{"id":"F2006B08712","name":"AD/DART/26 - Low Torque Switch","slug":"ad-dart-26-low-torque-switch","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51906,"registerId":"commonwealth-F2006B08712-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DART/26 - Low Torque Switch","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/26 Low Torque Switch 6/97\n\nApplicability: All Rolls Royce Dart series engines.\n\n \n\nRequirement: To ensure unapproved low torque switches are removed from service, inspect installed and spare low torque switches in accordance with Rolls Royce Service Bulletin Da61-13.\n\n \n\nNote: CAA (UK) AD 002-12-96 also refers.\n\n \n\nCompliance: Unless previously accomplished, no later than 30/6/97.\n\n \n\nThis Airworthiness Directive becomes effective on 22 May 1997.\n\n \n\nBackground: The manufacturer has advised that unapproved low torque switches have been found in service. These switches may give rise to difficulties during activation of the autofeathering system.\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 Directive enforces a narrowly defined safety action already signalled by the manufacturer: inspect and remove unapproved low torque switches on Dart engines (Requirement; Background). It does not expand applicability beyond Dart engines, add unrelated obligations, or change the types of action required; it simply mandates compliance with the manufacturer’s Service Bulletin by a set deadline (Applicability; Requirement; Compliance)."},"complexity_factors":["Narrow technical scope: applies only to Rolls Royce Dart series engines (Applicability).","Single, specific action required: inspect installed and spare low torque switches and remove unapproved items (Requirement).","Clear compliance deadline and effective date reduce procedural ambiguity (Compliance; Effective 22 May 1997).","Procedure detail delegated to a single manufacturer service bulletin (Da61-13), requiring technical execution but concentrating substantive criteria outside the AD (Requirement).","Potential operational complexity: locating all spares, identifying what counts as 'unapproved', sourcing approved replacements and scheduling downtime impose practical burdens on operators (Requirement; Background)."],"plain_english_summary":"What this directive does mechanically\n\n- Requires operators and maintainers to inspect every installed and spare low torque switch on Rolls Royce Dart series engines and remove any switches that are not approved. The inspection must follow the steps set out in Rolls Royce Service Bulletin Da61-13 (Requirement).\n- Sets a compliance deadline: actions must be completed by 30 June 1997 unless already done, and the Directive took effect on 22 May 1997 (Compliance; Effective 22 May 1997).\n\nWho this affects\n\n- Aircraft operators, owners and maintenance organisations using Rolls Royce Dart series engines (Applicability).\n- Suppliers and inventories of spare low torque switches because spares must also be inspected and, if unapproved, removed from service (Requirement).\n\nWhy the regulator issued it (claim in the source)\n\n- The manufacturer reported that some unapproved low torque switches were found in service and that these switches may cause difficulties when the autofeathering system activates (Background). The Directive implements a mandatory inspection and removal to address that reported risk (Requirement).\n\nOperational and economic mechanics, and practical effects\n\n- Who pays: Operators or their maintenance providers bear the direct costs of performing the inspections and of replacing any unapproved switches, including labour, parts, and any aircraft down-time incurred to meet the inspection/removal requirement (Requirement; Compliance).\n- Who decides on compliance actions: The Directive requires actions to be carried out in accordance with Rolls Royce Service Bulletin Da61-13, so technical detail and acceptance criteria come from the manufacturer’s service bulletin; the operator/maintainer decides how to schedule and carry out the work within the AD’s deadline (Requirement).\n- Compliance burden and implementation risk: The rule is narrowly targeted (all Dart engines) and prescriptive (inspect installed and spare switches per the listed service bulletin), so the main burdens are locating all installed and spare switches, following the service bulletin steps, and documenting completion before the compliance date (Applicability; Requirement; Compliance). If unapproved parts are found, sourcing approved replacements and scheduling downtime are likely additional burdens (Requirement).\n- Effects on private enterprise and markets: The Directive increases short-term demand for approved switches and for maintenance labour. Independent maintenance organisations can perform the inspections if authorised to service the engine type; spare-part suppliers of unapproved switches will be affected because their parts must be removed from service (Requirement). The text does not prescribe where replacement parts must be sourced or who may perform the work beyond following the service bulletin, so choice of maintainer and supplier remains governed by existing certification and contracting practices (Requirement).\n- Trade-offs and opportunity costs: Operators must allocate labour and aircraft availability to comply by the deadline instead of other work. The Directive prioritises immediate inspection/removal over optional scheduling flexibility (Compliance).\n- Discretion and enforcement: The Directive sets a mandatory action and deadline; there is little regulatory discretion for operators to delay beyond the stated compliance date absent further approval from the regulator. The Directive references a UK CAA AD but does not expand on enforcement mechanisms in this text (Note).\n\nNet effect in plain terms\n\n- The Directive compels operators of Dart engines to inspect and, if necessary, remove unapproved low torque switches in both installed and spare inventories by 30 June 1997, relying on the manufacturer’s service bulletin for the inspection procedure. The stated purpose is to address a manufacturer-reported risk that such switches may interfere with autofeather system activation (Requirement; Background; Compliance)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive addressing a specific technical defect. It has not expanded beyond its original purpose of removing unapproved switches from Dart engines. The scope remains tightly focused on the identified safety risk."},"complexity_factors":["Single, specific mechanical component addressed (low torque switches)","Only one substantive requirement: inspect and remove per manufacturer bulletin","No defined terms section","No cross-references to other legislation (only a non-binding note about UK authority)","Simple conditional structure: 'Unless previously accomplished' is the only exception","One clear compliance deadline","Background provided in plain language","Total length: approximately 150 words of substantive content"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it as a recall notice, but for aircraft parts.\n\n**What it does:** It orders airlines and aircraft operators to inspect and remove certain faulty \"low torque switches\" from Rolls Royce Dart engines. These switches are part of the engine's autofeathering system (a safety mechanism that adjusts propeller blades if an engine fails).\n\n**The problem:** The manufacturer discovered that some unapproved (counterfeit or non-genuine) switches had made their way into service. These dodgy switches could malfunction when the autofeather system tries to activate — potentially causing serious problems during engine failure.\n\n**Who must act:** Anyone operating aircraft with Rolls Royce Dart series engines (typically older turboprop aircraft like the Fokker F27 or some regional airliners).\n\n**What they must do:** Check all installed switches and spare parts in storage, following the manufacturer's specific instructions (Service Bulletin Da61-13). Remove any unapproved switches found.\n\n**Deadline:** All inspections and removals had to be completed by 30 June 1997.\n\n**Why it matters:** Faulty switches could prevent the autofeather system from working properly during an engine failure. In an emergency, this could lead to loss of aircraft control. The directive closes a safety loophole before it causes an accident."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dart-26-low-torque-switch","history":"/api/acts/ad-dart-26-low-torque-switch/history","analysis":"/api/acts/ad-dart-26-low-torque-switch/analysis","conflicts":"/api/acts/ad-dart-26-low-torque-switch/conflicts","importantCases":"/api/acts/ad-dart-26-low-torque-switch/important-cases","documents":"/api/acts/ad-dart-26-low-torque-switch/documents"}}