{"id":"F2006B08525","name":"AD/CFM56/21 - Stage 2 and 3 LPT Nozzle Segments - Replacement","slug":"ad-cfm56-21-stage-2-and-3-lpt-nozzle-segments-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51276,"registerId":"commonwealth-F2006B08525-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CFM56/21 - Stage 2 and 3 LPT Nozzle Segments - Replacement","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)  \n\nAIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\n![](image.001.png)  \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 CAR 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\nCFM International Turbine Engines \\- CFM56 Series\n\nAD/CFM56/21 Stage 2 and 3 LPT Nozzle Segments \\-\n\nReplacement\n\n  \n12/2002\n\nApplicability: CFM International CFM56-5B and CFM56-7B engines. Requirement: Action per the DGAC AD 2002-470(B).\n\nNote: DGAC AD 2002-470(B) refers.\n\nCompliance: As detailed in the requirement document.\n\nThis Airworthiness Directive becomes effective on 28 November 2002.\n\nBackground: The second and third stage LPT nozzles identified in this directive are found to be inadequate in limiting the maximum LPT speed in the event of LPT shaft failure. Hence they are removed from service.\n\n![Signature of Barry James Reid McKay Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nBarry James Reid McKay\n\nDelegate of the Civil Aviation Safety Authority 17 October 2002\n\n![](image.001.png)\n\nThe above AD is notified in the Commonwealth of Australia Gazette on 6 November 2002.\n\n  \n\nPage 1 of 1","sortOrder":0}],"analysis":{"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 AD maintains its original narrow scope — addressing a specific mechanical defect in specific engine models. It does not expand beyond its original safety purpose."},"complexity_factors":["Very short document (1 page)","Only 2 defined applicability criteria (engine models)","Single requirement referencing an external document (DGAC AD 2002-470(B))","No nested conditions or exceptions","No cross-references to other legislation beyond CAR 1998 Part 39","Straightforward compliance timeline ('as detailed in requirement document')"],"plain_english_summary":"This AD mandates replacement of second- and third-stage LPT nozzle segments on CFM56-5B and CFM56-7B engines after the DGAC AD 2002-470(B). It affects airlines and maintenance organizations using these engines because damaged or noncompliant nozzles can fail to limit engine speed if the LPT shaft breaks, risking engine overspeed and catastrophic failure."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The AD implements the corrective action described by the referenced DGAC AD for specified CFM56 engine models and nozzle segments (Applicability; Requirement; Background). There is no text indicating an expansion or narrowing of scope beyond that foreign AD: the directive simply adopts that requirement and sets an effective date, so scope appears unchanged from the original corrective intent."},"complexity_factors":["Technical specificity: addresses particular engine parts (Stage 2 and 3 LPT nozzle segments) and a failure mode (LPT shaft failure) (Background, Applicability).","Normative external reference: mandates compliance by citing a foreign airworthiness directive (DGAC AD 2002-470(B)), requiring operators to obtain and follow that document (Requirement, Note).","Compliance detail delegation: compliance timing and procedures are given in the referenced requirement document rather than fully in the AD, creating dependence on an external document for operative steps (Requirement, Compliance).","Operational burden: removal/replacement imposes maintenance scheduling costs, part procurement and downtime on operators and maintenance organisations (Applicability, Requirement).","Regulatory formality: issued under CAR 1998 subregulation 39.1(1) and signed by a CASA delegate, making noncompliance a regulatory issue (preamble/signature).","Narrow scope but technical identification needed: applicability lists engine models only; operators must identify affected engines/parts within fleets, which may require technical records review (Applicability).","Potential ambiguity locating operative instructions: the AD does not reproduce DGAC AD text, so implementers must source and interpret that external document (Requirement, Note)."],"plain_english_summary":"This Airworthiness Directive requires removal and replacement of certain Stage 2 and 3 low‑pressure turbine (LPT) nozzle segments on CFM56‑5B and CFM56‑7B engines, directing operators to follow DGAC AD 2002‑470(B). CASA's stated reason is that those nozzle segments do not adequately limit maximum LPT speed if the LPT shaft fails, so they must be removed from service. It affects aircraft operators and maintenance organisations, who must schedule and pay for the replacements and follow the timing and instructions in the Requirement and Compliance sections."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cfm56-21-stage-2-and-3-lpt-nozzle-segments-replacement","history":"/api/acts/ad-cfm56-21-stage-2-and-3-lpt-nozzle-segments-replacement/history","analysis":"/api/acts/ad-cfm56-21-stage-2-and-3-lpt-nozzle-segments-replacement/analysis","conflicts":"/api/acts/ad-cfm56-21-stage-2-and-3-lpt-nozzle-segments-replacement/conflicts","importantCases":"/api/acts/ad-cfm56-21-stage-2-and-3-lpt-nozzle-segments-replacement/important-cases","documents":"/api/acts/ad-cfm56-21-stage-2-and-3-lpt-nozzle-segments-replacement/documents"}}