{"id":"F2006L00401","name":"AD/GBK 117/8 Amdt 3 - Tail Boom Vertical Fin Spar","slug":"ad-gbk-117-8-amdt-3-tail-boom-vertical-fin-spar","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":117049,"registerId":"commonwealth-F2006L00401-current","compilationNumber":null,"startDate":"2026-04-03","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 117/8 Amdt 3 | Tail Boom Vertical Fin Spar | 3/2006 |\n| ------------------- | --------------------------- | ------ |\n\n| Applicability: | Models BK117A-1, A-3, A-4, B-1, B-2, and C-1 helicopters, all serial numbers.                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Incorporate Revision No. 35 (for MBB-BK117A-1 through B-2), and Revision No. 18 (for MBB-BK117C-1), into the MBB-BK117 Maintenance Manual.2. Inspect the vertical fin of the tail boom in accordance with the MBB-BK117 Maintenance Manual.3. If the inspection results are outside the allowable limits specified in the MBB-BK117 Maintenance Manual, ECD Customer Service must be consulted for advice on serviceability.Note: LBA AD D-1997-144R4 and Eurocopter Deutschland Alert Service Bulletin ASB-MBB-BK117-30-106 Revision 5 refer. |\n| Compliance:    | 1. Before 31 March 2006, unless already accomplished.2. As specified in the applicable MBB-BK117 Maintenance Manual.3. Before further flight.                                                                                                                                                                                                                                                                                                                                                                                                     |\n|                | This Amendment becomes effective on 16 March 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |\n| Background:    | This Directive was issued following a fatal accident overseas where the investigation revealed that the tail boom vertical fin had failed as a result of a fatigue crack that initiated on the left side of the vertical fin spar cap, and propagating across the cap and the web.Amendment 1 provided relief with a repair/modification scheme, and an extended inspection period post repair/modification.Amendment 2 introduced the latest revision of the Requirement document, which revised modification procedures.                        |\n\n|     | Amendment 3 is issued in response to a revision of the related LBA AD, which now requires that all necessary inspection tasks be accomplished in accordance with the applicable MBB-BK117 Maintenance Manual.The original issue of this Airworthiness Directive became effective on 9 May 1997. |\n| --- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n3 February 2006","sortOrder":0},{"sectionNumber":"AD/GBK 117/8 Amdt 3","sectionType":"part","heading":"AD/GBK 117/8 Amdt 3","content":"## AD/GBK 117/8 Amdt 3","sortOrder":1},{"sectionNumber":"Tail Boom Vertical Fin Spar","sectionType":"part","heading":"Tail Boom Vertical Fin Spar","content":"## Tail Boom Vertical Fin Spar","sortOrder":2},{"sectionNumber":"3/2006","sectionType":"part","heading":"3/2006","content":"## 3/2006","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"},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"Amendment 3 alters scope by aligning the AD with a revised LBA AD: inspection tasks must now be accomplished in accordance with the applicable MBB‑BK117 Maintenance Manual rather than by AD-prescribed steps. Earlier amendments provided a repair/modification relief scheme and revised modification procedures; Amendment 3 shifts the compliance mechanism toward the Maintenance Manual as the controlling document (Background / Requirement)."},"complexity_factors":["Applicability across six BK117 model variants and all serial numbers (Applicability)","Mandatory incorporation of specific Maintenance Manual revisions (Requirement: incorporate Revision No. 35 / No. 18)","Reliance on the MBB‑BK117 Maintenance Manual for inspection procedures and allowable limits rather than prescribing tasks in the AD text (Requirement / Amendment 3)","Mandatory consultation with ECD Customer Service if inspection findings exceed allowable limits, creating a decision-point with manufacturer discretion (Requirement)","Deadlines with both calendar and flight-continuation timing (Compliance: before 31 March 2006; before further flight)","Interplay with foreign and manufacturer documents: references to LBA AD D-1997-144R4 and Eurocopter ASB-MBB-BK117-30-106 Revision 5 (Requirement / Background)","History of prior amendments changing repair/modification relief and procedures, requiring operators to track amendment history (Background)"],"plain_english_summary":"Requires operators of all BK117 A-1, A-3, A-4, B-1, B-2 and C-1 helicopters to update their maintenance manuals to the specified revisions and to perform inspections of the tail‑boom vertical‑fin spar per those manual procedures; any findings outside allowable limits must be referred to ECD Customer Service. It follows a fatal overseas accident attributed to fatigue cracking and aligns Australian requirements with a revised German (LBA) AD. Operators and maintenance providers bear inspection and repair costs; the regulator sets fixed compliance deadlines."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This Amendment 3 remains tightly focused on its original purpose: preventing tail boom vertical fin failures due to fatigue cracking. While it updates the specific maintenance manual revisions required and responds to a German regulatory change (LBA AD revision), it does not expand beyond the original safety scope established in 1997. The amendments have refined procedures (adding repair schemes, extending inspection periods post-modification, updating document revisions) but have not broadened the directive to cover unrelated systems or aircraft components."},"complexity_factors":["Short, single-purpose directive with only 3 numbered requirements","Minimal defined terms (relies on external maintenance manual references rather than inline definitions)","Simple conditional logic: 'If inspection results are outside limits → consult manufacturer → no flight until resolved'","Cross-references to external documents (LBA AD D-1997-144R4, Eurocopter Alert Service Bulletin) but these are informational rather than operational dependencies","Clear compliance dates without nested exceptions or alternative compliance paths","Background provides clear safety rationale without adding procedural complexity"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of Eurocopter BK117A-1, A-3, A-4, B-1, B-2 and C-1 helicopters to inspect the tail boom’s vertical fin for fatigue cracking and update maintenance manuals.  \n\nPrompted by a fatal overseas crash, it mandates urgent inspections and grounds any helicopter with cracks beyond safe limits until Airbus (Eurocopter Deutschland) issues approved repair instructions — an immediate safety action with a March 2006 compliance deadline."}},"importantCases":[],"_links":{"self":"/api/acts/ad-gbk-117-8-amdt-3-tail-boom-vertical-fin-spar","history":"/api/acts/ad-gbk-117-8-amdt-3-tail-boom-vertical-fin-spar/history","analysis":"/api/acts/ad-gbk-117-8-amdt-3-tail-boom-vertical-fin-spar/analysis","conflicts":"/api/acts/ad-gbk-117-8-amdt-3-tail-boom-vertical-fin-spar/conflicts","importantCases":"/api/acts/ad-gbk-117-8-amdt-3-tail-boom-vertical-fin-spar/important-cases","documents":"/api/acts/ad-gbk-117-8-amdt-3-tail-boom-vertical-fin-spar/documents"}}