{"id":"F2006B07527","name":"AD/UH-1/13 - 42 degree Gearbox","slug":"ad-uh-1-13-42-degree-gearbox","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":50071,"registerId":"commonwealth-F2006B07527-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-1/13 42° Gearbox 8/2000","sectionType":"part","heading":"AD/UH-1/13 42° Gearbox 8/2000","content":"# AD/UH-1/13 42° Gearbox 8/2000\n\nApplicability: Model UH1A, UH1B, UH1E, UH1F, UH1H, UH1L, UH1P, TH1F and TH1L with 42° gearbox P/N 204-040-003-023 or -037 installed.\n\nRequirement: Action in accordance with the technical requirements of FAA AD 95-10-08.\n\nCompliance: Before further flight after the effective date of this directive, thereafter at intervals not exceeding 400 torque events; where a torque event is defined as:\n\n    a takeoff or a lift (internal or external).\n\nThis Airworthiness Directive becomes effective on 10 August 2000.\n\nBackground: There have been a high number of accidents related to 42° gearbox failures.\n\nInvestigation has found that the normal operating regimes of the helicopters exceed the number of torque events that were anticipated during the certification process. Any operations outside the limits specified in the flight manual will accelerate drive train and gearbox failure.\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"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific mechanical failure mode in a specific helicopter gearbox. It does not expand beyond the original safety purpose of preventing 42° gearbox failures through mandated inspections."},"complexity_factors":["Single, clearly defined applicability section (9 specific helicopter models, 2 part numbers)","Single requirement referencing external technical document (FAA AD 95-10-08) — complexity offloaded to US regulation","Simple compliance formula: immediate action + recurring interval (400 torque events)","Only one defined term ('torque event') with straightforward definition","No cross-references to Australian legislation beyond enabling regulation (CAR 1998 subreg 39.1(1))","No conditional exceptions, nested provisions, or alternative compliance paths","Total length: approximately 250 words of substantive text"],"plain_english_summary":"This CASA safety order applies to Bell UH-1 helicopters fitted with the 42-degree main gearbox, requiring operators to comply with FAA AD 95-10-08. It mandates an initial inspection before next flight and recurring checks every 400 \"torque events\" (takeoffs/lifts). The measure targets ageing gearboxes prone to failure under frequent heavy-use cycles and affects Australian operators—military, emergency services, and remaining civilian UH-1 fleets—to reduce risk of catastrophic in‑flight gearbox failure."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope matches its stated safety objective: it applies only to the listed UH-1/TH-1 models fitted with the two specified 42° gearbox part numbers and mandates the FAA AD 95-10-08 actions at defined 400-torque-event intervals. The text does not broaden applicability or impose obligations beyond addressing the gearbox unsafe condition described in the Background."},"complexity_factors":["Cross-reference to FAA AD 95-10-08 (Requirement) creates a dependence on an external technical document for the substantive actions required.","Narrow applicability by helicopter model and specific gearbox part numbers requires checks of aircraft configuration and maintenance records (Applicability).","Compliance measured in operational events (400 torque events) instead of calendar time imposes ongoing tracking and recordkeeping obligations (Compliance).","Definition of a 'torque event' as a takeoff or lift may create edge cases for internal vs external lifts and needs consistent interpretation (Compliance; definition).","Immediate compliance 'before further flight' after the effective date can cause operational disruption and potential grounding until inspections/repairs are completed (Compliance).","Enforcement and effectiveness rely on CASA delegate action and Gazette notification, creating administrative enforcement steps (signature/effective date/notification).","Background links the directive to accident history and certification assumptions, which defines the safety rationale but also ties scope to a technical finding (Background)."],"plain_english_summary":"Mandates that operators of specified UH-1/TH-1 helicopters fitted with 42° gearbox `P/N 204-040-003-023` or `-037` carry out the inspection/repair actions required by FAA AD `95-10-08` before further flight and thereafter at intervals no greater than 400 “torque events” (a takeoff or a lift) (Requirement; Compliance; Applicability). CASA enforces the directive; owners/operators pay for and must record the inspections and any repairs. The measure responds to repeated gearbox failures and higher-than-anticipated torque usage (Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-uh-1-13-42-degree-gearbox","history":"/api/acts/ad-uh-1-13-42-degree-gearbox/history","analysis":"/api/acts/ad-uh-1-13-42-degree-gearbox/analysis","conflicts":"/api/acts/ad-uh-1-13-42-degree-gearbox/conflicts","importantCases":"/api/acts/ad-uh-1-13-42-degree-gearbox/important-cases","documents":"/api/acts/ad-uh-1-13-42-degree-gearbox/documents"}}