{"id":"F2006B09389","name":"AD/ECUREUIL/85 - Exhaust Duct and Fuel Line Interefence","slug":"ad-ecureuil-85-exhaust-duct-and-fuel-line-interefence","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53715,"registerId":"commonwealth-F2006B09389-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\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/85 Exhaust Duct and Fuel Lin","sectionType":"part","heading":"AD/ECUREUIL/85 Exhaust Duct and Fuel Line Interference 7/2003","content":"# AD/ECUREUIL/85 Exhaust Duct and Fuel Line Interference 7/2003\n\nTX\n\nApplicability: AS 350 B3 helicopters equipped with the optional engine flushing system and modified per MOD 073098, and EC 130 B4 helicopters equipped with the optional engine flushing system.\n\nRequirement: 1. Check the condition of the fuel transfer line, the condition of the air exhaust duct, and the clearances in the interference area in accordance with paragraph 2.B.1 of Eurocopter AS 350 Alert Service Bulletin (ASB) No. 71.00.16 or Eurocopter EC 130 ASB 71A001 as applicable.\n\n    2. If wear marks are found:\n\n    Carry out the maintenance procedure detailed in the Engine Maintenance Manual Task 70-40-02-200-001-A01 if the wear is less than or equal to 0.05mm.\n    Replace the fuel line if the deepest wear mark is more than 0.05mm but less than 0.2mm.\n    Replace the fuel line if the deepest wear mark is more than 0.2mm\n\n    3. Replace any air exhaust duct found perforated.\n\n    4. Reposition the air exhaust duct where there is insufficient clearance between the duct and the fuel transfer line in accordance with paragraph 2.B.2 of the referenced ASB.\n\nNote: DGAC AD’s 2003-208(A) and 2003-209(A) refer.\n\n| Compliance: | 1.2. | For Requirement 1; Within 10 flight hours from the effective date of this Directive.a. For Requirement 2a; Before further flight. |\n| ----------- | ---- | --------------------------------------------------------------------------------------------------------------------------------- |\n|             | 2.   | b. For Requirement 2b; Within 50 flight hours or 1 month from the effective date of this Directive, whichever occurs first.       |\n|             | 2.   | c. For Requirement 2c; Before further flight.                                                                                     |","sortOrder":1}],"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 standard, narrow Airworthiness Directive addressing a specific unsafe condition (exhaust/fuel line interference) in specific helicopter models. It has not expanded beyond its original safety purpose."},"complexity_factors":["Short, single-purpose directive focused on one specific mechanical issue","Only 4 main requirements with clear conditional logic (if-then structure)","References external technical documents (Eurocopter Service Bulletins and Engine Maintenance Manual) rather than reproducing them","Simple applicability test based on aircraft model and two equipment criteria","Compliance deadlines are tiered but straightforward (immediate vs. 50 hours/1 month vs. 10 hours)","No nested definitions or extensive interpretation sections","Contains only one note referencing related French aviation authority directives (DGAC)"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of certain Eurocopter AS350 B3 (with MOD 073098) and EC130 B4 helicopters fitted with the optional engine flushing system to inspect and, if needed, repair or replace exhaust ducts and fuel lines where exhaust rubbing has caused wear. The aim is to prevent fuel leaks onto hot exhaust components and the resulting risk of in‑flight fire by mandating prompt corrective action when clearance or wear is unsafe."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This directive is narrowly focused on a single, identified unsafe condition (exhaust duct contacting the fuel transfer line) for specific helicopter models and equipment configurations. It prescribes inspection and remedial steps tied to measured wear thresholds and references manufacturer technical documents. There is no indication in the text that the directive broadens to other systems, models, or ongoing regulatory obligations beyond addressing that identified condition."},"complexity_factors":["Applies to two helicopter model types with a specific equipment configuration (AS 350 B3 with MOD 073098; EC 130 B4 with optional engine flushing system).","Four discrete required actions (inspect; three-tier wear response; replace perforated duct; reposition duct).","Three numeric wear thresholds (<=0.05 mm; >0.05 mm and <0.2 mm; >0.2 mm) that determine different remedies and compliance timings.","References to external technical documents (two different Eurocopter Alert Service Bulletins and a specific Engine Maintenance Manual task) for procedural detail.","Several short, differing compliance timeframes (within 10 flight hours; before next flight; within 50 flight hours or 1 month; before further flight) creating operational scheduling complexity.","Cross-reference to foreign authority ADs (DGAC ADs) but no substantive additional requirements included in the text.","Limited number of defined terms and minimal nested exceptions, so legal drafting is compact and direct."],"plain_english_summary":"**What this directive does (in plain English):**\n\n- It orders operators and maintenance organisations to inspect and, if necessary, repair or replace parts where the engine exhaust duct and a fuel transfer line are close enough to rub against one another on certain Eurocopter helicopters.