{"id":"F2006B08705","name":"AD/DART/2 - Fuel Burner Shroud Nut Hardness","slug":"ad-dart-2-fuel-burner-shroud-nut-hardness","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51891,"registerId":"commonwealth-F2006B08705-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DART/2 - Fuel Burner Shroud Nut Hardness","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)  Rolls Royce Turbine Engines - Dart Series\n\n \n\nAD/DART/2 Fuel Burner Shroud Nut Hardness 11/87\n\nApplicability: All Dart RDa-6, RDa-7 series engines fitted with fuel burners of any modification standard other than Mod. 1626.\n\n \n\nRequirement: 1. Inspect fuel burner shroud nuts for hardness in accordance with the requirements of Rolls Royce SB Da 73-68 and Da 73-A81 as applicable; or\n\n \n\n2. AD/RRT/15 Amdt 1.\n\n \n\nCompliance: As detailed in Requirement documents. Background: Reissue of AD/RRT/15 Amdt 1.\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":3,"scope_assessment":{"changed":false,"description":"The AD states it is a reissue of AD/RRT/15 Amdt 1 (Background). The directive restates the inspection requirement for fuel burner shroud nut hardness and continues to require compliance via the Rolls Royce service bulletins or the earlier AD (Requirement). There is no indication in the supplied text that the class of affected engines, the inspection obligation, or the acceptable compliance routes have been broadened or narrowed compared with the prior AD; therefore the scope appears unchanged in this reissue."},"complexity_factors":["Narrow technical focus (only Dart RDa-6 and RDa-7 engines with burners not at Mod. 1626) reduces breadth of affected parties (Applicability).","Dependency on external technical documents (Rolls Royce SB Da 73-68 and Da 73-A81, or AD/RRT/15 Amdt 1) for methods, thresholds and timing increases procedural complexity.","Two alternative compliance paths (follow the Rolls Royce SBs or AD/RRT/15 Amdt 1) requires operators to choose and interpret applicable documents (Requirement).","No timing, test method, or acceptance criteria written directly into the AD; those are delegated to referenced documents (Compliance), creating an implementation step to obtain and apply those documents.","Technical nature of 'hardness' testing implies need for specialised measurement equipment or facilities and potential parts replacement if the test fails, adding operational and cost complexity.","Regulatory cross-reference (reissue of a prior AD) requires checking previous AD text for continuity or differences (Background)."],"plain_english_summary":"This airworthiness directive (AD) instructs operators and maintainers of certain Rolls Royce Dart turbine engines to check the hardness of the fuel burner shroud nuts.\n\n- What it requires mechanically: Engines in the Dart RDa-6 and RDa-7 series that are fitted with fuel burners of any modification standard other than Mod. 1626 must have their fuel burner shroud nuts inspected for hardness. The inspection must be done either in accordance with the Rolls Royce service bulletins (SB Da 73-68 and Da 73-A81) referenced in the AD, or by following an earlier AD (AD/RRT/15 Amdt 1) (see \"Applicability\" and \"Requirement\"). Compliance timing and the exact test or pass/fail criteria are set out in those reference documents (see \"Compliance\").\n\n- Who this affects: Aircraft operators, maintenance organisations and maintenance personnel responsible for Dart RDa-6 and RDa-7 engines with fuel burners not at Mod. 1626. Those parties are responsible for arranging and paying for the inspections and any follow-up work.\n\n- Why it matters (stated purpose and practical implications): The AD is a reissue of a previous directive (\"Background: Reissue of AD/RRT/15 Amdt 1\"). The stated purpose is to ensure the fuel burner shroud nuts meet required hardness standards; the mechanical effect is to require testing and, where the inspection and the referenced documents require it, corrective action. Practically, compliance will typically require scheduled maintenance time, the testing procedure and acceptance criteria provided by the Rolls Royce service bulletins or the referenced AD, and potential repair or replacement of parts that fail the hardness check.\n\n- Who pays, who decides, and what changes in behaviour:\n  - Who pays: The operator or the organisation performing maintenance pays for the inspection work and for any parts replacement or repairs identified by the inspection (implied by the requirement for inspection and corrective action in the referenced documents).