{"id":"F2006B07282","name":"AD/TB10/15 - Oil Cooler Inlet And Outlet Elbows","slug":"ad-tb10-15-oil-cooler-inlet-and-outlet-elbows","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49231,"registerId":"commonwealth-F2006B07282-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TB10/15 - 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) TB9 and TB10 (Tobago) Series Aeroplanes\n\n \n\nAD/TB10/15 Oil Cooler Inlet And Outlet Elbows 1/91\n\nApplicability: All model TB9 and TB10 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, time-bound safety directive addressing a specific mechanical defect in specific aircraft models. It has not expanded beyond its original purpose of mandating repairs to oil cooler elbows."},"complexity_factors":["Extremely short document (under 200 words)","Only 2 substantive requirements: identify affected aircraft and follow external service bulletin","No defined terms section","No cross-references to other legislation (only a reference to a French aviation authority document and a manufacturer service bulletin)","Simple unconditional command structure ('Action in accordance with...')","Single compliance date with no exceptions or alternative methods"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it like a compulsory recall notice, but for aircraft instead of cars.\n\n**What it does:** It requires owners and operators of specific **Socata TB9 and TB10 \"Tobago\" light aircraft** to inspect and fix a dangerous problem with the **oil cooler inlet and outlet elbows** (the metal fittings that carry oil to cool the engine). These elbows were leaking, causing complete engine oil loss — which can lead to catastrophic engine failure mid-flight.\n\n**Who must act:** Anyone who owns or operates a Socata TB9 or TB10 aircraft.\n\n**What they must do:** Follow the repair instructions in **Socata Service Bulletin NR 50-1** (the manufacturer's official fix-it guide).\n\n**When:** The work had to be completed **before 31 January 1991**.\n\n**Why it matters:** Total engine oil loss means engine seizure and likely crash. This AD was issued after incidents proved the defect was real and deadly. Compliance was mandatory — flying without fixing this was illegal and dangerous."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Based on the text supplied, the AD's scope is the same as its stated purpose: it mandates corrective action for oil cooler inlet and outlet elbows on all TB9 and TB10 aircraft by requiring compliance with Socata Service Bulletin NR 50-1 prior to 31 January 1991. There is no indication in the document that the scope extends beyond those models, that it alters the technical remedy beyond the referenced service bulletin, or that it changes over time."},"complexity_factors":["Narrow applicability: applies only to Socata TB9 and TB10 models (Applicability).","Single, externally-referenced corrective action: compliance requires following Socata Service Bulletin NR 50-1 rather than detailed steps in the AD (Requirement).","Fixed, near-term deadline creates a time-pressure compliance obligation (Compliance).","Safety-critical technical issue: the Background links the defect to total engine oil loss, increasing urgency but not expanding scope (Background).","Cross-reference to a foreign authority AD (DGAC AD 90-143(A)) requires operators to be aware of related international documentation (Note)."],"plain_english_summary":"# What this directive does\n\n- This Airworthiness Directive (AD/TB10/15) requires all Socata TB9 and TB10 aircraft to have corrective work done on the oil cooler inlet and outlet elbows. (Applicability; Requirement)\n- The required work is to be performed in accordance with Socata Service Bulletin NR 50-1. (Requirement)\n- The work must be completed before 31 January 1991. (Compliance)\n\n# Why it was issued\n\n- The directive says oil leakage from the oil cooler inlet and outlet elbows has previously resulted in total engine oil loss. The manufacturer service bulletin is referenced as the means to address that fault. (Background; Requirement)\n- The AD also refers to a related DGAC airworthiness directive. (Note)\n\n# Who it affects and who decides\n\n- Who pays: owners/operators of TB9 and TB10 aircraft are responsible for having the work carried out. (Applicability; Requirement)\n- Who decides: the Civil Aviation Safety Authority issued the AD and makes compliance mandatory; the AD delegates the technical prescription to Socata's Service Bulletin NR 50-1. (Requirement)\n\n# What behaviour changes and the practical mechanics\n\n- Aircraft operators must obtain and implement the instructions in Service Bulletin NR 50-1 for each affected aircraft before the compliance date. (Requirement; Compliance)\n- Compliance is binary and time-limited: either the aircraft has the service performed by the deadline or it remains non-compliant with the AD. (Compliance)\n\n# Costs, incentives, trade-offs and implementation risks (source-grounded)\n\n- Direct cost and time: carrying out the service bulletin will require parts, labour and aircraft downtime; those costs fall on the aircraft owner/operator. (Requirement)\n- Risk reduction vs cost: the AD replaces the operator's choice with a mandatory action intended to reduce the risk of total engine oil loss identified in the Background. Operators trade the immediate cost and downtime of the mandated maintenance for a reduced risk of oil loss. (Background; Requirement)\n- Implementation dependency: to comply, operators must obtain and follow Socata Service Bulletin NR 50-1; the AD does not itself set the technical steps. This delegates technical detail to the manufacturer document referenced by the AD. (Requirement)\n- Regulatory alignment: the AD cross-references DGAC AD 90-143(A), indicating the measure aligns with a corresponding foreign authority action. (Note)\n\n# Compliance burden and discretion\n\n- Compliance burden: the AD creates an enforceable maintenance obligation with a calendar deadline (prior to 31 January 1991). Operators must schedule, fund and complete the work. (Compliance; Requirement)\n- Bureaucratic discretion: the regulator mandates compliance but the specific technical remedy is taken from the manufacturer's service bulletin; the AD therefore constrains operator choice while relying on the manufacturer's technical instructions. (Requirement)\n\n# Implementation risks and opportunity costs\n\n- If operators delay or omit the mandated action, the background states there is an existing risk that leakage can lead to total engine oil loss; the AD makes the remedial action compulsory to mitigate that risk. (Background; Requirement)\n- Opportunity cost: time and resources spent complying cannot be used elsewhere during the required maintenance window (Compliance; Requirement).\n\n(References: Applicability; Requirement; Note; Compliance; Background)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-tb10-15-oil-cooler-inlet-and-outlet-elbows","history":"/api/acts/ad-tb10-15-oil-cooler-inlet-and-outlet-elbows/history","analysis":"/api/acts/ad-tb10-15-oil-cooler-inlet-and-outlet-elbows/analysis","conflicts":"/api/acts/ad-tb10-15-oil-cooler-inlet-and-outlet-elbows/conflicts","importantCases":"/api/acts/ad-tb10-15-oil-cooler-inlet-and-outlet-elbows/important-cases","documents":"/api/acts/ad-tb10-15-oil-cooler-inlet-and-outlet-elbows/documents"}}