{"id":"F2006B06733","name":"AD/S-76/58 - Tail Gearbox Output Shaft","slug":"ad-s-76-58-tail-gearbox-output-shaft","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114560,"registerId":"commonwealth-F2006B06733-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/S-76/58 - Tail Gearbox Output Shaft","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Sikorsky S-76 Series Helicopters\n\n \n\nAD/S-76/58 Tail Gearbox Output Shaft 5/92\n\nApplicability: All model S76A, S76B and S76C helicopters up to and including S/N 760390. Requirement:               Action in accordance with Sikorsky Alert Service Bulletin No 76-66-27.\n\nCompliance: Within 150 hours time in service from 30 April 1992 or by 30 August 1992, whichever occurs first.\n\n \n\nBackground:  The manufacturer requires a one-time inspection of the tail rotor gearbox output shaft assembly internal bore for a surface irregularity/groove. Scoring in the bore area may initiate a premature fatigue failure.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2969},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This directive maintains its original narrow scope as a targeted safety inspection for a specific mechanical defect in identified helicopter models. It has not expanded beyond the original requirement to inspect the tail gearbox output shaft bore."},"complexity_factors":["References external technical manual (Sikorsky Alert Service Bulletin No 76-66-27) without reproducing the detailed inspection procedures","Dual-layer compliance deadline (flight hours versus calendar date)","Specific applicability limited to aircraft serial numbers up to 760390"],"plain_english_summary":"This Airworthiness Directive mandates a **one-time safety inspection** of the tail rotor gearbox output shaft on specific Sikorsky S-76 helicopters.\n\n**Who must comply?**\nOwners and operators of S-76A, S-76B, and S-76C helicopters with serial numbers up to 760390.\n\n**What must be done?**\nInspect the internal bore of the tail gearbox output shaft for scratches, grooves, or surface irregularities that could cause metal fatigue. Operators must follow the procedures in **Sikorsky Alert Service Bulletin No 76-66-27**.\n\n**Why is this required?**\nScratches or scoring inside the shaft create stress points that can lead to premature fatigue failure. If the tail rotor gearbox fails, the helicopter could become uncontrollable.\n\n**When must it be done?**\nThe inspection must be completed by the earlier of:\n* 150 flight hours after 30 April 1992, **or**\n* 30 August 1992"}},"importantCases":[],"_links":{"self":"/api/acts/ad-s-76-58-tail-gearbox-output-shaft","history":"/api/acts/ad-s-76-58-tail-gearbox-output-shaft/history","analysis":"/api/acts/ad-s-76-58-tail-gearbox-output-shaft/analysis","conflicts":"/api/acts/ad-s-76-58-tail-gearbox-output-shaft/conflicts","importantCases":"/api/acts/ad-s-76-58-tail-gearbox-output-shaft/important-cases","documents":"/api/acts/ad-s-76-58-tail-gearbox-output-shaft/documents"}}