{"id":"F2006B07526","name":"AD/UH-1/12 - Tail Rotor Driveshaft Hangar Bearings","slug":"ad-uh-1-12-tail-rotor-driveshaft-hangar-bearings","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":50068,"registerId":"commonwealth-F2006B07526-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/UH-1/12 Tail Rotor Driveshaft Hangar ","sectionType":"part","heading":"AD/UH-1/12 Tail Rotor Driveshaft Hangar Bearings 8/2000","content":"# AD/UH-1/12 Tail Rotor Driveshaft Hangar Bearings 8/2000\n\nApplicability: Model UH1A, UH1B, UH1E, UH1F, UH1H, UH1L, UH1P, TH1F, and TH1L.\n\nRequirement: Action in accordance with the technical requirements of FAA AD 94-22-09. Compliance: 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.\n\n![Signature of David Alan Villiers Delegate of the Civil Aviation Safety Authority](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":{"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive sticks to its stated intent: preventing contaminated tail‑rotor hangar bearings from returning to service by mandating the FAA‑specified corrective actions for the listed UH1/TH1 models (see Background and Requirement). It does not broaden applicability beyond the listed models or impose additional requirements beyond the FAA AD; compliance is immediate (‘before further flight’)."},"complexity_factors":["Cross‑reference to external FAA AD 94‑22‑09 for technical instructions (Requirement: “Action in accordance with the technical requirements of FAA AD 94-22-09”) — implementation depends on another regulator’s document.","Immediate compliance window (Compliance: “Before further flight after the effective date of this directive”) — creates operational disruption risk and urgent scheduling.","Narrow, specific applicability (Applicability: listed UH1A/B/E/F/H/L/P and TH1F/L models) — limits affected population but concentrates impact on those operators.","Safety‑critical maintenance tasks (bearing inspection/replace) require qualified personnel and parts — generates direct labour and parts costs for operators.","Limited administrative detail in the AD (no labour/parts estimates or serial/batch numbers in text) — may create uncertainty and require reference to FAA AD for precise procedures and scope.","Regulatory authority and binding nature stated (issued under subreg 39.1(1) of CAR 1998) — low discretion for operators to delay or vary compliance."],"plain_english_summary":"Requires operators of specified Bell UH‑1 and TH‑1 helicopter models to carry out the technical actions set out in FAA AD 94‑22‑09 (inspection/repair/replacement of tail‑rotor driveshaft hangar bearings) to prevent contaminated bearings re‑entering service. The requirement is mandatory and must be complied with “before further flight” after the directive’s effective date. CASA (delegate under CAR 1998 subreg 39.1(1)) issues the rule; operators pay the compliance costs and must ground affected aircraft until work is complete."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific manufacturing defect in specific helicopter models. It does not expand beyond the immediate safety issue of contaminated bearings."},"complexity_factors":["Very short document (under 300 words)","Only 1 substantive requirement (comply with FAA AD 94-22-09)","No defined terms section","No cross-references to other Australian legislation beyond the enabling regulation (CAR 1998 subreg 39.1(1))","Simple applicability list (9 specific model numbers)","Single compliance deadline (before further flight)","No conditional logic, exceptions, or nested provisions"],"plain_english_summary":"This AD requires owners/operators of certain Bell UH‑1 \"Huey\" helicopters to inspect or replace tail‑rotor driveshaft hangar bearings originating from contaminated manufacturing batches. It adopts FAA AD 94‑22‑09 and mandates completion before the next flight after 10 August 2000. The measure prevents in‑service installation of contaminated bearings that could fail in flight and cause loss of tail‑rotor control."}},"importantCases":[],"_links":{"self":"/api/acts/ad-uh-1-12-tail-rotor-driveshaft-hangar-bearings","history":"/api/acts/ad-uh-1-12-tail-rotor-driveshaft-hangar-bearings/history","analysis":"/api/acts/ad-uh-1-12-tail-rotor-driveshaft-hangar-bearings/analysis","conflicts":"/api/acts/ad-uh-1-12-tail-rotor-driveshaft-hangar-bearings/conflicts","importantCases":"/api/acts/ad-uh-1-12-tail-rotor-driveshaft-hangar-bearings/important-cases","documents":"/api/acts/ad-uh-1-12-tail-rotor-driveshaft-hangar-bearings/documents"}}