{"id":"F2006B08685","name":"AD/CT7/10 Amdt 2 - Propeller Gearbox(PGB)","slug":"ad-ct7-10-amdt-2-propeller-gearbox-pgb","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51834,"registerId":"commonwealth-F2006B08685-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CT7/10 Amdt 2 - Propeller Gearbox(PGB)","content":"![](image.001.png)\n\n![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/CT7/10 Amdt 1 and issues the following 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\n\nAD/CT7/10\n\nAmdt 2\n\n  \nPropeller Gearbox(PGB) 7/2004\n\nApplicability: General Electric Aircraft Engines (GEAE) CT7 series turboprop engines with propeller gearboxes (PGBs) identified by serial number (SN) in Table 1 of GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0452, dated 27 July 2001, and Table 1 of GEAE CT7 Turboprop Alert Service Bulletin (ASB) CT7-TP S/B 72-A0466 dated 17 April 2003. These engines are installed on, but not limited to, SAAB 340 series aeroplanes.\n\nRequirement: 1. Inspect the propeller gearbox (PGB) oil filter impending bypass button (IBB) for extension. If PGB oil filter IBB is extended, replace the oil filter and carry out inspections in accordance with 3.A of the Accomplishment Instructions contained in GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0453,dated 27 July 2001.\n\n    2. Replace left and right-hand idler gears in accordance with the Accomplishment Instructions GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0452, dated 27 July 2001.\n\n    3. If the PGB is mated to a Hamilton Standard propeller and the left and right-hand idler gears have not been replaced in accordance with the Accomplishment Instructions contained in GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0452,dated 27 July 2001, replace the PGB.\n\nNote: FAA AD 2004-07-09 Amdt 39-13553 refers.\n\nCompliance: For Requirement 1: Unless previously accomplished, initial inspection within 50 hours time-in-service (TIS) after the effective date of this AD and thereafter on each day of aircraft operation until compliance with Requirment 2 or 3 of this Directive is achieved.\n\nFor Requirement 2: At next workshop visit of the PGB after the effective date of this AD.\n\nFor Requirement 3: Before accumulating an additional 2,000 engine flight hours after the 6 August 2003, the effective date of amendment 1 of this Directive.\n\nThis Amendment becomes effective on 8 July 2004.\n\nGeneral Electric Turbine Engines \\- CT7 Series\n\nAD/CT7/10 Amdt 2 (continued)\n\nBackground: This AD is prompted by an on-going investigation that concluded that low-time PGB removals are due to accelerated wear of the PGB idler gears, rather than improperly hardened PGB input pinions. The actions specified in this AD are intended to prevent separation of the PGB left and right-hand idler gears, which could result in uncontained PGB failure and internal bulkhead damage, possibly prohibiting the auxiliary feathering system from fully feathering the propeller on certain PGB’s.\n\nAmendment 1 clarified the applicability and, for administrative reasons, brought forward the effective date by one day.\n\nThis amendment includes additional PGB and PGB gears as detailed in the reference documents. There are no changes to the inspection requirements.\n\n![Signature of James Coyne Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nJames Coyne\n\nDelegate of the Civil Aviation Safety Authority 28 May 2004\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 16 June 2004.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"Amdt 2 revokes the previous amendment and expands applicability by adding additional PGB serial numbers and PGB gears as detailed in the referenced GE service bulletins. Amendment 1 had clarified applicability and moved the effective date by one day; Amdt 2 keeps inspection requirements unchanged while broadening the set of affected gearboxes and gears."},"complexity_factors":["Applicability tied to PGB serial numbers listed in two external GE service bulletin tables (requires cross-referencing external documents).","Three-tiered requirements: recurring inspections until parts are replaced, mandatory gear replacement at next workshop visit, or full PGB replacement under a propeller-type condition.","Inspection frequency: initial within 50 flight hours and daily until replacement requirement met (operational burden and tracking).","Conditional compliance timing: replacement before an additional 2,000 engine flight hours counted from a prior amendment date (requires historical hour tracking).","Dependency on multiple external documents (GE Service Bulletins CT7-TP S/B 72-0452, 72-0453, ASB 72-A0466 and referenced FAA AD), increasing procedural complexity.","Revocation of the prior amendment and addition of PGBs/gears to applicability (administrative change affecting scope and record-keeping).","Technical maintenance tasks (inspections, gearbox/gear replacement) that require workshop capability and parts availability."],"plain_english_summary":"This Airworthiness Directive requires operators of specific General Electric CT7 turboprop engines with listed propeller gearboxes to inspect the propeller gearbox (PGB) oil-filter impending bypass button for extension, and to replace specified left and right idler gears or the entire PGB in certain cases. CASA explains the measures are intended to prevent idler-gear separation that can cause uncontained gearbox failure and impair propeller feathering. The rule affects aircraft operators and maintenance organisations that must follow the stated inspection intervals and GE service bulletin instructions."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"This Amendment 2 expands the scope beyond the original AD. The Background section explicitly states this amendment 'includes additional PGB and PGB gears as detailed in the reference documents' compared to Amendment 1. The original AD addressed improperly hardened input pinions; this version addresses accelerated wear of idler gears and adds more serial numbers to the affected list. The scope has grown from a specific pinion hardness issue to a broader gear wear problem affecting more components."},"complexity_factors":["Multiple cross-references to external GE service bulletins (CT7-TP S/B 72-0452, 72-A0466, and 72-0453) that are not reproduced in the text","Conditional logic with three alternative compliance paths (Requirements 1, 2, and 3) with interdependencies","Nested applicability criteria combining engine series, specific serial numbers from two separate tables, and propeller type (Hamilton Standard)","Multiple compliance timeframes using different metrics (hours time-in-service, workshop visits, engine flight hours, calendar dates)","Technical aviation terminology requiring specialized knowledge (PGB, IBB, feathering, uncontained failure, time-in-service)","Amendment structure referencing previous versions (Amdt 1) and effective dates that create overlapping compliance windows"],"plain_english_summary":"This AD requires operators of GE CT7-powered aircraft — notably Saab 340s using specific propeller gearboxes — to do daily oil-filter-indicator checks and to replace left/right idler gears at the next workshop visit; if the gearbox is mated to a Hamilton Standard propeller and gears haven’t been replaced, the entire gearbox must be swapped by the regulator’s flight‑hour deadline. \n\nIt responds to accelerated idler-gear wear that can cause uncontained gearbox failure, structural damage, and loss of propeller feathering, increasing emergency-landing risk."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ct7-10-amdt-2-propeller-gearbox-pgb","history":"/api/acts/ad-ct7-10-amdt-2-propeller-gearbox-pgb/history","analysis":"/api/acts/ad-ct7-10-amdt-2-propeller-gearbox-pgb/analysis","conflicts":"/api/acts/ad-ct7-10-amdt-2-propeller-gearbox-pgb/conflicts","importantCases":"/api/acts/ad-ct7-10-amdt-2-propeller-gearbox-pgb/important-cases","documents":"/api/acts/ad-ct7-10-amdt-2-propeller-gearbox-pgb/documents"}}