{"id":"F2006B08691","name":"AD/CT7/7 Amdt 1 - Stage 1 and Stage 2 Gas Generator Turbine Disks","slug":"ad-ct7-7-amdt-1-stage-1-and-stage-2-gas-generator-turbine-disks","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51856,"registerId":"commonwealth-F2006B08691-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CT7/7 Amdt 1 - Stage 1 and Stage 2 Gas Generator Turbine Disks","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 \\- CT7 Series\n\nAD/CT7/7\n\nAmdt 1\n\n  \nStage 1 and Stage 2 Gas Generator Turbine Disks 7/98\n\nApplicability: General Electric CT7-5, \\-7, and \\-9 series engines incorporating Gas Generator Turbine (GGT) disks, P/No. 6064T06P01(Stage 1) or 6064T12P01(Stage 2).\n\nRequirement: Perform a one time eddy current inspection of affected GGT disks in accordance with General Electric Service Bulletin (CT7-TP series) A72-393 Revision 1 dated 13 February 1997.\n\nNote 1: Disks inspected per the original issue of this Directive satisfy the intent of this amendment to the Directive.\n\nNote 2: FAA AD 97-25-07 also refers.\n\nNote 3: FAA AD 97-25-07 supersedes FAA AD 97-05-12.\n\nCompliance: Unless previously accomplished:\n\n    (a) For Stage 1 GGT disks identified in Table 1 of General Electric Service Bulletin (CT7-TP series) A72-393 Revision 1 that have accumulated 8,500 or more Cycles Since New (CSN) on the effective date of this Directive, inspect at the next GGT module removal or within 3 months of the effective date of this Directive whichever occurs first.\n\n    (b) For Stage 1 GGT disks identified in Table 1 of General Electric Service Bulletin (CT7-TP series) A72-393 Revision 1 that have accumulated less than 8,500 CSN, inspect at the next GGT module removal but not to exceed 9,000 CSN.\n\n    (c) For Stage 1 GGT disks identified in Table 2 of General Electric Service Bulletin (CT7-TP series) A72-393 Revision 1 that have accumulated 11,500 or more CSN on the effective date of this Directive, inspect at the next GGT module removal or within 3 months of the effective date of this Directive whichever occurs first.\n\n    (d) For Stage 1 GGT disks identified in Table 2 of General Electric Service Bulletin (CT7-TP series) A72-393 Revision 1 that have accumulated less than 11,500 CSN, inspect at the next GGT module removal but not to exceed 12,000 CSN.\n\n    (e) For Stage 2 GGT disks identified in Table 3 of General Electric Service Bulletin (CT7-TP series) A72-393 Revision 1 that have accumulated 8,500 or more (CSN) on the effective date of this Directive, inspect at the next GGT module removal or within 3 months of the effective date of this Directive whichever occurs first.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n    (f) For Stage 2 GGT disks identified in Table 3 of General Electric Service Bulletin (CT7-TP series) A72-393 Revision 1 that have accumulated less than 8,500 CSN, inspect at the next GGT module removal but not to exceed 9,000 CSN.\n\n    (g) For Stage 2 GGT disks identified in Table 4 of General Electric Service Bulletin (CT7-TP series) A72-393 Revision 1 that have accumulated 11,500 or more (CSN) on the effective date of this Directive, inspect at the next GGT module removal or within 3 months of the effective date of this Directive whichever occurs first.\n\n    (h) For Stage 2 GGT disks identified in Table 4 of General Electric Service Bulletin (CT7-TP series) A72-393 Revision 1 that have accumulated less than 11,500 CSN, inspect at the next GGT module removal but not to exceed 12,000 CSN.\n\n    (i) For Stage 1 and Stage 2 GGT disks not identified in Tables 1 through 4 of General Electric Service Bulletin (CT7-TP series) A72-393 Revision 1 that have accumulated 8,500 CSN or more on the effective date of this Directive, inspect at the next GGT module removal or within 3 months of the effective date of this Directive whichever occurs first.\n\n    (j) For Stage 1 and Stage 2 GGT disks not identified in Tables 1 through 4 of General Electric Service Bulletin (CT7-TP series) A72-393 Revision 1 that have accumulated less than 8,500 CSN, inspect at the next GGT module removal but not to exceed 9,000 CSN.\n\nThis amendment becomes effective on 18 June 1998.\n\nBackground: This Directive is prompted by a report of an uncontained Stage 2 GGT disk failure on take-off. The most likely cause of the failure of the disk was machining damage to a cooling hole during manufacture.\n\nGGT disk rupture can result in an uncontained failure that could cause damage to the aircraft.