\n  - Who decides: The Civil Aviation Safety Authority (via this AD) determines that an inspection is required; the specific method, timing and acceptance criteria are set in the Rolls Royce service bulletins or the alternative AD named in the Requirement section. Maintenance personnel decide how to schedule and carry out the inspections within those documents' instructions.\n  - Behaviour changes: Affected operators must schedule and carry out hardness tests on the fuel burner shroud nuts according to the referenced documents and perform any mandated corrective actions.\n\n- Compliance burden and implementation risk: The AD delegates technical detail to external documents (the Rolls Royce SBs or the earlier AD), so the operational burden depends on those documents' procedures. This creates dependency on external technical instructions for how to test and what remedial steps to take. The AD itself does not specify timing or test thresholds in-line; it requires compliance \"as detailed in Requirement documents\" (see \"Compliance\"), which means operators must obtain and follow those documents precisely. Potential costs are inspection labour, downtime while testing and any repairs or part replacements required.\n\n- Incentives, trade-offs and substitution effects: The directive concentrates its effect on operators of the specified engine models (concentrated cost) while aiming to reduce the risk associated with substandard shroud nuts (concentrated benefit to engine integrity and safety). Because the AD offers two compliance paths (the Rolls Royce SBs or AD/RRT/15 Amdt 1), operators can choose the route that fits their regulatory or maintenance practice, subject to the requirements in those documents. There is no expression in the AD itself of alternative mitigations or economic support; the practical trade-offs are maintenance time and parts costs versus removing or mitigating a potential mechanical risk.\n\nReferences to source sections: applicability is set out under \"Applicability\"; the action options are in \"Requirement\"; timing and detailed procedures are referenced in \"Compliance\"; historical note is in \"Background\"."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a narrow, technical maintenance directive focused on a specific hardware defect in a specific engine series. It has not expanded beyond its original safety purpose."},"complexity_factors":["Very short document (under 200 words)","Only 2 substantive requirements with an either/or structure","Minimal defined terms (only 'Mod. 1626' requires external knowledge)","No nested conditional logic or cross-references to other legislation beyond the alternative AD and service bulletins","Single applicability criterion (engine model + modification status)","Background section simply notes this is a reissue of prior directive"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). ADs are legally binding instructions that aircraft owners and operators must follow to fix unsafe conditions in aircraft or their parts.\n\n**What it does:** This specific directive (AD/DART/2) targets **Rolls-Royce Dart engines** — turboprop engines used in older aircraft like the Fokker F27 and Vickers Viscount. The problem involves **fuel burner shroud nuts** (metal fasteners that hold parts of the engine's fuel system together). These nuts may have incorrect hardness levels, which could cause them to crack or fail.\n\n**Who must act:** Anyone operating aircraft with **Dart RDa-6 or RDa-7 series engines** — specifically those with fuel burners that haven't been upgraded to \"Modification 1626\" (a factory upgrade that fixes this issue).\n\n**What they must do:** Operators must either:\n- **Inspect the nuts** for proper hardness following Rolls-Royce service bulletins (SB Da 73-68 or Da 73-A81), OR\n- **Follow an alternative directive** (AD/RRT/15 Amdt 1) which covers the same safety issue\n\n**Why it matters:** Failed shroud nuts could lead to fuel leaks, engine damage, or in-flight engine failure. This directive prevents catastrophic failures by ensuring critical fasteners meet strength specifications.\n\n**Compliance deadline:** As specified in the referenced Rolls-Royce documents (not a fixed date — depends on flight hours or calendar time in the original bulletins)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dart-2-fuel-burner-shroud-nut-hardness","history":"/api/acts/ad-dart-2-fuel-burner-shroud-nut-hardness/history","analysis":"/api/acts/ad-dart-2-fuel-burner-shroud-nut-hardness/analysis","conflicts":"/api/acts/ad-dart-2-fuel-burner-shroud-nut-hardness/conflicts","importantCases":"/api/acts/ad-dart-2-fuel-burner-shroud-nut-hardness/important-cases","documents":"/api/acts/ad-dart-2-fuel-burner-shroud-nut-hardness/documents"}}