{"id":"F2006B02452","name":"AD/ARRIEL/5 - Gas Generator Rear Bearing Oil Pipe","slug":"ad-arriel-5-gas-generator-rear-bearing-oil-pipe","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41708,"registerId":"commonwealth-F2006B02452-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ARRIEL/5 - Gas Generator Rear Bearing Oil Pipe","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nTurbomeca Turbine Engines \\- Arriel Series\n\nAD/ARRIEL/5 Gas Generator Rear Bearing Oil Pipe 12/86\n\nApplicability: Arriel 1A, 1A1, 1A2, 1B, 1C, 1C1, 1M engines.\n\nRequirement: Incorporate Turbomeca modification TU 144 in accordance with Turbomeca Service No. 72-292-0088.\n\nReference Document : Bureau Veritas Directive 86-147(B).\n\nCompliance: 1. Before installation in an aircraft.\n\n2. Not later than 30 November 1986.\n\nBackground: This Directive has been issued to reflect the requirements of Bureau Veritas Directive No. 86-147(B). The Directive requires the gas generator rear bearing oil pipe to be modified to prevent a failure which could result in an oil fire. Aerospatiale has recently advised of an inflight oil fire in an SA 365 Dauphin which resulted from rupture of the gas generator oil pressure pipe.","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 failure mode in specific engine models. It has not expanded beyond its original purpose of mandating a single modification to prevent oil fires."},"complexity_factors":["Very short document (approximately 150 words)","Only 7 engine models listed in applicability section","Single, unambiguous compliance requirement (install modification TU 144)","Clear deadline with only two alternative compliance paths","No defined terms section, no cross-references to other legislation beyond the reference document","Simple causal chain: identified hazard (oil fire) → specific mechanical fix → compliance deadline"],"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 as a \"recall notice\" for aircraft engines, but with legal force. If you don't comply, you can't legally fly.\n\n**What it does:** It requires a specific safety modification to certain Turbomeca Arriel helicopter engines. The fix involves installing a modified oil pipe (called \"modification TU 144\") to prevent the pipe from rupturing and causing an engine fire.\n\n**Who it affects:** Owners and operators of helicopters using Arriel 1A, 1A1, 1A2, 1B, 1C, 1C1, or 1M model engines. This includes aircraft like the Aerospatiale SA 365 Dauphin.\n\n**Why it matters:** A ruptured oil pipe can spray hot oil onto engine components, causing an in-flight fire. This actually happened — an SA 365 Dauphin experienced an inflight fire due to this exact failure. The directive prevents that catastrophic scenario.\n\n**When you must comply:** \n- **Immediately** — before installing the engine in any aircraft; OR\n- **No later than 30 November 1986** — for engines already in service.\n\n**The bottom line:** If you operate one of these engines, you must get this pipe modification done by the deadline. It's not optional — it's a legal requirement for airworthiness."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The Directive states it was issued to reflect the requirements of Bureau Veritas Directive No. 86-147(B) (Background). It requires the same modification and references the same external document, so it does not expand the covered engines or introduce additional measures beyond reflecting that directive."},"complexity_factors":["Narrow applicability: specific engine models listed (Applicability).","Single mandatory technical action: incorporate Turbomeca modification TU 144 per Turbomeca Service No. 72-292-0088 (Requirement).","Two straightforward compliance deadlines: before installation and a fixed calendar date (Compliance: 1–2).","Dependence on external technical documents for implementation (Reference Document; Requirement).","Safety-critical subject matter increases operational importance despite procedural simplicity (Background)."],"plain_english_summary":"This Directive, issued by the Civil Aviation Safety Authority, mandates Turbomeca modification TU 144 (per Service No. 72‑292‑0088) to the gas‑generator rear bearing oil pipe on Arriel 1-series engines to prevent oil‑pipe rupture and a possible inflight oil fire. It must be done before engine installation (or by 30 Nov 1986 for engines already in service) and references Bureau Veritas Directive 86‑147(B); responsibility falls to engine installers/maintainers."}},"importantCases":[],"_links":{"self":"/api/acts/ad-arriel-5-gas-generator-rear-bearing-oil-pipe","history":"/api/acts/ad-arriel-5-gas-generator-rear-bearing-oil-pipe/history","analysis":"/api/acts/ad-arriel-5-gas-generator-rear-bearing-oil-pipe/analysis","conflicts":"/api/acts/ad-arriel-5-gas-generator-rear-bearing-oil-pipe/conflicts","importantCases":"/api/acts/ad-arriel-5-gas-generator-rear-bearing-oil-pipe/important-cases","documents":"/api/acts/ad-arriel-5-gas-generator-rear-bearing-oil-pipe/documents"}}