{"id":"F2006B09240","name":"AD/DHC-8/81 - PCU Oil Pump","slug":"ad-dhc-8-81-pcu-oil-pump","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53140,"registerId":"commonwealth-F2006B09240-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\n![](image.001.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nBombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/DHC-8/81 PCU Oil Pump 9/2001","sectionType":"part","heading":"AD/DHC-8/81 PCU Oil Pump 9/2001","content":"# AD/DHC-8/81 PCU Oil Pump 9/2001\n\nApplicability: DHC-8 series 100, 200 and 300 aircraft, S/Nos 003 to 554 inclusive, not incorporating a back up pressure regulating valve per Bombardier Service Bulletin 8-61-31.\n\nRequirement: Incorporate a back up pressure regulating valve between the engine reduction gearbox and the auxiliary feather pump on both engines in accordance with Bombardier Service Bulletin 8-61-31.\n\nNote: Transport Canada AD CF-2001-12 refers.\n\nCompliance: At next scheduled engine shop visit after the effective date of this Airworthiness Directive but no later than 12 March 2003.\n\nThis Airworthiness Directive becomes effective on 6 September 2001.\n\nBackground: Incidents have occurred where failure of the oil pressure regulating valve in the PCU oil pump has caused excessive pressure build up resulting in fracture of the pump body, loss of engine oil and inability to feather the propeller.\n\n![](image.002.png)  \n\nEugene Paul Holzapfel\n\nDelegate of the Civil Aviation Safety Authority 26 July 2001\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 15 August 2001.","sortOrder":1}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific mechanical failure mode in a specific aircraft type. There is no evidence of scope creep; it targets exactly the unsafe condition described in the background."},"complexity_factors":["Single, specific mechanical modification required","Only one defined applicability criterion (aircraft series and serial numbers)","Clear, single-date compliance deadline with one alternative timing option","No nested exceptions or conditional logic","No cross-references to other legislation (only a non-binding note referencing a Canadian equivalent)","Total length: approximately 250 words","Straightforward cause-and-effect background explanation"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of Bombardier DHC‑8 Series 100/200/300 (S/N 003–554) that haven’t been modified to install a backup pressure‑regulating valve between the engine gearbox and the auxiliary feather pump. The valve prevents pump overpressure that can crack the pump, cause total engine oil loss and loss of feathering. Compliance is at the next scheduled engine visit after 6 Sep 2001, and no later than 12 Mar 2003."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD's scope is limited to DHC‑8 Series 100/200/300 aircraft S/N 003–554 that do not already have the backup valve and requires installing that valve per Bombardier Service Bulletin 8‑61‑31. The instrument sticks to the stated safety response in the text and does not expand requirements beyond that installation or to other systems."},"complexity_factors":["Applicability is narrowly defined by airframe series and serial number range and excludes aircraft that already incorporate the valve (Applicability/Requirement).","Mandates installation to a specific configuration in accordance with an external manufacturer Service Bulletin (Requirement), creating dependency on that document.","Compliance timing is conditional (at next scheduled engine shop visit) with an absolute backstop date (no later than 12 March 2003), requiring operators to plan maintenance windows (Compliance).","Safety justification rests on prior incidents of valve failure causing pump fracture, oil loss and inability to feather (Background), so the measure targets a single failure mode.","Issued by a CASA delegate under CAR 1998 subregulation 39.1(1), giving regulatory enforceability (header/signature).","Note cross-reference to Transport Canada AD CF‑2001‑12, indicating aligned foreign regulatory action (Note/Requirement).","Operational impacts (parts, labour, downtime) are not quantified in the AD, leaving cost and resource allocation to operators (Requirement/Compliance).","Effective date and Gazette notification establish enforceability timelines separate from compliance deadlines (Effective/Gazette)."],"plain_english_summary":"This Airworthiness Directive requires Bombardier DHC‑8 Series 100/200/300 aeroplane operators (S/N 003–554) that do not already have a backup pressure‑regulating valve to fit one between the engine reduction gearbox and the auxiliary feather pump, following Bombardier Service Bulletin 8‑61‑31. CASA (the delegate issuing the AD) sets compliance at the next scheduled engine shop visit but no later than 12 March 2003. The AD is intended to prevent pump fracture, engine oil loss and loss of propeller feathering; operators bear the cost and scheduling impact."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-81-pcu-oil-pump","history":"/api/acts/ad-dhc-8-81-pcu-oil-pump/history","analysis":"/api/acts/ad-dhc-8-81-pcu-oil-pump/analysis","conflicts":"/api/acts/ad-dhc-8-81-pcu-oil-pump/conflicts","importantCases":"/api/acts/ad-dhc-8-81-pcu-oil-pump/important-cases","documents":"/api/acts/ad-dhc-8-81-pcu-oil-pump/documents"}}