{"id":"F2006B07328","name":"AD/TB20/24 - Fuel Tank Outlet Filter","slug":"ad-tb20-24-fuel-tank-outlet-filter","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49370,"registerId":"commonwealth-F2006B07328-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TB20/24 - Fuel Tank Outlet Filter","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Aerospatiale (Socata) TB20 (Trinidad) Series Aeroplanes\n\n \n\nAD/TB20/24 Fuel Tank Outlet Filter 2/92\n\nApplicability:  Model TB20 and TB21 with serial number 1038 to 1308 inclusive. Aircraft S/N 1213, 1264 through 1267, 1284 through 1287, 1301 through 1304 and 1307 have previously been modified.\n\n \n\nRequirement: Action in accordance with the technical requirement of DGAC AD 91-246(A).\n\nNote: Socata TB airplanes SB Nr 61 refers.\n\nCompliance:  During the next periodic inspection after the 25 January 1992 or by 30 June 1992, whichever occurs first.\n\n \n\nBackground: This Directive has been raised to ensure sump volume and unusable fuel quantity are correct.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive for a specific aircraft type. It has not expanded beyond its original purpose of addressing a fuel system safety issue in specified Socata aircraft."},"complexity_factors":["Very short document (under 200 words)","Only 3 defined applicability criteria (model, serial number range, excluded serials)","Single technical requirement referencing external document","Simple compliance deadline (earlier of two dates)","No nested conditions, exceptions to exceptions, or cross-references to other legislation","Background explanation is straightforward and non-technical"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of certain **Socata TB20 and TB21 aeroplanes** (specific serial numbers 1038 to 1308, with some exceptions) to carry out a technical modification or inspection related to the **fuel tank outlet filter**.\n\n**Who it affects:**\n- Owners and operators of the specified Trinidad series aircraft\n- Maintenance organisations servicing these planes\n\n**Why it matters:**\nThe directive ensures the aircraft's **fuel sump volume** (the space where fuel collects before entering the engine) and **unusable fuel quantity** (fuel that can't be accessed during flight) meet safety standards. Getting this wrong could lead to fuel starvation — the engine cutting out because it can't access fuel even when there's some left in the tank.\n\n**What must happen:**\nThe required work must be done during the next scheduled periodic inspection after 25 January 1992, or by 30 June 1992 — whichever comes first. The technical details of what exactly to do are found in a French aviation authority document (DGAC AD 91-246(A)), with additional guidance in a manufacturer service bulletin (Socata SB Nr 61)."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive is a targeted airworthiness measure applying to specified TB20/TB21 serial numbers and requires compliance with an external DGAC AD to correct sump volume and unusable fuel quantities. The text presents a narrowly defined corrective requirement and a limited compliance window; it does not indicate any expansion or contraction of scope beyond that targeted measure."},"complexity_factors":["Narrow applicability defined by model and a specific inclusive serial-number range plus a list of serials noted as previously modified (Applicability)","Delegation of all technical detail to an external airworthiness directive (DGAC AD 91-246(A)) rather than including procedures in the text (Requirement)","Reference to a manufacturer service bulletin (Socata SB Nr 61) requiring access to and interpretation of that document (Note)","A fixed compliance window tied to the next periodic inspection after a given date or an absolute deadline, which affects scheduling (Compliance)","Regulatory context (issued as an AD under Civil Aviation Regulations Part 39-105) implies mandatory effect but does not itself set out enforcement or cost details"],"plain_english_summary":"What this directive does (mechanically)\n\n- Requires Model TB20 and TB21 aeroplanes (serial numbers 1038–1308 inclusive) to have work done on their fuel tank outlet/filter system in accordance with the technical instructions in DGAC AD 91-246(A). (Applicability; Requirement)\n- The stated mechanical aim is to ensure the sump volume and the quantity of unusable fuel are correct. (Background)\n- The directive cross-refers to Socata Service Bulletin No. 61 for related technical guidance. (Note)\n\nWho is affected\n\n- Aircraft owners/operators and maintenance organisations responsible for TB20/TB21 aeroplanes with serial numbers 1038 to 1308 inclusive. The directive notes that certain listed serial numbers (1213, 1264–1267, 1284–1287, 1301–1304 and 1307) have previously been modified. (Applicability)\n\nWhat must be done and when\n\n- The required action is to be carried out \"in accordance with the technical requirement of DGAC AD 91-246(A).\" The directive does not reproduce the technical steps; it delegates those specifics to the referenced DGAC airworthiness directive. (Requirement)\n- Compliance must take place during the next periodic inspection after 25 January 1992 or, if earlier, by 30 June 1992. That establishes a firm window for when the maintenance action must be completed. (Compliance)\n\nWho pays and who decides\n\n- Owners/operators (and their maintenance providers) bear the direct cost of performing the inspection/modification during the scheduled inspection window (Compliance; Requirement).\n- The Civil Aviation Safety Authority (by issuing this AD under the Civil Aviation Regulations) requires the action; the technical content and steps are prescribed by DGAC AD 91-246(A) and referenced Socata service information. (Requirement; Note)\n\nPractical implementation, incentives and trade-offs\n\n- Because the AD delegates technical detail to DGAC AD 91-246(A) and a Socata service bulletin, maintenance organisations must obtain and follow those external documents to comply. (Requirement; Note)\n- The timing requirement concentrates activity into the next periodic inspection period or by a fixed date, which limits when operators can schedule the work but allows it to be combined with routine maintenance. (Compliance)\n- The directive is narrowly targeted by model and serial number. That narrows the population bearing the compliance cost but requires careful application of serial-number records by operators and maintainers. (Applicability)\n- The directive does not itself describe sanctions, costs, or the specific technical steps; those are determined by the referenced technical documents and ordinary regulatory enforcement mechanisms. (Requirement; Note)\n\nWhat to watch for when implementing\n\n- Confirm whether an aircraft is among the serial numbers listed and whether it is one of the serials noted as having been previously modified before scheduling further work. (Applicability)\n- Obtain and follow DGAC AD 91-246(A) and Socata Service Bulletin No. 61 to ensure the maintenance action meets the required technical standard. (Requirement; Note)\n- Complete the work within the inspection window specified. (Compliance)\n\nSource citations: Applicability; Requirement; Compliance; Background; Note."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tb20-24-fuel-tank-outlet-filter","history":"/api/acts/ad-tb20-24-fuel-tank-outlet-filter/history","analysis":"/api/acts/ad-tb20-24-fuel-tank-outlet-filter/analysis","conflicts":"/api/acts/ad-tb20-24-fuel-tank-outlet-filter/conflicts","importantCases":"/api/acts/ad-tb20-24-fuel-tank-outlet-filter/important-cases","documents":"/api/acts/ad-tb20-24-fuel-tank-outlet-filter/documents"}}