{"id":"F2006B07322","name":"AD/TB20/19 - Oil Cooler Inlet and Outlet Elbows","slug":"ad-tb20-19-oil-cooler-inlet-and-outlet-elbows","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49352,"registerId":"commonwealth-F2006B07322-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TB20/19 - Oil Cooler Inlet and Outlet Elbows","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/TB20/19 Oil Cooler Inlet and Outlet Elbows 1/91\n\nApplicability: All model TB20 and TB21 aircraft.\n\n \n\nRequirement: Action in accordance with Socata Service Bulletin NR 50-1.\n\n \n\nNote: DGAC AD 90-143(A) refers.\n\n \n\nCompliance: Prior to 31 January 1991.\n\n \n\nBackground: Leakage from the oil cooler inlet and outlet elbow has resulted in total engine oil loss.\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\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, single-issue airworthiness directive focused specifically on oil cooler elbow defects in two aircraft models. It has not expanded beyond its original narrow safety purpose."},"complexity_factors":["Extremely short document (under 200 words)","Only 1 substantive requirement (comply with referenced service bulletin)","No defined terms section","No conditional logic or nested exceptions","Single cross-reference to French aviation authority directive (DGAC AD 90-143(A))","Clear, unambiguous applicability (two specific aircraft models)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It applies to specific French-made aircraft: the **Aerospatiale (Socata) TB20 and TB21 Trinidad series**.\n\n**What it does:**\n- Requires owners/operators to inspect or replace the **oil cooler inlet and outlet elbows** (metal pipe connections that carry engine oil to the cooling system)\n- The work must follow instructions in **Socata Service Bulletin NR 50-1** (the manufacturer's official repair notice)\n\n**Why it matters:**\n- These elbows were found to leak, causing **complete engine oil loss** — which can lead to catastrophic engine failure and potential crashes\n- The directive was issued to prevent accidents before they happen\n\n**Who must comply:**\n- Anyone operating TB20 or TB21 aircraft in Australia\n- Compliance was required **before 31 January 1991** (this is a historical directive, now long past its deadline)\n\n**Key point:** This is a **retrospective safety mandate** — not new law, but a specific technical order that was binding on aircraft operators at the time."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive’s scope is stated as applying to all TB20 and TB21 aircraft and mandating the actions in Socata Service Bulletin NR 50-1 to be completed before 31 January 1991. The text contains no indication that the scope was changed from the action it prescribes; the stated requirement, applicability and compliance deadline are internally consistent."},"complexity_factors":["Narrow technical scope limited to oil cooler inlet and outlet elbows on TB20/TB21 aircraft (Applicability; Background).","Single required action: comply with Socata Service Bulletin NR 50-1 (Requirement) — reduces procedural complexity but creates reliance on an external document.","Fixed compliance date (prior to 31 January 1991) imposes a simple temporal constraint (Compliance).","Safety-critical consequence (total engine oil loss) increases urgency but not legal complexity (Background).","Implementation complexity depends on availability of the referenced service bulletin, parts and maintenance capability rather than on the AD text itself (Requirement)."],"plain_english_summary":"Owners/operators of Aerospatiale (Socata) TB20 and TB21 aircraft must carry out the work in Socata Service Bulletin NR 50‑1 on the oil cooler inlet and outlet elbows by 31 January 1991. Issued by the Civil Aviation Safety Authority under the Civil Aviation Regulations, the AD aims to reduce oil‑leak risk that has led to total engine oil loss. Operators bear the costs, and compliance depends on access to the specified service bulletin, parts and maintenance capability."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tb20-19-oil-cooler-inlet-and-outlet-elbows","history":"/api/acts/ad-tb20-19-oil-cooler-inlet-and-outlet-elbows/history","analysis":"/api/acts/ad-tb20-19-oil-cooler-inlet-and-outlet-elbows/analysis","conflicts":"/api/acts/ad-tb20-19-oil-cooler-inlet-and-outlet-elbows/conflicts","importantCases":"/api/acts/ad-tb20-19-oil-cooler-inlet-and-outlet-elbows/important-cases","documents":"/api/acts/ad-tb20-19-oil-cooler-inlet-and-outlet-elbows/documents"}}