{"id":"F2006B10975","name":"AD/JT8D/13 - No. 4 1/2 Bearing - Removal From Service","slug":"ad-jt8d-13-no-4-1-2-bearing-removal-from-service","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56555,"registerId":"commonwealth-F2006B10975-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JT8D/13 - No. 4 1/2 Bearing - Removal From Service","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/13 No. 4 1/2 Bearing - Removal From Service 10/77\n\nApplicability: JT8D engine models containing Number 4 1/2 bearing P/N 707007, bearing S/Nos.\n\n800 through to 999, and S/Nos. 100A through to 214A. Document: 1. FAA AD 77-16-12 : Amendment 39-3008; or\n\n2. Pratt & Whitney Alert Service No. 4639, Rev. 2; or 3. AD/PW-T/44.\n\nCompliance: 1 December 1977.\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":2,"scope_assessment":{"changed":false,"description":"The instrument itself defines a precise, narrow scope (specific part number and serial-number ranges) and sets a compliance date. The text does not indicate any change to that scope from an earlier instrument; it references other documents for procedural details but does not state that the range of affected parts or the compliance obligation has been altered."},"complexity_factors":["Very narrow technical scope: single part number and two defined serial-number ranges (Applicability).","Clear, single action (removal from service) with a fixed compliance date (Compliance).","Dependence on external documents (FAA AD 77-16-12; Pratt & Whitney Alert Service No. 4639 Rev. 2; AD/PW-T/44) for procedural detail increases implementation steps despite the directive’s brevity (Document).","Operational complexity concentrated in maintenance logistics (identifying affected bearings, scheduling removals, arranging replacements), which requires technical/maintenance capability rather than legislative interpretation.","Brief text with little procedural detail, requiring consult of cross-referenced technical documents for full compliance instructions."],"plain_english_summary":"This AD mandates that, by 1 December 1977, Number 4 1/2 bearings (P/N 707007, S/Ns 800–999 and 100A–214A) be removed from service on affected JT8D engines. It cross‑references FAA AD 77‑16‑12, Pratt & Whitney Alert Service No. 4639 Rev. 2 and AD/PW‑T/44 for procedures. Owners, operators and maintenance organisations must locate, remove and replace the listed bearings, incurring the associated labor, parts and downtime."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive with a single specific purpose. It has not expanded beyond its original intent of removing defective bearings from service."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 3 defined applicability criteria (engine model, part number, serial number ranges)","Single compliance date with no conditional logic or exceptions","No cross-references to other legislation or regulations beyond informational document references","Straightforward command structure: identify affected parts → remove by date","No nested definitions or interpretive provisions"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** issued by Australia's Civil Aviation Safety Authority (CASA) that mandates the removal from service of a specific aircraft engine bearing.\n\n**What it does:**\n- Orders the immediate removal from service of **Number 4 1/2 bearings** (part number 707007) installed in **Pratt & Whitney JT8D series turbine engines**\n- Applies only to bearings with specific serial numbers: **800-999** and **100A-214A**\n\n**Who it affects:**\n- Airlines and aircraft operators using Pratt & Whitney JT8D engines (commonly found on Boeing 727 and 737-100/200 aircraft)\n- Maintenance organisations servicing these engines\n- Aircraft owners with affected engines installed\n\n**Why it matters:**\nAirworthiness Directives are legally binding safety orders. This directive was issued because the specified bearings were found to have a safety defect that could lead to engine failure. Compliance was mandatory by **1 December 1977**. Failure to comply would mean the aircraft cannot legally fly in Australian airspace.\n\n**Key documents referenced:**\n- The original US Federal Aviation Administration (FAA) directive (AD 77-16-12)\n- Pratt & Whitney's manufacturer service bulletin (Alert Service No. 4639)\n- A related Australian directive (AD/PW-T/44)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-jt8d-13-no-4-1-2-bearing-removal-from-service","history":"/api/acts/ad-jt8d-13-no-4-1-2-bearing-removal-from-service/history","analysis":"/api/acts/ad-jt8d-13-no-4-1-2-bearing-removal-from-service/analysis","conflicts":"/api/acts/ad-jt8d-13-no-4-1-2-bearing-removal-from-service/conflicts","importantCases":"/api/acts/ad-jt8d-13-no-4-1-2-bearing-removal-from-service/important-cases","documents":"/api/acts/ad-jt8d-13-no-4-1-2-bearing-removal-from-service/documents"}}