{"id":"F2006B07291","name":"AD/TB10/23 - Fuel Tank Internal Ribs","slug":"ad-tb10-23-fuel-tank-internal-ribs","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49256,"registerId":"commonwealth-F2006B07291-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TB10/23 - Fuel Tank Internal Ribs","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)  \nAerospatiale (Socata) TB9 and TB10 (Tobago) Series Aeroplanes\n\nAD/TB10/23 Fuel Tank Internal Ribs 3/95\n\nApplicability: TB aircraft serial numbers 1038 through 1442, 1444 through 1462, 1464 through\n\n1581, 1583 through 1606, 1608 through 1619, and 1629; and aircraft serial numbers 1 through 1037 on which the tank rib has been repaired since the application of modification No.78.\n\nRequirement: Action in accordance with Socata Mandatory Service Bulletin 10.084.57.\n\nNote: DGAC AD 94-247(A) refers.\n\nCompliance: Within 100 hours time in service after 2 March 1995 or prior to 31 December 1995, whichever occurs first.\n\nBackground: Tank sealant has been found obstructing the fuel tank internal rib drain holes. This Directive requires fuel tank internal inspections to ensure the necessary drain holes are clear.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific manufacturing/maintenance defect in a limited aircraft population. It has not expanded beyond its original purpose of ensuring fuel tank drain holes remain unobstructed."},"complexity_factors":["Very short document — approximately 150 words of substantive content","Only 4 defined applicability criteria (serial number ranges plus repair condition)","Single compliance action with clear deadline formula","No nested exceptions or conditional logic beyond the applicability criteria","Cross-reference to only one external technical document (Socata Service Bulletin) and one foreign AD","Plain language background explanation included"],"plain_english_summary":"This is an **Airworthiness Directive** — essentially a mandatory safety order for aircraft owners and operators.\n\n**What it does:**\nOrders inspections of fuel tanks on specific Socata TB9 and TB10 (Tobago) aeroplanes to check that drain holes in the internal ribs aren't blocked by sealant.\n\n**Who it affects:**\n- Owners and operators of specific serial-numbered TB aircraft (roughly serial numbers 1–1629, with some gaps)\n- Specifically includes older aircraft (serial 1–1037) that had tank rib repairs after a particular modification (No.78) was applied\n\n**Why it matters:**\nBlocked drain holes in fuel tank ribs can trap fuel or moisture, creating safety risks including potential fuel starvation or corrosion. The directive mandates a physical inspection to ensure these holes remain clear.\n\n**What must be done:**\nFollow the instructions in **Socata Mandatory Service Bulletin 10.084.57** — a technical document from the manufacturer specifying exactly how to inspect and fix the problem.\n\n**When it must be done:**\nWithin 100 hours of flying time after 2 March 1995, or before 31 December 1995 — whichever comes first.\n\n**Key terms explained:**\n- **Airworthiness Directive (AD):** A legally enforceable safety order issued by aviation regulators. Compliance is mandatory — you cannot legally fly the aircraft without doing what the AD says.\n- **Time in service:** Actual flight hours, not just calendar time.\n- **DGAC AD 94-247(A):** A reference to the equivalent French aviation safety order (DGAC is France's civil aviation authority), showing this issue was also recognised internationally."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument itself does not state any change of scope from an earlier text or intent. It prescribes inspections for the listed serial numbers (and for serials 1–1037 if the rib was repaired post-modification No.78), references the manufacturer’s service bulletin for the technical action, and sets a combined flight-hours/calendar compliance window. No amendment or expansion of applicability is described in the provided text."},"complexity_factors":["Applicability limited to specific serial number ranges and to aircraft with a specific past repair (requires checking records or physical confirmation). (Applicability)","Compliance deadline given as the earlier of flight hours after a date or a fixed calendar date — operators must track both time-in-service and the calendar limit. (Compliance)","Technical steps are delegated to the manufacturer’s mandatory service bulletin, so the work requires qualified maintenance providers and adherence to prescribed procedures. (Requirement)","Potential need to access internal fuel tank components (draining, depressurising, specialised inspection) increases practical maintenance complexity and downtime. (Requirement)","Enforcement and effective outcome depend on maintenance execution quality; the AD prescribes the action but not the micro-level quality control. (Requirement; Background)"],"plain_english_summary":"This AD requires owners/operators of specified Socata TB9/TB10 (Tobago) aeroplanes to inspect fuel-tank internal ribs for blocked drain holes and remove any obstructing sealant, performed per Socata Mandatory Service Bulletin 10.084.57. It applies to listed serial-number ranges (and earlier serials with tank repairs since Mod No.78). Compliance is due by the earlier of 100 flight hours after 2 Mar 1995 or before 31 Dec 1995. Direct costs and downtime are borne by aircraft owners/operators."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tb10-23-fuel-tank-internal-ribs","history":"/api/acts/ad-tb10-23-fuel-tank-internal-ribs/history","analysis":"/api/acts/ad-tb10-23-fuel-tank-internal-ribs/analysis","conflicts":"/api/acts/ad-tb10-23-fuel-tank-internal-ribs/conflicts","importantCases":"/api/acts/ad-tb10-23-fuel-tank-internal-ribs/important-cases","documents":"/api/acts/ad-tb10-23-fuel-tank-internal-ribs/documents"}}