{"id":"F2006B04388","name":"AD/BELL 205/52 - Tail Rotor Trunnion Bearing Housing","slug":"ad-bell-205-52-tail-rotor-trunnion-bearing-housing","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44213,"registerId":"commonwealth-F2006B04388-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 205/52 - Tail Rotor Trunnion Bearing Housing","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nBell Helicopter Textron 205 Series Helicopters\n\nAD/BELL 205/52 Tail Rotor Trunnion Bearing Housing 9/86\n\nDM\n\nApplicability: All model 205A and 205A-1 helicopters fitted with kit P/N 212-704-129-101 (refer SI 212-68).\n\nRequirement: Action in accordance with Bell Alert Service Bulletin No. 205-86-24, Revision A. Compliance: Part I of the Requirement Document:\n\nWithin 25 hours time in service or seven days whichever occurs first after\n\n6 August 1986 and thereafter at intervals not exceeding 25 hours time in service or 7 days, whichever occurs first, until Part II is complied with.\n\nPart II of the Requirement Document:\n\nWithin 150 hours time in service or 60 days whichever occurs first after 31 July 1986.\n\nBackground: A trunnion bearing housing end web has been found below specified dimensions.\n\nFailure of the housing caused excessive tail rotor vibration and loss of control.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive, as written, applies narrowly to Bell 205A and 205A-1 helicopters fitted with kit P/N 212-704-129-101 and requires interim inspections followed by a final corrective action in accordance with Bell Alert Service Bulletin No. 205-86-24, Revision A. The stated purpose is to address a specific dimensional defect in the trunnion bearing housing end web that has been linked to tail rotor vibration and loss of control. The text does not expand the affected population or the nature of required actions beyond those manufacturer-prescribed in the Service Bulletin; it instead prescribes timing for interim inspections and a deadline for the Part II action. (Applicability; Requirement; Compliance; Background)"},"complexity_factors":["Multiple timing metrics: short recurring interval (25 hours TIS or 7 days) and a separate final compliance window (150 hours TIS or 60 days) increase scheduling complexity. (Compliance: Part I; Part II)","Dependence on an external document (Bell Alert Service Bulletin No. 205-86-24, Revision A) for procedural detail—the AD mandates compliance but does not set out step-by-step actions. (Requirement)","Applicability limited to specific models fitted with a specified kit P/N creates a need to verify equipment fitment for each airframe. (Applicability)","Overlap of different effective dates (6 August 1986 for Part I timing reference; 31 July 1986 for Part II timing reference) requires careful interpretation for compliance start dates. (Compliance: Part I; Part II)","Interim versus final action structure (Part I repeated until Part II done) requires tracking continuing compliance until the terminating action is completed. (Requirement; Compliance)"],"plain_english_summary":"This AD requires owners/operators of Bell 205A and 205A‑1 helicopters fitted with kit P/N 212‑704‑129‑101 to perform recurring inspections and complete a mandated final corrective action per Bell Alert Service Bulletin 205‑86‑24 Revision A. It responds to a sub‑spec trunnion bearing housing end web that has caused excessive tail‑rotor vibration and loss of control. Operators must schedule and pay for inspections (short recurring intervals) until the final repair is done within the specified compliance window."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-limited Airworthiness Directive issued in 1986 to address a specific safety-critical defect. It has not expanded beyond its original purpose of mandating inspection and repair of the tail rotor trunnion bearing housing defect."},"complexity_factors":["Single discrete safety issue addressed (one mechanical defect)","Only two compliance pathways (interim inspections and permanent repair)","Minimal cross-referencing (only to specific Bell Service Bulletin and Service Instruction)","Clear applicability criteria (specific helicopter models and kit part number)","Straightforward time-based compliance triggers (flight hours or calendar days)","No nested exceptions or conditional logic","Short document (approximately 150 words)"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific Bell helicopters.\n\n**What it does:**\nOrders owners and operators of certain Bell 205 series helicopters to inspect and fix a dangerous defect in the **tail rotor trunnion bearing housing** — a critical component that helps stabilise the helicopter's tail rotor.\n\n**Who it affects:**\n- All Bell 205A and 205A-1 helicopters fitted with a specific modification kit (part number 212-704-129-101)\n- Helicopter operators, maintenance crews, and owners\n\n**Why it matters:**\nA manufacturing defect was discovered where the housing's end web was too thin. If this part fails, it causes severe tail rotor vibration and can lead to **complete loss of control** of the aircraft. This directive mandates urgent inspections and repairs to prevent crashes.\n\n**What must be done:**\n- **Immediate action:** Within 25 flight hours or 7 days (whichever comes first) after 6 August 1986, and then repeated every 25 hours/7 days until the permanent fix is done\n- **Permanent fix:** Within 150 flight hours or 60 days after 31 July 1986, following Bell's official repair instructions (Alert Service Bulletin 205-86-24, Revision A)\n\nThis is a **time-critical safety mandate** — non-compliance grounds the aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-205-52-tail-rotor-trunnion-bearing-housing","history":"/api/acts/ad-bell-205-52-tail-rotor-trunnion-bearing-housing/history","analysis":"/api/acts/ad-bell-205-52-tail-rotor-trunnion-bearing-housing/analysis","conflicts":"/api/acts/ad-bell-205-52-tail-rotor-trunnion-bearing-housing/conflicts","importantCases":"/api/acts/ad-bell-205-52-tail-rotor-trunnion-bearing-housing/important-cases","documents":"/api/acts/ad-bell-205-52-tail-rotor-trunnion-bearing-housing/documents"}}