{"id":"F2009L00459","name":"AD/JBK 117/31 - Tail Rotor Balance Weights","slug":"ad-jbk-117-31-tail-rotor-balance-weights","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":76994,"registerId":"commonwealth-F2009L00459-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Kawasaki BK 117 Series Helicopters","sectionType":"division","heading":"Kawasaki BK 117 Series Helicopters","content":"### Kawasaki BK 117 Series Helicopters\n\n| AD/JBK 117/31 | Tail Rotor Balance Weights | 3/2009 |\n| ------------- | -------------------------- | ------ |\n\n| Applicability: | All Model BK117 Series helicopters.                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Inspect the tail rotor balance weights and control levers in accordance with the instructions of Kawasaki Service Bulletin (SB) No. KSB-117-297 original issue, or later JCAB approved revision.If, during any inspection required by this Directive, damage is detected which exceeds the acceptable limits specified in SB No. KSB-117-297 original issue, or later JCAB approved revision, before further flight, replace the affected components with serviceable parts.Note: JCAB AD TCD-7416-2009 refers. |\n| Compliance:    | Within 2 months or 100 flight hours after 12 March 2009, whichever occurs first; and thereafter at intervals not to exceed 660 flight hours or 30 months, whichever occurs first.                                                                                                                                                                                                                                                                                                                               |\n|                | This Airworthiness Directive becomes effective on 12 March 2009.                                                                                                                                                                                                                                                                                                                                                                                                                                                |\n| Background:    | During a periodic inspection, corrosion was detected on the tail rotor balance weights in the area of the thread. At advanced stage, this corrosion could possibly destroy the threads. Unless prevented, undetected corrosion on the tail rotor balance weights in the area of the attachment threads could lead to failure of the threads, possible separation of tail rotor parts, and subsequent severe tail rotor vibration.                                                                               |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n22 January 2009","sortOrder":0},{"sectionNumber":"AD/JBK 117/31","sectionType":"part","heading":"AD/JBK 117/31","content":"## AD/JBK 117/31","sortOrder":1},{"sectionNumber":"Tail Rotor Balance Weights","sectionType":"part","heading":"Tail Rotor Balance Weights","content":"## Tail Rotor Balance Weights","sortOrder":2},{"sectionNumber":"3/2009","sectionType":"part","heading":"3/2009","content":"## 3/2009","sortOrder":3}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, targeted airworthiness directive addressing a specific safety defect in a specific helicopter model. The scope remains precisely limited to tail rotor balance weight corrosion inspection and replacement, consistent with the original safety purpose."},"complexity_factors":["Single, specific mechanical component addressed (tail rotor balance weights)","Only one primary compliance pathway with clear time/flight hour triggers","Minimal defined terms (only standard aviation acronyms like JCAB, SB, AD)","No nested exceptions or conditional logic — straightforward 'inspect and replace if damaged' requirement","Short document (approximately 200 words of substantive content)","Single cross-reference to Japanese aviation authority document (JCAB AD TCD-7416-2009)"],"plain_english_summary":"This AD requires operators and maintainers of Kawasaki BK 117 helicopters in Australia to inspect tail-rotor balance weights and control levers for corrosion (initially within 2 months or 100 flight hours after 12 Mar 2009, then every 660 flight hours or 30 months). Any corroded parts must be replaced before further flight. It addresses corrosion that can destroy threads, cause part separation, and lead to severe tail-rotor vibration and potential loss of control."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD's scope is limited to tail-rotor balance weights and control levers on all Kawasaki BK117 helicopters and requires inspections and replacement per the referenced service bulletin. The Directive matches the safety issue described (corrosion of attachment threads) and does not broaden coverage to other components or aircraft types."},"complexity_factors":["Single, well-defined technical action: inspect tail rotor balance weights and control levers per Kawasaki SB KSB-117-297","Clear pass/fail rule: replace components exceeding damage limits specified in the SB","Specified compliance timing: initial deadline (2 months or 100 flight hours after 12 March 2009) and recurring intervals (660 flight hours or 30 months)","Applicability limited to all BK117 series reduces cross-model complexity","Reliance on a manufacturer SB or later JCAB‑approved revision creates dependency on external document revisions","Operational burdens: scheduling inspections, possible aircraft downtime, parts sourcing and replacement costs for operators"],"plain_english_summary":"This Airworthiness Directive requires operators of all Kawasaki BK117 helicopters to inspect tail-rotor balance weights and control levers following Kawasaki Service Bulletin KSB-117-297 (or a later JCAB‑approved revision) and to replace any parts that exceed the bulletin’s damage limits. It sets initial and recurring compliance deadlines for those inspections.\n\nAircraft operators must arrange and pay for the inspections and any replacement parts, and CASA enforces the Directive. The measure targets thread corrosion that could cause tail-rotor part separation and severe vibration."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jbk-117-31-tail-rotor-balance-weights","history":"/api/acts/ad-jbk-117-31-tail-rotor-balance-weights/history","analysis":"/api/acts/ad-jbk-117-31-tail-rotor-balance-weights/analysis","conflicts":"/api/acts/ad-jbk-117-31-tail-rotor-balance-weights/conflicts","importantCases":"/api/acts/ad-jbk-117-31-tail-rotor-balance-weights/important-cases","documents":"/api/acts/ad-jbk-117-31-tail-rotor-balance-weights/documents"}}