{"id":"F2006B04341","name":"AD/BELL 204/38 - Tail Rotor Driveshaft Hangar Bearings","slug":"ad-bell-204-38-tail-rotor-driveshaft-hangar-bearings","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44156,"registerId":"commonwealth-F2006B04341-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.","sortOrder":0},{"sectionNumber":"AD/BELL 204/38 Tail Rotor Driveshaft Han","sectionType":"part","heading":"AD/BELL 204/38 Tail Rotor Driveshaft Hangar Bearings 8/2000","content":"# AD/BELL 204/38 Tail Rotor Driveshaft Hangar Bearings 8/2000\n\nApplicability: Model 204B.\n\nRequirement: Action in accordance with the technical requirements of FAA AD 92-13-10.\n\nCompliance: Before further flight after the effective date of this directive.\n\nThis Airworthiness Directive becomes effective on 10 August 2000.\n\nBackground: Following the loss of a Bell model 412 it was discovered that certain batch/s of bearings had been contaminated during manufacture. This directive is issued to preclude any of those bearings re-entering service in an Australian helicopter. It also follows the re-introduction of the AD Series after sixteen years.\n\n![](image.003.png)  \n\nDavid Alan Villiers\n\nDelegate of the Civil Aviation Safety Authority 6 July 2000\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 12 July 2000.","sortOrder":1}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope. It addresses a specific unsafe condition (contaminated bearings) in a specific aircraft model (Bell 204B) through a specific technical reference (FAA AD 92-13-10). The document explicitly notes it follows the re-introduction of the AD Series after sixteen years, but this is procedural context rather than scope creep."},"complexity_factors":["Very short document (under 300 words)","Only 1 defined term implicitly referenced (FAA AD 92-13-10)","Simple conditional structure: single applicability criterion (Model 204B) and single compliance deadline (before further flight after effective date)","No nested exceptions or conditional logic","Technical complexity is externalised — the actual engineering requirements live in a separate FAA document, not in this instrument itself","Minimal cross-referencing (only to CAR 1998 subregulation 39.1(1) and the FAA AD)"],"plain_english_summary":"This Airworthiness Directive makes FAA AD 92-13-10 legally mandatory in Australia for owners/operators of Bell Model 204B helicopters. It requires inspection or replacement of tail-rotor driveshaft hangar bearings before next flight because some bearings were contaminated during manufacture and can fail. Bearing failure could cause loss of tail-rotor control and a crash; CASA adopts the FAA instruction by reference rather than reproducing its technical steps."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD's scope is consistent with its stated purpose: prevent contaminated tail‑rotor hangar bearings re‑entering service. It applies narrowly to Model 204B and mandates immediate action per the FAA AD referenced (Applicability; Requirement; Compliance; Background)."},"complexity_factors":["Narrow applicability — specific to Bell Model 204B (Applicability).","Direct cross-reference to FAA AD 92-13-10 for technical instructions, so interpretive work is limited but reliant on external document (Requirement).","Immediate compliance deadline: \"before further flight\" creates urgent operational disruption and downtime costs (Compliance).","Traceability/parts identification risk: affected bearings are from contaminated manufacturing batches, requiring batch checks and possible parts replacement (Background).","Low regulatory discretion: issued under CAR 1998 subreg 39.1(1) by CASA delegate, leaving little room for alternative compliance approaches (Preamble)."],"plain_english_summary":"This Airworthiness Directive requires operators of Bell Model 204B helicopters to carry out the inspection/maintenance actions set out in FAA AD 92-13-10 for tail-rotor driveshaft hangar bearings, and to do so before the next flight (Applicability; Requirement; Compliance). CASA issued the directive under CAR 1998 subreg 39.1(1) in response to contaminated bearings found after a Bell 412 accident; operators therefore incur immediate parts, inspection and downtime costs (Preamble; Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-204-38-tail-rotor-driveshaft-hangar-bearings","history":"/api/acts/ad-bell-204-38-tail-rotor-driveshaft-hangar-bearings/history","analysis":"/api/acts/ad-bell-204-38-tail-rotor-driveshaft-hangar-bearings/analysis","conflicts":"/api/acts/ad-bell-204-38-tail-rotor-driveshaft-hangar-bearings/conflicts","importantCases":"/api/acts/ad-bell-204-38-tail-rotor-driveshaft-hangar-bearings/important-cases","documents":"/api/acts/ad-bell-204-38-tail-rotor-driveshaft-hangar-bearings/documents"}}