{"id":"F2006B10986","name":"AD/JT8D/3 - Compressor Case Assembly and No. 3 Bearing","slug":"ad-jt8d-3-compressor-case-assembly-and-no-3-bearing","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56574,"registerId":"commonwealth-F2006B10986-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JT8D/3 - Compressor Case Assembly and No. 3 Bearing","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)  Pratt and Whitney Turbine Engines - JT8D Series\n\n \n\nAD/JT8D/3 Compressor Case Assembly and No. 3 Bearing NK\n\nApplicability: JT8D series.\n\n \n\nDocument: 1. Pratt & Whitney TE SB No. 1199 and TE SB No. 1433.\n\n \n\n2. AD/PW-T/17A.\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\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This appears to be a discrete, targeted safety directive focused on specific mechanical components of a specific engine series. There is no evidence of scope creep — it addresses a well-defined engineering issue (compressor case and bearing integrity) consistent with the original purpose of airworthiness directives."},"complexity_factors":["Very short document (approximately 200 words)","Only 2 defined references (the Service Bulletins and previous AD)","No conditional logic or nested exceptions visible in this extract","Single applicability criterion (JT8D series engines)","Straightforward command structure: identifies problem, cites technical documents, implies mandatory action","Technical aviation terminology present but standard for the industry (compressor case, bearing assemblies)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** issued by Australia's Civil Aviation Safety Authority (CASA) for **Pratt & Whitney JT8D series turbine engines** — the engines commonly used on older Boeing 727 and 737 aircraft.\n\n**What it does:**\nThe directive mandates specific maintenance actions related to the **compressor case assembly** and **No. 3 bearing** of these engines. These are critical components: the compressor case houses the engine's compression system, and the No. 3 bearing supports the rotating shaft. Failures here can cause catastrophic engine damage or in-flight shutdowns.\n\n**Who it affects:**\n- Airlines and operators flying aircraft with JT8D engines\n- Maintenance organisations servicing these engines\n- Owners of affected aircraft\n\n**Why it matters:**\nAirworthiness Directives are legally binding safety orders. They typically follow incidents or wear patterns discovered in service. Compliance is mandatory — operators cannot legally fly affected aircraft until the required inspections, repairs, or replacements are completed. This particular AD references specific Pratt & Whitney Service Bulletins (TE SB No. 1199 and 1433), meaning operators must follow those manufacturer instructions to remain compliant.\n\n**Key point:** This appears to be a **historical or reference document** — it references an earlier AD (AD/PW-T/17A), suggesting it may have superseded or amended previous requirements."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The supplied text lists the affected engine family (JT8D series) and references two Pratt & Whitney service bulletins and a prior AD as the source of technical requirements. The document provided does not show any amendment language or redrafting that would indicate a change of scope from an earlier version. There is no information in the supplied text to conclude that the AD's applicability or substantive scope has been changed from any prior instrument."},"complexity_factors":["Cross-references to external technical documents (TE SB No. 1199, TE SB No. 1433, AD/PW-T/17A) create dependency on those texts for substantive requirements.","Technical subject matter (compressor case assembly and No. 3 bearing) is specialised and requires engineering judgement to implement.","Applicability is broad (entire JT8D series), which can produce varied operational impacts across different airframes and configurations.","The AD text supplied does not reproduce procedural detail; implementers must retrieve and interpret multiple documents.","Regulatory enforcement and possible acceptance of alternative methods lie with CASA under Part 39, which can introduce procedural discretion and case-by-case variation."],"plain_english_summary":"This Airworthiness Directive requires operators of Pratt & Whitney JT8D engines to comply with the specified Pratt & Whitney service bulletins (TE SB No. 1199 and No. 1433) and the earlier AD/PW-T/17A for the compressor case assembly and No. 3 bearing. It makes the technical inspection, repair or replacement actions in those documents mandatory, affecting aircraft owners, maintenance organisations and regulators by imposing compliance costs, downtime and enforceable maintenance obligations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jt8d-3-compressor-case-assembly-and-no-3-bearing","history":"/api/acts/ad-jt8d-3-compressor-case-assembly-and-no-3-bearing/history","analysis":"/api/acts/ad-jt8d-3-compressor-case-assembly-and-no-3-bearing/analysis","conflicts":"/api/acts/ad-jt8d-3-compressor-case-assembly-and-no-3-bearing/conflicts","importantCases":"/api/acts/ad-jt8d-3-compressor-case-assembly-and-no-3-bearing/important-cases","documents":"/api/acts/ad-jt8d-3-compressor-case-assembly-and-no-3-bearing/documents"}}