{"id":"F2007L04509","name":"AD/BELL 412/53 - Tail Rotor Blade Fwd Tip Weight Retention Block and Aft Tip Closure - 2","slug":"ad-bell-412-53-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure-2","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":70959,"registerId":"commonwealth-F2007L04509-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Bell Helicopter Textron 412 Series Helic","sectionType":"division","heading":"Bell Helicopter Textron 412 Series Helicopters","content":"### Bell Helicopter Textron 412 Series Helicopters\n\n| AD/BELL 412/53 | Tail Rotor Blade Fwd Tip Weight Retention Block and Aft Tip Closure - 2 | 13/2007 |\n| -------------- | ----------------------------------------------------------------------- | ------- |\n\n| Applicability: | Agusta Model AB412 helicopters, equipped with tail rotor blades part number212-010-750-009, -011, -105, -107, and -113.                                                                                                                                                                                                                                                     |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with Agusta Technical Bulletin 412-88 Revision B, or later ENAC approved revision.Note: ENAC AD 2005-139 refers.                                                                                                                                                                                                                                       |\n| Compliance:    | Within 100 flight hours after 20 December 2007, unless already accomplished in accordance with AD/BELL 412/44 Amdt 1.                                                                                                                                                                                                                                                       |\n|                | This Airworthiness Directive becomes effective on 20 December 2007.                                                                                                                                                                                                                                                                                                         |\n| Background:    | Reports were received of five occurrences of missing tail rotor blade forward tip weight retention blocks or aft tip closures that resulted in minor to substantial damage. Such damage could result in loss of a tail rotor blade, and subsequent loss of control of the helicopter.The requirements of this Directive were previously contained in AD/BELL 412/44 Amdt 1. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n7 November 2007","sortOrder":0},{"sectionNumber":"AD/BELL 412/53","sectionType":"part","heading":"AD/BELL 412/53","content":"## AD/BELL 412/53","sortOrder":1},{"sectionNumber":"Tail Rotor Blade Fwd Tip Weight Retentio","sectionType":"part","heading":"Tail Rotor Blade Fwd Tip Weight Retention Block and Aft Tip Closure - 2","content":"## Tail Rotor Blade Fwd Tip Weight Retention Block and Aft Tip Closure - 2","sortOrder":2},{"sectionNumber":"13/2007","sectionType":"part","heading":"13/2007","content":"## 13/2007","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 is a standard, narrow airworthiness directive targeting a specific mechanical defect in specific helicopter models. The scope remains tightly focused on the tail rotor blade tip components as originally intended. The reference to a prior directive (AD/BELL 412/44 Amdt 1) indicates this is a replacement or amendment consolidating previous requirements, not an expansion of scope."},"complexity_factors":["Very short document (approximately 200 words of substantive content)","Only 5 defined part numbers in applicability section","Single compliance pathway (reference to external technical bulletin)","Simple temporal trigger (100 flight hours after effective date)","No nested exceptions or conditional logic — only one exemption (prior compliance under AD/BELL 412/44 Amdt 1)","No internal cross-references to other legislation sections"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of Agusta Model AB412 helicopters fitted with tail-rotor blade P/Ns 212-010-750-009, -011, -105, -107, or -113 to inspect and repair the forward tip weight retention block and aft tip closure per Agusta Technical Bulletin 412‑88 Revision B (or later). Action must be done within 100 flight hours after 20 Dec 2007. It’s mandatory because separated tail-rotor components have been reported and could cause loss of control."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The AD restates requirements previously contained in AD/BELL 412/44 Amdt 1 and applies to the same subset of Agusta AB412 helicopters with the listed tail‑rotor blade part numbers. It preserves the previous corrective‑action requirement but specifies compliance via Agusta Technical Bulletin 412‑88 Revision B (or later ENAC‑approved revision) with the 100‑flight‑hour compliance window."},"complexity_factors":["Narrow, equipment‑specific applicability (Agusta AB412 with listed tail‑rotor blade part numbers) — operators must check fleet fitment.","Mandates compliance by reference to an external technical document (Agusta Technical Bulletin 412‑88 Rev B) or a later ENAC‑approved revision, requiring operators to obtain and follow that document.","Cross‑reference to prior AD (AD/BELL 412/44 Amdt 1) and ENAC AD 2005‑139 increases regulatory provenance and record‑keeping complexity.","Short compliance window (100 flight hours from effective date) requires operational scheduling and tracking.","Safety‑critical fault with potential severe consequences — maintenance must be performed correctly, raising implementation and quality‑control requirements.","Directive does not reproduce technical procedures; compliance depends on the TB’s details and ENAC approvals, creating dependency on external regulatory/technical decisions."],"plain_english_summary":"This Airworthiness Directive requires operators of Agusta AB412 helicopters fitted with specific Bell tail‑rotor blade part numbers to carry out the corrective actions set out in Agusta Technical Bulletin 412‑88 Revision B (or a later ENAC‑approved revision). The work must be done within 100 flight hours after 20 December 2007 (unless already done under the earlier AD). The measure addresses missing forward tip weight retention blocks and aft tip closures that have caused damage and could lead to loss of a tail‑rotor blade."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-412-53-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure-2","history":"/api/acts/ad-bell-412-53-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure-2/history","analysis":"/api/acts/ad-bell-412-53-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure-2/analysis","conflicts":"/api/acts/ad-bell-412-53-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure-2/conflicts","importantCases":"/api/acts/ad-bell-412-53-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure-2/important-cases","documents":"/api/acts/ad-bell-412-53-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure-2/documents"}}