{"id":"F2006B08461","name":"AD/CF6/17 - Stage 1 Fan Rotor Disc","slug":"ad-cf6-17-stage-1-fan-rotor-disc","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51106,"registerId":"commonwealth-F2006B08461-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CF6/17 - Stage 1 Fan Rotor Disc","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 - CF6 Series\n\n \n\nAD/CF6/17 Stage 1 Fan Rotor Disc 3/91\n\nApplicability: CF6 - 6, -45, -50, -80A.\n\n \n\nRequirement: Inspect the stage 1 fan disc dovetail post for cracks in accordance with the technical requirements of the FAA AD 91-01-04 Amdt 39-6847.\n\n \n\nNote: The GE SB 72-999, 965 and 575 covering the -50/-45, -6 and -80A series respectively refer.\n\n \n\nCompliance: As specified in the Requirement Document.\n\n \n\nBackground:  Five stage 1 fan discs have been discovered with cracks in the dovetail post area. The defect has the potential for multiple blade release, engine power loss and uncontained engine failure.\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":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD maintains a targeted scope: it requires inspections of the stage 1 fan disc dovetail post for specified CF6 engine models. It does not expand obligations beyond inspection and compliance with the referenced FAA AD and GE service bulletins, nor does it add new affected equipment outside the listed CF6 variants. (Applicability; Requirement; Note)"},"complexity_factors":["Cross-reference to an external FAA AD for the required technical inspection procedures rather than containing procedures in the instrument itself (Requirement).","Model coverage across four CF6 variants (-6, -45, -50, -80A) requiring attention to model-specific GE service bulletins (Applicability; Note).","Safety-critical nature of the component (stage 1 fan disc dovetail post) increasing operational and inspection prioritisation (Background).","Operational impacts from potential engine/component removal, downtime and repair if cracks are detected (Compliance; Requirement).","Reliance on OEM service bulletins for specific inspection steps concentrates technical authority outside the AD text (Note)."],"plain_english_summary":"This AD requires operators and maintenance organisations of GE CF6-6, -45, -50 and -80A engines to inspect the stage‑1 fan‑disc dovetail post for cracks, following the inspection procedures referenced in FAA AD 91‑01‑04 and GE service bulletins. It responds to discovered dovetail cracks that could cause blade release and uncontained engine failure. Compliance imposes inspection, downtime and repair costs and depends on correctly following the FAA/GE technical instructions."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific engine models. It has not expanded beyond its original purpose of mandating inspections for cracked fan discs."},"complexity_factors":["Single, specific mechanical component targeted (stage 1 fan disc dovetail post)","Only 4 engine models affected, clearly listed","Single compliance requirement: visual inspection per external FAA document","No conditional logic, exceptions, or alternative compliance methods","No defined terms section; plain technical language","Cross-reference to only one external document (FAA AD 91-01-04) plus optional service bulletins","Extremely short: approximately 150 words of substantive content"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft engines.\n\n**What it does:**\nOrders airlines and aircraft operators to inspect a specific part of General Electric CF6 jet engines (the \"stage 1 fan rotor disc\") for dangerous cracks.\n\n**Who it affects:**\nOperators of aircraft using CF6-6, CF6-45, CF6-50, or CF6-80A model engines. These engines power many older Boeing 747s, DC-10s, and Airbus A300s.\n\n**Why it matters:**\nFive engines were found with cracks in the \"dovetail post\" area — the slot where fan blades attach. If this part fails, multiple blades could break off simultaneously, causing catastrophic engine failure, power loss, or debris flying through the aircraft fuselage (an \"uncontained failure\"). The directive adopts a US Federal Aviation Administration (FAA) safety order to prevent crashes.\n\n**What operators must do:**\nFollow the inspection procedures in FAA AD 91-01-04, using the specific General Electric service bulletins mentioned for each engine variant."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cf6-17-stage-1-fan-rotor-disc","history":"/api/acts/ad-cf6-17-stage-1-fan-rotor-disc/history","analysis":"/api/acts/ad-cf6-17-stage-1-fan-rotor-disc/analysis","conflicts":"/api/acts/ad-cf6-17-stage-1-fan-rotor-disc/conflicts","importantCases":"/api/acts/ad-cf6-17-stage-1-fan-rotor-disc/important-cases","documents":"/api/acts/ad-cf6-17-stage-1-fan-rotor-disc/documents"}}