{"id":"F2006B08531","name":"AD/CFM56/6 - Fan Blade","slug":"ad-cfm56-6-fan-blade","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51292,"registerId":"commonwealth-F2006B08531-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CFM56/6 - Fan Blade","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nCFM International Turbine Engines \\- CFM56 Series\n\nAD/CFM56/6 Fan Blade 4/97\n\nApplicability: CFM International (CFMI) CFM56-3B-2 and CFM56-3C-1 engines.\n\nRequirement: Action in accordance with the technical requirements of FAA Airworthiness Directive 96-25-11.\n\nInstallation of fan blades incorporating 37 Deg midspan shrouds per CFMI Service Bulletin (CFM56-3/-3B/-3C) 72-543 is terminating action for the thrust limitations imposed by this Directive.\n\nNote: A flight manual amendment may be required depending on engine fan blade modification status.\n\nCompliance: Effective 27 March 1997, as specified in the Requirement Document.\n\nBackground: This Directive is raised to remove from service certain fan disc and fan blade hardware, to impose limits on thrust levels on certain engine configurations, and introduce new fan blade hardware that will remove limitations on thrust levels. These measures are intended to prevent a fan blade failure that could result in complete loss of engine power.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Scope is targeted to removing specified fan hardware, imposing thrust limits on the listed CFM56 engine models, and allowing termination by installing blades with 37° midspan shrouds per the cited service bulletin; it does not broaden applicability beyond those measures."},"complexity_factors":["Cross-reference to FAA Airworthiness Directive 96-25-11 (Requirement) — requires consulting and complying with an external technical AD.","Terminating action depends on CFMI Service Bulletin 72-543 (Requirement) — technical modification details are in the manufacturer’s SB, not this Directive.","Limited applicability to specific engine models (Applicability) — requires fleet identification and selective action.","Imposition of temporary thrust limitations (Requirement/Background) — introduces operational restrictions that affect scheduling and dispatch.","Potential need for flight manual amendment (Note) — administrative and regulatory paperwork for affected aircraft.","Fixed compliance effective date (Compliance) — deadline-driven work and parts availability risks.","Safety-critical nature (Background) — removal-from-service actions increase maintenance oversight and cost pressure on operators."],"plain_english_summary":"Requires removal of specified fan disc and fan blade hardware from CFMI CFM56-3B-2 and CFM56-3C-1 engines, imposes temporary thrust limits for affected configurations, and allows those limits to be lifted by installing fan blades with 37° midspan shrouds per CFMI Service Bulletin 72‑543 (terminating action).\n\nApplies to operators and maintainers of the listed engines and may require a flight manual amendment. The stated purpose is to prevent fan blade failure and loss of engine power; operators bear inspection, modification and operational-limit costs until terminating action is completed."},"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 preventing fan blade failures through hardware replacement or operational limitations."},"complexity_factors":["Very short document (approximately 200 words)","Only 2 defined applicability criteria (specific engine models)","Single primary requirement referencing an external FAA document","One terminating action condition (installation of modified blades)","No nested exceptions or conditional logic chains","Clear compliance date with no alternative timelines","Minimal cross-referencing (only to FAA AD 96-25-11 and one Service Bulletin)"],"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:**\nThis directive applies to specific CFM International jet engines (the CFM56-3B-2 and CFM56-3C-1 models, commonly used in Boeing 737 aircraft). It requires airlines and aircraft operators to:\n\n- **Remove from service** certain fan disc and fan blade hardware that has been identified as unsafe\n- **Limit thrust levels** on engines that haven't been modified yet (this reduces stress on the components)\n- **Install improved fan blades** that have a specific design feature (37-degree midspan shrouds) — once this upgrade is done, the thrust limitations can be lifted\n\n**Why it matters:**\nThe faulty hardware could cause a **fan blade failure**, which could lead to **complete engine failure** in flight. This directive prevents that catastrophic outcome by forcing operators to either restrict engine power or replace the problematic parts.\n\n**Who it affects:**\nAirlines and aircraft operators flying planes with these specific CFM56 engines. They must comply by March 27, 1997, following the technical requirements set out in a US Federal Aviation Administration (FAA) directive.\n\n**Key point:** Operators who install the upgraded fan blades (per the manufacturer's Service Bulletin 72-543) can remove the thrust restrictions and return to normal operations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cfm56-6-fan-blade","history":"/api/acts/ad-cfm56-6-fan-blade/history","analysis":"/api/acts/ad-cfm56-6-fan-blade/analysis","conflicts":"/api/acts/ad-cfm56-6-fan-blade/conflicts","importantCases":"/api/acts/ad-cfm56-6-fan-blade/important-cases","documents":"/api/acts/ad-cfm56-6-fan-blade/documents"}}