{"id":"F2006B10357","name":"AD/HILLER 12/3 - Tail Rotor Blade Assembly - Provision of Vent Hole","slug":"ad-hiller-12-3-tail-rotor-blade-assembly-provision-of-vent-hole","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115969,"registerId":"commonwealth-F2006B10357-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HILLER 12/3 - Tail Rotor Blade Assembly - Provision of Vent Hole","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 12/3 Tail Rotor Blade Assembly - Provision\n\nof Vent Hole Applicability: All models UH-12A, UH-12B and UH-12C. Document:               Hiller SIL No. 133.\n\nCompliance: Before 15 February 1961.\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\n2/61\n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2167},"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"This is the original issuance of the directive, maintaining a narrow technical scope focused solely on the physical modification (vent hole provision) of tail rotor blade assemblies for the specified Hiller models. There is no evidence of scope creep into broader operational or airworthiness areas."},"complexity_factors":["Single, unambiguous compliance action with no sub-steps or alternatives","Narrow applicability limited to three specifically named aircraft models","No defined terms, interpretation sections, or cross-references to other legislation","Absolute compliance deadline with no extensions or conditional exceptions"],"plain_english_summary":"Owners and operators of Hiller UH-12A, UH-12B and UH-12C helicopters must modify the tail rotor blade assembly by adding a vent hole per the manufacturer’s Service Information Letter No. 133. This mandatory airworthiness directive prevents trapped moisture, internal corrosion and blade imbalance that could cause catastrophic tail rotor failure; the required compliance date was 15 February 1961."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hiller-12-3-tail-rotor-blade-assembly-provision-of-vent-hole","history":"/api/acts/ad-hiller-12-3-tail-rotor-blade-assembly-provision-of-vent-hole/history","analysis":"/api/acts/ad-hiller-12-3-tail-rotor-blade-assembly-provision-of-vent-hole/analysis","conflicts":"/api/acts/ad-hiller-12-3-tail-rotor-blade-assembly-provision-of-vent-hole/conflicts","importantCases":"/api/acts/ad-hiller-12-3-tail-rotor-blade-assembly-provision-of-vent-hole/important-cases","documents":"/api/acts/ad-hiller-12-3-tail-rotor-blade-assembly-provision-of-vent-hole/documents"}}