{"id":"F2006B04451","name":"AD/BELL 206/137 - Fuel Drain Tubes","slug":"ad-bell-206-137-fuel-drain-tubes","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44288,"registerId":"commonwealth-F2006B04451-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 206/137 - Fuel Drain Tubes","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBell Helicopter Textron Canada (BHTC) 206 and Agusta Bell 206 Series Helicopters\n\nAD/BELL 206/137 Fuel Drain Tubes 9/96\n\nApplicability: To the following model and S/N Bell helicopters:\n\n| Model: | 206L-1 | S/N 45154 to 45790 |\n| ------ | ------ | ------------------ |\n|        | 206L-3 | 51001 to 51612     |\n|        | 206L-4 | 52001 to 52158     |\n\nRequirement: To ensure fuel being drained from the airframe fuel filter is not being forced upwards into the fuel pump seal or starter generator seal, rework the drain tubes as detailed in Bell Alert Service Bulletin 206L-96-103 Revision A dated 25 March 1996.\n\nNote: Transport Canada AD CF-96-10 dated 26 April 1996 refers.\n\nCompliance: Unless previously carried out, prior to 30 October 1996.\n\nBackground: There has been reports of fuel migrating up to the fuel pump and starter-generator through their respective drain tubes during airframe fuel filter drainage. If not corrected a fire hazard could result.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD applies to the specified Bell 206L-1, L-3 and L-4 serial number ranges and requires a single rework action by a set deadline. The text shows no change in scope within the document: it identifies affected aircraft (Applicability), prescribes the corrective action and method (Requirement), and specifies the compliance deadline (Compliance). No expansion or narrowing of the stated applicability or required action is indicated in the supplied text."},"complexity_factors":["Single, prescriptive technical action required (rework drain tubes per named service bulletin) reduces legal complexity but requires technical work (Requirement).","Applicability limited to specific models and serial number ranges — administrative step to verify affected aircraft (Applicability).","Fixed compliance deadline creates scheduling and operational constraints for operators (Compliance).","Mandated reliance on a manufacturer service bulletin for the detailed procedure transfers technical complexity to that external document (Requirement).","No quantified cost or alternative-compliance pathway in the AD increases practical uncertainty for operators arranging work (Requirement, Compliance)."],"plain_english_summary":"### What this directive does\n\nThis Airworthiness Directive (AD) orders owners/operators of certain Bell 206L series helicopters to have the fuel drain tubes reworked so that fuel drained from the airframe fuel filter cannot be forced upward into the fuel pump seal or the starter-generator seal. The technical rework must follow Bell Alert Service Bulletin 206L-96-103 Revision A (25 March 1996). (See: Requirement.)\n\n### Which aircraft are affected\n\nOnly Bell 206L-1, 206L-3 and 206L-4 helicopters within the stated serial number ranges are covered. Owners/operators should check their aircraft serial numbers against the ranges in the Applicability section. (See: Applicability.)\n\n### Who decides and who pays\n\n- The Civil Aviation Safety Authority (CASA) is the issuing authority for this AD (header). Compliance is mandatory unless already carried out. (See: Compliance.)\n- The operator or aircraft owner is responsible for having the rework performed and therefore for the cost, downtime and arranging the work. The AD does not set out any compensation or funding. (See: Requirement, Compliance.)\n\n### What you must do and by when\n\n- Have the drain tubes reworked in accordance with the named Bell Alert Service Bulletin. (See: Requirement.)\n- If the rework has not already been done, it must be completed before 30 October 1996. (See: Compliance.)\n\n### Why the work is required (stated safety issue)\n\nThe AD says there have been reports of fuel migrating up the drain tubes into the fuel pump and starter-generator during fuel filter drainage. If not corrected, that fuel migration could create a fire hazard. The AD cites that safety concern as the reason for the mandated rework. (See: Background.)