{"id":"F2006B06334","name":"AD/PR/6 Amdt 12 - Retirement Lives of Components","slug":"ad-pr-6-amdt-12-retirement-lives-of-components","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47510,"registerId":"commonwealth-F2006B06334-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PR/6 Amdt 12 - Retirement Lives of Components","content":"![](image.001.png)\n\n![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nOn the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/PR/6 Amdt 11 and issues the following AD under subregulation 39.1 (1) of CASR 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\n![](image.001.png)\n\nPropellers \\- Variable Pitch - Dowty Rotol\n\nAD/PR/6\n\nAmdt 12\n\n  \nRetirement Lives of Components 13/2004\n\nApplicability: As detailed in the Requirement Documents.\n\nNote: The aeronautical products as detailed in the Requirement Documents are propeller components fitted to Rolls Royce Dart Series Engines.\n\nRequirement: As applicable, retire listed propeller components in accordance with the following documents or later approved revisions as approved by the UK CAA.\n\n    Dowty Rotol SB No 61-542-1;\n\n    2. Dowty Rotol SB No 61-542-2, Rev. 2;\n\n    3. Dowty Rotol SB No 61-542-3, Rev. 2;\n\n    4. Dowty Rotol SB No 61-542-3A, Rev. 1;\n\n    5. Dowty Rotol SB No 61-542-4;\n\n    6. Dowty Rotol SB No 61-542-5;\n\n    7. Dowty Rotol SB No 61-542-6, Rev. 2;\n\n    8. Dowty Rotol SB No 61-542-10, Rev. 3;\n\n    9. Dowty Rotol SB No 61-542-11;\n\n    10. Dowty Rotol SB No 61-542-13, Rev. 1.\n\n    11. Retire all propeller hub and driving centre assemblies listed in Dowty Aerospace Gloucester (formely Dowty Rotol) B 61-542-18, Rev 3, before exceeding 33,000 total time in service.\n\n    12. Dowty Aerospace Gloucester (Formel Dowty Rotol) SB No 61-954 Rev. 6\\. Compliance: As detailed in the Requirement Documents.\n\nThis Amendment becomes effective on 23 December 2004.\n\nPropellers \\- Variable Pitch - Dowty Rotol\n\nAD/PR/6 Amdt 12 (continued)\n\nBackground: This amendment clarifies that the types of propellers and propeller components detailed in this Directive are those fitted to Rolls Royce Dart Series engines. In addition the revision status of the requirement documents can now reflect the documents latest revision.\n\n![Signature of James Coyne, Delegate of the Civil Aviation Safety Authority.](image.002.png)  \n\nJames Coyne\n\nDelegate of the Civil Aviation Safety Authority 9 November 2004\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 1 December 2004.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"The amendment remains tightly focused on its original purpose: establishing retirement lives for Dowty Rotol propeller components. The changes from Amendment 11 are minor clarificatory updates (confirming applicability to Rolls Royce Dart engines and allowing latest document revisions) rather than expansion into new aircraft types, components, or regulatory domains."},"complexity_factors":["Heavy reliance on external technical documents (12 separate service bulletins) that are not reproduced in the AD itself — operators must cross-reference multiple external manuals","Mixed revision tracking: some bulletins specify exact revisions (Rev. 2, Rev. 3), others don't, creating inconsistency in compliance requirements","Dual naming convention for the manufacturer (Dowty Rotol vs Dowty Aerospace Gloucester, including typo 'Formel' for 'Formerly') adds confusion","Specific numeric threshold (33,000 hours) embedded in text rather than tabulated, making it easy to miss","Conditional applicability ('As detailed in the Requirement Documents') means the full scope isn't visible in the AD text itself","Regulatory cross-reference to subregulation 39.1(1) of CASR 1998 establishes legal basis but requires external knowledge of aviation law"],"plain_english_summary":"This AD revokes Amendment 11 and issues Amendment 12, imposing mandatory life limits on Dowty Rotol variable-pitch propeller components fitted to Rolls Royce Dart engines (common on older Fokker F27 and Vickers Viscount types). Operators must retire specified parts at defined hours/cycles—critical assemblies must be removed before 33,000 total hours—to prevent fatigue-related failures.\n\nIt also clarifies applicability to Dart‑engine installations and permits using the latest approved technical bulletin revisions."},"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment is primarily clarifying and administrative. It narrows the applicability description (explicitly stating the components are those fitted to Rolls‑Royce Dart series engines) and permits the AD to refer to the latest revisions of the named Dowty Rotol service bulletins provided those revisions are approved by the UK CAA. Those are clarifications to how the original requirements are identified and updated rather than a substantive expansion of the AD's operational scope or new types of requirements."