{"id":"F2006B02442","name":"AD/ARRIEL/10 - 2nd Stage Turbine Nozzle Guide Vanes","slug":"ad-arriel-10-2nd-stage-turbine-nozzle-guide-vanes","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41698,"registerId":"commonwealth-F2006B02442-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ARRIEL/10 - 2nd Stage Turbine Nozzle Guide Vanes","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nTurbomeca Turbine Engines \\- Arriel Series\n\nAD/ARRIEL/10 2nd Stage Turbine Nozzle Guide Vanes 11/98\n\nApplicability: All Arriel 1 turboshaft engines.\n\nRequirement: 1. Arriel 1A, 1A1, 1A2, 1B engines incorporating modification TU 76 but not incorporating modification TU 197 or TU 202 and, Arriel 1C, 1C1, 1C2, 1D, 1D1,1K, 1K1, 1S engines not incorporating modification TU 197 or TU 202:\n\nCarry out a check of the engine for unusual noises during engine run down and a check of the gas generator for free rotation in accordance with Turbomeca Service Bulletin No. 292 72 0181, revision 3 dated 15/9/95.\n\n    2. All Arriel 1 engines incorporating modification TU 197:\n\n    Carry out a check of the engine for unusual noises during engine run-down in accordance with the requirements of Turbomeca Service Bulletin No. 292 72 0212 Revision 3 dated 25/6/98.\n\n    b. Carry out a boroscope inspection of the 2nd stage turbine nozzle guide vane in accordance with the requirements of Turbomeca Service Bulletin No. 292 72 0212 Revision 3 dated 25/6/98.\n\nNote: Requirement 1 and Requirement 2a of this Directive may be performed by the pilot in command, but not a student pilot. Certification by a pilot shall be carried out by entering on the maintenance release; Compliance with AD/ARRIEL/10 Requirement 1 or 2a, as applicable, the pilot’s signature and the pilot’s licence number.\n\nA copy of this Directive and the Requirement Document shall be carried with the applicable aircraft Maintenance Release.\n\n    3. All Arriel 1B, 1D, 1D1 engines incorporating modification TU 76 but not incorporating modifications TU 197 or TU 202.\n\nReplace the 2nd stage turbine nozzle guide vane in accordance with the requirements of Turbomeca Service Bulletin No. 292 72 0150 (Mod TU 202).\n\nNote: DGAC Airworthiness Directive 98-311(A) refers.\n\nCompliance: 1. As detailed in the Requirement Document with a revised effective date of 8 October 1998.\n\n    2. As detailed in the Requirement Document with a revised effective date of 8 October 1998.\n\n    3. Unless previously accomplished before further flight after the effective date of this Directive.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nNote: The manufacturer has advised completion of a program to ensure incorporation of modifications TU 197 or TU 202 in engines installed in single engine helicopters known to be in service in Australia.\n\nThis airworthiness directive becomes effective on 8 October 1998.\n\nBackground: This AD replaces AD/ARRIEL/8 which was issued to address reports of 2nd stage turbine nozzle guide vane deterioration that resulted in a number of turbine failure events. The new Directive reflects a general update by the French DGAC and also provides for inspections based on engine cycles rather than engine hours.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"This Directive replaces AD/ARRIEL/8 and changes scope by updating inspection criteria (moving from engine hours to engine cycles) and by differentiating requirements based on TU modifications; it also adds a mandatory replacement requirement for certain TU 76 engines and permits pilot‑performed run‑down checks as set out in the cited Service Bulletins."},"complexity_factors":["Applicability spans all Arriel 1 variants listed (multiple serial models), creating many configuration permutations to check.","Different mandated actions depending on which Turbomeca modifications are incorporated (TU 76, TU 197, TU 202), so compliance paths diverge by engine build state.","Three distinct action types: run‑down noise checks, gas‑generator free‑rotation checks, borescope inspection, and mandatory vane replacement for a subset of engines.","Permits pilot (but not student pilot) to perform and certify some run‑down checks; creates a non‑standard compliance actor and a specific certification entry requirement (pilot signature and licence number).","Primary instructions are external: multiple Turbomeca Service Bulletins cited with revision numbers and dates, requiring operators to obtain and follow those documents.","Timing and compliance rules vary: some tasks follow the Requirement Document’s revised effective date (8 Oct 1998), while replacement is required 'before further flight' for affected engines.","Administrative burden: a copy of the Directive and Requirement Document must be carried with the aircraft Maintenance Release.","Background change noted from the previous directive: inspection criteria shift from engine hours to engine cycles, altering tracking and maintenance planning."],"plain_english_summary":"This airworthiness directive requires operators of helicopters fitted with Turbomeca Arriel 1 engines to carry out specified inspections of the 2nd‑stage turbine nozzle guide vanes and, for certain engine configurations, to replace those vanes. The authority says the measure responds to reports of vane deterioration and turbine failures and moves inspection triggers from engine hours to engine cycles; operators bear the cost of inspections and any replacements, and some run‑down checks may be performed and signed off by a pilot."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive with a clear, narrow scope: addressing a specific mechanical failure mode in a specific engine series. The document reflects its original intent to mandate safety actions for the 2nd stage turbine nozzle guide vane issue without scope creep."},"complexity_factors":["Multiple applicability categories based on engine model and modification status (TU 76, TU 197, TU 202)","Three distinct requirement sets with different compliance actions","Cross-references to external manufacturer documents (Turbomeca Service Bulletins) that are not reproduced in the directive itself","Conditional logic determining which requirements apply to which engines","Specific compliance dates and effective dates that vary by requirement","Mixed performer eligibility (pilots vs. maintenance engineers) depending on which requirement is being satisfied"],"plain_english_summary":"This Airworthiness Directive requires operators of Turbomeca Arriel 1 series turboshaft engines to carry out run‑down noise checks, free‑spin and boroscope inspections, and, where specified, replacement of the 2nd stage turbine nozzle guide vane to prevent vane deterioration and engine failure. It affects all helicopters with Arriel 1 variants (requirements vary by modification), allows pilots to perform simple checks, and updates a prior AD with cycle‑based intervals. Effective 8 October 1998."},"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-arriel-10-2nd-stage-turbine-nozzle-guide-vanes","history":"/api/acts/ad-arriel-10-2nd-stage-turbine-nozzle-guide-vanes/history","analysis":"/api/acts/ad-arriel-10-2nd-stage-turbine-nozzle-guide-vanes/analysis","conflicts":"/api/acts/ad-arriel-10-2nd-stage-turbine-nozzle-guide-vanes/conflicts","importantCases":"/api/acts/ad-arriel-10-2nd-stage-turbine-nozzle-guide-vanes/important-cases","documents":"/api/acts/ad-arriel-10-2nd-stage-turbine-nozzle-guide-vanes/documents"}}