{"id":"F2006B04727","name":"AD/BN-2/16 - Carburettor Air Box - Modification","slug":"ad-bn-2-16-carburettor-air-box-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44491,"registerId":"commonwealth-F2006B04727-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BN-2/16 - Carburettor Air Box - Modification","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)  Pilatus Britten-Norman BN-2 Series Aeroplanes\n\n \n\nAD/BN-2/16 Carburettor Air Box - Modification NK\n\nApplicability: All models not incorporating Mod. No. NB/M/362. Document:  Britten-Norman SB No. BN-2/SB.28.\n\nCompliance: Within 25 hours time in service after 29 May 1970.\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\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 from 1970. It has not expanded beyond its original narrow purpose of mandating a specific safety modification to the carburettor air box on BN-2 aircraft."},"complexity_factors":["Extremely short document (single page)","Only 4 operative provisions: applicability, reference document, compliance deadline, and aircraft type","No defined terms section","No cross-references to other legislation beyond the enabling Civil Aviation Regulations 1998","Simple conditional logic (applies to all models NOT incorporating a specific modification)","Single compliance action required"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by the Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998.\n\n**What it does:** It requires owners and operators of **Pilatus Britten-Norman BN-2 series aircraft** (commonly known as Islander aircraft) to modify the **carburettor air box** — a component that supplies air to the engine's fuel mixing system.\n\n**Who must comply:** Anyone operating a BN-2 aircraft that does **not** already have Modification No. NB/M/362 installed.\n\n**What must be done:** The modification must be carried out following the manufacturer's Service Bulletin BN-2/SB.28.\n\n**When:** Within 25 hours of flight time after 29 May 1970.\n\n**Why it matters:** Airworthiness Directives are legally binding safety instructions. Non-compliance means the aircraft cannot legally fly. This particular directive addresses a specific technical defect or safety risk in the carburettor air intake system that could affect engine performance or safety."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The provided instrument itself defines a narrow scope: BN‑2 series aircraft not incorporating Mod. No. NB/M/362 must be modified per BN‑2/SB.28 within 25 hours TIS after 29 May 1970. There is no information in the text supplied that indicates a change from an earlier or original scope; therefore no change from original intent can be identified from the material provided. (Applicability; Document; Compliance)"},"complexity_factors":["Single, narrowly framed mandatory action (modify carburettor air box). (title)","Clear applicability clause: only BN-2 models not incorporating Mod. NB/M/362. (Applicability)","Short, fixed compliance deadline (25 hours time in service after 29 May 1970). (Compliance)","Dependence on an external technical document (Britten‑Norman SB BN‑2/SB.28) for implementation details. (Document)","No alternative compliance paths, exemptions or staged requirements stated in the text, reducing procedural complexity. (entire instrument)"],"plain_english_summary":"What this instrument does (mechanically)\n\n- Requires a specific modification to the carburettor air box on Pilatus Britten-Norman BN-2 series aeroplanes that do not already have Modification No. NB/M/362. (Applicability)\n- Directs that the modification be carried out in accordance with Britten-Norman Service Bulletin BN-2/SB.28. (Document)\n- Sets a mandatory compliance deadline: the work must be completed within 25 hours time in service after 29 May 1970. (Compliance)\n\nWho this affects\n\n- Aircraft owners and operators of Pilatus Britten-Norman BN-2 series aeroplanes that have not had Mod. No. NB/M/362 fitted. (Applicability)\n- Maintenance organisations, mechanics and parts suppliers engaged to perform the modification, because they must carry out the work to the manufacturer's service bulletin. (Document)\n- The Civil Aviation Safety Authority (CASA) as the issuing authority and enforcer, by virtue of this being an airworthiness directive. (header)\n\nWhy it matters (purpose-claim and practical consequences)\n\n- As an airworthiness directive, it directs a mandatory technical change to aircraft equipment; the stated instrument name indicates the change concerns the carburettor air box. The document itself does not set out the safety rationale in detail, so the directive’s practical effect is to require a field modification to restore or maintain airworthiness. (title; Applicability; Document)\n\nWho pays, who decides, and what behaviour changes\n\n- Who pays: aircraft owners/operators pay for parts, labour, and any aircraft downtime required to complete the modification. (Applicability; Compliance)\n- Who decides: the regulator issued the directive; the work must be carried out in accordance with the manufacturer’s service bulletin, so the manufacturer prescribes the technical method. (header; Document)\n- Behaviour changes required: affected aircraft must be modified within the specified 25‑hour time window or otherwise be out of compliance with this directive. Maintenance providers must schedule and perform the modification per BN-2/SB.28. (Compliance; Document)\n\nCosts, incentives, trade-offs, and implementation considerations\n\n- Immediate costs and burdens: parts, labour and aircraft downtime to effect the modification. These are borne by owners/operators. (Applicability; Compliance)\n- Timing pressure: a 25‑hour time‑in‑service compliance window from a fixed date creates a short scheduling horizon for affected operators. That increases the risk of aircraft being grounded until the modification is done. (Compliance)\n- Dependency on external document: the AD mandates compliance by reference to the Britten‑Norman service bulletin BN‑2/SB.28, so the exact technical steps, parts list and labour estimate depend on that bulletin. This links regulatory compliance to manufacturer-provided instructions. (Document)\n- Enforcement and discretion: the directive sets a mandatory requirement and a fixed deadline; the text gives no discretion for alternative methods or later timelines within this instrument. Enforcement actions, if any, would be taken by the regulator. (header; Compliance)\n\nPotential concentrated and diffuse effects (based on the instrument’s mechanics)\n\n- Concentrated effects: maintenance providers and parts suppliers who carry out the modification will receive immediate work. (Document)\n- Diffuse effects: the direct costs (parts, labour, downtime) are spread across the set of affected aircraft owners/operators. (Applicability; Compliance)\n\nRisks and substitution effects\n\n- Implementation risk: if parts, qualified personnel, or workshop availability are limited, affected aircraft may be grounded until the modification is completed. (Document; Compliance)\n- Substitution: the directive requires the specific modification per the service bulletin; the instrument does not specify approved alternatives, so substitution is constrained unless the regulator or manufacturer provides an approved equivalent elsewhere. (Document)\n\nSource citations: the summary is based on the instrument header, the \"Applicability\", \"Document\" and \"Compliance\" lines in the provided text."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bn-2-16-carburettor-air-box-modification","history":"/api/acts/ad-bn-2-16-carburettor-air-box-modification/history","analysis":"/api/acts/ad-bn-2-16-carburettor-air-box-modification/analysis","conflicts":"/api/acts/ad-bn-2-16-carburettor-air-box-modification/conflicts","importantCases":"/api/acts/ad-bn-2-16-carburettor-air-box-modification/important-cases","documents":"/api/acts/ad-bn-2-16-carburettor-air-box-modification/documents"}}