{"id":"F2006B11175","name":"AD/LTS/12 - Cast Material Axial Compressor","slug":"ad-lts-12-cast-material-axial-compressor","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56873,"registerId":"commonwealth-F2006B11175-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LTS/12 - Cast Material Axial Compressor","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/12 Cast Material Axial Compressor 12/95\n\nApplicability: All LTS101 series engines\n\nRequirement: Replace Part Numbers (P/N) 4-101-006-20, -21, -24, -26, -35, -36 and -40 cast material axial compressor rotors in accordance with the requirements of AlliedSignal (formerly Textron Lycoming) Service Bulletin (SB) LT 101-72-30-0088 Rev. 5.\n\nNote: FAA Airworthiness Directive 95-16-04 refers.\n\nCompliance: As detailed in the Requirement Document with a revised effective date of 9 November 1995.\n\nBackground: This Directive has been issued to remove from service certain cast material axial compressor rotors and replace those rotors with a wrought material axial compressor rotor. The requirement follows advice of 36 reports of cast material axial compressor blade failures. Compressor blade failure may result in power loss and an inflight engine shutdown.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The Directive’s scope, as stated in the instrument, applies to all LTS101 series engines fitted with the listed cast axial compressor rotor part numbers and requires their replacement with a wrought rotor per the manufacturer’s Service Bulletin. The text contains no indication that the scope has been broadened or narrowed from an earlier or original intent; it specifies the affected parts, the replacement action, the compliance reference (Service Bulletin), and an effective date. (Applicability, Requirement, Compliance, Background)"},"complexity_factors":["Narrow applicability limited to LTS101 series engines and a short list of specific part numbers (Applicability, Requirement)","Action is a single, defined remedial step (replace specified parts) referenced to a single manufacturer Service Bulletin (Requirement)","External cross-reference to the manufacturer’s Service Bulletin (LT 101-72-30-0088 Rev. 5) creates a dependency on a separate document for procedural detail (Requirement)","Fixed compliance timing (revised effective date of 9 November 1995) reduces scheduling ambiguity but imposes a hard deadline for operators (Compliance)","Safety justification rests on reported incidents (36 reports) rather than a complex regulatory framework, limiting interpretive complexity (Background)"],"plain_english_summary":"Owners/operators of AlliedSignal (Lycoming) LTS101 turbine engines fitted with specified cast axial compressor rotors (listed part numbers) must remove those rotors and replace them with a wrought-material rotor per the manufacturer’s Service Bulletin. The mandate responds to multiple cast-blade failures that risk inflight power loss/engine shutdown, shifting replacement costs and downtime to operators."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete airworthiness directive with a single, specific safety purpose: replacing faulty compressor rotors in one engine series. It has not expanded beyond its original intent."},"complexity_factors":["Very short document (under 300 words)","Only 7 specific part numbers to identify","Single clear requirement: replace specific parts per manufacturer bulletin","No nested exceptions or conditional logic","No defined terms section — uses standard aviation terminology","Cross-reference to only one external document (the Service Bulletin)","Straightforward compliance deadline (single date: 9 November 1995)"],"plain_english_summary":"This is a **safety order for aircraft engines**. It requires owners and operators of certain AlliedSignal (Lycoming) LTS101 turbine engines to replace specific faulty compressor parts.\n\n**What it does:**\n- **Targets:** All engines in the LTS101 series\n- **The problem:** Certain cast metal compressor rotors (parts numbered 4-101-006-20, -21, -24, -26, -35, -36, and -40) have been failing. There have been 36 reported cases of these blades breaking.\n- **The risk:** If these blades fail, the engine can lose power and shut down mid-flight — obviously dangerous.\n- **The fix:** Replace the faulty cast metal rotors with stronger \"wrought material\" (forged/solid metal) rotors, following the manufacturer's Service Bulletin LT 101-72-30-0088 Revision 5.\n\n**Who must comply:** Anyone operating aircraft with these engines — typically helicopter operators and owners, as the LTS101 is commonly used in helicopters.\n\n**Why it matters:** This is a mandatory safety directive. Non-compliance means flying with a known defect that could cause engine failure. The directive references an American FAA order (95-16-04), showing Australia is adopting a US safety finding."}},"importantCases":[],"_links":{"self":"/api/acts/ad-lts-12-cast-material-axial-compressor","history":"/api/acts/ad-lts-12-cast-material-axial-compressor/history","analysis":"/api/acts/ad-lts-12-cast-material-axial-compressor/analysis","conflicts":"/api/acts/ad-lts-12-cast-material-axial-compressor/conflicts","importantCases":"/api/acts/ad-lts-12-cast-material-axial-compressor/important-cases","documents":"/api/acts/ad-lts-12-cast-material-axial-compressor/documents"}}