{"id":"F2006B09347","name":"AD/ECUREUIL/40 - Tail Rotor Gearbox Casing","slug":"ad-ecureuil-40-tail-rotor-gearbox-casing","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53568,"registerId":"commonwealth-F2006B09347-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ECUREUIL/40 - Tail Rotor Gearbox Casing","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/40 Tail Rotor Gearbox Casing 1/88\n\nApplicability: All model AS 350 series helicopters.\n\nRequirement: 1. Inspect the tail rotor gearbox casing in accordance with Para 1C(2) of SB No.\n\n05.18.\n\n2. Inspect and modify the tail rotor gearbox in accordance with Para 1C(3) of SB No. 05.18.\n\nCompliance: For Para 1. Within 50 hours time in service after 25 November 1987 and thereafter at intervals not exceeding 50 hours time in service, until modification AMS 350A07- 8535 (polishing blend radii) is incorporated. After modification, inspect at intervals not exceeding 400 hours time in service.\n\nFor Para 2. Prior to exceeding 1100 hours total time in service or within 100 hours time in service after 25 November 1987, whichever is the later.\n\nBackground: The manufacturer has received reports at cracking in the blade horn support yoke radius just inboard at where the tail rotor control bellcrank pivot bolt is located.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2818},"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This directive remains focused on its original purpose: addressing the specific safety defect of cracking in the tail rotor gearbox casing of AS 350 helicopters. There is no indication of scope expansion beyond this specific airworthiness issue."},"complexity_factors":["References external technical documents (Service Bulletin No. 05.18 and modification AMS 350A07-8535) without reproducing their content","Dual compliance timelines with conditional logic ('whichever is the later')","Technical aviation terminology requiring specialized knowledge to interpret","Two-phase maintenance regime (pre-modification and post-modification) with different inspection intervals"],"plain_english_summary":"This Airworthiness Directive from CASA applies to all Eurocopter AS350 (Ecureuil/Squirrel) helicopters and requires repeated inspections of the tail rotor gearbox casing and a one-time modification (polish/blend per AMS 350A07-8535 and follow-up per Service Bulletin 05.18) to prevent cracking.\n\nCracks in the blade-horn support yoke radius could cause loss of tail rotor control and a catastrophic spin. Initial inspection: within 50 flight hours after 25 Nov 1987; modification: before 1,100 total hours or within 100 hours after 25 Nov 1987, whichever is later."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ecureuil-40-tail-rotor-gearbox-casing","history":"/api/acts/ad-ecureuil-40-tail-rotor-gearbox-casing/history","analysis":"/api/acts/ad-ecureuil-40-tail-rotor-gearbox-casing/analysis","conflicts":"/api/acts/ad-ecureuil-40-tail-rotor-gearbox-casing/conflicts","importantCases":"/api/acts/ad-ecureuil-40-tail-rotor-gearbox-casing/important-cases","documents":"/api/acts/ad-ecureuil-40-tail-rotor-gearbox-casing/documents"}}