{"id":"F2006B10353","name":"AD/HILLER 12/26 - Rotor Tachometer Generator - Replacement","slug":"ad-hiller-12-26-rotor-tachometer-generator-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115961,"registerId":"commonwealth-F2006B10353-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HILLER 12/26 - Rotor Tachometer Generator - Replacement","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 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Hiller UH-12 Series Helicopters\n\n \n\nAD/HILLER 12/26 Rotor Tachometer Generator - Replacement 5/79\n\nApplicability: Model UH-12D and UH-12E helicopters with Soloy Turbine Conversion using 22A580 tachometer generators in the rotors position.\n\n \n\nDocument: 1. Soloy Conversions SB 03-560; or\n\n \n\n2. FAA AD 79-03-07.\n\n \n\nCompliance: Within 200 hours’ time in service after 31 May 1979.\n\n \n\nBackground:  The new rotor tachometer generator type is expected to reduce the number of failures being experienced with the present generators. The repeated execution of emergency procedures involving unnecessary external load deployment and full autorotation following false low rotor speed warning system activation should be avoided, thereby reducing the hazard to the aircraft.\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 instrument targets a specific component on a defined subset of aircraft and mandates replacement within a fixed service-time window, as stated in the AD. The AD text gives no indication it broadens or narrows scope beyond that original requirement; compliance and technical implementation are delegated to the referenced Soloy SB or FAA AD."},"complexity_factors":["Narrow applicability: applies only to UH‑12D and UH‑12E with Soloy turbine conversion using 22A580 rotor tachometer generators (Applicability).","Clear compliance deadline: single, short deadline specified — within 200 hours’ time in service after 31 May 1979 (Compliance).","Dependency on external documents: compliance requires following Soloy SB 03‑560 or FAA AD 79‑03‑07 (Document), so operators must obtain and follow those technical instructions.","Technical specificity: identifies a particular part number (22A580), requiring technical checks and parts procurement.","Operational burden on operators: replacement imposes direct costs for parts, maintenance labour and aircraft downtime (implied by the need to perform the work within the compliance window).","Safety rationale stated but procedural: Background identifies the hazard (false low‑rotor warnings leading to unwarranted emergency procedures) but the AD relies on referenced documents for installation/technical details."],"plain_english_summary":"This Airworthiness Directive requires owners/operators of Hiller UH‑12D and UH‑12E helicopters converted by Soloy using 22A580 rotor tachometer generators to replace those generators. The replacement must be completed within 200 hours’ time in service after 31 May 1979, following Soloy Service Bulletin 03‑560 or FAA AD 79‑03‑07. The stated aim is to reduce false low‑rotor warnings and avoid unnecessary emergency procedures; operators pay for parts, labour and downtime caused by the mandated replacement."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive targeting a specific mechanical defect in a narrow class of aircraft. It has not expanded beyond its original purpose of mandating a parts replacement to address a known safety hazard."},"complexity_factors":["Very short document (approximately 150 words)","Only 2 defined applicability criteria (model type and specific generator part number)","Single compliance requirement with clear deadline","No cross-references to other legislation or complex conditional logic","Straightforward technical background with single causal chain (faulty part → false warning → unnecessary emergency procedure → safety risk)","Binary applicability test (either your helicopter matches the description or it doesn't)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of certain **Hiller UH-12D and UH-12E helicopters** (those fitted with a Soloy Turbine Conversion) to replace the **rotor tachometer generator** — a device that measures and reports how fast the helicopter's rotor blades are spinning.\n\n**Who it affects:**\n- Owners and operators of Hiller UH-12D and UH-12E helicopters with Soloy Turbine Conversions\n- Specifically those using **22A580 tachometer generators** in the rotor position\n\n**Why it matters:**\nThe old generators were failing and triggering **false low rotor speed warnings**. This was causing pilots to unnecessarily execute emergency procedures — including dropping external loads and performing full autorotation (a type of emergency landing where the engine is disengaged). These false alarms created real danger. The new generator type should fail less often, making flights safer and reducing unnecessary emergency manoeuvres.\n\n**When it had to be done:**\nWithin **200 hours of flight time** after 31 May 1979.\n\n**Key documents referenced:**\n- Soloy Conversions Service Bulletin 03-560\n- FAA Airworthiness Directive 79-03-07 (the US equivalent safety order)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-hiller-12-26-rotor-tachometer-generator-replacement","history":"/api/acts/ad-hiller-12-26-rotor-tachometer-generator-replacement/history","analysis":"/api/acts/ad-hiller-12-26-rotor-tachometer-generator-replacement/analysis","conflicts":"/api/acts/ad-hiller-12-26-rotor-tachometer-generator-replacement/conflicts","importantCases":"/api/acts/ad-hiller-12-26-rotor-tachometer-generator-replacement/important-cases","documents":"/api/acts/ad-hiller-12-26-rotor-tachometer-generator-replacement/documents"}}