\n\n### Implementation and compliance notes (practical mechanics and trade-offs)\n\n- The AD prescribes a manufacturer procedure (the Bell Alert Service Bulletin) as the method of compliance; operators must obtain and follow that technical document. That concentrates technical decision-making on the manufacturer’s instructions while the regulator mandates the outcome. (See: Requirement.)\n- The directive sets a firm compliance deadline. Missing the deadline leaves the aircraft non-compliant with the AD and leaves the reported hazard unaddressed. (See: Compliance, Background.)\n- The AD does not quantify the cost, labour hours, or aircraft downtime required for the rework. Those economic effects (payments for parts, labour, ground time, and any logistics to obtain the service bulletin and parts) are the operator’s responsibility. (See: Requirement, Compliance.)\n- The AD references a related Transport Canada AD. That is noted as related information rather than a separate requirement in this text. (See: Note.)\n\n### Risks, incentives and implementation friction\n\n- Incentive for operators: comply to eliminate the reported fuel-migration/fire hazard and meet regulatory obligations. (See: Background, Requirement, Compliance.)\n- Implementation friction: operators must source the service bulletin, schedule work, potentially take the helicopter out of service, and pay for parts and labour. The AD does not provide alternative compliance options or exemptions other than noting previously completed work. (See: Requirement, Compliance.)\n- Discretion: the directive is prescriptive (mandated rework per the service bulletin) with no discretionary alternative set out in the AD text. (See: Requirement.)\n\nThis summary is limited to the content of the AD text and describes what the AD requires, who bears costs and responsibility, and the practical compliance mechanics set out in the document. It does not evaluate the underlying technical method in the manufacturer’s service bulletin or estimate costs not listed in the AD."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific helicopter models. It has not expanded beyond its original purpose of preventing fuel migration and fire hazards in the identified aircraft."},"complexity_factors":["Very short document (under 300 words)","Only 3 defined model/serial number ranges in applicability table","Single, clear requirement referencing one external technical document","No nested exceptions or conditional logic","Simple compliance deadline with single exemption ('unless previously carried out')","No cross-references to other legislation beyond a note about a Canadian equivalent directive"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order for aircraft owners and operators. It applies to specific models of Bell helicopters (the 206L-1, 206L-3, and 206L-4 series with certain serial numbers).\n\n**What it does:**\nThe directive requires owners to modify the fuel drain tubes on these helicopters. The problem is that when mechanics drain fuel from the airframe fuel filter (a routine maintenance task), fuel can accidentally flow upward into seals around the fuel pump and starter-generator. This creates a **fire risk**.\n\n**What must be done:**\nHelicopter operators must follow the instructions in a specific Bell technical bulletin (Alert Service Bulletin 206L-96-103 Revision A) to rework the drain tubes. This essentially reroutes or modifies the drainage system so fuel goes down and out, not up into sensitive equipment.\n\n**Who it affects:**\n- Owners and operators of specific Bell 206L helicopter models\n- Maintenance engineers working on these aircraft\n- The Civil Aviation Safety Authority (CASA), which enforces compliance\n\n**Why it matters:**\nFuel leaking onto hot engine components or electrical equipment can cause fires. This directive prevents that by fixing a design flaw in the drainage system. The compliance deadline was 30 October 1996, meaning this was an urgent safety fix that had to be completed quickly.\n\n**Key point:** This is not optional. Airworthiness Directives are legally binding — you cannot fly the aircraft until the work is done."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-206-137-fuel-drain-tubes","history":"/api/acts/ad-bell-206-137-fuel-drain-tubes/history","analysis":"/api/acts/ad-bell-206-137-fuel-drain-tubes/analysis","conflicts":"/api/acts/ad-bell-206-137-fuel-drain-tubes/conflicts","importantCases":"/api/acts/ad-bell-206-137-fuel-drain-tubes/important-cases","documents":"/api/acts/ad-bell-206-137-fuel-drain-tubes/documents"}}