{"id":"F2007L02360","name":"AD/BELL 206/161 Amdt 1 - Power Turbine RPM Steady State Operation","slug":"ad-bell-206-161-amdt-1-power-turbine-rpm-steady-state-operation","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":67693,"registerId":"commonwealth-F2007L02360-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Bell Helicopter Textron Canada (BHTC) 20","sectionType":"division","heading":"Bell Helicopter Textron Canada (BHTC) 206 and Agusta Bell 206 Series Helicopters","content":"### Bell Helicopter Textron Canada (BHTC) 206 and Agusta Bell 206 Series Helicopters\n\n| AD/BELL 206/161 Amdt 1 | Power Turbine RPMSteady State Operation | 9/2007 |\n| ---------------------- | --------------------------------------- | ------ |\n\n| Applicability: | Bell Helicopter Textron Canada (BHTC) Model 206L-3 serial numbers 51001 through 51612, and 206L-4 helicopters serial numbers 52001 through 52313.Helicopters fitted with two 250-C20R engines as per Supplementary Type Certificate (STC) SR00036SE are excluded.                                                                                                                                                                                                                                                                                                                                                                                               |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Insert the appropriate flight manual revisions, BHT-206L3-FM-1, Revision 6, dated 26 April 2005, or BHT-206L4-FM-1, Revision 6, dated 26 April 2005, or later Transport Canada approved revisions, into the rotorcraft flight manual and advise the pilot of this change.2. Install the decal as per Alert Service Bulletin 206L-05-134, dated 8 June 2005, or later Transport Canada revisions. It is permissible to locally manufacture the decal with white lettering on a black background, minimum 10 point font size.Note: Transport Canada AD CF-2005-28R1 dated 14 June 2007 refers.                                                                 |\n| Compliance:    | Within 30 calendar days after the effective date of this directive.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |\n|                | This Amendment becomes effective on 30 August 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |\n| Background:    | Transport Canada has been advised of multiple reports of failure of the third stage turbine wheel used in both the Rolls-Royce 250-C30S and 250-C47B engines. There have been eight in-flight failures reported. Rolls-Royce has determined that detrimental vibrations can occur within a particular range of turbine speed as a potential contributing factor to these failures. BHTC revised their rotorcraft flight manual and provided a decal to inform pilots to avoid steady state operations at these engine turbine speeds.This amendment excludes those helicopters incorporating STC SR00036SE from the AD with no change to the technical content. |\n\n|     | The original issue of this AD became effective 27 October 2005. |\n| --- | --------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n20 July 2007","sortOrder":0},{"sectionNumber":"AD/BELL 206/161 Amdt 1","sectionType":"part","heading":"AD/BELL 206/161 Amdt 1","content":"## AD/BELL 206/161 Amdt 1","sortOrder":1},{"sectionNumber":"Power Turbine RPMSteady State Operation","sectionType":"part","heading":"Power Turbine RPMSteady State Operation","content":"## Power Turbine RPM  \nSteady State Operation","sortOrder":2},{"sectionNumber":"9/2007","sectionType":"part","heading":"9/2007","content":"## 9/2007","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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This amendment narrows applicability by explicitly excluding helicopters fitted with STC SR00036SE while leaving the technical requirements (manual revision and decal) unchanged; the original AD (effective 27 Oct 2005) did not include that exclusion."},"complexity_factors":["Narrow applicability limited to specific serial-number ranges (easy to identify)","Tasks are non-technical (manual insertion and decal installation) with a short 30‑day compliance window","Exclusion for helicopters with STC SR00036SE narrows scope and requires checking modification status","References Transport Canada AD and allows later Transport Canada‑approved revisions (some administrative dependence on regulator approvals)","Technical rationale (turbine vibration at certain speeds) requires pilots to alter operating behaviour rather than hardware changes"],"plain_english_summary":"This directive requires operators of specified Bell 206L‑3 (S/N 51001–51612) and 206L‑4 (S/N 52001–52313) helicopters to insert Transport Canada‑approved revisions to the rotorcraft flight manual and install a cockpit decal that warns pilots to avoid steady‑state operation in a particular power‑turbine speed range. It responds to reported third‑stage turbine wheel failures linked to vibration. Operators pay for the manual update and decal; pilots must change power‑setting behaviour; STC SR00036SE‑fitted helicopters are excluded."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment maintains the original scope and intent of the 2005 Airworthiness Directive. The only modification is the addition of a specific exclusion for helicopters with STC SR00036SE, which narrows rather than expands applicability. The core safety purpose — preventing turbine wheel failures through operational restrictions — remains unchanged."},"complexity_factors":["Single, specific technical requirement with two clear action items (manual update + decal installation)","Limited applicability scope with explicit serial number ranges","One straightforward exclusion criterion (STC SR00036SE)","No nested conditional logic or cross-references to other legislation","Clear compliance timeframe (30 calendar days)","Minimal defined terms (only standard aviation abbreviations like STC, AD, RPM)","Document appears to be a regulatory instrument of only a few pages with repetitive header formatting artifacts"],"plain_english_summary":"This AD requires owners/operators of specified Bell 206L-3 and 206L-4 helicopters to update flight manuals and install a cockpit warning decal to prevent steady-state operation in a power turbine RPM range linked to harmful vibrations. It responds to eight in‑flight third‑stage turbine wheel failures in Rolls‑Royce engines. Amendment 1 only adds an exclusion for helicopters with twin 250‑C20R engines under STC SR00036SE. Compliance: by 29 September 2007."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-206-161-amdt-1-power-turbine-rpm-steady-state-operation","history":"/api/acts/ad-bell-206-161-amdt-1-power-turbine-rpm-steady-state-operation/history","analysis":"/api/acts/ad-bell-206-161-amdt-1-power-turbine-rpm-steady-state-operation/analysis","conflicts":"/api/acts/ad-bell-206-161-amdt-1-power-turbine-rpm-steady-state-operation/conflicts","importantCases":"/api/acts/ad-bell-206-161-amdt-1-power-turbine-rpm-steady-state-operation/important-cases","documents":"/api/acts/ad-bell-206-161-amdt-1-power-turbine-rpm-steady-state-operation/documents"}}