{"id":"F2006B08693","name":"AD/CT7/9 - Compressor Variable Geometry Schedule","slug":"ad-ct7-9-compressor-variable-geometry-schedule","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51861,"registerId":"commonwealth-F2006B08693-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\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 \\- CT7 Series","sortOrder":0},{"sectionNumber":"AD/CT7/9 Compressor Variable Geometry Sc","sectionType":"part","heading":"AD/CT7/9 Compressor Variable Geometry Schedule 6/2003","content":"# AD/CT7/9 Compressor Variable Geometry Schedule 6/2003\n\nTX\n\nApplicability: All CT7-9B engines.\n\nNote 1: These engines are known to be installed on but not limited to SAAB Aircraft 340B aeroplanes.\n\nRequirement: 1. Determine the Variable Geometry (VG) rigging schedule for both engines. If the compressor VGs are rigged to VG schedule N using GEAE Service Bulletin (SB) CT7-TP S/B 72-0328 or GEAE Alert Service Bulletin (ASB) CT7-TP S/B 72- A0328 Revision 1 no further action is required.\n\nNote 2: The engines with Serial Numbers (S/Ns) listed in Table 1 of this directive are known to have been rigged to VG schedule N1.\n\n    2. If the compressor VGs on both engines on the aeroplane are rigged to VG schedule N1, accomplish the following:\n\n    rig the compressor VG on one engine to VG schedule N in accordance with 3.A.(1) through 3.A.(12) of the Accomplishment instructions of GEAE ASB No. CT7-TP S/B 72-A0328 Revision 1; and\n    rig the compressor VG on the remaining engine to VG schedule N in accordance with 3.A.(1) through 3.A.(12) of the Accomplishment instructions of GEAE ASB No. CT7-TP S/B 72-A0328 Revision 1.\n\n    3. If the compressor VG on one engine on the aeroplane is rigged to VG schedule N1, rig the engine to the VG schedule N in accordance with 3.A.(1) through 3.A.(12) of the Accomplishment instructions of GEAE (ASB) No. CT7-TP S/B 72-A0328 Revision 1.\n    4. Do not install any GE CT7-9B engine rigged to VG schedule N1 on a SAAB Aircraft AB 340B aircraft.","sortOrder":1},{"sectionNumber":"Table 1 S/N’s of Engines Known to Have B","sectionType":"part","heading":"Table 1 S/N’s of Engines Known to Have Been Rigged to VG Schedule N1.","content":"## Table 1 S/N’s of Engines Known to Have Been Rigged to VG Schedule N1.\n\n| 785102 | 785104 | 785106 | 785107 | 785109 | 785111 |\n| ------ | ------ | ------ | ------ | ------ | ------ |\n| 785112 | 785113 | 785117 | 785118 | 785125 | 785128 |\n| 785129 | 785131 | 785133 | 785136 | 785138 | 785148 |\n| 785150 | 785151 | 785152 | 785154 | 785160 | 785185 |\n| 785188 | 785211 | 785231 | 785232 | 785234 | 785235 |\n| 785237 | 785239 | 785241 | 785257 | 785259 | 785265 |\n| 785266 | 785275 | 785322 | 785325 | 785326 | 785334 |\n| 785375 | 785391 | 785400 | 785459 | 785460 | 785462 |\n| 785465 | 785474 | 785476 | 785477 | 785480 | 785481 |\n| 785487 | 785499 | 785506 | 785534 | 785538 | 785554 |\n| 785569 | 785591 | 785592 | 785598 | 785603 | 785700 |\n| 785759 |        |        |        |        |        |\n\nNote 3: FAA Emergency AD 2003-08-52 refers.\n\nCompliance: 1. Within 30 flight hours or 3 days from the effective date of this directive. 2a. Within 30 flight hours or 3 days from the effective date of this directive,\n\nwhichever is the later.\n\n2b. Within 100 flight hours or 10 days from the effective date of this directive, whichever occurs first.\n\n    3. Within 100 flight hours or 10 days from the effective date of this directive, whichever occurs first.\n\n    4. From the effective date of this directive.\n\nThis Airworthiness Directive becomes effective on 17 April 2003.","sortOrder":2}],"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":4,"scope_assessment":{"changed":true,"description":"The AD changes allowable engine configuration by requiring engines rigged to VG schedule N1 to be re-rigged to schedule N and by prohibiting installation of any CT7-9B engine rigged to N1 on SAAB 340B aircraft (Requirement 2–4, Note 2). It therefore narrows permitted operational and installation options and imposes mandatory corrective maintenance within short compliance windows (Compliance)."