{"id":"F2006B09585","name":"AD/ENST 28/29 - Rotor Head Hub","slug":"ad-enst-28-29-rotor-head-hub","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54290,"registerId":"commonwealth-F2006B09585-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ENST 28/29 - Rotor Head 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)  \nEnstrom F-28 Series Helicopters\n\nAD/ENST 28/29 Rotor Head Hub 12/86 TX\n\nApplicability: All models.\n\nRequirement: 1. Inspect the upper and lower rotor head hub plates in accordance with Enstrom Service Directive Bulletin No. 0072 Paragraph A.\n\n2. Inspect the upper and lower hub plates and other hub components in accordance with Enstrom Service Directive Bulletin No. 0072 Paragraph C.\n\nCompliance: For Para 1: Within 25 hours time in service after 31 October 1986 and thereafter at intervals not exceeding 50 hours time in service.\n\nFor Para 2: Within 25 hours time in service after 31 October 1986 for helicopters known to have experienced blade strikes, sudden stoppages or heavy landings.\n\nBackground: The manufacturer has received three reports of cracking in the upper and lower hub plates.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2140},"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This airworthiness directive maintains its original narrow scope: mandating safety inspections for a specific helicopter component following reported defects. No legislative scope creep detected."},"complexity_factors":["References external technical bulletin (Enstrom Service Directive No. 0072) without reproducing the inspection procedures in the text","Time-based compliance calculations requiring tracking of 'hours time in service'","Conditional requirements triggered by operational history (blade strikes, sudden stoppages, heavy landings)","Technical aviation terminology requiring specialized engineering knowledge to interpret"],"plain_english_summary":"Operators of Enstrom F-28 helicopters must inspect the upper and lower rotor head hub plates for cracking per the manufacturer’s service directive. An initial check is required soon after the compliance date, with recurring inspections at regular flight-hour intervals and additional checks after blade strikes, hard landings, or sudden engine stoppures.\n\nThis responds to reported hub-plate cracks that, if undetected, could lead to rotor failure and catastrophic accidents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-enst-28-29-rotor-head-hub","history":"/api/acts/ad-enst-28-29-rotor-head-hub/history","analysis":"/api/acts/ad-enst-28-29-rotor-head-hub/analysis","conflicts":"/api/acts/ad-enst-28-29-rotor-head-hub/conflicts","importantCases":"/api/acts/ad-enst-28-29-rotor-head-hub/important-cases","documents":"/api/acts/ad-enst-28-29-rotor-head-hub/documents"}}