{"id":"F2006B10861","name":"AD/JBK 117/11 - Rotor Mast Assembly","slug":"ad-jbk-117-11-rotor-mast-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56357,"registerId":"commonwealth-F2006B10861-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JBK 117/11 - Rotor Mast Assembly","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)  Kawasaki BK 117 Series Helicopters\n\n \n\nAD/JBK 117/11 Rotor Mast Assembly 12/97\n\nApplicability: All Kawasaki BK 117 helicopters fitted with either main rotor mast P/N 4639 205 016 or 4639 205 011.\n\n \n\nRequirement: Inspect the main rotor mast assembly flange for cracking in accordance with Kawasaki Service Bulletin KSB-117-134 dated 4 September 1997.\n\n \n\nNote: LBA AD 97-276 refers.\n\n \n\nCompliance: Unless previously carried out, prior to further flight after the effective date inspect the main rotor mast flange for cracking. Thereafter, re inspect at intervals not exceeding 100 hours time in service.\n\n \n\nThis airworthiness directive becomes effective on 6 November 1997.\n\n \n\nBackground: The manufacturer has advised that cracking has been found in the flange area of a main rotor mast.\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\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1269},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This directive maintains a narrow, targeted scope focused solely on the identified safety defect in specific rotor mast assemblies. It does not expand beyond the original safety purpose of preventing catastrophic failure due to flange cracking."},"complexity_factors":["Single, unambiguous safety requirement with no conditional exceptions","Minimal cross-referencing (only one service bulletin and one foreign AD citation)","Short document length with plain language instructions","Clear applicability limited to two specific part numbers on one aircraft series"],"plain_english_summary":"**What this is:** A mandatory safety order (called an Airworthiness Directive) requiring helicopter operators to inspect a critical part—the main rotor mast—for dangerous cracks.\n\n**Who it affects:** Anyone operating a **Kawasaki BK 117 helicopter** that has a main rotor mast with part number 4639 205 016 or 4639 205 011.\n\n**What you must do:**\n- **Immediately inspect** the rotor mast flange (the connecting surface) for cracks before flying again, following the exact procedure in Kawasaki Service Bulletin KSB-117-134.\n- **Repeat the inspection** every 100 hours of flight time thereafter.\n\n**Why it matters:** The manufacturer discovered cracks in the rotor mast flange—a failure here could cause the main rotor to detach in flight, leading to catastrophic accident. This rule ensures the defect is caught before it causes an accident.\n\n**Key dates:** The directive took effect on **6 November 1997**, and compliance was required immediately for affected aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jbk-117-11-rotor-mast-assembly","history":"/api/acts/ad-jbk-117-11-rotor-mast-assembly/history","analysis":"/api/acts/ad-jbk-117-11-rotor-mast-assembly/analysis","conflicts":"/api/acts/ad-jbk-117-11-rotor-mast-assembly/conflicts","importantCases":"/api/acts/ad-jbk-117-11-rotor-mast-assembly/important-cases","documents":"/api/acts/ad-jbk-117-11-rotor-mast-assembly/documents"}}