{"id":"F2007L04510","name":"AD/BELL 412/44 Amdt 2 - Tail Rotor Blade Fwd Tip Weight Retention Block and Aft Tip Closure","slug":"ad-bell-412-44-amdt-2-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":70961,"registerId":"commonwealth-F2007L04510-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 412/44 Amdt 2 | Tail Rotor Blade Fwd Tip WeightRetention Block and Aft Tip Closure | 13/2007 |\n| --------------------- | ------------------------------------------------------------------ | ------- |\n\n| Applicability: | Model 412, 412CF, and 412EP helicopters with a tail rotor blade part number212-010-750-009 through -129, all serial numbers, except serial numbers with a prefix of “A” or “AFS” and the number 11926, 13351, 13367, 13393, 13400, 13402, 13515, 13540, 13568, 13595 through 13602, 13619, and subsequent assigned numbers, installed. |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. Inspect the tail rotor blade forward tip weight retention block and aft tip closure for adhesive bond voids. Remove any tail rotor blade with a void in excess of that allowed by the Component Repair and Overhaul Manual limitations.2. Inspect the forward tip weight retention block attachment countersink screws in four locations to determine if the head of each countersink screw is flush with the surface of the abrasion strip. The locations of these four screws are depicted on Figure 1 of Bell Helicopter Textron Inc. Alert Service Bulletin (ASB)412-00-106 Revision D or 412CF-00-13 Revision D, or later FAA approved revisions, as applicable. If any of these screws are set below the surface of the abrasion strip or are covered with filler material, install shear pins in accordance with the Accomplishment Instructions, Part A, Shear Pin Installation paragraphs, of ASB 412-00-106 Revision D or 412CF-00-13 Revision D, or later FAA approved revisions, as applicable.3. Install the aft tip closure rivets, re-identify the modified blade by adding an “FM”, and dynamically balance the tail rotor hub assembly in accordance with the Accomplishment Instructions, Part B, Aft Tip Closure Rivet Installation paragraphs, of ASB 412-00-106 Revision D or 412CF-00-13 Revision D, or later FAA approved revisions, as applicable.Note: FAA AD 2007-22-02 Amdt 39-15238 refers. |\n| Compliance: | Within 100 hours time in service after 20 December 2007, unless already accomplished. |\n| | This Amendment becomes effective on 20 December 2007. |\n\n| Background: | The FAA received reports 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.Amendment 1 included the Agusta Model AB412 helicopter in applicability, and update Applicability and Requirement information to the latest manufacturer’s documentation.Amendment 2 is issued in response to a new FAA AD, which expands the applicability to include other part and serial-numbered blades. Additionally, the AD clarifies the requirement to re-identify the modified blade by adding “FM” after the part number, and requires dynamically balancing the tail rotor. The previously included requirements for Agusta Model AB412 helicopters have been relocated to a new Bell 412 Series Helicopter AD in Issue 13/2007. |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n\n![](image.001.png) \nDavid Villiers \nDelegate of the Civil Aviation Safety Authority\n\n7 November 2007","sortOrder":0},{"sectionNumber":"AD/BELL 412/44 Amdt 2","sectionType":"part","heading":"AD/BELL 412/44 Amdt 2","content":"## AD/BELL 412/44 Amdt 2","sortOrder":1},{"sectionNumber":"Tail Rotor Blade Fwd Tip WeightRetention","sectionType":"part","heading":"Tail Rotor Blade Fwd Tip WeightRetention Block and Aft Tip Closure","content":"## Tail Rotor Blade Fwd Tip Weight \nRetention Block and Aft Tip Closure","sortOrder":2},{"sectionNumber":"13/2007","sectionType":"part","heading":"13/2007","content":"## 13/2007","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"Amendment 2 expands the AD’s applicability to include additional blade part and serial numbers, clarifies the requirement to re‑identify modified blades by adding “FM”, and adds a mandatory dynamic balancing step. It also relocates previously included Agusta AB412 requirements to a separate Bell 412 Series AD (Background)."