{"id":"F2006B10582","name":"AD/HU 269/106 - Main Transmission Pinion Assembly and Ring Gear","slug":"ad-hu-269-106-main-transmission-pinion-assembly-and-ring-gear","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116427,"registerId":"commonwealth-F2006B10582-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HU 269/106 - Main Transmission Pinion Assembly and Ring Gear","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)  \nSchweizer (Hughes) 269 Series Helicopters\n\nAD/HU 269/106 Main Transmission Pinion Assembly and Ring Gear\n\n  \n2/98\n\nApplicability: All model 269A, 269A-1, 269B, 269C and TH-55A helicopters incorporating main rotor transmissions containing the following pinion assemblies and ring gears, which are installed individually or as a set.\n\nP/N 269A5103-31 or \\-41 pinion assembly identified by the letters EGR, ACR or the manufacturer code number 23751 (EGR) or 57152 (ACR).\n\nP/N 269A5104-5 ring gear identified by the letters EGR, ACR or the manufacturer code number 23751 (EGR) or 57152 (ACR).\n\nRequirement: Unless previously carried out, inspect the pinion and ring gear teeth in accordance with Schweizer Service Bulletin B-244.2 dated 19 February 1996. Pinion assemblies and ring gears removed from service as a result of this directive shall be permanently retired from service.\n\nNote: FAA AD 97-23-06 Amdt 39-10194 refers.\n\nCompliance: Before further flight from the effective date should a clicking or tapping sound or other unusual noise or vibration be noted while operating the helicopter or, if a metal particle is found on the magnetic drain plug during routine maintenance.\n\nWithin the next 50 hours time in service from the effective date. Thereafter, re inspect at intervals not exceeding 50 hours time in service until ring gear P/N 269A5104-5 has been replaced with ring gear P/N 269A5104-7, S/N S2100 or higher.\n\nNote Installation of the P/N 269A5104-7 ring gear with S/N S2100 or higher provides terminating action for this directive.\n\nThis airworthiness directive becomes effective on 29 January 1998.\n\nBackground: Failure of a gear tooth from the main rotor transmission ring gear have been reported.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard, targeted airworthiness directive focused on a specific mechanical defect in defined helicopter models. The scope remains tightly constrained to the identified pinion assemblies and ring gears with no evidence of scope creep beyond the original safety purpose."},"complexity_factors":["Specific part number identification required (4 different identifiers: EGR, ACR, 23751, 57152)","Dual compliance pathways (immediate condition-based vs. scheduled 50-hour intervals)","Cross-reference to external document (Schweizer Service Bulletin B-244.2) and FAA AD 97-23-06","Conditional termination clause requiring specific replacement part with serial number threshold (S2100 or higher)","Mandatory retirement provision for removed parts"],"plain_english_summary":"CASA requires owners/operators of Schweizer/Hughes 269 series (including TH-55A) helicopters fitted with certain pinion and ring-gear parts to inspect the main rotor transmission for wear, cracking, or metal contamination and to retire failed gears.  \n\nIf unusual noises, vibrations, or metal in the oil are found, inspect before next flight; scheduled inspections recur until replaced with the specified improved gear. This prevents gear-tooth failure that could cause loss of control."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"Scope remains focused on the specified pinion assemblies and ring gear for listed 269-series helicopters, requiring inspection, retirement of defective parts and replacement with a stated P/N/S/N to terminate inspections. The directive does not expand or narrow the set of affected parts or models beyond the Applicability and Requirement text."},"complexity_factors":["Applicability covers multiple 269-series models but only specific part numbers and manufacturer/identification marks (Applicability).","Inspection procedure is delegated to Schweizer Service Bulletin B-244.2, creating reliance on an external document for technical steps (Requirement).","Compliance is conditional (unusual noise/vibration or metal particle) and also periodic (within 50 hours and every 50 hours) until terminating action, which adds operational scheduling complexity (Compliance).","Terminating action requires replacement with a specific ring gear part number and serial number (P/N 269A5104-7, S/N S2100+)—a discrete parts procurement constraint (Note).","Parts removed because of the directive must be permanently retired, imposing disposal/replacement cost and record-keeping obligations (Requirement).","Cross-reference to FAA AD and an effective date creates regulatory interdependence and retroactive compliance timing (Note; effective date 29 January 1998)."],"plain_english_summary":"Requires operators of Schweizer (Hughes) 269-series helicopters fitted with specified main-transmission pinion (P/N 269A5103-31/-41) and ring gear (P/N 269A5104-5) to inspect gear teeth per Schweizer Service Bulletin B-244.2, permanently retire any parts removed, and fit ring gear P/N 269A5104-7 (S/N S2100+) to terminate inspections. Inspections must be done before further flight if unusual noise/vibration or metal particles are found, and within 50 flight-hours thereafter, repeating every 50 hours until the replacement is fitted. Operators pay for inspections, repairs and replacement; maintenance personnel follow the bulletin. Purpose stated: prevent ring-gear tooth failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-269-106-main-transmission-pinion-assembly-and-ring-gear","history":"/api/acts/ad-hu-269-106-main-transmission-pinion-assembly-and-ring-gear/history","analysis":"/api/acts/ad-hu-269-106-main-transmission-pinion-assembly-and-ring-gear/analysis","conflicts":"/api/acts/ad-hu-269-106-main-transmission-pinion-assembly-and-ring-gear/conflicts","importantCases":"/api/acts/ad-hu-269-106-main-transmission-pinion-assembly-and-ring-gear/important-cases","documents":"/api/acts/ad-hu-269-106-main-transmission-pinion-assembly-and-ring-gear/documents"}}