{"id":"F2006B10382","name":"AD/HS 125/104 - Engine Exhaust Duct","slug":"ad-hs-125-104-engine-exhaust-duct","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116029,"registerId":"commonwealth-F2006B10382-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HS 125/104 - Engine Exhaust Duct","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)  British Aerospace BAe 125 Series Aeroplanes\n\n \n\nAD/HS 125/104 Engine Exhaust Duct 2/90\n\nThis AD contents has been removed from the listing because the aircraft model is not currently on the register.\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":2,"scope_assessment":{"changed":true,"description":"Originally the AD applied to the British Aerospace BAe 125 series with subject \"Engine Exhaust Duct\" (AD/HS 125/104, 2/90). The entry has been removed from the listing because \"the aircraft model is not currently on the register,\" which narrows the instrument's present applicability in the listing to no registered aircraft. The listing does not state whether the AD has been revoked, superseded, archived, or simply omitted pending re-registration, so the change in listing status reduces apparent scope but leaves the formal legal disposition unspecified. (Source: AD title and removal statement.)"},"complexity_factors":["Very short source text with no operative or technical requirements provided","Regulatory context (AD under Part 39) implies technical/regulatory complexity, but details are absent","Removal from listing creates uncertainty about current legal status (cancellation vs. temporary removal)","Limited stakeholders explicitly named (CASA and BAe 125 series), reducing apparent scope"],"plain_english_summary":"- What this instrument is, mechanically:\n  - This is an Airworthiness Directive (AD) issued under the Civil Aviation Regulations 1998, Part 39, titled \"AD/HS 125/104 — Engine Exhaust Duct\" and dated 2/90. (Source: header and AD title.)\n  - An AD is a regulatory instrument that directs action on a specified aircraft type or component; in this case the subject identified is the engine exhaust duct for British Aerospace BAe 125 series aeroplanes. (Source: AD title and type designation.)\n  - The text on the listing for this AD has been removed because \"the aircraft model is not currently on the register.\" (Source: final line of the listing.)\n\n- Who decides and who this affects:\n  - The Civil Aviation Safety Authority (CASA) issues ADs under Part 39 of the Civil Aviation Regulations 1998. (Source: document header.)\n  - An AD of this form would apply to operators and owners of the specified aircraft model while those aircraft are on the Australian register. The listing entry indicates that, at present, there are no aircraft of that model on the register, and the AD contents were therefore removed from the public listing. (Source: AD title and removal statement.)\n\n- Why it matters (purpose-claims and limits of the source):\n  - The AD is framed around the engine exhaust duct, so its stated purpose is to require some corrective or preventive action relating to that component. That purpose-claim is implied by the title; the listing does not provide the operative requirements or corrective actions. (Source: AD title; absence of further text.)\n  - Because the listing entry has been removed for the stated administrative reason (no registered examples of the model), the directive is not presented in the listing as an active compliance obligation for currently registered aircraft. (Source: removal statement.)\n\n- Practical effects, incentives and implementation notes (what can be read from the listing):\n  - If the BAe 125 series were on the register, operators would be the parties required to follow any AD requirements; the listing does not specify the measures, timing, or costs. (Source: AD format and removal statement.)\n  - The listing provides no details about inspection methods, replacement parts, approved repairs, costs, or enforcement mechanisms. That lack of operational detail means the listing alone does not permit assessment of compliance burden, required expenditures, or likely behavioural changes beyond the fact of an AD having been issued. (Source: entire entry.)\n\n- Trade-offs, risks and uncertainty visible in the source:\n  - The only concrete trade-off recorded is administrative: the AD entry was removed from the public listing because the model is not on the register, which narrows the AD's present applicability. The listing does not say whether the AD was cancelled, superseded, archived, or remains in force for aircraft if/when they are registered again. (Source: removal statement; absence of further disposition language.)\n\n- Bottom line in plain terms:\n  - This listing records that an airworthiness directive titled AD/HS 125/104 (Engine Exhaust Duct) existed for the BAe 125 series (issued 2/90), but the AD’s text has been removed from the listing on the stated ground that that aircraft model is not currently on the Australian register. The listing does not provide the AD’s operative requirements or cost/implementation details, so it does not allow a concrete assessment of compliance burdens or economic effects beyond the administrative change in listing status. (Source: entire entry.)"},"kimi_summary":{"content_quality":"rejected","complexity_score":1,"rejection_reason":"This is a navigation stub or placeholder page indicating an Airworthiness Directive has been removed from the register. It contains no substantive legislative content — only metadata, a title, and a single sentence explaining the directive's removal. There are no operative provisions, requirements, or legal text to analyse.","scope_assessment":{"changed":false,"description":"Not applicable — this is a decommissioned regulatory instrument with no active scope."},"complexity_factors":["Document is a stub/placeholder with no operative provisions","No defined terms, cross-references, or conditional logic","Consists entirely of metadata and a single explanatory sentence","No substantive regulatory content to analyse"],"plain_english_summary":"This document is an **Airworthiness Directive (AD)** — a safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific maintenance or inspections on aircraft.\n\n**What it covers:**\n- **Aircraft type:** British Aerospace BAe 125 series business jets\n- **Topic:** Engine exhaust duct (the piping that channels hot exhaust gases away from the engine)\n- **Original issue:** 2/90 (February 1990)\n\n**Current status:**\nThe directive has been **removed from active listings** because no BAe 125 aircraft are currently registered in Australia. This means the safety requirement no longer applies — not because the safety issue was resolved, but because there are no affected aircraft in the country to enforce it against.\n\n**Why this matters:**\nAirworthiness Directives are legally binding safety instructions. When an aircraft type disappears from Australia's register, CASA \"parks\" the associated ADs rather than formally repealing them. This keeps the regulatory record clean while preserving the ability to reactivate the directive if an aircraft of this type returns to Australian skies."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hs-125-104-engine-exhaust-duct","history":"/api/acts/ad-hs-125-104-engine-exhaust-duct/history","analysis":"/api/acts/ad-hs-125-104-engine-exhaust-duct/analysis","conflicts":"/api/acts/ad-hs-125-104-engine-exhaust-duct/conflicts","importantCases":"/api/acts/ad-hs-125-104-engine-exhaust-duct/important-cases","documents":"/api/acts/ad-hs-125-104-engine-exhaust-duct/documents"}}