{"id":"F2009L00181","name":"AD/GBK 117/22 - Tail Rotor - Balance Weights","slug":"ad-gbk-117-22-tail-rotor-balance-weights","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":76622,"registerId":"commonwealth-F2009L00181-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Eurocopter BK 117 Series Helicopters","sectionType":"division","heading":"Eurocopter BK 117 Series Helicopters","content":"### Eurocopter BK 117 Series Helicopters\n\n| AD/GBK 117/22 | Tail Rotor - Balance Weights | 2/2009 |\n| ------------- | ---------------------------- | ------ |\n\n| Applicability: | Eurocopter Deutschland (ECD) GmbH Models MBB-BK 117 A-1,MBB-BK 117 A-3, MBB-BK 117 A-4, MBB-BK 117 B-1, MBB-BK 117 B-2 and MBB-BK 117 C-1 helicopters, all serial numbers.                                                                                                                                                                                                                                                                                                                                                        |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Inspect the tail rotor balance weights and control levers in accordance with ECD BK117 Alert Service Bulletin (ASB) No. MBB-BK117-30-113.2. If, during any inspection as detailed in Requirement 1 of this AD, damage is detected which exceeds the acceptable limits as specified in the ASB, replace the affected components with serviceable parts.Replacement of parts does not constitute terminating action for the repetitive inspection requirements of this AD.Note: EASA AD 2008-0206 dated 25 November 2008 refers. |\n| Compliance:    | For Requirement 1 - Within the next 2 months or 100 flight hours (FH), whichever occurs first after the effective date of this AD, and thereafter at intervals not to exceed 600 FH (+ 60 FH) or 48 months (+ 6 months), whichever occurs first.For Requirement 2 - Before further flight.                                                                                                                                                                                                                                        |\n|                | This Airworthiness Directive becomes effective on 12 February 2009.                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n| Background:    | During a periodical inspection, corrosion was detected on the tail rotor balance weights in the area of the attachment thread. This condition, if not detected and corrected, could lead to failure of the threads, possibly resulting in separation of tail rotor parts, subsequent severe tail rotor vibration and consequent loss of control of the helicopter.                                                                                                                                                                |\n\n|     | For the reasons described above, this AD requires repetitive visual inspections of the tail rotor balance weights and control levers to identify any damage and the replacement of damaged components. |\n| --- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n22 December 2008","sortOrder":0},{"sectionNumber":"AD/GBK 117/22","sectionType":"part","heading":"AD/GBK 117/22","content":"## AD/GBK 117/22","sortOrder":1},{"sectionNumber":"Tail Rotor - Balance Weights","sectionType":"part","heading":"Tail Rotor - Balance Weights","content":"## Tail Rotor - Balance Weights","sortOrder":2},{"sectionNumber":"2/2009","sectionType":"part","heading":"2/2009","content":"## 2/2009","sortOrder":3}],"analysis":{"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"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope: addressing a specific corrosion issue in tail rotor balance weights on specific BK 117 helicopter models. There is no evidence of scope creep or expansion beyond the original safety purpose."},"complexity_factors":["Single, clearly defined applicability (6 specific helicopter models)","Two straightforward requirements: inspect, and replace if necessary","Simple compliance timeline: initial inspection within 2 months/100 flight hours, then repetitive intervals","Only one external reference (EASA AD 2008-0206) noted for context","No nested definitions, cross-references to other legislation, or conditional exceptions","Total length is approximately 300 words"],"plain_english_summary":"This AD requires operators and maintainers of Eurocopter BK 117 A‑1/A‑3/A‑4/B‑1/B‑2/C‑1 helicopters to inspect tail rotor balance weights and control levers for corrosion or damage, and replace any parts that exceed limits. Inspections must be repeated every 600 flight hours or 48 months.\n\nIt responds to corrosion found in balance weight attachment threads that could lead to thread failure, tail‑rotor separation, severe vibration and potential loss of control."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive addresses corrosion found on tail-rotor balance weights for the listed BK117 models by mandating inspections and replacements per the ECD ASB and setting recurring intervals. The scope aligns with that corrective intent as described in the instrument; there is no indication in the text that the applicability or substantive requirements were broadened or narrowed beyond addressing the identified corrosion risk."},"complexity_factors":["Multiple BK117 model variants listed and applicability to all serial numbers increases the pool of affected operators.","Inspections must follow an external manufacturer Alert Service Bulletin (ASB) for acceptable damage limits, requiring cross-referencing and access to that document.","Repetitive inspection regime uses dual triggers (flight hours or calendar months) with explicit tolerance windows (+60 FH / +6 months) complicating scheduling and tracking.","Replacement of damaged parts is mandatory and replacements do not terminate the recurring inspection requirement, creating ongoing operational and recordkeeping burden.","Immediate grounding requirement for damaged components ('before further flight') imposes urgent compliance and potential operational disruption.","Safety-critical nature of tail-rotor components raises low tolerance for inspection error and may require conservative maintenance actions and parts availability planning.","Directive issued by a CASA delegate establishes regulator-enforced compliance, with administrative discretion over enforcement and timelines."],"plain_english_summary":"Requires operators of specified Eurocopter BK 117 models to inspect tail-rotor balance weights and control levers per the manufacturer’s Alert Service Bulletin and to replace any parts that exceed the ASB’s damage limits. The Civil Aviation Safety Authority issued the directive; operators bear the cost and scheduling burden (initial check within 2 months or 100 flight‑hours, then recurrent checks at set flight‑hour or calendar intervals). The stated purpose is to prevent thread failure, part separation, severe vibration and potential loss of control."}},"importantCases":[],"_links":{"self":"/api/acts/ad-gbk-117-22-tail-rotor-balance-weights","history":"/api/acts/ad-gbk-117-22-tail-rotor-balance-weights/history","analysis":"/api/acts/ad-gbk-117-22-tail-rotor-balance-weights/analysis","conflicts":"/api/acts/ad-gbk-117-22-tail-rotor-balance-weights/conflicts","importantCases":"/api/acts/ad-gbk-117-22-tail-rotor-balance-weights/important-cases","documents":"/api/acts/ad-gbk-117-22-tail-rotor-balance-weights/documents"}}