{"id":"F2006B11036","name":"AD/JT9D/7 - No. 3 Bearing Breather Temp Check and Replacement of Main Bearing Breather Tube Steel Elbow","slug":"ad-jt9d-7-no-3-bearing-breather-temp-check-and-replacement-of-main-bearing-breather-tube-steel-elbow","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56648,"registerId":"commonwealth-F2006B11036-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JT9D/7 - No. 3 Bearing Breather Temp Check and Replacement of Main Bearing Breather Tube Steel Elbow","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/7 No. 3 Bearing Breather Temp Check and Replacement of Main Bearing Breather Tube Steel Elbow\n\n\n10/76\n\n \n\nApplicability: JT9D-3A, -7, -7A, -7H, -7AH, -7F and -20 turbofan engines incorporating labyrinth solid land seals P/Nos. 589733, 589741, 647189 or 729774.\n\n \n\nDocument: 1. FAA AD 76-20-03 : Amendment 39-2731; or\n\n \n\n2. AD/PW-T/37.\n\n \n\nCompliance: As detailed in 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","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The supplied text sets out an airworthiness requirement for a clearly defined set of engines and refers to external Requirement Documents for procedural detail (FAA AD 76-20-03 or AD/PW-T/37). The instrument itself does not indicate any change of scope from an earlier instrument within the text provided; it limits applicability by engine models and seal part numbers and delegates procedural content to the referenced documents (Applicability; Document; Compliance)."},"complexity_factors":["Reference to external Requirement Documents (FAA AD 76-20-03 or AD/PW-T/37) for substantive procedural and timing details increases reliance on other texts (Document; Compliance).","Narrow technical applicability defined by multiple engine model variants and specific part numbers (JT9D-3A, -7, -7A, -7H, -7AH, -7F and -20; seal P/Ns 589733, 589741, 647189, 729774) requires technical checking against fleet inventory (Applicability).","The text prescribes an action category (temperature check and replacement of a component) but does not include inspection criteria, acceptable limits or replacement instructions—these are delegated, which raises interpretive steps for implementers (Compliance).","Operational impact depends on spare-part availability and maintenance scheduling, information not contained in the instrument, so implementers must consult the referenced documents and supply chains to plan compliance (Document; Compliance).","The AD is short and prescriptive in outcome but procedural in content, creating modest complexity for legal compliance while leaving technical complexity to the referenced Requirement Document (Document; Compliance)."],"plain_english_summary":"What this instrument does (mechanically)\n\n- Requires a temperature check of the No. 3 bearing breather and replacement of the steel elbow in the main bearing breather tube on a defined set of Pratt & Whitney JT9D turbofan engines (see \"Applicability\"). (Applicability)\n- Directs compliance to follow the procedures and timing set out in a separate \"Requirement Document\", by referring operators to either FAA AD 76-20-03 (Amendment 39-2731) or AD/PW-T/37. (Document; Compliance)\n\nWho this affects and who pays\n\n- Affects operators, owners, and maintenance organisations responsible for JT9D-3A, -7, -7A, -7H, -7AH, -7F and -20 engines that incorporate labyrinth solid land seals with part numbers 589733, 589741, 647189 or 729774. Those engines are listed in the Applicability section. (Applicability)\n- The cost of performing the temperature check, any subsequent replacement of the steel elbow, and associated labour, parts and aircraft downtime will be borne by the operator or owner who must comply with the directive. The AD itself places the obligation to comply on those responsible for the affected engines. (Applicability; Compliance)\n\nWhy it matters (official rationale and practical test against costs and implementation)\n\n- The instrument references an FAA airworthiness directive or a Pratt & Whitney AD as the Requirement Document; the official direction is to carry out the actions specified there. (Document)\n- Practically, following the Requirement Document will impose an immediate compliance task (inspection) and a possible part-replacement task if the inspection indicates it. The concrete costs are therefore inspection labour and any replacement parts plus associated aircraft out-of-service time; those costs are not enumerated in this text but will be determined by the Requirement Document and by operators' maintenance arrangements. (Compliance)\n- The directive concentrates its effect on a defined subset of engines (specific JT9D model variants with specified seal P/Ns). That concentrates the burden on