{"id":"F2006B11178","name":"AD/LTS/15 - Gas Generator Rotor","slug":"ad-lts-15-gas-generator-rotor","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56876,"registerId":"commonwealth-F2006B11178-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LTS/15 - Gas Generator Rotor","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/15 Gas Generator Rotor 10/96\n\nApplicability: All LTS101 series engines.\n\nRequirement: To prevent a total loss of engine power, in-flight engine shutdown and possible damage to the aircraft, identify the serial number of gas producer rotor discs installed in applicable engines and remove from service discs as detailed in Textron Lycoming Service Bulletin Number LT 101-72-50-0150.\n\nNote: FAA Airworthiness Directive 96-12-27 refers.\n\nCompliance: As detailed in the requirement document with an effective date of 12 September 1996.\n\nBackground: This directive has been issued to require the removal from service of certain gas producer rotor discs. The requirement reflects advice from the manufacturer of a possible broaching discrepancy occurring during the manufacture of certain gas producer rotor discs that could result in cracks developing in those discs.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope remains aligned with the instrument’s stated intent: identify and remove from service certain gas producer rotor discs in LTS101 series engines that may have a manufacture-related broaching discrepancy leading to cracks. The AD applies to all LTS101 engines but limits removals to discs listed in the manufacturer’s service bulletin; there is no indication in the source text that the scope has been expanded or narrowed from that stated intent (Applicability; Requirement; Background)."},"complexity_factors":["Narrow technical scope limited to LTS101 series engines and specific gas producer rotor discs (Applicability).","Single, prescriptive compliance action: identify serial numbers and remove affected discs per a named service bulletin (Requirement).","Dependence on an external technical document (Textron Lycoming Service Bulletin LT 101-72-50-0150) for operative detail (Requirement).","Fixed compliance date creates scheduling and logistical considerations for operators (Compliance).","Technical judgment limited to matching serial numbers and performing removals; limited regulatory discretion but potential operational complexity from parts availability and maintenance capacity (Requirement; Background)."],"plain_english_summary":"What this instrument does mechanically\n\n- The Civil Aviation Safety Authority requires operators of all AlliedSignal (Lycoming) LTS101 series turbine engines to check whether a gas producer (gas generator) rotor disc with certain serial numbers is fitted and to remove any affected discs from service. The removal must be done in accordance with Textron Lycoming Service Bulletin LT 101-72-50-0150 (Requirement; Applicability). The directive takes effect from 12 September 1996 (Compliance).\n\nOfficial purpose-claim\n\n- The directive states its aim is to prevent total loss of engine power, in-flight engine shutdown and possible aircraft damage by removing certain rotor discs that may develop cracks due to a possible broaching discrepancy during manufacture (Background).\n\nWho decides and who acts\n\n- The Civil Aviation Safety Authority issues and enforces the directive (title and heading). The manufacturer (Textron Lycoming) supplies the service bulletin that identifies which serial-numbered discs are affected and prescribes removal instructions; operators and maintenance organisations must carry out the inspections and removals (Requirement; Note).\n\nWho pays and what behaviours change\n\n- Aircraft operators or owners of helicopters/aircraft fitted with LTS101 engines bear the direct costs: time to inspect serial numbers, remove and replace affected rotor discs, and any consequential aircraft downtime and maintenance labour (Requirement; Compliance). Maintenance organisations incur compliance workload. The directive changes operator behaviour from routine maintenance to mandatory serial-number checks and removal where specified.\n\nCompliance mechanics and discretion\n\n- Compliance is achieved by following the manufacturer’s service bulletin (Requirement). The AD cross-references a corresponding FAA Airworthiness Directive (Note). There is limited administrative discretion: operators must follow the described identification and removal steps rather than exercising broader judgment (Requirement; Compliance).\n\nCosts, incentives and trade-offs (mechanisms, not verdicts)\n\n- Concentrated benefit: operators whose aircraft would otherwise suffer an in-flight engine failure gain the safety benefit. Concentrated compliance cost: owners/operators of affected engines must fund inspections, part removals and replacements and accept aircraft downtime (Requirement; Background). The directive shifts the immediate financial burden to these parties while the stated safety benefit accrues to aircraft occupants and the broader flying public (Background).\n\n- Supply and implementation risk: the effectiveness depends on accurate serial-number identification, availability of replacement rotor discs, and maintenance capacity to perform removals per the service bulletin (Requirement; Compliance). If replacement parts are limited, operators may face extended grounding times.\n\n- Incentive effects: operators have a clear incentive to comply promptly to avoid the safety risk the AD identifies; some may seek alternative engines or suppliers over time if replacement costs or downtime are significant (inferred from the requirement to remove and replace discs).\n\nLimitations and scope of the directive\n\n- The AD applies only to LTS101 series engines and only to discs identified in the manufacturer’s service bulletin (Applicability; Requirement). The directive’s stated technical cause is a possible broaching discrepancy in manufacture that could lead to cracks (Background).\n\nSource citations\n\n- Applicability, Requirement, Note, Compliance and Background sections of AD/LTS/15 (Gas Generator Rotor) provide the basis for the above summary."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific manufacturing defect in a specific engine series. It has not expanded beyond its original purpose of mandating inspection and replacement of defective rotor discs."},"complexity_factors":["Single, specific mechanical issue addressed (gas producer rotor disc defect)","Only one substantive requirement: identify serial numbers and remove affected parts","No defined terms section — uses plain technical language","Minimal conditional logic — applies to 'all' engines in the series without exceptions","Single cross-reference to FAA Airworthiness Directive 96-12-27 and manufacturer service bulletin LT 101-72-50-0150","Extremely short document (approximately 150 words of substantive text)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order for aircraft engines. It applies to all **LTS101 series turbine engines** made by AlliedSignal (formerly Lycoming).\n\n**What it does:**\n- Requires aircraft operators to check the serial numbers of specific engine parts called **gas producer rotor discs** (critical spinning components in the engine's core)\n- Forces removal from service of certain discs identified in a manufacturer service bulletin\n\n**Why it matters:**\n- A manufacturing defect (called a \"broaching discrepancy\" — essentially a machining error during production) could cause cracks in these discs\n- If a cracked disc fails in flight, the engine could lose all power, shut down unexpectedly, or damage the aircraft\n- This is a **safety-critical fix** — non-compliance means flying with a potentially catastrophic defect\n\n**Who must comply:**\n- Anyone operating aircraft with LTS101 series engines\n- Compliance deadline: 12 September 1996 (as specified in the referenced service bulletin)\n\n**Key point:** This isn't optional maintenance advice — it's a legally enforceable requirement under Australian civil aviation law, backed by the Civil Aviation Safety Authority (CASA)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-lts-15-gas-generator-rotor","history":"/api/acts/ad-lts-15-gas-generator-rotor/history","analysis":"/api/acts/ad-lts-15-gas-generator-rotor/analysis","conflicts":"/api/acts/ad-lts-15-gas-generator-rotor/conflicts","importantCases":"/api/acts/ad-lts-15-gas-generator-rotor/important-cases","documents":"/api/acts/ad-lts-15-gas-generator-rotor/documents"}}