{"id":"F2006B10371","name":"AD/HILLER 12/9 Amdt 1 - Horizontal Stabiliser Spar - Inspection","slug":"ad-hiller-12-9-amdt-1-horizontal-stabiliser-spar-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116004,"registerId":"commonwealth-F2006B10371-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HILLER 12/9 Amdt 1 - Horizontal Stabiliser Spar - Inspection","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 12/9\n\nAmdt 1\n\n\nHorizontal Stabiliser Spar - Inspection 3/78\n\n \n\nApplicability: All models UH-12, UH-12A, UH-12B and UH-12C.\n\n \n\nRequirement: Remove the horizontal stabiliser, and with the aid of a lens of not less than 8X power, inspect the spar tube for cracking in the vicinity of the stabiliser attachment bolt holes.\n\n \n\nCompliance: At intervals not exceeding 300 hours’ time in service.\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":true,"description":"The document is titled as Amendment 1 to AD/HILLER 12/9, indicating it amends a prior directive. The provided text shows the current applicability, the inspection requirement (including the 8X magnification) and the 300-hour compliance interval, but the original AD text is not included here, so specific differences between the original and this amendment cannot be identified from the supplied material."},"complexity_factors":["Clear, narrow applicability limited to UH-12, UH-12A, UH-12B and UH-12C (Applicability).","A single, concrete action required: remove the horizontal stabiliser and inspect the spar tube for cracking (Requirement).","A specific technical minimum is given (lens of not less than 8X) but the AD does not prescribe inspection technique, inspector qualifications, or sign-off authority—this increases implementation choices for operators (Requirement; absence of procedural detail).","A single, recurring compliance interval is set at 300 hours TIS, which is simple to track but creates recurring maintenance scheduling (Compliance).","Removal and reinstallation of the stabiliser is required, creating explicit labour and downtime costs inherent in compliance (Requirement)."],"plain_english_summary":"This AD mandates removal and inspection of the horizontal stabiliser on Hiller UH‑12/A/B/C helicopters to check the stabiliser spar tube around attachment bolt holes for cracking, using a lens of at least 8× magnification, and repeating the inspection every 300 hours TIS. Owners/operators must carry out and fund the work; the AD sets the inspection requirement and interval but leaves inspection technique, who performs/signs off, corrective actions, and recordkeeping to operator procedures."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive maintaining its original purpose: mandating recurring safety inspections for a specific aircraft component. Amendment 1 suggests a revision to the original AD/HILLER 12/9, but the scope remains tightly focused on the horizontal stabiliser spar inspection requirement."},"complexity_factors":["Extremely short document (approximately 150 words)","Only 4 defined applicability criteria (specific helicopter models)","Single, straightforward mechanical requirement with no conditional logic","No cross-references to other legislation or regulations","Simple compliance metric (300 hours time in service)","No exceptions, exemptions, or nested provisions","Technical but not legally complex — describes a physical inspection procedure rather than legal obligations"],"plain_english_summary":"This is an **Airworthiness Directive** — 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 **Hiller UH-12 series helicopters** (models UH-12, UH-12A, UH-12B, and UH-12C) to inspect a critical part called the **horizontal stabiliser spar** — the structural tube that helps keep the helicopter stable in flight.\n\n**The specific task:**\n- Remove the horizontal stabiliser from the aircraft\n- Using a magnifying lens of at least **8 times magnification** (8X), carefully examine the spar tube for cracks around the bolt holes where the stabiliser attaches\n\n**How often:**\nThis inspection must be done **every 300 hours of flight time** (\"time in service\").\n\n**Why it matters:**\nCracks in the stabiliser spar could lead to structural failure, potentially causing loss of control of the helicopter. This directive ensures a recurring safety check to catch problems before they become catastrophic. Ignoring this directive is illegal — aircraft cannot fly legally without complying."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hiller-12-9-amdt-1-horizontal-stabiliser-spar-inspection","history":"/api/acts/ad-hiller-12-9-amdt-1-horizontal-stabiliser-spar-inspection/history","analysis":"/api/acts/ad-hiller-12-9-amdt-1-horizontal-stabiliser-spar-inspection/analysis","conflicts":"/api/acts/ad-hiller-12-9-amdt-1-horizontal-stabiliser-spar-inspection/conflicts","importantCases":"/api/acts/ad-hiller-12-9-amdt-1-horizontal-stabiliser-spar-inspection/important-cases","documents":"/api/acts/ad-hiller-12-9-amdt-1-horizontal-stabiliser-spar-inspection/documents"}}