{"id":"F2006B01803","name":"AD/A109/19 Amdt 2 - Tail Rotor Hub","slug":"ad-a109-19-amdt-2-tail-rotor-hub","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41001,"registerId":"commonwealth-F2006B01803-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/A109/19 Amdt 2 - Tail Rotor Hub","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)  \nAgusta A109 Series Helicopters\n\nAD/A109/19\n\nAmdt 2\n\n  \nTail Rotor Hub 9/95\n\nApplicability: All A109C helicopters equipped with Fork Assy P/N 109-8131-05-109 and \\-113 installed on Tail rotor Assy P/N 1009-8131-02-115.\n\nRequirement: 1. Inspect in accordance with Bollettino Technico Telegrafico No. 109-8 Rev. A, and\n\n2. Modify in accordance with Bollettino Technico No. 109-100.\n\nNote: RAI AD 95-101 refers.\n\nCompliance: 1. In accordance with the Requirement Document until modified, and\n\n2. Prior to 31 March 1997.\n\nFor Requirement 1 the effective date was 25 January 1992\\. This amendment is effective 17 August 1995.\n\nBackground: The initial issue of this Directive was to address cracking of the flange of the tail rotor grip. Amendment 1 extended the inspection to the -113 part number grip.\n\nAmendment 2 provides terminating action through modification.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The legislation maintains its original narrow scope — addressing a specific mechanical defect in specific Agusta A109C helicopter tail rotor components. While Amendment 1 expanded applicability to include an additional part number (-113), and Amendment 2 added a terminating modification, these are natural evolutions within the original safety purpose. The directive has not grown beyond addressing tail rotor hub cracking in the specified aircraft."},"complexity_factors":["Very short document (under 300 words)","Only 4 defined part numbers in the applicability section","Simple two-step requirement structure (inspect, then modify)","Single cross-reference to a related airworthiness directive (RAI AD 95-101)","Clear compliance deadline (hard date of 31 March 1997)","No nested exceptions or conditional logic — requirements apply uniformly to all affected aircraft","References to external technical documents rather than reproducing technical specifications inline"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific maintenance actions on certain helicopters.\n\n**What it does:**\n- **Targets:** Agusta A109C helicopters with specific tail rotor hub part numbers (Fork Assy P/N 109-8131-05-109 and -113, installed on Tail Rotor Assy P/N 1009-8131-02-115).\n- **Requires two actions:**\n  1. **Inspection:** Check the tail rotor hub for cracks following a specific technical bulletin (Bollettino Technico Telegrafico No. 109-8 Rev. A).\n  2. **Modification:** Permanently fix the issue by modifying the part according to another technical bulletin (Bollettino Technico No. 109-100).\n\n**Why it matters:** The tail rotor keeps a helicopter stable and prevents it from spinning. Cracking in the tail rotor grip flange (the part that holds the rotor blade) could cause catastrophic failure, loss of control, and crash. This AD prevents accidents by catching cracks early and ultimately requiring a permanent fix.\n\n**Deadlines:**\n- Inspections must continue until the modification is done.\n- The modification must be completed before 31 March 1997.\n\n**History:** Originally issued in 1992 to address cracking issues, expanded in a previous amendment to cover more part numbers, and this version (Amendment 2) provides the final solution — a mandatory modification that \"terminates\" (ends) the need for ongoing inspections."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The directive’s scope, compared with the original issue, was expanded and then adjusted. The initial AD targeted cracking of the tail rotor grip flange (Background). Amendment 1 extended the inspection requirement to include the -113 part-number grip (Background). Amendment 2 introduced a required modification that is described as a terminating action for the ongoing inspection requirement, thereby changing the ongoing compliance regime from indefinite inspections to a one-time modification plus no further inspections once modified (Background; Amendment 1; Amendment 2; Compliance)."},"complexity_factors":["Narrow applicability limited to A109C helicopters fitted with specific part numbers (Applicability)","Two-step requirement structure: mandatory inspection (per a technical telegram) until the modification is done, plus a mandated modification (Requirement)","Compliance timeline with a hard deadline for modification (prior to 31 March 1997) and an earlier effective date for inspections (25 January 1992) (Compliance)","Reliance on external technical documents (Bollettino Technico Telegrafico No. 109-8 Rev. A and Bollettino Technico No. 109-100) that contain the operational details but are not reproduced in the AD (Requirement)","Amendment history that changed the instrument’s reach (Amendment 1 extended inspection to -113 grip; Amendment 2 added terminating modification) (Background; Amendment 2)"],"plain_english_summary":"This AD requires affected Agusta A109C helicopters fitted with tail rotor fork assemblies P/N 109-8131-05-109 or -113 (on Tail rotor Assy P/N 1009-8131-02-115) to undergo inspections per Bollettino Technico Telegrafico No. 109-8 Rev. A until they are modified per Bollettino Technico No. 109-100.  \n\nThe rule, issued by CASA to address flange cracking, makes the modification a terminating action and sets a completion deadline (31 March 1997), placing compliance costs and scheduling on owners/operators."}},"importantCases":[],"_links":{"self":"/api/acts/ad-a109-19-amdt-2-tail-rotor-hub","history":"/api/acts/ad-a109-19-amdt-2-tail-rotor-hub/history","analysis":"/api/acts/ad-a109-19-amdt-2-tail-rotor-hub/analysis","conflicts":"/api/acts/ad-a109-19-amdt-2-tail-rotor-hub/conflicts","importantCases":"/api/acts/ad-a109-19-amdt-2-tail-rotor-hub/important-cases","documents":"/api/acts/ad-a109-19-amdt-2-tail-rotor-hub/documents"}}