operators that use those combinations and narrows the population required to take action. (Applicability)\n\nImplementation features, discretion and risk\n\n- The AD delegates the procedural detail (timing, inspection method, acceptance criteria, and replacement instructions) to the referenced Requirement Document. That means regulators and operators rely on that external document to determine the exact compliance steps and schedule. (Document; Compliance)\n- Because the AD refers to external documents for the exact requirements, implementation risk and compliance burden depend on the availability and content of those documents and on spare-part availability and maintenance capacity; this text itself does not provide timing, methods, or replacement-part lists. (Document; Compliance)\n\nBehavioural and market effects (mechanical channels, not value judgements)\n\n- Operators who have the affected engines must schedule inspections and, where required, replace the steel elbow component. That shifts activity to maintenance providers and parts suppliers and may generate spare-parts demand for the specified elbow and for labour to complete the work. (Applicability; Compliance)\n- The AD constrains private choice for affected equipment by mandating a technical action to maintain continued airworthiness; the exact constraints (how often, to what standard) are contained in the Requirement Document referenced. (Document; Compliance)\n\nSummary sentence\n\n- This airworthiness directive requires a No. 3 bearing breather temperature check and the replacement of the main bearing breather tube steel elbow for specific JT9D engine models with listed seal part numbers; compliance is required as detailed in the referenced Requirement Document (FAA AD 76-20-03 or AD/PW-T/37), with costs and scheduling obligations falling to the engine operators and maintainers. (Applicability; Document; Compliance)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused on a specific mechanical component in specific engine models. It has not expanded beyond its original purpose of addressing the bearing breather tube issue identified in 1976."},"complexity_factors":["Very short document (approximately 200 words)","Only 4 defined part numbers in applicability section","No nested conditional logic or exceptions","Single compliance pathway (follow referenced document)","No cross-references to other legislation beyond the two source documents","Straightforward applicability criteria (specific engine models + specific part numbers)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** issued by Australia's Civil Aviation Safety Authority (CASA) that mandates safety checks and part replacements for specific Pratt & Whitney jet engines used in aircraft.\n\n**What it does:**\n- Requires operators to perform temperature checks on the \"No. 3 Bearing Breather\" (a ventilation component that releases pressure from a specific engine bearing)\n- Mandates replacement of a steel elbow fitting in the main bearing breather tube system\n\n**Who it affects:**\n- Owners and operators of aircraft using **JT9D series turbofan engines** (specifically models -3A, -7, -7A, -7H, -7AH, -7F, and -20)\n- Only applies to engines with specific labyrinth seal part numbers: 589733, 589741, 647189, or 729774\n\n**Why it matters:**\nAirworthiness Directives are legally binding safety orders. They are issued when aviation regulators discover a condition that makes an aircraft or component unsafe. This AD addresses potential failures in the engine's bearing breather system that could lead to engine damage or failure if not corrected. Non-compliance grounds the aircraft (makes it illegal to fly).\n\n**Key details:**\n- **Compliance:** Follow the procedures in FAA AD 76-20-03 or the Australian equivalent AD/PW-T/37\n- **Origin:** Based on a US Federal Aviation Administration directive from 1976\n- **Legal basis:** Civil Aviation Regulations 1998, Part 39"}},"importantCases":[],"_links":{"self":"/api/acts/ad-jt9d-7-no-3-bearing-breather-temp-check-and-replacement-of-main-bearing-breather-tube-steel-elbow","history":"/api/acts/ad-jt9d-7-no-3-bearing-breather-temp-check-and-replacement-of-main-bearing-breather-tube-steel-elbow/history","analysis":"/api/acts/ad-jt9d-7-no-3-bearing-breather-temp-check-and-replacement-of-main-bearing-breather-tube-steel-elbow/analysis","conflicts":"/api/acts/ad-jt9d-7-no-3-bearing-breather-temp-check-and-replacement-of-main-bearing-breather-tube-steel-elbow/conflicts","importantCases":"/api/acts/ad-jt9d-7-no-3-bearing-breather-temp-check-and-replacement-of-main-bearing-breather-tube-steel-elbow/important-cases","documents":"/api/acts/ad-jt9d-7-no-3-bearing-breather-temp-check-and-replacement-of-main-bearing-breather-tube-steel-elbow/documents"}}