{"id":"F2006B07473","name":"AD/TPE 331/8 - Oil Sample and Filter Inspection","slug":"ad-tpe-331-8-oil-sample-and-filter-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49874,"registerId":"commonwealth-F2006B07473-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TPE 331/8 - Oil Sample and Filter Inspection","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  AlliedSignal (Garrett/AiResearch) Turbine Engines - TPE 331 Series\n\n \n\nAD/TPE 331/8 Oil Sample and Filter Inspection 3/86\n\nApplicability: All TPE-331-1 and 2 engines.\n\n \n\nRequirement: Carry out an oil sample and oil filter inspection in accordance with AiResearch SB No. 624 dated 28 August 1970 or later FAA approved revision; or\n\n \n\nAD/AIR-T/7.\n\n \n\nNote: FAA AD 70-19-2 also refers.\n\n \n\nCompliance: In accordance with AiResearch SB No. 624.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-purpose safety directive focused specifically on oil system monitoring for two specific engine models. It has not expanded beyond its original narrow technical scope."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 2 defined applicability criteria (engine models TPE-331-1 and -2)","Single primary requirement with one alternative compliance path","No nested exceptions or conditional logic","Cross-references only to external technical documents (Service Bulletin 624, FAA AD 70-19-2, AD/AIR-T/7) rather than internal legislative provisions","No interpretation section or defined terms"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It applies to specific aircraft engines: the **AlliedSignal (formerly Garrett/AiResearch) TPE 331 Series, specifically models -1 and -2**.\n\n**What it requires:**\nOwners and operators of these engines must **inspect oil samples and oil filters** on a regular basis. The exact method and timing for these inspections must follow a technical document called **AiResearch Service Bulletin No. 624** (dated 28 August 1970 or any later version approved by the US Federal Aviation Administration).\n\n**Why it matters:**\nOil analysis and filter inspection are critical for **detecting internal engine damage early** — things like metal particles from worn bearings or other components. Catching these signs early prevents catastrophic engine failure in flight, which could lead to accidents.\n\n**Alternative compliance:**\nOperators can also comply by following a different Australian directive called **AD/AIR-T/7** instead of the Service Bulletin.\n\n**Key point:** This is not optional. Airworthiness Directives are legally binding safety requirements. Non-compliance means the aircraft cannot be considered airworthy (legally safe to fly)."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive keeps a narrow, unchanged scope: it applies to all TPE-331-1 and TPE-331-2 engines and requires the same specific action (oil sample and oil filter inspection) to be carried out in accordance with AiResearch SB No. 624 or the alternative AD. There is no indication in the text that the population of engines in scope or the required action has been broadened or narrowed from the stated Applicability and Requirement."},"complexity_factors":["Narrow technical scope: applies only to TPE-331-1 and TPE-331-2 engines (Applicability).","References external technical document (AiResearch SB No. 624) and FAA-approved revisions, creating dependency on an outside source for procedural detail (Requirement; Compliance).","Provides an alternative compliance path (AD/AIR-T/7), which requires operators to identify which document they will use (Requirement).","Regulatory enforcement context is implicit (appears in CASA Schedule of Airworthiness Directives), but the AD text itself is short and prescriptive rather than procedurally complex (header; Requirement)."],"plain_english_summary":"What this directive does (mechanically)\n\n- It requires that every AlliedSignal (Garrett/AiResearch) TPE-331-1 and TPE-331-2 engine have an oil sample taken and the oil filter inspected. (Applicability; Requirement)\n- The inspection must be carried out in accordance with AiResearch Service Bulletin No. 624 dated 28 August 1970, or a later revision of that bulletin that has been approved by the FAA. As an alternative, compliance may be achieved by following AD/AIR-T/7. (Requirement)\n- The compliance instruction in this instrument repeats the AiResearch SB No. 624 requirement. (Compliance)\n- The instrument