{"id":"F2006B10263","name":"AD/GBK 117/4 - Landing Gear Electrical Bonding","slug":"ad-gbk-117-4-landing-gear-electrical-bonding","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55938,"registerId":"commonwealth-F2006B10263-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/GBK 117/4 - Landing Gear Electrical Bonding","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)  Eurocopter BK 117 Series Helicopters\n\n \n\nAD/GBK 117/4 Landing Gear Electrical Bonding 12/91\n\nApplicability: All MBB-BK 117 aircraft serial No 7001 through 7261 inclusive. Requirement:  Action in accordance with MBB Alert SB 117 -90-104.\n\nCompliance: Within 50 hours time in service after 12 December 1991.\n\n \n\nBackground: The existing bonding of the landing gear to the helicopter has been determined by the manufacturer to be inadequate to ensure satisfactory elimination of electrostatic charges.\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\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific technical defect in a specific aircraft model. It has not expanded beyond its original purpose of mandating a landing gear electrical bonding fix."},"complexity_factors":["Extremely short document — only 8 substantive lines","Single, unambiguous requirement referencing an external technical standard","No defined terms section, no conditional logic, no exceptions","Clear applicability criteria (specific serial number range)","Simple compliance deadline (50 hours time in service after fixed date)"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of certain **MBB-BK 117 helicopters** (serial numbers 7001 through 7261) to fix an electrical safety problem with the landing gear.\n\n**The problem:**\nThe landing gear isn't properly \"bonded\" (electrically connected) to the rest of the helicopter. This means **static electricity can build up** and won't safely discharge, creating a fire or explosion risk — especially during refuelling or in flight.\n\n**What must be done:**\nFollow the manufacturer's emergency service bulletin (MBB Alert SB 117-90-104) to improve the electrical bonding. This must be completed **within 50 flight hours** after 12 December 1991.\n\n**Who it affects:**\nAnyone operating these specific BK 117 helicopters in Australia — typically emergency services, police, or charter operators.\n\n**Why it matters:**\nElectrostatic discharge can ignite fuel vapours. This directive prevents potential catastrophic fires by ensuring static electricity safely dissipates through the aircraft's structure rather than sparking."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The text sets a single, specific scope: it applies to all MBB-BK 117 aircraft serial numbers 7001–7261 and requires action according to MBB Alert SB 117-90-104 within 50 hours TIS. Nothing in the instrument indicates a change from that stated scope or a widening/narrowing of applicability; the AD implements the manufacturer’s determination about inadequate bonding (Applicability; Requirement; Compliance; Background)."},"complexity_factors":["Narrow and explicit applicability limited to serial numbers 7001–7261 (Applicability).","Mandate delegates technical detail to an external document: MBB Alert SB 117-90-104 (Requirement).","Short, fixed compliance window (50 hours time in service after 12 December 1991) creates operational scheduling pressure (Compliance).","Technical work concerns electrical bonding — requires qualified maintenance but the AD does not specify qualifications or parts (Requirement; Background).","Instrument is procedurally simple but operationally dependent on the content of the referenced service bulletin (Requirement)."],"plain_english_summary":"This Airworthiness Directive requires operators of Eurocopter MBB‑BK 117 helicopters serial numbers 7001–7261 to modify or check landing‑gear electrical bonding per MBB Alert SB 117‑90‑104. It makes the manufacturer’s fix mandatory within 50 hours’ time‑in‑service after 12 December 1991 to address inadequate elimination of electrostatic charges. Operators/owners must carry out and fund the work."},"summary":{"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"The directive applies exclusively to MBB-BK 117 aircraft with serial numbers 7001 through 7261 and no changes to the scope are indicated."},"complexity_factors":["aircraft serial numbers","service bulletin compliance"],"plain_english_summary":"This is a narrow airworthiness directive issued by the Civil Aviation Safety Authority. It applies to Eurocopter BK 117 series helicopters and is titled AD/GBK 117/4 Landing Gear Electrical Bonding. The directive covers all MBB-BK 117 aircraft with serial numbers 7001 through 7261 inclusive. It requires operators to perform work in line with MBB Alert Service Bulletin 117-90-104. Compliance must occur within 50 hours time in service after 12 December 1991. The background indicates that the existing landing gear bonding was inadequate to ensure satisfactory elimination of electrostatic charges. This is relevant to owners, operators and maintenance providers of these specific helicopters. Visitors searching for BK 117 safety information will find this applicable only to the listed serial numbers. The practical point is that the electrical bonding improvement is mandatory for airworthiness. The action should have been completed by early 1992 at the latest. If you have an aircraft in this serial range, review its maintenance records to confirm the bonding meets the service bulletin standard. This ensures the helicopter can safely dissipate static electricity and avoids any regulatory issues during inspections or operations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-gbk-117-4-landing-gear-electrical-bonding","history":"/api/acts/ad-gbk-117-4-landing-gear-electrical-bonding/history","analysis":"/api/acts/ad-gbk-117-4-landing-gear-electrical-bonding/analysis","conflicts":"/api/acts/ad-gbk-117-4-landing-gear-electrical-bonding/conflicts","importantCases":"/api/acts/ad-gbk-117-4-landing-gear-electrical-bonding/important-cases","documents":"/api/acts/ad-gbk-117-4-landing-gear-electrical-bonding/documents"}}