\n\n**Which aircraft are affected:**\n\n- AS 350 B3 helicopters that have the optional engine flushing system and that have been modified by MOD 073098. (See \"Applicability\").\n- EC 130 B4 helicopters that have the optional engine flushing system. (See \"Applicability\").\n\n**Required checks and corrective actions (mechanical steps):**\n\n- Inspect the fuel transfer line, the air exhaust duct, and the clearances where they could interfere, following the relevant Eurocopter Alert Service Bulletin (ASB). (Requirement 1; see the two ASBs referenced.)\n- If wear marks are found on the fuel line, take one of three actions depending on how deep the wear is:\n  - If wear is less than or equal to 0.05 mm: follow the Engine Maintenance Manual procedure specified (maintenance task 70-40-02-200-001-A01). (Requirement 2.a)\n  - If the deepest wear mark is > 0.05 mm but < 0.2 mm: replace the fuel line. (Requirement 2.b)\n  - If the deepest wear mark is > 0.2 mm: replace the fuel line before further flight. (Requirement 2.c)\n- If the exhaust duct is perforated (holed), replace the duct. (Requirement 3)\n- If the clearance between duct and fuel line is insufficient, reposition the exhaust duct according to the ASB instructions. (Requirement 4)\n\n**Timing / compliance deadlines:**\n\n- The inspection required by Requirement 1 must be done within 10 flight hours from the directive's effective date. (Compliance: Requirement 1)\n- If the wear found is <= 0.05 mm, the maintenance action must be performed before the next flight. (Compliance: Requirement 2.a)\n- If the wear is > 0.05 mm but < 0.2 mm, the fuel line must be replaced within 50 flight hours or within 1 month from the effective date, whichever comes first. (Compliance: Requirement 2.b)\n- If wear is > 0.2 mm, replacement must be done before further flight. (Compliance: Requirement 2.c)\n\n**Where the technical instructions come from:**\n\n- The directive points operators to Eurocopter Alert Service Bulletin AS 350 No. 71.00.16 or EC 130 ASB 71A001 (as applicable) for inspection and repositioning details, and to the Engine Maintenance Manual task named above for the maintenance procedure. (Requirement and notes.)\n\n**Who pays, who decides, and what changes in behaviour:**\n\n- Aircraft owners/operators pay for the inspection labour, measuring, and any parts and replacement work. Approved maintenance organisations will perform or certify the work under the referenced maintenance manual and ASB procedures.\n- Operators must schedule the inspection within the short compliance window (10 flight hours), and then act depending on wear results: either perform the maintenance task, replace the fuel line, replace the exhaust duct, or reposition the duct. That can cause aircraft downtime while parts or approval for the work are arranged.\n\n**Purpose claim and testing it against practical effects:**\n\n- The directive's stated purpose is to correct an unsafe condition where the exhaust duct can rub on a fuel transfer line (see the preamble wording quoted in the AD). The concrete mechanisms used are inspection, measurement thresholds for wear, and mandated repair or replacement steps (Requirement 1–4; Compliance).\n- Costs and incentives: the safety benefit (reduced risk from fuel-line abrasion or perforation) is concentrated on operators and passengers of affected aircraft; the cost (inspection, measurement, replacement parts, downtime) is borne by operators. The directive does not create ongoing monitoring requirements beyond the immediate inspections and remedial steps set out here, but parts replacement may impose short-term cash and scheduling costs.\n- Implementation risks and practical points: the AD relies on accurate measurement of very small wear depths (0.05 mm and 0.2 mm thresholds). The method of measurement and who qualifies to make that measurement are determined by normal maintenance practice and the referenced ASB/maintenance manual. Access to spare fuel lines or exhaust ducts and workshop availability will affect downtime. The AD points to specific Eurocopter documents for technical detail, so following those documents is necessary to comply correctly. (Requirement; referenced ASBs and Engine Maintenance Manual.)\n\n**Other procedural notes:**\n\n- The AD cross-references French DGAC ADs (2003-208(A) and 2003-209(A)) as related documents; it otherwise relies on the Eurocopter ASBs and the Engine Maintenance Manual for the detailed technical instructions. (Note and Requirement.)\n\n**Net effect:**\n\n- Operators of the listed Eurocopter models with the optional engine flushing system must inspect for and eliminate friction/wear between the exhaust duct and fuel transfer line within short timeframes, using the measurement thresholds and corrective actions set out in the directive and the referenced manufacturer documents. This imposes immediate inspection and potential repair or replacement costs in exchange for addressing the identified unsafe condition."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ecureuil-85-exhaust-duct-and-fuel-line-interefence","history":"/api/acts/ad-ecureuil-85-exhaust-duct-and-fuel-line-interefence/history","analysis":"/api/acts/ad-ecureuil-85-exhaust-duct-and-fuel-line-interefence/analysis","conflicts":"/api/acts/ad-ecureuil-85-exhaust-duct-and-fuel-line-interefence/conflicts","importantCases":"/api/acts/ad-ecureuil-85-exhaust-duct-and-fuel-line-interefence/important-cases","documents":"/api/acts/ad-ecureuil-85-exhaust-duct-and-fuel-line-interefence/documents"}}