{"id":"F2009L00691","name":"AD/A109/62 - Engine - Power Turbine Speed - Operational Limitation","slug":"ad-a109-62-engine-power-turbine-speed-operational-limitation","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":77627,"registerId":"commonwealth-F2009L00691-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/A109/62 | Engine - Power TurbineSpeed - Operational Limitation | 4/2009 TX |\n| ---------- | ---------------------------------------------------- | --------- |\n\n| Applicability: | Agusta S.p.A. A109A, A109AII and A109C helicopters, all serial numbers if equipped with Rolls-Royce Corporation (formerly Allison) engine model 250-C20B or 250-C20R/1 with a third stage turbine wheel having part number (P/N) 23065833 installed. |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Requirement: | Accomplish the requirements specified below in accordance with the instructions of Agusta BT 109-129 dated 16 February 2009.1. Avoid steady-state operation in the 95-97% N2 range for more than 60 seconds in single or cumulative events. If steady-state operation in the 95-97% N2 range exceeds 60 seconds in single or cumulative events, before further flight perform specific corrective actions as per Rolls-Royce CEB A-1400 Rev. 3.Note 1: Steady-state operation is defined as any manoeuvre during which an attempt is being made to maintain a constant engine speed within 2% N2.2. Install on the instruments panel below or near the “ENGINE & ROTOR RPM POWER TURBINE (N2)” indicator, in an area visible by the pilot(s), one of the two decals (depending on the applicable instruments panel configuration) shown in figure 1 of Agusta BT 109-129 reporting the following text:“MIN. CONT. 97% N2 - MIN. TRANS. 95% N2”3. A109A and A109AII helicopters:Insert page 5 or 6, as applicable depending on the helicopter model, of Agusta BT 109-129 in the Flight Manual, Section I - OPERATING LIMITATIONS, paragraph “POWER PLANT LIMITATIONS”.4. A109C helicopters:Insert page 7 of Agusta BT 109-129 in the Flight Manual, Section I -LIMITATIONS, paragraph “POWER PLANT AND TRANSMISSION LIMITATIONS”.The use of later approved revisions of the documents detailed in this AD is acceptable for compliance with the requirements of this AD. |\n\n| | Note 2: EASA Emergency AD 2009-0037-E dated 19 February 2009 refers. |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Compliance: | For Requirements 1 through 4 - Within the next 5 flight hours after the effective date of this AD but no later than 28 February 2009, whichever occurs first. |\n| | This Airworthiness Directive becomes effective on 23 February 2009. |\n| Background: | Following several third stage turbine wheel failures, the engine Type Certificate holder, Rolls-Royce Corporation, issued Commercial Engine Bulletin (CEB) A-1400 Rev. 3 to introduce an operational limitation on the power turbine N2 speed range (95% - 97%) for more than 60 seconds in single or cumulative events for engines with a third stage turbine wheel having P/N 23065833 installed.Thereafter, Agusta issued Bollettino Tecnico (BT) 109-129 to introduce the same operating limitation, which is also required by this AD, on the affected helicopters. |\n\n![](image.001.png) \nDavid Villiers \nDelegate of the Civil Aviation Safety Authority\n\n20 February 2009","sortOrder":0},{"sectionNumber":"AD/A109/62","sectionType":"part","heading":"AD/A109/62","content":"## AD/A109/62","sortOrder":1},{"sectionNumber":"Engine - Power TurbineSpeed - Operationa","sectionType":"part","heading":"Engine - Power TurbineSpeed - Operational Limitation","content":"## Engine - Power Turbine \nSpeed - Operational Limitation","sortOrder":2},{"sectionNumber":"4/2009 TX","sectionType":"part","heading":"4/2009 TX","content":"## 4/2009 TX","sortOrder":3}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope as an emergency safety directive addressing a specific mechanical failure mode in defined helicopter/engine combinations. It has not expanded beyond its initial purpose of operational limitation and crew alerting."},"complexity_factors":["Single, specific technical requirement with clear numeric thresholds (95-97% N2, 60 seconds)","Limited applicability scope (3 helicopter models, 2 engine models, 1 specific part number)","Four distinct but straightforward compliance actions (operational limitation, decal installation, manual insertion x2)","Cross-reference to external technical documents (Agusta BT 109-129, Rolls-Royce CEB A-1400 Rev. 3) but with clear incorporation by reference","Simple conditional logic (if exceeded 60 seconds, then perform corrective actions)","No nested exceptions or complex definitional sections","Short document length with minimal legislative machinery"],"plain_english_summary":"This AD imposes an urgent operating limit on Agusta A109A/A109AII/A109C helicopters with certain Rolls‑Royce 250‑C20B or 250‑C20R/1 engines (turbine wheel P/N 23065833): pilots must not operate the power turbine between 95–97% N2 for more than 60 seconds cumulative per flight. It also requires a cockpit decal, Flight Manual amendment, and inspections per Rolls‑Royce bulletin if the limit is exceeded. Compliance is immediate (5 flight hours or by 28 Feb 2009)."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive implements a narrowly targeted operational limitation and documentation changes to address third‑stage turbine wheel failures on engines with P/N 23065833. It follows manufacturer bulletins and does not broaden applicability beyond the specified helicopter models and engine configuration."},"complexity_factors":["Targeted applicability: only A109A/A109AII/A109C helicopters with engines 250‑C20B or 250‑C20R/1 having third‑stage turbine wheel P/N 23065833 (Applicability).","Operational constraint with a precise numeric threshold and time limit: avoid steady‑state N2 95–97% for >60 seconds; 'steady‑state' defined as maintaining N2 within 2% (Requirement 1, Note 1).","Mandatory corrective actions before further flight if the threshold is exceeded, referencing an external manufacturer bulletin (Rolls‑Royce CEB A‑1400 Rev.3) which operators must obtain and follow (Requirement 1).","Simple non‑structural compliance actions: install a decal visible to pilots and insert specified pages into the Flight Manual (Requirements 2–4).","Short, urgent compliance window: within 5 flight hours or by 28 February 2009, creating immediate operational and administrative tasks (Compliance).","Reliance on external documents (Agusta BT 109‑129 and Rolls‑Royce CEB) and allowance for later approved revisions increases dependency on manufacturer/CASA approvals (Requirement, Note 2).","Enforcement and operational monitoring rests with operators and pilots (who must avoid the range and act if exceeded) and maintenance/airworthiness staff (who must fit decals and amend manuals), creating discrete but distributed compliance responsibilities."],"plain_english_summary":"This directive applies to Agusta A109A, A109AII and A109C helicopters fitted with Rolls‑Royce 250‑C20B or 250‑C20R/1 engines that have a third‑stage turbine wheel P/N 23065833. It requires pilots to avoid holding power turbine speed (N2) in the 95–97% range for more than 60 seconds, mandates a cockpit decal and inserts pages into the Flight Manual, and requires corrective actions per Rolls‑Royce CEB A‑1400 Rev.3 if the limit is exceeded. Compliance is required within the next 5 flight hours."}},"importantCases":[],"_links":{"self":"/api/acts/ad-a109-62-engine-power-turbine-speed-operational-limitation","history":"/api/acts/ad-a109-62-engine-power-turbine-speed-operational-limitation/history","analysis":"/api/acts/ad-a109-62-engine-power-turbine-speed-operational-limitation/analysis","conflicts":"/api/acts/ad-a109-62-engine-power-turbine-speed-operational-limitation/conflicts","importantCases":"/api/acts/ad-a109-62-engine-power-turbine-speed-operational-limitation/important-cases","documents":"/api/acts/ad-a109-62-engine-power-turbine-speed-operational-limitation/documents"}}