{"id":"F2006B10266","name":"AD/GBK 117/9 - Rotor Mast Assembly","slug":"ad-gbk-117-9-rotor-mast-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55945,"registerId":"commonwealth-F2006B10266-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/GBK 117/9 - Rotor Mast Assembly","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)  \nEurocopter BK 117 Series Helicopters\n\nAD/GBK 117/9 Rotor Mast Assembly 12/97\n\nApplicability: All MBB BK 117 helicopters fitted with either main rotor mast assembly P/N 4639205016 or 4639205011.\n\nRequirement: Inspect the main rotor mast assembly flange for cracking in accordance with Eurocopter Alert Service Bulletin MBB-BK-117-10-114 dated August 27, 1997.\n\nNote: LBA AD 97-276 refers.\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\nThis airworthiness directive becomes effective on 6 November 1997.\n\nBackground: The manufacturer has advised that cracking has been found in the flange area of a main rotor mast assembly.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1678},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is the original issuance of Airworthiness Directive AD/GBK 117/9. The scope remains tightly focused on the specific rotor mast assemblies identified in the original safety concern, with no expansion beyond the original intent to address cracking in the flange area of these specific parts."},"complexity_factors":["Extremely limited scope (only 2 specific part numbers: 4639205016 and 4639205011)","Single technical requirement (visual inspection for cracking only)","Simple recurring interval (every 100 hours time in service)","No defined terms or interpretation sections","Relies on single external technical reference (Eurocopter Alert Service Bulletin) for procedural details"],"plain_english_summary":"**What this is:** A mandatory safety inspection order for helicopter operators.\n\n**Who it affects:** Anyone operating an MBB BK 117 helicopter fitted with specific main rotor mast assemblies (part numbers 4639205016 or 4639205011).\n\n**What you must do:** Inspect the main rotor mast flange (the connecting surface) for cracks. You must follow the procedures in Eurocopter Alert Service Bulletin MBB-BK-117-10-114 dated 27 August 1997.\n\n**When:**\n- First inspection: Before flying the helicopter again after 6 November 1997\n- Repeat inspections: Every 100 hours of flight time (\"time in service\")\n\n**Why this matters:** The manufacturer discovered cracking in the rotor mast flange area. This is a critical safety issue because the rotor mast holds the main rotor blades; failure could cause catastrophic loss of the aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-gbk-117-9-rotor-mast-assembly","history":"/api/acts/ad-gbk-117-9-rotor-mast-assembly/history","analysis":"/api/acts/ad-gbk-117-9-rotor-mast-assembly/analysis","conflicts":"/api/acts/ad-gbk-117-9-rotor-mast-assembly/conflicts","importantCases":"/api/acts/ad-gbk-117-9-rotor-mast-assembly/important-cases","documents":"/api/acts/ad-gbk-117-9-rotor-mast-assembly/documents"}}