{"id":"F2006B10974","name":"AD/JT8D/11 - First Stage Fan Hubs","slug":"ad-jt8d-11-first-stage-fan-hubs","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56554,"registerId":"commonwealth-F2006B10974-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JT8D/11 - First Stage Fan Hubs","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/11 First Stage Fan Hubs 4/77\n\nApplicability: All JT8D-1, -1A, -1B, -7, -7A and -7B engines fitted with front compressor front hub P/N 504101 with S/Nos. listed in Table 1 of PWA Alert SB No. 4661 which have accumulated 6000 cycles or more in service.\n\n \n\nDocument: 1. FAA AD 77-03-06 : Amendment 39-2828; or\n\n \n\n2. AD/PW-T/42.\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 instrument specifies a narrow scope: JT8D-1/1A/1B/7/7A/7B engines fitted with front compressor hub P/N 504101 with serial numbers listed in Table 1 of PWA Alert SB No. 4661 and that have accumulated 6,000 or more cycles (Applicability). The directive does not indicate any alteration to that scope within the text provided, nor does it include language suggesting the scope has been expanded or narrowed from an earlier version. The directive instead requires compliance with the external Requirement Document for the listed items (Document; Compliance)."},"complexity_factors":["Dependence on external documents for the substantive requirements (FAA AD 77-03-06 or AD/PW-T/42) rather than containing detailed steps in the directive itself (Document; Compliance).","Applicability tied to specific part number and to serial numbers listed in an external Table 1 of PWA Alert SB No. 4661, requiring parties to cross-check records and the service bulletin (Applicability).","A numeric usage threshold (>= 6,000 cycles) that requires operators to verify and produce accurate cycle-count records (Applicability).","Unspecified content and timelines in the AD itself (\"As detailed in the Requirement Document\"), which creates interpretation and implementation reliance on the referenced materials (Document; Compliance).","Operational coordination costs: inspection/repair scheduling, potential engine downtime, parts availability and use of certified maintenance providers (Applicability; Compliance).","Enforcement and compliance monitoring depend on reading of external technical documents and record audits rather than on text contained in the AD, increasing administrative and procedural steps for both regulators and operators (Document; Compliance)."],"plain_english_summary":"What this instrument does (mechanically)\n\n- This airworthiness directive applies to a subset of Pratt & Whitney JT8D turbine engines. It targets engines of models JT8D-1, -1A, -1B, -7, -7A and -7B that are fitted with a specific front compressor hub (part number 504101) and whose hub serial numbers are listed in Table 1 of PWA Alert Service Bulletin No. 4661, provided those hubs have accumulated 6,000 or more cycles in service (Applicability).\n- The directive requires the affected engines to be dealt with in the way set out in the referenced Requirement Document. The Requirement Document is contained in or represented by either FAA Airworthiness Directive 77-03-06 (Amendment 39-2828) or AD/PW-T/42 (Document). The directive’s compliance obligation is stated as “As detailed in the Requirement Document” (Compliance).\n\nWho it affects\n\n- Owners and operators of the listed JT8D engine models who have engines with front compressor hub P/N 504101 and one of the serial numbers listed in Table 1 of PWA Alert SB No. 4661, and whose hub(s) have >= 6,000 cycles (Applicability).\n- Maintenance organisations, certified repair stations and other entities that carry out inspections, removals or replacements required by the referenced Requirement Document (Document; Compliance).\n\nWho pays and who decides\n\n- The economic burden of complying — for example, inspecting, removing, repairing or replacing a hub, engine grounding time, parts and labour — falls on the operators/owners and the maintenance organisations they engage, as they must carry out the actions in the Requirement Document (Applicability; Compliance).\n- The directive delegates the technical content and precise required actions to the referenced documents (FAA AD 77-03-06 or AD/PW-T/42). The regulator enforces compliance with those actions by making them mandatory through this directive (Document; Compliance).\n\nWhat behaviour changes\n\n- Operators must identify whether an engine has the specified hub P/N and a serial number listed in Table 1 of PWA Alert SB No. 4661 and check accumulated cycles (Applicability).