{"id":"F2006B10595","name":"AD/HU 269/23 Amdt 8 - Main Rotor Gear Drive Assembly - Inspection and Replacement","slug":"ad-hu-269-23-amdt-8-main-rotor-gear-drive-assembly-inspection-and-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116453,"registerId":"commonwealth-F2006B10595-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HU 269/23 Amdt 8 - Main Rotor Gear Drive Assembly - Inspection and Replacement","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)  Schweizer (Hughes) 269 Series Helicopters\n\n \n\nAD/HU 269/23\n\nAmdt 8\n\n\nMain Rotor Gear Drive Assembly - Inspection and Replacement\n\n\n11/81\n\n \n\nApplicability: All models fitted with P/N 269A5175, 269A5175-3 or 269A5175-5 main rotor gear drive, incorporating P/N 269A5179 or 269A5179-3 drive shaft.\n\n \n\nDocument: Hughes SIN N-179.\n\n \n\nNote: FAA AD 81-17-04 refers.\n\n \n\nCompliance: In accordance with the requirement document.\n\n \n\nBackground:  The Directive is raised in issue to reflect current manufacturers data and FAA requirements. Hughes SIN N-179 supersedes N-114-3 N-143, and additionally reduces the life of P/N 269A5179 or 269A5179-3 shaft and coupling assemblies. Installation of P/N 269A5194 carrier assembly(N-142-1) is now mandatory.\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":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is Amendment 8 to an existing Airworthiness Directive first issued in 1981 (as indicated by '11/81'). The amendment stays within the original scope of ensuring main rotor gear drive safety. It simply updates the directive to reflect new manufacturer data and shortened component lifespans — a routine safety maintenance update rather than scope expansion."},"complexity_factors":["Very short document (approximately 200 words)","Only 3 defined part numbers in applicability section","Single compliance requirement: 'In accordance with the requirement document'","No nested conditions or exceptions","No cross-references to other legislation beyond a single note about FAA AD 81-17-04","Background section provides clear rationale without legal technicality"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific maintenance actions on certain helicopters.\n\n**What it does:**\n- **Targets:** Schweizer (formerly Hughes) 269 series helicopters with specific part numbers for their main rotor gear drive systems\n- **Requires:** Inspection and replacement of the main rotor gear drive assembly — the critical component that transfers power from the engine to the main rotor blades\n- **Why:** The drive shaft and coupling assemblies (parts 269A5179 or 269A5179-3) have had their approved service life **reduced** due to safety concerns. Additionally, a specific carrier assembly (part 269A5194) must now be installed — this was previously optional but is now mandatory\n\n**Who it affects:**\n- Owners and operators of affected Schweizer/Hughes 269 helicopters\n- Licensed aircraft maintenance engineers\n- Flying schools and commercial operators using these aircraft\n\n**Why it matters:** The main rotor gear drive is essential for flight — if it fails, the helicopter loses lift and cannot stay airborne. This directive prevents catastrophic failure by forcing replacement of components before they reach their newly-shortened safe lifespan. It aligns Australian requirements with updated US Federal Aviation Administration (FAA) safety standards."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"Yes. The amendment supersedes earlier SINs (N-114-3, N-143), reduces the life limits for P/N 269A5179/269A5179-3 shaft and coupling assemblies, and makes installation of P/N 269A5194 carrier assembly mandatory. Compliance is directed to Hughes SIN N-179 and the AD cross-references FAA AD 81-17-04 (Applicability; Background; Document; Note)."},"complexity_factors":["Multiple specific part numbers and assemblies listed (Applicability).","Mandates actions by reference to an external manufacturer document (Hughes SIN N-179) rather than prescribing full procedures in the directive (Document / Compliance).","Supersedes earlier service instructions and changes life limits (Background), requiring operators to reconcile old records with new limits.","Mandatory installation of a different carrier assembly (P/N 269A5194) creates a retrofit/parts-supply requirement (Background).","Cross-reference to FAA AD 81-17-04 introduces interjurisdictional compliance considerations (Note).","Operational impact on maintenance scheduling and inventory due to reduced life limits and compulsory replacement (implicit in Background and Compliance)."],"plain_english_summary":"Mechanically, this directive shortens the allowed service life for certain main rotor drive shafts and couplings and makes installation of a revised carrier assembly mandatory. It applies to Schweizer (Hughes) 269-series helicopters fitted with the specified gear-drive and drive-shaft part numbers and requires operators to inspect and replace those parts in accordance with Hughes SIN N-179, changing maintenance intervals and replacement obligations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-269-23-amdt-8-main-rotor-gear-drive-assembly-inspection-and-replacement","history":"/api/acts/ad-hu-269-23-amdt-8-main-rotor-gear-drive-assembly-inspection-and-replacement/history","analysis":"/api/acts/ad-hu-269-23-amdt-8-main-rotor-gear-drive-assembly-inspection-and-replacement/analysis","conflicts":"/api/acts/ad-hu-269-23-amdt-8-main-rotor-gear-drive-assembly-inspection-and-replacement/conflicts","importantCases":"/api/acts/ad-hu-269-23-amdt-8-main-rotor-gear-drive-assembly-inspection-and-replacement/important-cases","documents":"/api/acts/ad-hu-269-23-amdt-8-main-rotor-gear-drive-assembly-inspection-and-replacement/documents"}}