{"id":"F2006B10348","name":"AD/HILLER 12/19 - Main Rotor Blades - Inspection","slug":"ad-hiller-12-19-main-rotor-blades-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56115,"registerId":"commonwealth-F2006B10348-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HILLER 12/19 - Main Rotor Blades - 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 12/19 Main Rotor Blades - Inspection 11/71\n\nApplicability: All models.\n\n \n\nRequirement: 1. Carry out a visual inspection for cracks in the main rotor blades P/No. 53100.\n\n \n\nNote: This inspection may be performed and certified by the pilot.\n\n \n\n2. Inspect blades P/N 53100 for cracks using an approved dye penetrant method.\n\n \n\nNote: Any blades found defective shall be removed from service before further flight.\n\n \n\nCompliance: For Para. 1 - Before further flight.\n\n \n\nFor Para. 2 - Within 10 hours’ time in service after 16 Nov. 1971.\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's stated applicability and requirements are internally consistent. It applies to all Hiller UH-12 models but limits the action to blades with part number 53100 (Applicability; Requirement 1–2). The text does not indicate any expansion or narrowing of scope beyond those statements, so there is no evidence in the document itself that the scope was changed from its stated purpose."},"complexity_factors":["Narrow scope limited to Hiller UH-12 series and a single blade part number (P/No. 53100). (Applicability; Requirement 1–2)","Two-step inspection regime: immediate pilot-certifiable visual check and a separate approved dye-penetrant inspection. (Requirement 1; Requirement 2; Note to Para. 1)","Clear, short compliance deadlines: before further flight for the visual check; within 10 hours’ TIS after 16 Nov 1971 for dye-penetrant. (Compliance)","Requirement for an “approved” dye-penetrant method introduces some procedural complexity because the directive does not specify who approves methods or who must perform the inspection. (Requirement 2)","Operational implications for pilots (may certify visual inspection) and operators (cost and logistics for dye-penetrant inspection/replacement) are present but not elaborated in the text. (Note to Para. 1; Note after Requirement 2)"],"plain_english_summary":"This directive requires operators of Hiller UH‑12 helicopters fitted with main rotor blades P/N 53100 to carry out an immediate visual crack inspection before further flight (the pilot may perform and sign off) and a dye‑penetrant inspection within 10 hours TIS after 16 Nov 1971. Any defective blade must be removed. It shifts short‑term compliance to flight crews and creates a scheduled maintenance obligation and associated costs for owners/operators."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-purpose safety directive focused specifically on Hiller UH-12 main rotor blade inspections. It has not expanded beyond its original intent — it addresses exactly the safety issue it was designed for (blade cracking) with no additional provisions or creeping scope."},"complexity_factors":["Very short document (under 200 words)","Only 2 substantive requirements with clear compliance deadlines","Single defined term (P/No. 53100 - part number)","No cross-references to other legislation or regulations","Simple conditional logic: 'if defective, remove from service'","Straightforward applicability (all models of one aircraft series)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\nThis directive orders owners and operators of **Hiller UH-12 series helicopters** to inspect the main rotor blades (specifically part number 53100) for cracks.\n\n**Who it affects:**\nAnyone who owns, operates, or maintains a Hiller UH-12 helicopter — a vintage helicopter model originally designed in the 1940s-50s.\n\n**What must be done:**\n- **Immediately:** A visual check for cracks in the rotor blades. This can be done by the pilot themselves.\n- **Within 10 flight hours after 16 November 1971:** A more thorough inspection using dye penetrant testing (a special chemical method that makes tiny cracks visible). This requires proper equipment and certification.\n\n**Why it matters:**\nCracks in main rotor blades can cause catastrophic failure in flight. This AD was issued to prevent accidents by catching blade fatigue before it becomes dangerous. The \"11/71\" in the title indicates this dates from November 1971, making it a historical directive for a classic aircraft type still flying in Australia.\n\n**Key point:** If blades are found cracked, they must be removed from service immediately — no exceptions."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hiller-12-19-main-rotor-blades-inspection","history":"/api/acts/ad-hiller-12-19-main-rotor-blades-inspection/history","analysis":"/api/acts/ad-hiller-12-19-main-rotor-blades-inspection/analysis","conflicts":"/api/acts/ad-hiller-12-19-main-rotor-blades-inspection/conflicts","importantCases":"/api/acts/ad-hiller-12-19-main-rotor-blades-inspection/important-cases","documents":"/api/acts/ad-hiller-12-19-main-rotor-blades-inspection/documents"}}