{"id":"F2006B07335","name":"AD/TB20/30 - Fuel Tank Internal Ribs","slug":"ad-tb20-30-fuel-tank-internal-ribs","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49391,"registerId":"commonwealth-F2006B07335-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TB20/30 - 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) TB20 (Trinidad) Series Aeroplanes\n\nAD/TB20/30 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, time-bound safety directive addressing a specific manufacturing defect. It has not expanded beyond its original purpose of ensuring fuel tank drain holes remain unobstructed."},"complexity_factors":["Single, specific technical requirement (inspect and clear drain holes)","Limited applicability (specific aircraft serial numbers only)","No nested exceptions or conditional logic","Only 2 defined reference documents (the Service Bulletin and the French DGAC AD)","Clear, fixed compliance deadline","Short document (approximately 150 words)"],"plain_english_summary":"**What this is:** 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:** It requires owners and operators of certain Socata TB20 Trinidad aeroplanes to inspect their fuel tanks. Specifically, they must check that small drain holes in the internal ribs (structural supports inside the fuel tank) aren't blocked by sealant. Blocked drain holes could trap fuel or moisture, creating safety risks.\n\n**Who must comply:** Owners/operators of TB20 aircraft with specific serial numbers listed in the directive — mainly aircraft built between certain serial number ranges, plus some older aircraft that had a particular repair done.\n\n**What action is required:** Follow the instructions in Socata's Mandatory Service Bulletin 10.084.57 (the manufacturer's official repair/inspection guide).\n\n**When it must be done:** Within 100 hours of flying time after 2 March 1995, or before 31 December 1995 — whichever comes first.\n\n**Why it matters:** Blocked drain holes in fuel tanks can lead to fuel trapping, corrosion, or other hazardous conditions. This directive prevents potential fuel system failures or fire risks."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The instrument, as presented, applies to a specified set of TB20 serial numbers (and to earlier serials where the tank rib was repaired since modification No.78), requires inspection and clearing of drain holes per Socata Mandatory Service Bulletin 10.084.57, and sets a clear compliance window. Nothing in the text indicates a change from that stated scope or an expansion beyond the stated applicability and requirements (see \"Applicability\", \"Requirement\", \"Compliance\")."},"complexity_factors":["Narrow and explicit applicability expressed as specific serial-number ranges and a conditional clause for repaired tanks (Applicability).","Single, specific required action but procedural detail is deferred to an external document (Socata Mandatory Service Bulletin 10.084.57) (Requirement).","A dual-mode compliance window (100 hours TIS after a date or a fixed calendar cut-off), which creates a concrete scheduling constraint (Compliance).","Reference to an external foreign AD (DGAC AD 94-247(A)) and to a manufacturer service bulletin increases reliance on outside documents for full procedural clarity (Note; Requirement)."],"plain_english_summary":"This directive requires owners/operators of specified Aerospatiale (Socata) TB20 serial-numbered aircraft to have fuel-tank internal rib drain holes inspected and cleared per Socata Mandatory Service Bulletin 10.084.57, within 100 flight hours after 2 March 1995 or by 31 December 1995, whichever is earlier. It responds to sealant‑blocking of drain holes, imposes a one‑off inspection/repair cost and scheduling burden, and is enforced by the Civil Aviation Safety Authority."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tb20-30-fuel-tank-internal-ribs","history":"/api/acts/ad-tb20-30-fuel-tank-internal-ribs/history","analysis":"/api/acts/ad-tb20-30-fuel-tank-internal-ribs/analysis","conflicts":"/api/acts/ad-tb20-30-fuel-tank-internal-ribs/conflicts","importantCases":"/api/acts/ad-tb20-30-fuel-tank-internal-ribs/important-cases","documents":"/api/acts/ad-tb20-30-fuel-tank-internal-ribs/documents"}}