{"id":"F2006B02451","name":"AD/ARRIEL/4 - Turbine Case Identification Plate Removal","slug":"ad-arriel-4-turbine-case-identification-plate-removal","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41707,"registerId":"commonwealth-F2006B02451-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ARRIEL/4 - Turbine Case Identification Plate Removal","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 - 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Turbomeca Turbine Engines - Arriel Series\n\n \n\nAD/ARRIEL/4 Turbine Case Identification Plate Removal 8/86\n\nApplicability: All Arriel Series I engines.\n\n \n\nRequirement: Action in accordance with Bureau Veritas Directive 86-29(B).\n\n \n\nReference Document - Turbomeca S.B. Arriel No. 72-292-0093.\n\n \n\nCompliance: In accordance with Requirement Document.\n\n \n\nBackground: This Directive has been issued to require compliance with Bureau Veritas Directive 86-29(B). The Directive requires removal of the turbine module identification plate to allow inspection of the turbine case for corrosion. This requirement has become necessary following blow-out of a turbine case in service with a reported loss of power.\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":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The text provided sets a single, specific change: mandatory removal of the turbine module identification plate on Arriel Series I engines to permit inspection for corrosion, required to be carried out in accordance with Bureau Veritas Directive 86-29(B) and referencing Turbomeca S.B. Arriel No. 72-292-0093 (\"Applicability\"; \"Requirement\"; \"Reference Document\"). Nothing in the instrument text indicates an expansion or contraction of that scope from the stated purpose in the Background (which links the requirement to a turbine case blow-out and loss of power). Therefore the scope as described appears unchanged from the stated original intent in the AD text."},"complexity_factors":["Narrow technical scope: applies only to Turbomeca Arriel Series I engines (\"Applicability\").","Delegation to external technical documents (Bureau Veritas Directive 86-29(B) and Turbomeca S.B. Arriel No. 72-292-0093) for procedural detail (\"Requirement\"; \"Reference Document\").","Safety-critical maintenance action requiring physical access and potential downtime and repair (\"Requirement\"; \"Background\").","Clear regulatory provenance but limited textual detail in the AD itself — operational specifics are in the referenced documents (header; \"Compliance\")."],"plain_english_summary":"This AD requires removal of the turbine-module identification plate on Turbomeca Arriel Series I engines to permit inspection of the turbine case for corrosion following a reported case failure. It is mandatory for affected operators and delegates the inspection and corrective- action procedures to Bureau Veritas Directive 86‑29(B) and Turbomeca SB 72‑292‑0093, with operators bearing labour, downtime and repair costs."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue safety directive addressing a specific mechanical failure mode. It has not expanded beyond its original purpose of preventing turbine case failures due to corrosion."},"complexity_factors":["Very short document (under 200 words)","Only 1 defined applicability criterion ('All Arriel Series I engines')","No nested exceptions or conditional logic — single mandatory action","No cross-references to other legislation or regulations beyond the two technical documents","Straightforward linear structure: applicability → requirement → compliance → background"],"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) for aircraft engines.\n\n**What it does:** It requires owners and operators of **Turbomeca Arriel Series I turbine engines** to remove a specific identification plate from the turbine module (the hot, spinning part of the engine). This allows mechanics to inspect the turbine case (the outer shell) for **corrosion** (rust or deterioration from heat and moisture).\n\n**Why it matters:** A turbine case blew out on an engine in service, causing a loss of power. This could lead to engine failure in flight — potentially catastrophic for helicopters or aircraft using these engines. The directive prevents this by ensuring hidden corrosion is found before it causes structural failure.\n\n**Who must comply:** Anyone operating aircraft with Arriel Series I engines (commonly used in helicopters like the Eurocopter AS350 and EC130).\n\n**How to comply:** Follow the specific instructions in **Bureau Veritas Directive 86-29(B)** and **Turbomeca Service Bulletin 72-292-0093** — technical documents that detail exactly how to remove the plate and inspect the case."}},"importantCases":[],"_links":{"self":"/api/acts/ad-arriel-4-turbine-case-identification-plate-removal","history":"/api/acts/ad-arriel-4-turbine-case-identification-plate-removal/history","analysis":"/api/acts/ad-arriel-4-turbine-case-identification-plate-removal/analysis","conflicts":"/api/acts/ad-arriel-4-turbine-case-identification-plate-removal/conflicts","importantCases":"/api/acts/ad-arriel-4-turbine-case-identification-plate-removal/important-cases","documents":"/api/acts/ad-arriel-4-turbine-case-identification-plate-removal/documents"}}