also notes that FAA Airworthiness Directive 70-19-2 is relevant. (Note)\n\nWho this affects and who decides\n\n- Who is bound: operators or owners of TPE-331-1 and TPE-331-2 engines (those engines are named in the Applicability). They are required to have the specified oil sample and oil filter inspection carried out. (Applicability; Requirement)\n- Who sets the method: the directive prescribes the inspection method by reference to AiResearch SB No. 624 (or an FAA-approved later revision) or to AD/AIR-T/7. That reference determines the technical steps to be taken. (Requirement; Compliance)\n- Enforcement/issuance context: this item appears in the Civil Aviation Safety Authority schedule of airworthiness directives. The directive therefore operates through the regulatory framework that issues these ADs. (header)\n\nWho pays, incentives and behaviour changes\n\n- Who pays: the direct costs (labour, any sampling/analysis costs, parts and any associated downtime) fall on the operator or owner who must carry out the inspection. (Requirement; Compliance)\n- What operators must do differently: schedule and perform oil sampling and filter inspection in the manner specified by the referenced service bulletin or alternative AD; they may need to obtain the referenced documents and, if applicable, an FAA-approved revision. (Requirement; Compliance)\n- Incentives created: operators gain a clear, mandated procedure for inspection (reducing ambiguity about what to do), while they incur recurring inspection costs and potential aircraft downtime. The directive reduces the operator’s choice about inspection method by requiring adherence to a specified SB or AD. (Requirement)\n\nCompliance burden, discretion and implementation considerations\n\n- Compliance burden: the action is a maintenance task (oil sampling and filter inspection). That imposes time and labour requirements, and may require sample handling, analysis or filter access/removal depending on the SB’s procedures. The directive does not itself set technical steps beyond the external SB; the SB does. (Requirement; Compliance)\n- Dependence on external documents and approvals: the AD requires following AiResearch SB No. 624 or a later FAA-approved revision. That creates a dependence on an external manufacturer service bulletin and on FAA approval for later revisions; operators or maintainers must obtain and follow those external documents. (Requirement)\n- Limited regulatory discretion within the AD: the AD prescribes a particular compliance route (SB No. 624 or AD/AIR-T/7). There is no open-ended discretion in this text to adopt a different method unless that method is provided for in the alternative AD or in an FAA-approved revision. (Requirement)\n\nTrade-offs, opportunity costs and risks\n\n- Trade-offs: the directive trades operator time and direct maintenance costs against whatever preventive effect the inspection is intended to achieve. The text identifies the inspection requirement but does not quantify costs or benefits. (Requirement)\n- Opportunity cost: resources spent on these prescribed inspections cannot be used for other maintenance activities or operations during that time. (Requirement)\n- Implementation risk and clarity: because the AD points to an external service bulletin and to FAA-approved revisions, operators must track the correct version of the SB or the alternative AD; ambiguity could arise if multiple revisions or approval statuses exist. The AD’s short text makes the SB the operative technical specification and so shifts the detailed implementation risk to the SB document. (Requirement; Note)\n\nReferences in the instrument\n\n- Applicability: “All TPE-331-1 and 2 engines.”\n- Requirement: follow AiResearch SB No. 624 (28 August 1970) or a later FAA-approved revision, or comply with AD/AIR-T/7.\n- Compliance: “In accordance with AiResearch SB No. 624.”\n- Note: refers to FAA AD 70-19-2."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tpe-331-8-oil-sample-and-filter-inspection","history":"/api/acts/ad-tpe-331-8-oil-sample-and-filter-inspection/history","analysis":"/api/acts/ad-tpe-331-8-oil-sample-and-filter-inspection/analysis","conflicts":"/api/acts/ad-tpe-331-8-oil-sample-and-filter-inspection/conflicts","importantCases":"/api/acts/ad-tpe-331-8-oil-sample-and-filter-inspection/important-cases","documents":"/api/acts/ad-tpe-331-8-oil-sample-and-filter-inspection/documents"}}