},"complexity_factors":["Applicability covers all CT7-9B engines but highlights a specific list of serial numbers known to be rigged to N1 (Table 1) — adds targeting complexity (Requirement, Note 2, Table 1).","Actions depend on the rigging status of both engines on an aeroplane (different steps if both engines are N1, one engine N1, or neither) — conditional requirements increase operational complexity (Requirement 1–3).","Multiple, short compliance windows with different triggers (30 flight hours/3 days; 100 flight hours/10 days; and immediate prohibition from effective date) require rapid scheduling and record checks (Compliance).","Mandatory use of an external manufacturer Alert Service Bulletin (GEAE ASB CT7-TP S/B 72-A0328 Rev 1) for the prescribed re-rigging steps delegates technical detail to that document and requires maintenance capability familiar with the ASB (Requirement references).","Prohibition on installation of N1-rigged engines on SAAB 340B creates an ongoing operational constraint for parts interchange and inventory management (Requirement 4).","Cross-reference to FAA Emergency AD increases regulatory interplay and may require operators to track parallel foreign directives (Note 3).","Technical nature of VG rigging means work must be performed by appropriately qualified maintenance organisations, creating labour, downtime and certification burdens."],"plain_english_summary":"This Airworthiness Directive requires operators of GE CT7-9B engines to check the compressor Variable Geometry (VG) rigging and, where VG is set to schedule N1, re-rig the engine(s) to schedule N following GEAE ASB CT7-TP S/B 72-A0328 Revision 1. It also prohibits installing any CT7-9B engine rigged to VG schedule N1 on SAAB 340B aircraft. The AD affects engine owners, maintenance organisations and SAAB 340B operators and imposes short compliance windows to correct an identified unsafe condition."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted Airworthiness Directive addressing a specific unsafe condition in a specific engine model. It has not expanded beyond its original safety purpose."},"complexity_factors":["Short, single-purpose directive focused on one specific technical issue","Clear conditional structure (if-then logic in Requirements 1-4)","Only one defined term of note ('VG' = Variable Geometry)","Heavy reliance on external technical documents (GE Service Bulletin CT7-TP S/B 72-A0328 Revision 1) — operators must cross-reference manufacturer instructions","Multiple compliance deadlines creating a tiered urgency system (30 flight hours/3 days vs 100 flight hours/10 days)","Specific serial number table (66 engines listed) creates precise but narrow applicability"],"plain_english_summary":"This emergency safety order covers GE CT7-9B turbine engines on SAAB 340B aircraft after some were assembled with the wrong Variable Geometry (VG) schedule (N1 instead of N), creating a potentially unsafe engine condition. Operators must inspect VG schedules, re-rig affected engines within tight deadlines (as short as 30 flight hours/3 days for two-wrong cases, 100 hours/10 days otherwise), and must not install N1-scheduled engines. It affects SAAB 340B operators, maintenance crews, and 66 listed engines."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ct7-9-compressor-variable-geometry-schedule","history":"/api/acts/ad-ct7-9-compressor-variable-geometry-schedule/history","analysis":"/api/acts/ad-ct7-9-compressor-variable-geometry-schedule/analysis","conflicts":"/api/acts/ad-ct7-9-compressor-variable-geometry-schedule/conflicts","importantCases":"/api/acts/ad-ct7-9-compressor-variable-geometry-schedule/important-cases","documents":"/api/acts/ad-ct7-9-compressor-variable-geometry-schedule/documents"}}