{"id":"F2006B08680","name":"AD/CT58/5 - Stage 1 and Stage 2 Turbine Wheel","slug":"ad-ct58-5-stage-1-and-stage-2-turbine-wheel","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51807,"registerId":"commonwealth-F2006B08680-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CT58/5 - Stage 1 and Stage 2 Turbine Wheel","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 - 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  General Electric Turbine Engines - CT58 Series\n\n \n\nAD/CT58/5 Stage 1 and Stage 2 Turbine Wheel 9/85\n\nApplicability: All CT58 engine fitted with Stage 1 and 2 turbine wheels listed in SB (CT58) 72-126, Rev. 1.\n\n \n\nDocument:  General installation in an aircraft following next complete overhaul after 23 March 1970; or\n\n \n\nAD/GE-T/14A.\n\n \n\nCompliance: Before installation in an aircraft following next complete overhaul after 23 March 1970.\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":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This appears to be the original scope of the AD. It is a targeted safety directive addressing specific turbine wheel models in a specific engine series, consistent with typical airworthiness directive practice."},"complexity_factors":["Very short document (approximately 150 words)","Only 1 defined reference (SB CT58-72-126 Rev. 1)","Single compliance trigger (post-overhaul installation after fixed date)","No nested exceptions or conditional logic","Clear applicability statement with specific engine model and part reference","Cross-reference to only one other document (the Service Bulletin)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It applies to **General Electric CT58 series turbine engines** used in aircraft.\n\n**What it does:**\n- Requires inspection or replacement of **Stage 1 and Stage 2 turbine wheels** (critical rotating parts inside the engine that extract energy from hot gases to power the aircraft).\n- The directive references a specific **Service Bulletin (SB) CT58-72-126, Revision 1**, which lists the affected turbine wheels.\n\n**Who it affects:**\n- Operators and maintainers of aircraft using CT58 engines with the specified turbine wheels.\n\n**When compliance is required:**\n- Before the engine is installed in an aircraft **after its next complete overhaul following 23 March 1970**.\n\n**Why it matters:**\nTurbine wheels spin at extreme speeds and temperatures. If they fail, the engine can destroy itself and potentially damage the aircraft. This AD ensures potentially defective or life-limited parts are addressed before the engine returns to service, preventing catastrophic failures."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The instrument, as presented, applies to all CT58 engines fitted with Stage 1 and 2 turbine wheels listed in Service Bulletin (CT58) 72-126, Rev. 1, and requires compliance with the referenced installation procedure or AD/GE-T/14A before installation following the next complete overhaul after 23 March 1970 (Applicability; Document; Compliance). The text does not indicate any change in scope from that stated purpose; it remains a targeted installation requirement for the specified parts and engines."},"complexity_factors":["Reliance on external technical documents (SB (CT58) 72-126 Rev.1 and AD/GE-T/14A) for the detailed technical steps, increasing implementation complexity beyond the AD text (Document; Applicability).","Timing trigger tied to 'next complete overhaul after 23 March 1970', which requires checking each engine's overhaul history to determine applicability (Compliance).","Narrow, part-specific applicability reduces scope but concentrates technical and compliance requirements on a subset of operators and maintenance providers (Applicability).","The AD text is brief and does not include procedural detail, creating a need to obtain and interpret the referenced documents (Document).","Historic dating and cross-references can create ambiguity for operators dealing with long service-life engines and multiple overhaul cycles (Compliance)."],"plain_english_summary":"This Airworthiness Directive requires that certain Stage 1 and 2 turbine wheels for GE CT58 engines (listed in SB CT58‑72‑126 Rev.1) be installed in aircraft only after following the referenced installation procedure or AD/GE‑T/14A, with compliance required before installation at the next complete overhaul after 23 March 1970. It affects operators, overhaul/maintenance organisations and parts suppliers, creating a time‑triggered procedural obligation and shifting compliance costs and technical responsibility to those who overhaul and reinstall the wheels."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ct58-5-stage-1-and-stage-2-turbine-wheel","history":"/api/acts/ad-ct58-5-stage-1-and-stage-2-turbine-wheel/history","analysis":"/api/acts/ad-ct58-5-stage-1-and-stage-2-turbine-wheel/analysis","conflicts":"/api/acts/ad-ct58-5-stage-1-and-stage-2-turbine-wheel/conflicts","importantCases":"/api/acts/ad-ct58-5-stage-1-and-stage-2-turbine-wheel/important-cases","documents":"/api/acts/ad-ct58-5-stage-1-and-stage-2-turbine-wheel/documents"}}