{"id":"F2006B11023","name":"AD/JT9D/3 - Diffuser Case","slug":"ad-jt9d-3-diffuser-case","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56630,"registerId":"commonwealth-F2006B11023-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JT9D/3 - Diffuser Case","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 - JT9D Series\n\n \n\nAD/JT9D/3 Diffuser Case 8/72\n\nApplicability: Model JT9D-3A fitted with P/N 669647 diffuser cases. Document:  1. Pratt & Whitney SB No. 2901, Rev. 9; or\n\n2. AD/PW-T/29A.\n\n \n\nCompliance: In accordance with the Requirement Document.\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":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused on a specific engine component. It has not expanded beyond its original purpose of addressing the diffuser case issue on the specified engine model."},"complexity_factors":["Extremely short document (approximately 150 words)","No defined terms section — relies entirely on external referenced documents","Simple conditional structure: single applicability criterion (model JT9D-3A + specific part number)","Single compliance requirement referencing external technical documents","No nested exceptions or conditional logic","Minimal cross-referencing (only two external documents cited)"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998.\n\n**What it does:** It requires specific maintenance or inspection actions on a particular aircraft engine part — the **diffuser case** (a component that helps manage airflow in a jet engine) — on Pratt & Whitney JT9D-3A engines.\n\n**Who it affects:** \n- **Operators** of aircraft using Pratt & Whitney JT9D-3A engines\n- Specifically, those engines fitted with diffuser cases bearing **part number 669647**\n\n**What must be done:** Operators must follow the instructions in one of two referenced documents:\n- Pratt & Whitney Service Bulletin No. 2901, Revision 9; or\n- Another Airworthiness Directive referenced as AD/PW-T/29A\n\n**Why it matters:** Airworthiness Directives are legally binding safety instructions. They typically address discovered defects, wear patterns, or failure risks that could affect flight safety. Non-compliance can ground an aircraft. This particular AD (numbered AD/JT9D/3, originally issued 8/72) ensures that a known issue with specific diffuser cases is properly managed before it creates a safety hazard."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The text provides a targeted applicability and directs compliance with specified external documents. There is no information in this text indicating a change to the instrument’s original scope or applicability; the AD defines the scope as JT9D-3A engines fitted with diffuser case P/N 669647 and requires compliance with the identified Requirement Document(s). (Applicability; Document; Compliance.)"},"complexity_factors":["Narrow technical applicability (specific engine model and specific part number) — (Applicability).","Primary obligations are contained in external documents rather than in the AD text itself, requiring cross-reference to determine actions and costs — (Document; Compliance).","Lack of explicit procedural detail or stated rationale in the AD text increases reliance on the referenced Requirement Document(s) for operational interpretation — (Compliance).","Regulatory formality (appears in Schedule of Airworthiness Directives) implies mandatory effect and regulatory enforcement context, which may require regulatory knowledge to interpret in practice — (Header).","Use of technical terms (engine model, part number, service bulletin identifiers) requires specialist maintenance/regulatory knowledge to implement correctly — (Applicability; Document)."],"plain_english_summary":"This Airworthiness Directive requires operators of Pratt & Whitney JT9D-3A engines fitted with diffuser case P/N 669647 to comply with the specified Requirement Document (Pratt & Whitney SB No. 2901 Rev. 9 or AD/PW-T/29A). It is mandatory under the Civil Aviation Safety Authority schedule and affects owners, operators and maintenance providers of the identified engines. The AD itself does not set out the corrective tasks or rationale—those details are in the referenced documents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jt9d-3-diffuser-case","history":"/api/acts/ad-jt9d-3-diffuser-case/history","analysis":"/api/acts/ad-jt9d-3-diffuser-case/analysis","conflicts":"/api/acts/ad-jt9d-3-diffuser-case/conflicts","importantCases":"/api/acts/ad-jt9d-3-diffuser-case/important-cases","documents":"/api/acts/ad-jt9d-3-diffuser-case/documents"}}