{"id":"F2006B09334","name":"AD/ECUREUIL/21 Amdt 1 - Main G/Box Bevel Reduction Gear Module","slug":"ad-ecureuil-21-amdt-1-main-g-box-bevel-reduction-gear-module","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53520,"registerId":"commonwealth-F2006B09334-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ECUREUIL/21 Amdt 1 - Main G/Box Bevel Reduction Gear Module","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nEurocopter AS 350 (Ecureuil) Series Helicopters\n\nAD/ECUREUIL/21\n\nAmdt 1\n\n  \nMain G/Box Bevel Reduction Gear Module 11/85\n\nApplicability: All model AS 350 helicopters fitted with a maingear box containing the bevel reduction gear assembly part number 350A32.0300.00, 01 and 02, not modified under A.M.S. 07.7082, A.M.S. 07.7083 or A.M.S. 07.7098.\n\nRequirement: AS 350 SB 05.10. Rev. 1.\n\nNote: Bureau Veritas AD 82-176-28(B) refers.\n\nCompliance: PART 1: Within 10 hours time in service after 31st March 1983 and every 50 hours, prior to compliance with Part 2, carry out the visual check.\n\nPART 2: Within 300 hours time in service after 31 March 1983, carry out the screw tightening check, as a one time only inspection.\n\nPART 3: Every 300 hours time in service, after compliance with Part 2, carry out the visual check.\n\nBackground: The manufacturer advises that there have been several cases of sheared and loose bolts, securing the bevel ring gear to the vertical shaft, found during maintenance operations. This directive is amended to add modification A.M.S. 07.7098 to the list of exclusion in the aircraft applicability.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a narrow, technical airworthiness directive focused on a specific mechanical defect in specific helicopter models. The amendment simply expands the list of excluded (already-fixed) aircraft by one modification number. The scope remains tightly focused on the original safety issue."},"complexity_factors":["Single specific aircraft type and limited part number range","Three sequential compliance parts with clear time-in-service triggers","Four specific modification exclusions to track","References to external manufacturer service bulletin (AS 350 SB 05.10 Rev. 1) and French aviation authority document (Bureau Veritas AD 82-176-28(B))","No nested conditional logic or extensive defined terms","Straightforward amendment adding one item to existing exclusion list"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspections of the main gearbox bevel ring gear bolts on certain Eurocopter AS350 helicopters (specific gearbox part numbers) because bolts have been found sheared or loose, posing risk of catastrophic rotor failure. It requires an initial and recurring visual/tightness inspection schedule unless the helicopter is already modified by listed manufacturer service bulletins.\n\nAmendment 1 adds service bulletin A.M.S. 07.7098 to the exclusion list."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"The amendment narrows the directive's scope by adding modification A.M.S. 07.7098 to the list of exclusions in aircraft applicability, thereby exempting helicopters modified under that A.M.S. from the inspection and tightening requirements (see Background). Other requirements remain as originally issued."},"complexity_factors":["Narrow applicability: applies only to AS350 models fitted with bevel reduction gear P/N 350A32.0300.00, .01, .02 and not modified under listed A.M.S. modifications","Prescriptive compliance schedule: short‑interval visual checks and a one‑time screw‑tightening check with specific time‑in‑service deadlines (10h/50h/300h)","Technical maintenance tasks: requires competent maintenance personnel to perform visual inspections and screw tightening to manufacturer SB standards (AS 350 SB 05.10 Rev.1)","Cross-references: relies on a manufacturer service bulletin and references a Bureau Veritas AD, requiring operators/maintainers to consult external documents","Amendment effect: changes applicability by adding A.M.S. 07.7098 to exclusions, altering who must comply"],"plain_english_summary":"This Airworthiness Directive requires operators of Eurocopter AS350 helicopters with specified main gearbox bevel reduction gear part numbers to perform short-term and recurring visual inspections and a one‑time screw‑tightening check to address reported loose or sheared bolts (see Compliance and Requirement). CASA states the action aims to prevent gearbox separation; operators pay for inspections and any corrective maintenance. The amendment narrows applicability by excluding helicopters modified under A.M.S. 07.7098, shifting compliance obligations away from those modified aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ecureuil-21-amdt-1-main-g-box-bevel-reduction-gear-module","history":"/api/acts/ad-ecureuil-21-amdt-1-main-g-box-bevel-reduction-gear-module/history","analysis":"/api/acts/ad-ecureuil-21-amdt-1-main-g-box-bevel-reduction-gear-module/analysis","conflicts":"/api/acts/ad-ecureuil-21-amdt-1-main-g-box-bevel-reduction-gear-module/conflicts","importantCases":"/api/acts/ad-ecureuil-21-amdt-1-main-g-box-bevel-reduction-gear-module/important-cases","documents":"/api/acts/ad-ecureuil-21-amdt-1-main-g-box-bevel-reduction-gear-module/documents"}}