{"id":"F2006B08671","name":"AD/CT58/13 - Stage 1 Turbine Wheels","slug":"ad-ct58-13-stage-1-turbine-wheels","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51771,"registerId":"commonwealth-F2006B08671-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CT58/13 - Stage 1 Turbine Wheels","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/CT58/13 Stage 1 Turbine Wheels 9/85\n\nApplicability: All CT58 engine models fitted with P/No. 4002T17P02 Stage 1 turbine wheels with the following S/Nos: 7753, 7761, 7762, 7767, 7768, 7783, 7799, 7803, 7811, 7815,\n\n7817, 7819, 7820, 7823, 7824, 7828, 7839, 7845 and 7846.\n\n \n\nDocument: 1. General Electric SB (CT58) A72-159; or\n\n \n\n2. FAA AD 81-02-02, Amendment 39-4004; or AD/GE-T/35A\n\nCompliance: As detailed in requirement document No. 1.\n\n \n\nBackground:  This Directive is raised in issue in order to add more Stage 1 turbine wheel S/Nos. to the affected listing and to reference the applicable FAA Airworthiness Directive.\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 AD maintains its original narrow scope — addressing specific safety concerns with specific Stage 1 turbine wheels on CT58 engines. The 'Background' explicitly states this is an amendment to 'add more... S/Nos. to the affected listing,' which is a routine expansion within the original safety purpose, not a scope creep into new regulatory areas."},"complexity_factors":["Very short document (under 300 words)","Only 4 defined elements: applicability (part/serial numbers), document references, compliance trigger, and background","No nested conditional logic — compliance is simply 'follow the service bulletin'","No cross-references to other legislation or regulations beyond citing the parent Civil Aviation Regulations 1998","Single purpose: expand list of affected serial numbers from a previous directive","Technical content is externalised — the actual engineering requirements live in referenced documents (SB A72-159, FAA AD 81-02-02)"],"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). Think of it like a recall notice for aircraft parts, but legally binding.\n\n**What it does:** It requires inspection or replacement of specific **Stage 1 turbine wheels** (critical rotating parts in jet engines) on **General Electric CT58 series engines**. Only certain wheels are affected — those with specific part numbers AND specific serial numbers listed in the document.\n\n**Who it affects:** \n- Aircraft operators using CT58 engines (commonly found in helicopters like the Sikorsky S-61 and some fixed-wing aircraft)\n- Maintenance engineers and organisations responsible for keeping these engines airworthy\n\n**Why it matters:** Turbine wheels spin at extreme speeds and temperatures. If one fails, it can destroy the engine and potentially cause a crash. This AD expands an earlier safety notice to cover additional serial numbers of wheels that may have manufacturing defects or wear issues.\n\n**What must be done:** Operators must follow the instructions in **General Electric Service Bulletin A72-159** (or equivalent FAA documents) to check or replace the affected wheels. The \"Compliance\" section says to follow Document 1's requirements — meaning the actual technical work is detailed in that separate engineering document, not repeated here."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This issue of the AD expands the scope of affected parts by adding additional Stage 1 turbine wheel serial numbers to the listing and explicitly references the applicable FAA Airworthiness Directive. The Background states the directive was raised to add more S/Ns and to reference the FAA AD (Background)."},"complexity_factors":["Narrow, explicit applicability limited to a specific engine type and a finite list of serial numbers (Applicability).","Substantive requirements are delegated to external documents (General Electric SB A72-159; FAA AD 81-02-02; AD/GE-T/35A), so the AD itself contains little procedural detail (Document; Compliance).","Multiple possible reference documents listed can require operators to determine which document and which provisions apply to their case (Document).","The AD does not state inspection intervals, corrective actions, or timelines within its text — these are set out in the referenced requirement document, creating operational dependence (Compliance)."],"plain_english_summary":"The Civil Aviation Safety Authority mandates that CT58 engines containing certain Stage 1 turbine wheel serial numbers be maintained in accordance with a referenced GE service bulletin or the applicable FAA airworthiness directive. The AD’s change is narrow—adding serial numbers to the affected list—and it points to external documents for inspection, repair and timing details.\n\nOwners/operators of affected engines must carry out and pay for the required actions and downtime per those referenced documents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ct58-13-stage-1-turbine-wheels","history":"/api/acts/ad-ct58-13-stage-1-turbine-wheels/history","analysis":"/api/acts/ad-ct58-13-stage-1-turbine-wheels/analysis","conflicts":"/api/acts/ad-ct58-13-stage-1-turbine-wheels/conflicts","importantCases":"/api/acts/ad-ct58-13-stage-1-turbine-wheels/important-cases","documents":"/api/acts/ad-ct58-13-stage-1-turbine-wheels/documents"}}