},"complexity_factors":["Detailed applicability with part-number range and multiple serial-number exclusions increases identification and record-checking burden (Applicability).","Multiple technical inspection standards referenced (adhesive bond void tolerances governed by the Component Repair and Overhaul Manual) require specialist maintenance judgement (Requirement 1).","Mandated hardware work (shear-pin installation, aft‑closure rivets) must follow specific service bulletin procedures, raising procedural and tooling demands (Requirement 2–3 and ASB references).","Cross-references to external documents and approvals: Bell ASBs (412-00-106 or 412CF-00-13, Revision D or later) and FAA AD 2007-22-02 create dependency on later approved revisions and bilateral regulatory materials (Requirement notes).","Administrative steps: re-identification by adding “FM” and mandatory dynamic balancing add record‑keeping and test requirements beyond simple inspections (Requirement 3).","Short compliance window (within 100 flight hours from the effective date) concentrates scheduling and operational burden for operators (Compliance).","Background history (reported failures; relocation of Agusta requirements) shows the instrument’s scope has been modified over prior amendments, necessitating attention to versioning and applicability (Background)."],"plain_english_summary":"Requires inspection and corrective work on forward tip weight‑retention blocks and aft tip closures of specified Bell 412 tail rotor blades, and, where needed, removal, shear‑pin installation, aft‑closure rivets, re‑identification (add “FM”) and dynamic balancing. \n\nAffects operators and maintenance organisations of Bell 412/412CF/412EP helicopters with the listed blade part/serial numbers; compliance must occur within 100 flight hours of 20 December 2007 to address reported occurrences of missing parts that could lead to blade loss."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"This Amendment 2 has expanded beyond the original AD's scope. The Background section explicitly states that Amendment 2 'expands the applicability to include other part and serial-numbered blades' compared to the original AD and Amendment 1. Additionally, Amendment 2 adds new requirements (dynamic balancing and the 'FM' re-identification marking) that were not in previous versions. The Agusta Model AB412 coverage from Amendment 1 has been removed from this AD and relocated to a separate Bell 412 Series Helicopter AD, indicating the legislation has been unbundled and redistributed rather than simply growing monolithically."},"complexity_factors":["Extensive serial number exclusions requiring careful cross-referencing (14 specific serial numbers plus ranges and prefixes)","Multiple manufacturer document references (Bell Alert Service Bulletins 412-00-106 Rev D and 412CF-00-13 Rev D) that must be consulted for full compliance instructions","Three distinct technical requirements with different compliance actions (inspection/removal, shear pin installation, rivet installation with re-identification and balancing)","Conditional logic in Requirement 2 (if-then structure based on screw depth/filler presence)","Amendment history creates layered applicability (Amendment 2 expands scope from previous versions and relocates Agusta AB412 requirements to a separate AD)","Cross-reference to FAA AD 2007-22-02 for additional context"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspections and corrective work on certain Bell 412, 412CF and 412EP tail rotor blades after reports of missing tip-weight retention blocks and aft tip closures that could lead to loss of a tail rotor blade and loss of control. \n\nAffected operators must inspect and repair tip bonds and fastenings, install required hardware and markings, and dynamically balance the tail rotor within 100 flight hours of 20 Dec 2007. Compliance is mandatory to mitigate a crash risk."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-412-44-amdt-2-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure","history":"/api/acts/ad-bell-412-44-amdt-2-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure/history","analysis":"/api/acts/ad-bell-412-44-amdt-2-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure/analysis","conflicts":"/api/acts/ad-bell-412-44-amdt-2-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure/conflicts","importantCases":"/api/acts/ad-bell-412-44-amdt-2-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure/important-cases","documents":"/api/acts/ad-bell-412-44-amdt-2-tail-rotor-blade-fwd-tip-weight-retention-block-and-aft-tip-closure/documents"}}