{"id":"F2006B08494","name":"AD/CF6/56 - HP Stage 1 Turbine Discs","slug":"ad-cf6-56-hp-stage-1-turbine-discs","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51193,"registerId":"commonwealth-F2006B08494-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nGeneral Electric Turbine Engines \\- CF6 Series","sortOrder":0},{"sectionNumber":"AD/CF6/56 HP Stage 1 Turbine Discs 7/200","sectionType":"part","heading":"AD/CF6/56 HP Stage 1 Turbine Discs 7/2004","content":"# AD/CF6/56 HP Stage 1 Turbine Discs 7/2004\n\nApplicability: General Electric CF6-80C2A5F, CF6-80C2B5F, CF6-80C2B7F and CF6-80C2D1F turbofan engines with high pressure turbine (HPT) stage 1 discs, part number (P/Ns) 1531M84G10 or 1531M84G12 installed.\n\nRequirement: 1. Replace HPT stage 1 discs, P/N 1531M84G10 and 1531M84G12.\n\n2. Do not install HPT stage 1 discs, P/N 1531M84G10 and 1531M84G12.\n\nNote: FAA AD 2004-07-13 Amdt 39-13557 refers.\n\nCompliance: For Requirement 1: At or before the disc accumulates 10,720 cycles since new (CSN).\n\nFor Requirement 2: That have exceeded 10,720 CSN.\n\nThis Airworthiness Directive becomes effective on 8 July 2004.\n\nBackground: This Directive is prompted by an updated low-cycle-fatigue (LCF) analysis of the HPT stage 1 disc. The action specified in this Directive are intended to prevent LCF cracking of the HPT stage 1 disc due to exceeding the life limit, which could result in an uncontained engine failure and damage to the aeroplane.\n\n![Signature of James Coyne Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nJames Coyne\n\nDelegate of the Civil Aviation Safety Authority 28 May 2004\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 16 June 2004.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument sets a defined life limit and an installation prohibition for the named parts. The AD text itself does not indicate a change to its own applicability or scope after issuance; it implements the life‑limit derived from the updated LCF analysis (Background) and prescribes the replacement and installation rules (Requirement/Compliance)."},"complexity_factors":["Narrow applicability to specific engine variants and two part numbers (Applicability) — reduces legal and technical breadth.","Single numeric life limit (10,720 CSN) to track and enforce (Compliance) — straightforward but requires accurate cycle records.","Two simple mandates (replace by life limit; do not install beyond life) (Requirement) — low regulatory layering.","Technical rationale tied to updated LCF analysis (Background) — requires technical acceptance but no complex inspection regime.","Legal issuing authority stated (subregulation 39.1(1) CASR 1998) — clear administrative basis.","Cross-reference to FAA AD (Note) — introduces cross-jurisdictional alignment considerations for operators following multiple regulators."],"plain_english_summary":"This Airworthiness Directive requires replacement of specified high‑pressure turbine (HPT) stage 1 discs (P/Ns 1531M84G10 and 1531M84G12) on certain GE CF6‑80C2 engines at or before 10,720 cycles since new and prohibits installing discs that have exceeded that life. CASA issued the AD under subregulation 39.1(1) of CASR 1998 to address an updated low‑cycle‑fatigue analysis and reduce the risk of uncontained engine failure. It affects aircraft operators, owners and maintenance organisations who must bear replacement costs and schedule the work to comply."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific metallurgical failure mode in identified engine components. The scope remains precisely limited to the originally identified unsafe condition and affected parts."},"complexity_factors":["Single, clearly defined applicability section limited to 4 specific engine models and 2 part numbers","Only 2 operational requirements with no sub-paragraphs or conditional exceptions","Straightforward compliance trigger based on a single numerical threshold (10,720 cycles since new)","No defined terms section or interpretation provisions","No cross-references to other legislation beyond a single non-binding note referencing the corresponding FAA directive","Background section provides clear safety rationale without legal caveats"],"plain_english_summary":"This CASA safety order bans use and installation of specific GE CF6-80C2 high‑pressure turbine discs (PN 1531M84G10/12) once they exceed 10,720 flight cycles and requires their replacement before that limit. It affects airlines, operators and maintenance organisations using those engine variants because the discs can develop low‑cycle fatigue that risks uncontained engine failure and catastrophic airframe damage."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cf6-56-hp-stage-1-turbine-discs","history":"/api/acts/ad-cf6-56-hp-stage-1-turbine-discs/history","analysis":"/api/acts/ad-cf6-56-hp-stage-1-turbine-discs/analysis","conflicts":"/api/acts/ad-cf6-56-hp-stage-1-turbine-discs/conflicts","importantCases":"/api/acts/ad-cf6-56-hp-stage-1-turbine-discs/important-cases","documents":"/api/acts/ad-cf6-56-hp-stage-1-turbine-discs/documents"}}