{"id":"F2006B06719","name":"AD/S-76/38 - Main Rotor Gear Box No. 1 and No. 2 Input Bevel Pinion Housing Assemblies - Inspection","slug":"ad-s-76-38-main-rotor-gear-box-no-1-and-no-2-input-bevel-pinion-housing-assemblies-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114539,"registerId":"commonwealth-F2006B06719-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/S-76/38 - Main Rotor Gear Box No. 1 and No. 2 Input Bevel Pinion Housing Assemblies - Inspection","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\n# AD/S-76/38 Main Rotor Gear Box No. 1 and No. 2 Input Bevel\n\nPinion Housing Assemblies - Inspection\n\nApplicability: As per the Requirement Document. Requirement: Sikorsky S.B. No. 76-66-19.\n\nCompliance: 1. Prior to the issue of an initial Certificate of Airworthiness; or\n\n# 6/85\n\n \n\n2. Prior to the installation of a MRGB called up in the Requirement Document.\n\n \n\nBackground: During the overhaul of a gearbox, the manufacturer found a torque loss on the input bevel pinion housing assembly retaining nuts.\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":2054},"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This airworthiness directive maintains its original targeted scope, addressing a specific safety defect identified in Sikorsky S-76 gearbox components. It does not appear to have expanded beyond the initial safety concern regarding torque loss in retaining nuts."},"complexity_factors":["Incorporates external technical standard by reference (Sikorsky Service Bulletin 76-66-19) without reproducing its contents","Requires cross-referencing with Requirement Document for full applicability details","Uses aviation-specific acronyms (MRGB for Main Rotor Gear Box, S.B. for Service Bulletin)","Technical mechanical terminology (bevel pinion housing assemblies, retaining nuts)"],"plain_english_summary":"**Safety check for helicopter gearboxes.** This directive requires owners of Sikorsky S-76 helicopters to inspect specific parts of the main rotor gearbox—namely the input bevel pinion housing assemblies—before the aircraft is first certified or before installing certain gearboxes.\n\n**The problem:** During routine overhaul, the manufacturer found that retaining nuts on these assemblies could lose their proper torque (come loose). This is serious because these nuts hold critical gearbox components together; if they fail, the gearbox could fail, potentially causing the helicopter to crash.\n\n**What must be done:** Operators must follow the inspection procedures in Sikorsky Service Bulletin No. 76-66-19. This ensures the nuts are properly tightened and secured before the helicopter flies."}},"importantCases":[],"_links":{"self":"/api/acts/ad-s-76-38-main-rotor-gear-box-no-1-and-no-2-input-bevel-pinion-housing-assemblies-inspection","history":"/api/acts/ad-s-76-38-main-rotor-gear-box-no-1-and-no-2-input-bevel-pinion-housing-assemblies-inspection/history","analysis":"/api/acts/ad-s-76-38-main-rotor-gear-box-no-1-and-no-2-input-bevel-pinion-housing-assemblies-inspection/analysis","conflicts":"/api/acts/ad-s-76-38-main-rotor-gear-box-no-1-and-no-2-input-bevel-pinion-housing-assemblies-inspection/conflicts","importantCases":"/api/acts/ad-s-76-38-main-rotor-gear-box-no-1-and-no-2-input-bevel-pinion-housing-assemblies-inspection/important-cases","documents":"/api/acts/ad-s-76-38-main-rotor-gear-box-no-1-and-no-2-input-bevel-pinion-housing-assemblies-inspection/documents"}}