{"id":"F2006B10350","name":"AD/HILLER 12/22 Amdt 3 - Main Rotor Hub","slug":"ad-hiller-12-22-amdt-3-main-rotor-hub","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56119,"registerId":"commonwealth-F2006B10350-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HILLER 12/22 Amdt 3 - Main Rotor Hub","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nHiller UH-12 Series Helicopters\n\nAD/HILLER 12/22\n\nAmdt 3\n\n  \nMain Rotor Hub 7/97\n\nApplicability: All models Hiller UH-12 series helicopters with main rotor hubs Part Number 51437, 51437-6, 51437-7, 51437-8, 51437-9, 51437-11, 51437-901 and 51437-11-911 fitted.\n\nNote: Part number 51437-11-911 had been incorrectly listed as 51437-11-011 in the previous amendment.\n\nRequirement: Inspect the inside of the main rotor hub in the area opposite the control rotor trunnion attachments for cracks, using a dye penetrant technique.\n\nNote: FAA AD 73-20-03 refers.\n\nCompliance: Inspect before 50 hours’ time in service since last inspected in accordance with a previous amendment of this directive or before 5 hours’ time in service after 19 June 1997, whichever occurs later. Thereafter, inspect at intervals not exceeding 50 hours’ time in service.\n\nThis amendment becomes effective on 19 June 1997.\n\nBackground: This amendment removes the need for fluorescent dye penetrant inspection which was introduced by the previous amendment. Further information supplied to the authority has indicated that colour contrast dye penetrant will continue to provide adequate detection of cracks in the main rotor hub.\n\nAmendment ‘A’ added additional part number hubs to the initial issue of this directive. The description of the required inspection was simplified and a note referring to the FAA AD 73-20-03 was added.\n\nAmendment 2 of this airworthiness directive became effective on 24 April 1997. Apart from requiring use of fluorescent penetrant inspection a part number error in the applicability was corrected.\n\nAmendment A of this airworthiness directive became effective on 30 September 1980.\n\nThe original issue of this airworthiness directive became effective on 29 August 1975.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The amendment adjusts scope and implementation mechanics: it adds and corrects applicable part numbers (Applicability), removes the requirement for fluorescent dye penetrant and permits colour‑contrast dye penetrant (Background), and simplifies the inspection description (Background). The underlying safety target (detect cracking in the main rotor hub) remains the same, but the set of affected hub part numbers and the required inspection technique were altered."},"complexity_factors":["Narrow, specific applicability limited to listed main rotor hub part numbers (Applicability).","Technical inspection requirement (dye penetrant inspection of hub interior opposite control rotor trunnion attachments) requiring specialised technique and access (Requirement).","Timing rule with conditional deadline: inspect before 50 hours since last inspection or within 5 hours after 19 June 1997, whichever is later, then every 50 hours (Compliance) — creates a short initial compliance window for some operators.","Change in accepted inspection materials: removal of mandatory fluorescent penetrant in favour of colour‑contrast dye penetrant (Background) — affects maintenance suppliers and choices.","Cross‑reference to FAA AD 73‑20‑03 (Requirement/Background) creates reliance on external standard for context.","Amendment history and corrected part‑number entries increase record/identification burden on operators and maintainers (Background/Applicability)."],"plain_english_summary":"This airworthiness directive requires owners/operators of Hiller UH‑12 helicopters fitted with certain main rotor hub part numbers to inspect inside the main rotor hub opposite the control rotor trunnion attachments for cracks using a dye‑penetrant method. Inspections must be done before 50 hours' time in service since the last inspection (or within 5 hours after 19 June 1997, whichever is later) and then every 50 hours; the amendment allows colour‑contrast dye penetrant instead of fluorescent and cites FAA AD 73‑20‑03."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose: ensuring crack detection in Hiller UH-12 main rotor hubs. While it has been amended three times since 1975, these changes have been technical corrections (part number fixes) and method refinements (reverting to colour contrast dye). The scope has not expanded beyond this specific safety-critical helicopter component."},"complexity_factors":["Single, specific technical requirement (dye penetrant inspection)","Limited applicability (one helicopter series, specific part numbers)","Simple compliance timeline (50-hour intervals with initial deadline)","Minimal cross-referencing (one reference to FAA AD 73-20-03)","No nested conditions or exceptions","Short document (approximately 250 words)","Only 8 specific part numbers listed"],"plain_english_summary":"This safety rule requires owners/operators and maintenance engineers of Hiller UH-12 helicopters with specified 51437-series main rotor hubs to inspect the hub for cracks using dye-penetrant methods, with initial and recurring checks around a 50‑flight‑hour interval. It corrects a previous part-number error and restores use of colour‑contrast (non‑fluorescent) dye. The measure targets early detection of hub cracks to prevent catastrophic in‑flight failure."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-hiller-12-22-amdt-3-main-rotor-hub","history":"/api/acts/ad-hiller-12-22-amdt-3-main-rotor-hub/history","analysis":"/api/acts/ad-hiller-12-22-amdt-3-main-rotor-hub/analysis","conflicts":"/api/acts/ad-hiller-12-22-amdt-3-main-rotor-hub/conflicts","importantCases":"/api/acts/ad-hiller-12-22-amdt-3-main-rotor-hub/important-cases","documents":"/api/acts/ad-hiller-12-22-amdt-3-main-rotor-hub/documents"}}