{"id":"F2006B06358","name":"AD/PT6A/18 - No. 2 Bearing Oil Pressure Tube","slug":"ad-pt6a-18-no-2-bearing-oil-pressure-tube","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47588,"registerId":"commonwealth-F2006B06358-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PT6A/18 - No. 2 Bearing Oil Pressure Tube","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 Canada Turbine Engines - PT6A Series\n\n \n\nAD/PT6A/18 No. 2 Bearing Oil Pressure Tube 10/85\n\nApplicability: PT6A-38, PT6A-41, PT6A-45A engines with S/Nos. as specified in the requirement document.\n\n \n\nDocument: 1. Pratt & Whitney of Canada SB No. 3099, Rev. 2; or\n\n \n\n2. AD/UAC-T/28A.\n\n \n\nCompliance: Within 100 hours time in service after 28 February, 1978.\n\n \n\nBackground:  This Directive is reissued in order to reflect the manufacturers latest reference document which completes the listing of engine serial numbers affected and clarifies new part assembly instructions.\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 straightforward maintenance directive focused on a specific safety issue in defined engine models. The reissue simply updates the reference documentation to complete the serial number listing and clarify assembly instructions — it does not expand the scope beyond the original safety purpose of addressing the No. 2 Bearing Oil Pressure Tube issue."},"complexity_factors":["Single, specific mechanical component addressed (No. 2 Bearing Oil Pressure Tube)","Limited applicability: only three specific engine models (PT6A-38, PT6A-41, PT6A-45A) with enumerated serial numbers","Simple compliance trigger: time-in-service hours after a fixed date","Only two reference documents cited","No nested exceptions, conditional logic, or defined terms section","Extremely short document (approximately 150 words of substantive content)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** issued by Australia's Civil Aviation Safety Authority (CASA) that applies to specific Pratt & Whitney Canada PT6A aircraft engines.\n\n**What it does:**\n- Requires owners and operators of certain PT6A-38, PT6A-41, and PT6A-45A engines to inspect or replace the **No. 2 Bearing Oil Pressure Tube** — a critical component that supplies oil to the engine's second bearing.\n\n**Who it affects:**\n- Aircraft operators using the specified engine models with particular serial numbers listed in the manufacturer's service bulletin.\n\n**Why it matters:**\n- Oil pressure tube failures can cause catastrophic engine damage or in-flight engine failure. This directive ensures safety-critical maintenance is performed to prevent mechanical failures.\n\n**Key requirements:**\n- **Compliance deadline:** Within 100 hours of engine operation after 28 February 1978\n- **Reference documents:** Pratt & Whitney Service Bulletin No. 3099 (Revision 2) or an alternative Australian directive (AD/UAC-T/28A)\n\n**Background:** This is a reissued directive that updates the original to include a complete list of affected engine serial numbers and clarifies assembly instructions for replacement parts."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The directive was reissued to reflect the manufacturer’s latest reference document, which (according to the AD) \"completes the listing of engine serial numbers affected and clarifies new part assembly instructions\" (Background). Mechanically, that means the set of engines covered and the precise assembly/repair procedure were updated compared with the prior issuance: operators must therefore re-check whether their engines fall within the now-complete serial-number list and follow the clarified instructions in the referenced documents (Applicability; Document; Background)."},"complexity_factors":["Technical specificity is delegated to external documents (Pratt & Whitney SB No. 3099 Rev.2 or AD/UAC-T/28A), requiring operators to consult those sources for detailed steps.","Applicability depends on engine serial numbers listed only in the referenced documents, not fully stated in the AD itself.","A short, fixed compliance window is specified (100 hours after 28 Feb 1978), creating an operational deadline to identify affected engines and schedule work.","Regulatory formality: the AD is issued under the Civil Aviation Regulations Part 39 framework, imposing a legal maintenance obligation.","Reissue changes scope by completing serial-number listing and clarifying assembly instructions, adding an element of change-management for operators who complied under the earlier edition."],"plain_english_summary":"This Airworthiness Directive mandates specific maintenance on the No.2 bearing oil‑pressure tube for certain Pratt & Whitney Canada PT6A‑38, PT6A‑41 and PT6A‑45A engines (serial numbers as listed in the referenced documents). Operators must follow Pratt & Whitney SB No.3099 Rev.2 or AD/UAC‑T/28A and complete the work within 100 hours TIS after 28 Feb 1978. The reissue updates the engine serial‑number list and clarifies assembly instructions; affected owners/operators bear compliance costs."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pt6a-18-no-2-bearing-oil-pressure-tube","history":"/api/acts/ad-pt6a-18-no-2-bearing-oil-pressure-tube/history","analysis":"/api/acts/ad-pt6a-18-no-2-bearing-oil-pressure-tube/analysis","conflicts":"/api/acts/ad-pt6a-18-no-2-bearing-oil-pressure-tube/conflicts","importantCases":"/api/acts/ad-pt6a-18-no-2-bearing-oil-pressure-tube/important-cases","documents":"/api/acts/ad-pt6a-18-no-2-bearing-oil-pressure-tube/documents"}}