n- Costs: recurring labour and any parts/repairs found necessary during inspections. (Requirement; Compliance)\n- Incentives: the directive increases the chance that a bearing defect will be found before flight, reducing immediate safety risk at the cost of increased inspection burden. (Background; Compliance)\n- Compliance burden: daily manual checks and any recordkeeping or downtime required by findings in the Service Bulletin. (Requirement; Compliance)\n- Implementation risk: effective compliance depends on operators having timely access to and following the Bell Alert Service Bulletin and correctly identifying affected bearing serial numbers. (Requirement; Applicability)\n\n### What to check next (mechanical steps and references)\n\n- Confirm whether a helicopter has bearings with P/N 204-040-623-003 and serial-number prefixes \"T\" or \"N\" prior to N4000, or whether it has -005 bearings with \"T\" or \"N\" prefixes. (Applicability)\n- Obtain and follow Bell Alert Service Bulletin 205-91-43 Revision A for the exact inspection procedure and any required subsequent actions. (Requirement)\n- Perform the inspection daily before the first flight as required. (Compliance)\n\n(References in parentheses indicate the section of the AD that states the point.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive issued in response to a specific fatal accident and identified production defect. It has not expanded beyond its original purpose of mandating daily inspections for the affected bearing batches."},"complexity_factors":["Single, specific requirement (daily inspection)","Narrow applicability limited to two helicopter models and specific part/serial number combinations","No defined terms section or interpretation provisions","No conditional logic or nested exceptions","Cross-reference to only one external document (Bell Service Bulletin) and one related FAA directive","Extremely short document (approximately 150 words of substantive content)"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific maintenance actions on aircraft.\n\n**What it does:**\nOrders owners and operators of certain **Bell 205 series helicopters** to perform a **daily inspection** of the tail rotor driveshaft hangar bearings before the first flight each day.\n\n**Who it affects:**\n- All **Bell 205A and 205A-1** helicopter models\n- Specifically those fitted with certain part-numbered bearings (P/N 204-040-623-003 with serial numbers starting with \"T\" or \"N\" below N4000, OR P/N ending in -005 with serial numbers starting with \"T\" or \"N\")\n\n**Why it matters:**\nA **fatal accident** revealed that some bearings from specific production batches could fail. This directive prevents further accidents by catching potential bearing failures before they cause catastrophic tail rotor failure (which can cause loss of control and crash).\n\n**What must be done:**\n- Follow the inspection procedure in **Bell Alert Service Bulletin 205-91-43 Revision A**\n- Do this **every day before the first flight**, starting **12 January 1992**\n\n**Key point:** This is not optional. Airworthiness Directives are legally binding safety requirements. Ignoring them grounds the aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-205-60-tail-rotor-driveshaft-hangar-bearings","history":"/api/acts/ad-bell-205-60-tail-rotor-driveshaft-hangar-bearings/history","analysis":"/api/acts/ad-bell-205-60-tail-rotor-driveshaft-hangar-bearings/analysis","conflicts":"/api/acts/ad-bell-205-60-tail-rotor-driveshaft-hangar-bearings/conflicts","importantCases":"/api/acts/ad-bell-205-60-tail-rotor-driveshaft-hangar-bearings/important-cases","documents":"/api/acts/ad-bell-205-60-tail-rotor-driveshaft-hangar-bearings/documents"}}