},"complexity_factors":["Short document with a single concrete action: mandatory retirement of listed components","References to 11 specific Dowty Rotol service bulletins plus two Dowty Aerospace Gloucester documents","One explicit numeric life limit (33,000 total time in service) for hub and driving centre assemblies","Allowance for later revisions of the Requirement Documents, but only if approved by the UK CAA (external approval dependency)","Use of the phrase \"as applicable\" and \"as detailed in the Requirement Documents\" introduces conditionality tied to the SBs rather than in the AD text","Revokes previous amendment (AD/PR/6 Amdt 11) — administrative replacement rather than adding nested exceptions","Relies on cross‑jurisdictional approval (UK CAA) rather than embedding all technical detail"],"plain_english_summary":"**What this instrument does (mechanics)**\n\n- This is an Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) under CASR subregulation 39.1(1). It revokes the previous AD (AD/PR/6 Amdt 11) and replaces it with Amendment 12.\n- It requires operators and maintainers to retire specific Dowty Rotol propeller components fitted to Rolls‑Royce Dart series engines according to a list of Dowty Rotol service bulletins (SBs) or later revisions of those SBs approved by the UK Civil Aviation Authority (UK CAA). The SBs named are Nos. 61‑542‑1, 61‑542‑2 (Rev. 2), 61‑542‑3 (Rev. 2), 61‑542‑3A (Rev. 1), 61‑542‑4, 61‑542‑5, 61‑542‑6 (Rev. 2), 61‑542‑10 (Rev. 3), 61‑542‑11, and 61‑542‑13 (Rev. 1), plus Dowty Aerospace Gloucester B 61‑542‑18 (Rev. 3) and SB 61‑954 (Rev. 6).\n- A specific numeric life limit is included: all propeller hub and driving centre assemblies listed in Dowty Aerospace Gloucester B 61‑542‑18 Rev. 3 must be retired before exceeding 33,000 total time in service. Other retirement instructions follow the referenced SBs.\n- Compliance must be carried out in accordance with the Requirement Documents (the listed SBs), and the AD became effective on 23 December 2004.\n\n**Who is affected**\n\n- Aircraft owners/operators and maintenance organisations that operate aircraft equipped with Dowty Rotol variable‑pitch propellers fitted to Rolls‑Royce Dart series engines.\n- Maintenance providers who must follow the referenced service bulletins and keep records proving retirement at the specified lives.\n- Potentially parts suppliers and overhaul facilities that provide replacement components.\n\n**Why it matters (stated purpose and practical effect)**\n\n- The AD’s stated purpose (Background) is to clarify that the listed propellers/components are those fitted to Rolls‑Royce Dart engines and to allow the referenced requirement documents to reflect their latest revision status.\n- Practically, the AD makes the retirement lives and replacement of listed propeller components mandatory. That changes maintenance schedules, creates replacement costs, and requires record‑keeping to demonstrate compliance.\n\n**Who pays, who decides, and what behaviour changes**\n\n- Who pays: aircraft owners/operators pay for the inspection, removal, overhaul or replacement of the retired components and any associated aircraft downtime.\n- Who decides: CASA (through its delegate) issues and enforces the AD. The technical retirement instructions are contained in Dowty Rotol service bulletins; the AD allows later revisions of those SBs only if approved by the UK CAA.\n- Behaviour changes: operators must monitor component time‑in‑service, comply with the retirement schedules in the referenced SBs, and retire hub/driving centre assemblies before 33,000 hours. Maintenance planning must include these retirements and associated parts procurement.\n\n**Trade‑offs, implementation risks and compliance burdens**\n\n- Direct costs: predictable recurring costs for replacement components and possible increased downtime as components reach mandatory retirement life.\n- Opportunity costs: aircraft may be out of service earlier than otherwise, affecting utilisation and scheduling.\n- Administrative burden: maintaining accurate time‑in‑service records and ensuring work conforms to the exact revision of SBs approved by the UK CAA.\n- Regulatory coordination risk: the AD relies on SBs and later revisions as approved by the UK CAA; reliance on an overseas authority creates a dependency for approved revisions and may delay or complicate local compliance if there are differences in approvals.\n- Enforcement and discretion: CASA enforces the AD; technical detail and permissible revisions are controlled by the SBs and UK CAA approvals rather than being spelled out in detail in the AD itself.\n\n**Net effect (mechanical, not evaluative)**\n\n- The Directive makes specific component retirement limits mandatory for a defined set of propeller components, enforces at least one numeric life limit (33,000 total time in service for listed hub/centre assemblies), and ties compliance to Dowty Rotol service bulletins (including later UK CAA‑approved revisions). It clarifies applicability to Dart‑engine installations and allows the referenced documents to reflect their latest revision status."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pr-6-amdt-12-retirement-lives-of-components","history":"/api/acts/ad-pr-6-amdt-12-retirement-lives-of-components/history","analysis":"/api/acts/ad-pr-6-amdt-12-retirement-lives-of-components/analysis","conflicts":"/api/acts/ad-pr-6-amdt-12-retirement-lives-of-components/conflicts","importantCases":"/api/acts/ad-pr-6-amdt-12-retirement-lives-of-components/important-cases","documents":"/api/acts/ad-pr-6-amdt-12-retirement-lives-of-components/documents"}}