{"id":"F2006B08458","name":"AD/CF6/14 - High Pressure Turbine Discs","slug":"ad-cf6-14-high-pressure-turbine-discs","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51098,"registerId":"commonwealth-F2006B08458-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CF6/14 - High Pressure Turbine Discs","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)  \nGeneral Electric Turbine Engines \\- CF6 Series\n\nAD/CF6/14 High Pressure Turbine Discs 1/91\n\nApplicability: CF6-45/50 series engines.\n\nRequirement: Remove from service, first stage high pressure turbine discs P/N 9264M57P01, 9264M57P02, 1322M88P04, 1322M88P05, 1322M88P07, 9283M31P02,\n\n9283M55P04 and 9283M55P05 in accordance with the compliance schedule of this Directive.\n\nNote: FAA AD 90-19-09 refers.\n\nCompliance: Effective 24 January 1991:\n\n    Remove within 100 cycles in service (CIS) after the effective date of this AD, discs with greater than or equal to 7,500 CSN.\n\n    2. Remove at the next engine shop visit, but no later than 1,000 CIS after the effective date of this AD or prior to accumulating 7,600 CSN, whichever occurs first, discs with greater than or equal to 6,000 CSN, but less than 7,500 CSN.\n\n    3. Remove at the next engine shop visit after accumulating 5,500 CSN, but no later than 1,500 CIS after the effective date of this AD or prior to accumulating 7,000 CSN, whichever occurs first, discs with greater than or equal to 4,000 CSN, but less than 6,000 CSN.\n\n    4. Remove prior to exceeding 5,500 CSN, discs with less than 4,000 CSN.\n\n    5. Thereafter, remove affected discs from service and replace with a serviceable disc prior to exceeding 5,500 CSN.\n\nNote: CF6-50 Series Service Bulletin 72-966, dated September 1, 1989, introduces a new HPT stage one disc, P/N 1473M65P02, which has an FAA approved time limit of 15,000 CSN.\n\nBackground: This Directive has been issued to require removal of certain high pressure turbine discs from service. The requirement follows advice of an uncontained stage one high pressure turbine disc fracture event. Investigation of the disc fracture event found six similar discs to be cracked.","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"},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The Directive confines action to listed CF6-45/50 first-stage HPT discs and imposes a removal/replacement schedule; it implements the safety response described (uncontained fracture and cracked discs) and aligns with referenced FAA AD and service bulletin rather than expanding applicability beyond those parts."},"complexity_factors":["Multiple affected part numbers (several P/Ns listed) increasing tracking burden","Tiered compliance schedule keyed to CSN bands and CIS windows (different removal deadlines per CSN range)","Deadlines tied both to elapsed CIS after effective date and to next engine shop visit, creating coordination complexity","Cross-references to FAA AD 90-19-09 and a manufacturer service bulletin for replacement part/time limit","Replacement requirement introduces supply and logistics considerations (serviceable disc or new P/N with different life limit)","Effective date and short initial removal windows (e.g. 100 CIS for highest CSN band) increase operational pressure"],"plain_english_summary":"This directive requires operators of GE CF6-45/50 engines to remove specified first-stage high-pressure turbine discs and replace them on a tiered schedule based on each disc's cycles since new (CSN) and cycles in service (CIS). It targets particular part numbers after an uncontained disc fracture and the discovery of similar cracks. Operators and maintenance providers pay for removals, replacements and shop visits; compliance imposes discrete timing windows, record-keeping and parts-tracking obligations to mitigate fracture risk."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a discrete safety directive addressing a specific mechanical defect in specific engine models. The scope remains tightly focused on the original safety issue — removal of cracked high-pressure turbine discs — without expansion into broader regulatory areas."},"complexity_factors":["Multiple conditional compliance deadlines based on three different usage thresholds (CSN ranges)","Nested timing requirements using 'whichever occurs first' logic","Cross-reference to US FAA directive (AD 90-19-09) and manufacturer service bulletin","Technical aviation terminology requiring specialist knowledge (CSN, CIS, P/N numbers)","Five distinct compliance pathways with overlapping conditions"],"plain_english_summary":"This CASA Airworthiness Directive orders the immediate removal of specific high‑pressure turbine discs from General Electric CF6‑45/50 engines after an uncontained disc failure and discovery of cracked discs. It addresses a catastrophic risk where a fractured disc can breach the engine case and endanger the aircraft and occupants.\n\nIt affects Australian operators of CF6‑45/50‑equipped aircraft (e.g., older 747, DC‑10, A300). Removal deadlines vary by accumulated flight cycles, and replacement discs are also subject to early removal limits."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cf6-14-high-pressure-turbine-discs","history":"/api/acts/ad-cf6-14-high-pressure-turbine-discs/history","analysis":"/api/acts/ad-cf6-14-high-pressure-turbine-discs/analysis","conflicts":"/api/acts/ad-cf6-14-high-pressure-turbine-discs/conflicts","importantCases":"/api/acts/ad-cf6-14-high-pressure-turbine-discs/important-cases","documents":"/api/acts/ad-cf6-14-high-pressure-turbine-discs/documents"}}