{"id":"F2006B08464","name":"AD/CF6/20 - High Pressure Compressor Rotor Stages 11 to 14 Vane to Spool Rubs","slug":"ad-cf6-20-high-pressure-compressor-rotor-stages-11-to-14-vane-to-spool-rubs","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51113,"registerId":"commonwealth-F2006B08464-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CF6/20 - High Pressure Compressor Rotor Stages 11 to 14 Vane to Spool Rubs","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\n# AD/CF6/20 High Pressure Compressor Rotor Stages\n\n11 to 14 Vane to Spool Rubs\n\nApplicability: CF6-80A and CF6-80C2.\n\n \n\nRequirement: Action in accordance with the Technical Requirements of FAA AD 91-15-25 Amendment 39-7090.\n\n \n\nNote: GE Service Bulletins 72-459 Revision 2 and 72-130 Revision 2 refer.\n\n# 11/91\n\n \n\nCompliance: As specified in the Requirement Document with an effective date of 28 November 1991.\n\n \n\nBackground: The FAA AD is prompted by reports of HPCR stages 11-14 spool-shafts found in service with spool rub. This condition, if not corrected could result in 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","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD adopts and requires compliance with the technical requirements of FAA AD 91-15-25 (Amendment 39-7090) for CF6-80A and CF6-80C2 engines and points to GE Service Bulletins for related work. The instrument does not indicate any expansion or narrowing of scope beyond those external documents; there is no text in this AD that changes the stated applicability or technical mandate from the referenced FAA AD. (Applicability; Requirement; Note)"},"complexity_factors":["Cross-reference to external technical document (FAA AD 91-15-25) rather than containing procedures directly (Requirement)","Reference to manufacturer service bulletins for details (Note)","Narrow applicability limited to two engine models (CF6-80A and CF6-80C2) (Applicability)","Safety-critical subject matter (uncontained engine failure) increases operational urgency and scrutiny (Background)","Fixed effective compliance date requires action within a set timeframe (Compliance)"],"plain_english_summary":"### What this instrument does\n\nThis is an Airworthiness Directive (AD) issued under the Civil Aviation Safety Authority requiring action on certain General Electric CF6 turbine engines. It directs that operators of the affected engines must carry out the technical actions set out in the referenced FAA airworthiness directive (FAA AD 91-15-25 Amendment 39-7090). (Requirement)\n\n### Which engines are affected\n\n- CF6-80A and CF6-80C2 engines. (Applicability)\n\n### What operators must do, mechanically\n\n- Perform the inspections, repairs or modifications described in FAA AD 91-15-25 (the “Requirement Document”). The AD also points operators to GE Service Bulletins 72-459 Revision 2 and 72-130 Revision 2 as related documents. (Requirement; Note)\n- Comply by the effective date stated in the Requirement Document (effective 28 November 1991). (Compliance)\n\n### Why the AD was issued (stated risk)\n\n- The FAA AD was prompted by reports of high-pressure compressor rotor (HPCR) stages 11–14 spool-shafts being found with vane-to-spool rubs in service. The AD states that, if not corrected, the condition could result in uncontained engine failure. (Background)\n\n### Who pays and who decides\n\n- The Civil Aviation Safety Authority has issued the AD as the regulatory instrument, but the AD requires operators to follow the technical requirements specified in the FAA AD. The practical work (inspections, repairs or modifications) will fall to the engine owners/operators and their maintenance providers. (Requirement)\n\n### Compliance burden and implementation risk\n\n- Compliance requires following an external technical document (FAA AD 91-15-25) and related GE service bulletins; the AD does not reproduce the technical steps itself. That creates a compliance process of locating and implementing external technical procedures. (Requirement; Note)\n- The AD sets a specific effective date for compliance, which fixes the timing for inspections/repairs. (Compliance)\n- The declared safety consequence of non‑compliance is uncontained engine failure, which is the stated driver for regulatory action. (Background)\n\n### How this affects private choices and operations\n\n- Operators must allocate maintenance resources (labour, shop visits, parts) and scheduling to meet the AD requirements described in the FAA document and service bulletins. (Requirement; Note)\n- The AD’s technical requirements are external to this instrument; choices about how to meet them (which approved repair facility, whether to replace or repair parts) remain with operators within the bounds of the FAA AD and applicable maintenance approval processes. (Requirement)\n\n### Trade-offs, incentives and practical notes\n\n- The AD creates a compliance cost for affected engine operators (inspection/repair work and associated downtime). (Requirement; Note)\n- The stated incentive is risk reduction: correcting spool rubs aims to prevent uncontained engine failure. (Background)\n- The AD relies on an external FAA technical mandate and GE service bulletins to set the detailed actions; that cross-reference centralises technical detail outside the AD itself and concentrates interpretative weight in those documents. (Requirement; Note)\n\nFor the exact inspection intervals, corrective actions and any parts or procedures required, operators must consult FAA AD 91-15-25 Amendment 39-7090 and the GE service bulletins referenced. (Requirement; Note; Compliance)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive implementing a foreign (FAA) safety order for specific engine models. The scope remains tightly focused on the original safety issue (HPCR vane-to-spool rubs) and has not expanded beyond this specific mechanical defect in these specific engine variants."},"complexity_factors":["Very short document (under 300 words)","Only 2 defined applicability terms (CF6-80A and CF6-80C2 engine models)","Single requirement referencing external document (FAA AD 91-15-25)","No nested conditional logic or exceptions","No cross-references to other Australian legislation beyond Civil Aviation Regulations 1998 Part 39","Straightforward compliance date with no alternative methods or escalations"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft engines.\n\n**What it does:**\nIt requires owners and operators of specific General Electric jet engines (the CF6-80A and CF6-80C2 models) to follow a technical safety procedure originally issued by the US Federal Aviation Administration (FAA).\n\n**The safety problem:**\nThe engines can develop a dangerous condition where parts inside the high-pressure compressor rub against each other (specifically, vanes rubbing against spool-shafts in stages 11-14). If left unchecked, this could cause the engine to break apart in flight — what's called an \"uncontained engine failure,\" where debris could damage the aircraft or injure people.\n\n**Who must act:**\nAnyone operating aircraft with these specific GE CF6 engines in Australia.\n\n**What they must do:**\nFollow the technical instructions in FAA AD 91-15-25 (a US safety order), which involves inspections and repairs to prevent the rubbing problem. Two specific GE service bulletins (technical repair guides) provide the detailed instructions.\n\n**When:**\nBy 28 November 1991 (the effective date).\n\n**Why it matters:**\nThis prevents catastrophic engine failures that could bring down aircraft or kill passengers and crew. Airworthiness directives are legally binding — ignoring them means the aircraft cannot fly legally."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cf6-20-high-pressure-compressor-rotor-stages-11-to-14-vane-to-spool-rubs","history":"/api/acts/ad-cf6-20-high-pressure-compressor-rotor-stages-11-to-14-vane-to-spool-rubs/history","analysis":"/api/acts/ad-cf6-20-high-pressure-compressor-rotor-stages-11-to-14-vane-to-spool-rubs/analysis","conflicts":"/api/acts/ad-cf6-20-high-pressure-compressor-rotor-stages-11-to-14-vane-to-spool-rubs/conflicts","importantCases":"/api/acts/ad-cf6-20-high-pressure-compressor-rotor-stages-11-to-14-vane-to-spool-rubs/important-cases","documents":"/api/acts/ad-cf6-20-high-pressure-compressor-rotor-stages-11-to-14-vane-to-spool-rubs/documents"}}