\n\nThis amendment reflects a revision to the General Electric SB that corrects the respective disk serial numbers in the various tables to avoid confusion where the same serial number appears in more than one table. In addition, the inspection thresholds have been increased and the calendar time intervals decreased to comply with GE’s risk analysis model.\n\nThe original issue of this Directive became effective on 17 July 1997.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"The amendment revises the GE service bulletin tables (correcting serial numbers) and alters inspection triggers by increasing cycle thresholds while shortening calendar compliance intervals. Mechanically this changes when affected disk inspections must occur and requires operators to recheck serial‑number lists against the revised tables (Background)."},"complexity_factors":["Multiple cycle‑based thresholds (e.g. 8,500; 9,000; 11,500; 12,000 CSN) that determine different inspection timing windows","Different requirements for Stage 1 vs Stage 2 disks and for disks listed in four separate service‑bulletin tables","Cross‑reference dependency on General Electric Service Bulletin A72‑393 Revision 1 for serial numbers and inspection procedure","Choice between inspection at next GGT module removal or within specified calendar time (creates scheduling complexity for operators)","Notes and FAA AD cross‑references that affect interpretation (e.g. prior inspections satisfying the amendment)","Amendment corrects table serial numbers and modifies thresholds/times, so implementers must reconcile previous records with revised tables"],"plain_english_summary":"This Directive requires a one‑time eddy‑current inspection of certain Stage 1 and Stage 2 gas‑generator turbine (GGT) disks on General Electric CT7‑5, ‑7 and ‑9 engines, following GE Service Bulletin A72‑393 Rev 1. Aircraft operators must schedule and pay for inspections according to cycle‑based and calendar windows tied to GGT module removal; the regulator enforces compliance to reduce the risk of uncontained disk rupture (Background; Compliance)."},"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":4,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose: preventing turbine disk failures in GE CT7 engines. The changes from the original 1997 directive are technical corrections (fixing serial number table errors) and refined risk-based timing adjustments — not scope expansion. The directive does not extend to other engine types, other aircraft systems, or broader operational requirements."},"complexity_factors":["Multiple conditional compliance pathways based on: (a) Stage 1 vs Stage 2 disks, (b) which table the disk appears in (Tables 1-4), (c) cycles accumulated (8,500 vs 11,500 vs other thresholds), and (d) whether disk is listed in tables or not — resulting in 10 distinct compliance scenarios (paragraphs a-j)","Cross-reference dependency: Full compliance requires obtaining and interpreting General Electric Service Bulletin A72-393 Revision 1, which is not reproduced in the directive","Technical terminology requiring domain knowledge: 'eddy current inspection', 'Cycles Since New (CSN)', 'Gas Generator Turbine (GGT) module removal', 'uncontained failure'","Nested temporal conditions: 'whichever occurs first' logic combining calendar time (3 months) with maintenance events (next module removal) or cycle limits","Part number specificity: Requires matching exact part numbers (6064T06P01, 6064T12P01) and serial numbers across multiple tables in an external document"],"plain_english_summary":"This CASA safety order mandates a one‑time eddy‑current inspection of specific turbine disks in GE CT7‑5/7‑9 series engines after a disk failure risk was identified. Operators of affected helicopters and regional aircraft must inspect within cycle‑based deadlines (sooner for high‑use engines) to prevent uncontained disk failures. It amends a 1997 directive (earlier compliant inspections remain valid) and mirrors a similar FAA order."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ct7-7-amdt-1-stage-1-and-stage-2-gas-generator-turbine-disks","history":"/api/acts/ad-ct7-7-amdt-1-stage-1-and-stage-2-gas-generator-turbine-disks/history","analysis":"/api/acts/ad-ct7-7-amdt-1-stage-1-and-stage-2-gas-generator-turbine-disks/analysis","conflicts":"/api/acts/ad-ct7-7-amdt-1-stage-1-and-stage-2-gas-generator-turbine-disks/conflicts","importantCases":"/api/acts/ad-ct7-7-amdt-1-stage-1-and-stage-2-gas-generator-turbine-disks/important-cases","documents":"/api/acts/ad-ct7-7-amdt-1-stage-1-and-stage-2-gas-generator-turbine-disks/documents"}}