\n- If an engine meets the applicability criteria, the operator must follow the inspection, removal or replacement steps and any times or limits set out in the Requirement Document (Document; Compliance).\n\nMechanics, incentives and trade-offs (source-attributed)\n\n- The directive channels the regulator’s requirement into pre-existing technical documents rather than reproducing the procedures in full: it makes compliance contingent on following FAA AD 77-03-06 or AD/PW-T/42 (Document). That reduces repetition in the instrument but requires operators to obtain and apply external technical documents to determine required actions (Document; Compliance).\n- Compliance imposes identifiable private costs on operators and maintenance providers: locating and checking serial numbers in PWA Alert SB No. 4661, verifying engine cycle counts, performing whatever inspections or replacements the Requirement Document mandates, and any resulting engine downtime (Applicability; Document; Compliance).\n- The directive’s practical effect depends on record quality and supply of replacement parts and maintenance capacity. Those operational constraints affect how quickly an operator can comply and the calendar cost of compliance (Applicability; Document; Compliance).\n\nImplementation and compliance risks\n\n- The AD’s operative text refers to an external Table 1 (PWA Alert SB No. 4661) and to external Requirement Documents (FAA AD 77-03-06 or AD/PW-T/42). If operators lack access to or misunderstand those referenced materials, determining applicability and the required steps is harder (Applicability; Document; Compliance).\n- Because the directive does not itself state inspection intervals, corrective actions or exact compliance timeframes, enforcement and interpretation rely on the content of the referenced documents and on the regulator’s application of the AD (Document; Compliance).\n\nConcise operational summary\n\n- If you operate one of the JT8D engine models listed and your engine has front compressor hub P/N 504101 with a serial number shown in Table 1 of PWA Alert SB No. 4661 and 6,000+ cycles, you must follow the actions set out in FAA AD 77-03-06 or AD/PW-T/42. The actions, timing and technical steps are those contained in the referenced Requirement Document (Applicability; Document; Compliance)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific engine models. It has not expanded beyond its original purpose of ensuring airworthiness of the identified fan hub component."},"complexity_factors":["Very short document (approximately 150 words)","Only 4 defined elements: applicability criteria, document references, compliance method, and the specific part/serial number cross-reference","No nested conditional logic or exceptions—simple binary applicability test (does your engine match these criteria? Yes/No)","Single cross-reference to external documents (FAA AD and Pratt & Whitney service bulletin)","Clear, unambiguous compliance instruction ('As detailed in the Requirement Document')"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** issued by Australia's Civil Aviation Safety Authority (CASA) that mandates safety inspections or replacements for specific Pratt & Whitney jet engines used in aircraft.\n\n**What it does:**\n- Requires operators to take corrective action on **JT8D series turbine engines** (specifically models -1, -1A, -1B, -7, -7A and -7B)\n- Targets engines fitted with a specific front compressor hub part (P/N 504101) with serial numbers listed in a Pratt & Whitney service bulletin\n- Only applies to engines that have been used for **6,000 flight cycles or more**\n\n**Who it affects:**\n- Airlines and aircraft operators in Australia using these specific Pratt & Whitney engines (commonly found on older Boeing 727 and 737 aircraft)\n- Maintenance organisations servicing these engines\n\n**Why it matters:**\nAirworthiness Directives are legally binding safety orders. They typically issue when a manufacturer or regulator discovers a defect that could cause engine failure, potentially leading to catastrophic accidents. This directive likely addresses fatigue or cracking issues in the first stage fan hub—a critical rotating component. Non-compliance grounds the aircraft (meaning it cannot legally fly)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jt8d-11-first-stage-fan-hubs","history":"/api/acts/ad-jt8d-11-first-stage-fan-hubs/history","analysis":"/api/acts/ad-jt8d-11-first-stage-fan-hubs/analysis","conflicts":"/api/acts/ad-jt8d-11-first-stage-fan-hubs/conflicts","importantCases":"/api/acts/ad-jt8d-11-first-stage-fan-hubs/important-cases","documents":"/api/acts/ad-jt8d-11-first-stage-fan-hubs/documents"}}