{"id":"F2006B10256","name":"AD/GBK 117/1 Amdt 1 - Tail Rotor Blade Bonding","slug":"ad-gbk-117-1-amdt-1-tail-rotor-blade-bonding","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55927,"registerId":"commonwealth-F2006B10256-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/GBK 117/1 Amdt 1 - Tail Rotor Blade Bonding","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 117/1\n\nAmdt 1\n\n  \nTail Rotor Blade Bonding 2/94\n\nApplicability: All models fitted with tail rotor blades P/n 117-31742 serial numbers 63 to 82\\. Requirement: Action in accordance with Japan Civil Aviation Bureau AD TCD 2589-2-90. Compliance: For Tail Rotor Blades with:\n\n    less than five hours time in service prior to 23 July 1990, replace prior to further flight, and\n\n    2. more than five hours time in service prior to 23 July 1990, inspect prior to each flight in accordance with the Requirement Document.\n\n    3. this amendment is effective 3 February 1994.\n\nNote: The previous effective date of this Directive was 24 August 1987.\n\nBackground: Some blades may have had inadequate bonding. Amendment 1 is to reflect the latest issue of the requirement document.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose: addressing bonding defects in specific tail rotor blades. Amendment 1 simply updates the reference to the latest Japanese requirement document without expanding the scope to other components or helicopter models."},"complexity_factors":["Very short document (under 200 words)","Only 3 defined applicability criteria (part number, serial number range, model series)","Simple binary compliance structure (replace vs inspect based on flight hours threshold)","Single cross-reference to external document (Japan Civil Aviation Bureau AD TCD 2589-2-90)","No nested exceptions or conditional logic beyond the flight hours test","Clear effective date with straightforward background explanation"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority for **Eurocopter BK 117 helicopters**.\n\n**What it does:**\n- Requires specific safety actions on certain tail rotor blades (part numbers 117-31742, serial numbers 63-82)\n- These blades may have **inadequate bonding** (a manufacturing defect where components aren't properly glued/attached together)\n\n**Who must act:**\n- Owners and operators of BK 117 helicopters with the affected tail rotor blades\n\n**What must be done:**\n- **New blades** (less than 5 flight hours before 23 July 1990): **Replace immediately** before flying again\n- **Used blades** (more than 5 flight hours before that date): **Inspect before every single flight** following the Japanese aviation authority's procedures\n\n**Why it matters:**\nTail rotor blade failure can cause catastrophic loss of control. This directive prevents crashes by ensuring defective blades are either replaced or constantly monitored. The amendment updates the rules to match the latest Japanese safety standards (since these helicopters were originally certified there)."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The amendment updates the directive to reflect the latest issue of the referenced Requirement Document (Background) but does not change the listed applicability (same part number and serial-number range) or the core compliance prescriptions (replace if <5 hours TIS before 23 July 1990; inspect before every flight if >5 hours TIS prior to that date) as set out in this AD (Applicability; Compliance). Therefore the operational scope and required actions remain the same; the change is documentary (updated reference) rather than a substantive expansion or narrowing of covered helicopters or mandated actions."},"complexity_factors":["Narrow applicability tied to a specific part number and limited serial-number range (Applicability).","Two-tier compliance rule keyed to an aircraft's time-in-service before a historical cutoff date (Compliance items 1–2).","Reference to an external Requirement Document (Japan Civil Aviation Bureau AD TCD 2589-2-90) for inspection procedures, requiring operators to consult another authority (Requirement).","High-frequency operational requirement for some blades (pre-flight inspection before every flight) increasing ongoing procedural burden (Compliance, item 2).","Amendment history and effective-date changes require operators to track which version of the Requirement Document applies (Compliance item 3; Note; Background)."],"plain_english_summary":"This AD requires operators of Eurocopter BK 117s fitted with tail rotor blades P/N 117-31742, S/N 63–82, to follow the Japan CAA inspection/replacement instructions: blades with <5 hours TIS before 23 July 1990 must be replaced before next flight; blades with >5 hours TIS must receive the prescribed pre‑flight inspection. Operators bear the costs. The measure targets a risk of inadequate blade bonding."}},"importantCases":[],"_links":{"self":"/api/acts/ad-gbk-117-1-amdt-1-tail-rotor-blade-bonding","history":"/api/acts/ad-gbk-117-1-amdt-1-tail-rotor-blade-bonding/history","analysis":"/api/acts/ad-gbk-117-1-amdt-1-tail-rotor-blade-bonding/analysis","conflicts":"/api/acts/ad-gbk-117-1-amdt-1-tail-rotor-blade-bonding/conflicts","importantCases":"/api/acts/ad-gbk-117-1-amdt-1-tail-rotor-blade-bonding/important-cases","documents":"/api/acts/ad-gbk-117-1-amdt-1-tail-rotor-blade-bonding/documents"}}