{"id":"F2006L01544","name":"AD/A109/53 - Tail Rotor - Flange Assembly","slug":"ad-a109-53-tail-rotor-flange-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":59233,"registerId":"commonwealth-F2006L01544-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Agusta A109 Series Helicopters","sectionType":"division","heading":"Agusta A109 Series Helicopters","content":"### Agusta A109 Series Helicopters\n\n| AD/A109/53 | Tail Rotor - Flange Assembly | 7/2006 TX |\n| ---------- | ---------------------------- | --------- |\n\n| Applicability: | Agusta A109S helicopters up to S/N 22010 except S/N 22007, where maintenance activity has been carried out at least once on the Flange Assembly P/N109-0131-33-105 of the Tail Rotor Trunnion P/N 109-0131-30-101.                                                                                                                                             |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Check the torque applied to the Flange P/N 109-0131-33-105 in accordance with Agusta Alert “Bollettino Tecnico” 109S-2 or later approved revision.Note: EASA Emergency AD 2006-0120-E dated 15 May 2006 refers.                                                                                                                                                |\n| Compliance:    | Before further flight after the effective date of this AD.                                                                                                                                                                                                                                                                                                     |\n|                | This Airworthiness Directive becomes effective on 18 May 2006.                                                                                                                                                                                                                                                                                                 |\n| Background:    | The failure of the threaded pin of Trunnion P/N 109-0131-30-101 on an Agusta A109S caused the subsequent loss of the connected Flange P/N 109-0131-33-105, resulting in a sudden and noticeable increase in the vibration level. An investigation showed that the pin is likely to break due to over-torquing of Flange P/N109-0131-33-105 during maintenance. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n16 May 2006","sortOrder":0},{"sectionNumber":"AD/A109/53","sectionType":"part","heading":"AD/A109/53","content":"## AD/A109/53","sortOrder":1},{"sectionNumber":"Tail Rotor - Flange Assembly","sectionType":"part","heading":"Tail Rotor - Flange Assembly","content":"## Tail Rotor - Flange Assembly","sortOrder":2},{"sectionNumber":"7/2006 TX","sectionType":"part","heading":"7/2006 TX","content":"## 7/2006 TX","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":3,"scope_assessment":{"changed":false,"description":"This is a targeted emergency airworthiness directive addressing a specific mechanical failure mode. The scope remains precisely focused on the identified safety risk — tail rotor flange assembly failures due to over-torquing. No evidence of scope creep beyond the original safety purpose."},"complexity_factors":["Highly specific applicability criteria involving serial number ranges and maintenance history","Multiple nested part numbers (P/N references) that must be cross-referenced","References external technical documents (Agusta Alert Bollettino Tecnico 109S-2 and EASA Emergency AD 2006-0120-E)","Conditional trigger: only applies if maintenance activity has been carried out at least once on the specific flange assembly","Aviation-specific terminology and regulatory framework (Airworthiness Directive structure)"],"plain_english_summary":"Emergency AD requires immediate, before‑further‑flight torque verification of the tail‑rotor flange on Agusta A109S helicopters (serials up to 22010, except 22007) if that flange assembly (P/N 109-0131-33-105) has been maintained. Over‑torqued threaded pins can cause flange detachment, severe vibration, and possible loss of control; compliance follows Agusta TB 109S-2."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"Scope remains limited to a one‑time torque check on Flange P/N 109‑0131‑33‑105 for Agusta A109S helicopters up to S/N 22010, except S/N 22007 where maintenance has already been carried out. The instrument does not expand to other parts, models, or recurring programmes; it mandates immediate compliance and defers technical detail to the Agusta Alert Bollettino Tecnico (Applicability; Requirement; Compliance; Background)."},"complexity_factors":["Narrow, part‑specific applicability limited to Agusta A109S up to S/N 22010 with an explicit exception for S/N 22007 (Applicability).","Single, clearly defined action: verify torque on Flange P/N 109‑0131‑33‑105 (Requirement).","Immediate compliance timing — must be done before further flight after the AD’s effective date (Compliance): raises short‑term operational scheduling pressure.","Dependence on an external maintenance procedure document (Agusta Alert Bollettino Tecnico 109S‑2 or later) for technical steps and acceptable criteria (Requirement).","Technical competence required to measure/adjust torque and determine whether prior maintenance exempts a helicopter — imposes a modest maintenance burden and record‑checking (Requirement; Applicability).","Root cause concerns tied to over‑torquing of the flange leading to threaded‑pin failure and increased vibration — the AD targets a specific mechanical failure mode identified in investigation (Background).","One‑off mitigation rather than recurring inspection reduces ongoing compliance complexity but requires accurate maintenance history verification (Applicability; Compliance)."],"plain_english_summary":"Requires a one‑time torque check of the tail‑rotor flange (P/N 109‑0131‑33‑105) on specified Agusta A109S helicopters. It applies to helicopters up to serial number 22010 except SN 22007 (where the flange has already been worked on). The stated purpose is to prevent threaded‑pin failure caused by over‑torquing (Background). The check must be done before further flight and performed in accordance with Agusta Alert Bollettino Tecnico 109S‑2 or a later approved revision (Requirement; Compliance)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-a109-53-tail-rotor-flange-assembly","history":"/api/acts/ad-a109-53-tail-rotor-flange-assembly/history","analysis":"/api/acts/ad-a109-53-tail-rotor-flange-assembly/analysis","conflicts":"/api/acts/ad-a109-53-tail-rotor-flange-assembly/conflicts","importantCases":"/api/acts/ad-a109-53-tail-rotor-flange-assembly/important-cases","documents":"/api/acts/ad-a109-53-tail-rotor-flange-assembly/documents"}}