{"id":"F2006B10346","name":"AD/HILLER 12/17 Amdt 4 - Control Rotor Blade Assemblies","slug":"ad-hiller-12-17-amdt-4-control-rotor-blade-assemblies","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56110,"registerId":"commonwealth-F2006B10346-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HILLER 12/17 Amdt 4 - Control Rotor Blade Assemblies","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\n# AD/HILLER 12/17\n\nAmdt 4\n\nApplicability: All models.\n\n# Control Rotor Blade Assemblies 3/87\n\n \n\nRequirement: Action in accordance with Fairchild Hiller SB No 36-1 Rev 3. Compliance:  At each scheduled inspection for Maintenance Release issue.\n\nBackground:  Amendment 4 to this Directive aligns the repetitive inspections with that for issue of Maintenance Release.\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\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive remains tightly focused on its original purpose: ensuring safety inspections of control rotor blade assemblies on Hiller UH-12 helicopters. Amendment 4 makes only a procedural timing adjustment (aligning inspections with Maintenance Release issuance) without expanding the scope to additional aircraft systems, models, or operational contexts."},"complexity_factors":["Extremely short document — approximately 150 words of substantive content","Only one operational requirement (follow the manufacturer's service bulletin)","Single defined term implicitly understood (Maintenance Release)","No nested exceptions, conditional logic, or cross-references to other legislation","Straightforward amendment history (Amendment 4) with clear purpose statement","Single applicability clause covering all models"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) for Hiller UH-12 series helicopters.\n\n**What it does:** It requires owners and operators of these helicopters to inspect their **control rotor blade assemblies** (the parts that help steer and stabilise the helicopter) following a specific manufacturer's service bulletin (Fairchild Hiller SB No 36-1 Rev 3).\n\n**Who it affects:** Anyone who owns, operates, or maintains any model of Hiller UH-12 helicopter in Australia.\n\n**When you must comply:** At every scheduled inspection when applying for or renewing a **Maintenance Release** (the official document that says an aircraft is safe to fly — similar to a roadworthy certificate for a car).\n\n**Why it matters:** This amendment (Amendment 4) simply updates *when* these safety inspections must happen — aligning them with Maintenance Release inspections rather than some other schedule. This makes compliance simpler and ensures critical rotor components are checked regularly before the helicopter is cleared to fly."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 4 modifies the timing regime: it aligns the Directive’s repetitive inspections with inspections carried out for issue of a Maintenance Release. The change therefore alters when inspections must be performed (now at each scheduled Maintenance Release inspection) while keeping the technical standard specified by Fairchild Hiller SB No 36-1 Rev 3. (Background / Compliance / Requirement)"},"complexity_factors":["Reference to an external technical document (Fairchild Hiller SB No 36-1 Rev 3) — the AD delegates substantive inspection detail to the Service Bulletin, requiring users to obtain and interpret that SB.","Change in inspection timing: Amendment 4 aligns repetitive inspections with Maintenance Release inspections, which requires maintenance-planning adjustments.","Broad applicability (all UH-12 models) — simple breadth but no model-specific distinctions in the AD text.","Concise Directive text with limited procedural detail — lowers statutory complexity but increases operational reliance on the Service Bulletin.","No explicit alternative compliance or exemption language in the Directive text — leaves implementation questions (e.g. approved alternatives) to the regulator’s processes or to the SB."],"plain_english_summary":"What this instrument does, mechanically\n\n- It requires all Hiller UH-12 series helicopters to have their control rotor blade assemblies inspected and any prescribed actions carried out in accordance with Fairchild Hiller Service Bulletin No 36-1 Rev 3. (Requirement)\n- The inspection/action must be done at each scheduled inspection that is carried out for the purpose of issuing a Maintenance Release. (Compliance)\n- Amendment 4 changes the timing regime by aligning the repetitive inspections required by the Directive with the inspections that occur when a Maintenance Release is issued. (Background)\n\nWho it affects and who decides\n\n- Affected: owners and operators of Hiller UH-12 series helicopters (Applicability). They are the parties who must ensure the inspections and any required work are carried out. (Requirement / Compliance)\n- Decider/regulator: the Civil Aviation Safety Authority implements this as an airworthiness directive under the Commonwealth regulatory framework (header: Civil Aviation Regulations 1998, Part 39 — Schedule of Airworthiness Directives).\n\nHow it works in practice\n\n- The Directive does not set the detailed inspection steps itself; it directs operators to follow the technical content of Fairchild Hiller SB No 36-1 Rev 3. Operators must consult that Service Bulletin to know the exact inspection tasks and corrective actions. (Requirement)\n- The timing for repeating those inspections is tied to the operator’s scheduled inspections for issuing a Maintenance Release — that is the required compliance point. (Compliance / Background)\n\nCosts, incentives, trade-offs and implementation notes (source-grounded)\n\n- Who pays: the operator/owner bears the direct cost of performing the inspections and taking any corrective action called for by the Service Bulletin, because the Directive makes those inspections mandatory at each scheduled Maintenance Release inspection. (Requirement / Compliance)\n- Incentives: because the Directive mandates compliance with a specific Service Bulletin, operators are incentivised to follow that SB’s procedures rather than a different unapproved process. (Requirement)\n- Compliance burden: operators must incorporate the SB’s inspection/action requirements into each scheduled Maintenance Release inspection cycle, which alters routine maintenance planning. The Directive itself prescribes timing (Maintenance Release inspections) but not the detailed tasks — those are in the SB. (Compliance / Requirement)\n- Bureaucratic discretion and implementation risk: the Directive fixes the technical standard by reference to a particular Service Bulletin (SB No 36-1 Rev 3). That central reference transfers the substantive inspection specifications from the Directive text to the SB; practical compliance therefore depends on access to and application of the SB’s content. The Directive does not set out exceptions or alternative compliance pathways in its text. (Requirement)\n- Effects on private maintenance providers and market choices: by making a named Service Bulletin the required standard, the Directive channels work to providers who can and will carry out inspections to that standard. Operators who previously used other inspection practices must adopt the SB or obtain an approved alternative. The Directive applies to all UH-12 models, so it creates a uniform technical requirement across that fleet. (Requirement / Applicability)\n\nNet mechanical effect\n\n- Mechanically, Amendment 4 changes when the repetitive inspections occur by aligning them with Maintenance Release inspections and mandates following Fairchild Hiller SB No 36-1 Rev 3 for the inspection and any remedial work. (Compliance / Requirement / Background)\n\nSource citations: statements above are taken from the Directive text: Applicability (\"All models\"), Requirement (\"Action in accordance with Fairchild Hiller SB No 36-1 Rev 3\"), Compliance (\"At each scheduled inspection for Maintenance Release issue\"), and Background (\"Amendment 4 ... aligns the repetitive inspections with that for issue of Maintenance Release\")."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hiller-12-17-amdt-4-control-rotor-blade-assemblies","history":"/api/acts/ad-hiller-12-17-amdt-4-control-rotor-blade-assemblies/history","analysis":"/api/acts/ad-hiller-12-17-amdt-4-control-rotor-blade-assemblies/analysis","conflicts":"/api/acts/ad-hiller-12-17-amdt-4-control-rotor-blade-assemblies/conflicts","importantCases":"/api/acts/ad-hiller-12-17-amdt-4-control-rotor-blade-assemblies/important-cases","documents":"/api/acts/ad-hiller-12-17-amdt-4-control-rotor-blade-assemblies/documents"}}