{"id":"F2006B09327","name":"AD/ECUREUIL/104 - Hydraulic Fluid in Cold Weather","slug":"ad-ecureuil-104-hydraulic-fluid-in-cold-weather","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53489,"registerId":"commonwealth-F2006B09327-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nEurocopter AS 350 (Ecureuil) Series Helicopters","sortOrder":0},{"sectionNumber":"AD/ECUREUIL/104 Hydraulic Fluid in Cold ","sectionType":"part","heading":"AD/ECUREUIL/104 Hydraulic Fluid in Cold Weather 10/2004","content":"# AD/ECUREUIL/104 Hydraulic Fluid in Cold Weather 10/2004\n\nApplicability: AS 350 helicopter versions B, BA, BB, B1, B2, B3 and D, that operate in a flight envelope where the outside air temperature (OAT) is below -15 C (+5 F).\n\nRequirement: Insert the following into the aircraft flight manual: “Do not operate the helicopter in an environment where the OAT is below \\-15 C (+5 F) unless the hydraulic system fluid has been replaced in the previous 110 flight hours or 1 calendar month, whichever occurs first”.\n\nThis may be accomplished by placing a copy of this Directive in the aircraft flight manual at Section 2 Limitations, or in Supplement 4 Instructions for operation in cold weather.\n\nNote 1: DGAC AD F-2004-055 refers. (EASA reference no. 2004-4046 of April 20 2004).\n\nNote 2: Where operation in an environment where the OAT is below \\-15 C (+5 F) is anticipated, the due date for the next hydraulic oil change could be entered in the Maintenance Release as maintenance required.\n\nCompliance: Within 14 days of the effective date of this Directive.\n\nThis Airworthiness Directive becomes effective on 30 September 2004.\n\nBackground: Ice has formed in some parts of the flight control system where the hydraulic system was highly contaminated with water, causing malfunction in helicopters operating at below -15 C (+5 F). This Directive requires the flight crew to be aware of the maintenance requirement before commencing cold weather operations.\n\n![Signature of Gary J Carr, Delegate of the Civil Aviation Safety Authority.](image.002.jpeg)  \n\nGary J Carr\n\n![](image.001.png)Delegate of the Civil Aviation Safety Authority 20 August 2004","sortOrder":1}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with a narrow, specific safety purpose: preventing hydraulic system failures in cold weather for a particular helicopter type. The scope remains tightly focused on the original safety issue identified (ice formation in flight controls due to water contamination) and has not expanded beyond this specific operational scenario."},"complexity_factors":["Single, clearly defined applicability (specific helicopter models and temperature threshold)","One straightforward requirement with two alternative compliance methods (insert in Section 2 or Supplement 4)","Simple temporal compliance trigger (14 days from effective date)","Only 2 brief notes providing reference information, not creating additional obligations","No defined terms section, no cross-references to other legislation beyond a reference to a French aviation directive","Background section provides clear safety rationale without creating legal conditions"],"plain_english_summary":"This Airworthiness Directive requires operators of Eurocopter AS350 (B/BA/BB/B1/B2/B3/D) helicopters to ensure hydraulic fluid was changed within the last 110 flight hours or within one month before any flight in temperatures below −15°C. It responds to control-ice failures from water-contaminated fluid and mandates inserting a warning into the flight manual (to be done within 14 days of 30 Sept 2004) so aircraft aren’t flown in those freezing conditions without fresh fluid."},"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The Directive retains the original technical and operator scope: it applies only to the listed AS350 variants when operating in environments with OAT below −15°C and imposes an AFM limitation plus a specified hydraulic‑fluid replacement interval. It does not expand affected aircraft types or relax the maintenance requirement; it echoes the referenced DGAC/EASA ADs."},"complexity_factors":["Model‑specific applicability (AS350 B, BA, BB, B1, B2, B3, D) — Applicability","Clear technical trigger (OAT below −15°C) that creates conditional application — Applicability","Maintenance timing condition (replace hydraulic fluid within prior 110 flight hours or 1 calendar month) — Requirement","Regulatory action limited to AFM insertion or supplement entry (operational/documentation change) — Requirement","Short administrative compliance window (within 14 days of effective date) — Compliance","Optional operational recording method (enter due date in Maintenance Release) adds procedural choices for operators — Note 2","Cross‑reference to foreign ADs (DGAC AD F‑2004‑055 / EASA ref) requiring consideration of international guidance — Note 1","Safety rationale tied to contamination/ice risk requires operational judgement about when cold‑weather operations will occur — Background"],"plain_english_summary":"This Directive requires operators of Eurocopter AS350 (models B, BA, BB, B1, B2, B3 and D) to add a flight‑manual limitation: do not operate where outside air temperature is below −15°C unless the hydraulic fluid was replaced within the previous 110 flight hours or 1 calendar month (whichever comes first). It is intended to prevent flight‑control malfunctions caused by ice from water‑contaminated hydraulic fluid; operators must update the AFM and track oil‑change timing within 14 days of the Directive."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ecureuil-104-hydraulic-fluid-in-cold-weather","history":"/api/acts/ad-ecureuil-104-hydraulic-fluid-in-cold-weather/history","analysis":"/api/acts/ad-ecureuil-104-hydraulic-fluid-in-cold-weather/analysis","conflicts":"/api/acts/ad-ecureuil-104-hydraulic-fluid-in-cold-weather/conflicts","importantCases":"/api/acts/ad-ecureuil-104-hydraulic-fluid-in-cold-weather/important-cases","documents":"/api/acts/ad-ecureuil-104-hydraulic-fluid-in-cold-weather/documents"}}