{"id":"F2006B07474","name":"AD/TPE 331/9 - Oil Sample and Pressure Oil Filter - Inspection","slug":"ad-tpe-331-9-oil-sample-and-pressure-oil-filter-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49878,"registerId":"commonwealth-F2006B07474-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TPE 331/9 - Oil Sample and Pressure Oil Filter - Inspection","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 (Garrett/AiResearch) Turbine Engines \\- TPE 331 Series\n\nAD/TPE 331/9 Oil Sample and Pressure Oil Filter \\- Inspection 3/86\n\nApplicability: Models TPE-331-1-100F, 101B, 101E, 101F, 101J, 101L, \\-101Z, 151, 151A, 151G, \\- 151K, TPE-331-2-201A, 201C, TPE-331-2UA-203D, \\-203P, TPE-331-25AA, 25AB,\n\n25DA, 25FA, TPE-331-43A, 43BL, TPE-331-47A, TPE-331-55A, 55B. TPE-331-\n\n61A, TPE-331-71 not incorporating SB No. 632, 659 or TPE-331-72-0064.\n\nRequirement: Comply with the requirements of AiResearch SB No. 628 Rev. 8 with the following exceptions:\n\n    Oil samples and oil filter elements for laboratory examination are to be forwarded to:\n\nMobil Oil Laboratories Francis Street Yarraville VIC 3013 AUSTRALIA\n\n    2. Prior to operation of the engine in excess of 50 hours time in service from the time of removal of the filter and oil sampling, the owner or operator shall have received written confirmation of the satisfactory results from Mobil Oil Laboratories; or\n\nAD/AIR-T/8C.\n\nNote: FAA AD 71-5-7 as amended by Amendments 39-1180, 39-1277 and 39-1430 also refers to this subject.\n\nCompliance: Within 50 hours time in service after 31 January 1977 and thereafter at intervals not exceeding 50 hours time in service.\n\nBackground: This Directive is revised to reflect the approval of Mobil Oil Laboratories of Melbourne to carry out oil sample and filter element analysis. Garrett Turbine Engine Company Service Information Letter No. P331-97, Revision 1, dated 1 July 1981 refers.","sortOrder":0}],"analysis":{"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":3,"scope_assessment":{"changed":false,"description":"This directive maintains its original narrow scope. It was issued to address oil contamination monitoring for specific TPE 331 engines and was revised only to update the approved laboratory location (to an Australian facility) and reference current service bulletins. The core purpose — mandatory oil sampling every 50 flight hours — remains unchanged from the original 1977 directive."},"complexity_factors":["Single, specific technical requirement with clear compliance deadline (50 hours time in service)","Limited applicability — only 24 specific engine models listed, with explicit exclusions for modified engines","One primary cross-reference to AiResearch Service Bulletin No. 628 Rev. 8 (the technical standard being adopted)","Two straightforward exceptions/modifications to the referenced standard (laboratory location and written confirmation requirement)","No nested conditional logic or defined terms section","Short document (approximately 250 words) with clear structure: Applicability, Requirement, Compliance, Background"],"plain_english_summary":"This CASA Airworthiness Directive mandates periodic oil-filter removal and oil sampling for certain AlliedSignal (Garrett/AiResearch) TPE331 turbine engines used on small aircraft and helicopters, excluding engines already modified by specific service bulletins.  \n\nSamples and filter elements must be sent to Mobil Oil Laboratories (Yarraville) every 50 flight hours, and the aircraft may not exceed 50 hours until written confirmation of satisfactory results is received. The measure detects early engine wear or damage to prevent in‑flight failures."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The directive was revised to approve Mobil Oil Laboratories (Melbourne/Yarraville) to carry out the required oil sample and filter element analyses and requires forwarding samples there. Apart from specifying the approved laboratory and forwarding address, the directive keeps the SB No. 628 Rev. 8 requirements and the 50‑hour inspection interval unchanged (Requirement; Background)."},"complexity_factors":["Narrow technical scope limited to specific TPE‑331 models and exclusions (Applicability).","Mandatory reliance on an external service bulletin (AiResearch SB No. 628 Rev. 8) creates dependence on a separate document for procedural detail (Requirement).","Specified single laboratory destination for samples adds an operational step and potential logistical cost (Requirement — Mobil Oil Laboratories address).","Short, recurring compliance interval (every ≤50 hours) imposes frequent sampling and administrative burden (Compliance).","A dated compliance commencement (within 50 hours after 31 Jan 1977) introduces legacy timing language that may need contextual interpretation (Compliance, Background)."],"plain_english_summary":"_This directive requires owners/operators_ of specified AlliedSignal (Garrett/AiResearch) TPE‑331 engines (except those fitting certain service bulletins) to take oil samples and send pressure‑oil‑filter elements for laboratory analysis under AiResearch SB No. 628 Rev. 8, and to obtain written satisfactory results before operating the engine beyond 50 hours after sampling. Samples are to be forwarded to Mobil Oil Laboratories in Yarraville; inspections must begin within 50 hours after 31 January 1977 and recur at intervals not exceeding 50 hours (Requirement; Compliance)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tpe-331-9-oil-sample-and-pressure-oil-filter-inspection","history":"/api/acts/ad-tpe-331-9-oil-sample-and-pressure-oil-filter-inspection/history","analysis":"/api/acts/ad-tpe-331-9-oil-sample-and-pressure-oil-filter-inspection/analysis","conflicts":"/api/acts/ad-tpe-331-9-oil-sample-and-pressure-oil-filter-inspection/conflicts","importantCases":"/api/acts/ad-tpe-331-9-oil-sample-and-pressure-oil-filter-inspection/important-cases","documents":"/api/acts/ad-tpe-331-9-oil-sample-and-pressure-oil-filter-inspection/documents"}}