{"id":"F2006B11183","name":"AD/LTS/4 Amdt 1 - Gas Producer Turbine","slug":"ad-lts-4-amdt-1-gas-producer-turbine","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56884,"registerId":"commonwealth-F2006B11183-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LTS/4 Amdt 1 - Gas Producer Turbine","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)  \nAlliedSignal (Lycoming) Turbine Engines \\- LTS 101 Series\n\nAD/LTS/4\n\nAmdt 1\n\n  \nGas Producer Turbine 9/86\n\nApplicability: All LT101 engines with G.P. Turbine Rotor assemblies which do not have metal blade dampeners incorporated.\n\nRequirement: Install improved Gas Producer Turbine Rotor assemblies P/N 4-111-050 \\-37/-38/ \\- 39/-40/-41/-42/-43/-44/-45/-46/-47/-49/-50 and -51 in accordance with Lycoming Service Bulletin No. LT 101-72-50-0079 Rev. 1.\n\nNote: FAA AD 86-10-04 Amdt 39-5299 refers.\n\nCompliance: 1. For LT101-700 Series engines: Prior to G.P. Turbine achieving 300 total operating hours in service or within 200 turbine operating hours after 27 January 1986 whichever is the greater but not later than 31 October 1986.\n\n2. For LT101-600 Series engines: In accordance with the Requirement Document. Background: This Directive is amended to reflect the manufacturer's Revision 1 to SB LT 101-72-\n\n50-0079 and to reference FAA AD 86-10-04 Amdt 39-5299. The FAA AD has tightened the manufacturer's compliance statement by imposing a calendar time limit for embodiment. This Directive is amended to incorporate a latest date for embodiment and add additional gas producer turbines by Pt/No.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"Yes. The Background states the Directive was amended to reflect the manufacturer's Revision 1 to the Service Bulletin and to reference FAA AD 86-10-04; the FAA AD imposed a calendar time limit and the Directive was amended to add a latest embodiment date and additional gas producer turbine part numbers, tightening and expanding the original scope (Background)."},"complexity_factors":["Multiple specific replacement part numbers must be identified and installed, creating parts-management complexity (Requirement).","Different compliance triggers for engine series — LT101-700 uses operating-hour thresholds plus a hard calendar deadline; LT101-600 follows the Service Bulletin schedule — requiring separate tracking regimes (Compliance 1 & 2).","Mandate cross-references an external manufacturer Service Bulletin (LT 101-72-50-0079 Rev.1) and FAA AD 86-10-04, requiring operators to consult multiple documents to confirm compliance steps and timing (Requirement; Background).","Amendment introduced a latest calendar date for embodiment and added additional turbine part numbers, altering prior scope and creating a retroactive deadline to manage (Background).","Compliance implies procurement, installation and associated downtime costs for owners/operators, and administrative enforcement by the Civil Aviation authority (Requirement; Compliance)."],"plain_english_summary":"This Airworthiness Directive requires owners/operators of Lycoming LT101 turbine engines without metal blade dampeners to install specified improved Gas Producer Turbine rotor assemblies (listed part numbers) following Lycoming Service Bulletin LT 101-72-50-0079 Rev.1. \n\nCompliance differs by model: LT101-700 engines must be retrofitted by a combination of operating-hour and calendar deadlines; LT101-600 engines must comply per the Service Bulletin. Owners pay for parts and installation; CASA enforces the mandate and references FAA AD 86-10-04."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose: mandating replacement of specific faulty turbine rotor assemblies. The amendment slightly expands the scope by adding more approved replacement part numbers and tightening compliance deadlines to match US FAA requirements, but this represents refinement rather than scope creep. The core safety objective — preventing gas producer turbine failures — remains unchanged from the original AD/LTS/4."},"complexity_factors":["Short, single-purpose directive (approximately 250 words)","Only 4 defined applicability criteria (engine series, part numbers, presence/absence of dampeners)","Two distinct compliance pathways based on engine sub-series (700 vs 600)","Cross-reference to one FAA Airworthiness Directive and one manufacturer service bulletin","Multiple part numbers listed in sequence (-37 through -51)","Time-based compliance calculation requires interpreting 'whichever is the greater' logic for 700-series engines"],"plain_english_summary":"This CASA Airworthiness Directive mandates replacement of faulty Gas Producer Turbine Rotor assemblies in certain AlliedSignal (Lycoming) LTS 101 series engines that lack metal blade dampeners. It affects operators of LT101-powered helicopters and light aircraft, legally grounding affected engines until upgraded parts are installed to prevent blade failure and possible crashes. Amendment 1 tightens compliance deadlines and expands covered part numbers, aligning with the FAA."}},"importantCases":[],"_links":{"self":"/api/acts/ad-lts-4-amdt-1-gas-producer-turbine","history":"/api/acts/ad-lts-4-amdt-1-gas-producer-turbine/history","analysis":"/api/acts/ad-lts-4-amdt-1-gas-producer-turbine/analysis","conflicts":"/api/acts/ad-lts-4-amdt-1-gas-producer-turbine/conflicts","importantCases":"/api/acts/ad-lts-4-amdt-1-gas-producer-turbine/important-cases","documents":"/api/acts/ad-lts-4-amdt-1-gas-producer-turbine/documents"}}