{"id":"F2006B04758","name":"AD/BN-2/47 - Wing Tip Tank Selector Switches - Modification","slug":"ad-bn-2-47-wing-tip-tank-selector-switches-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44522,"registerId":"commonwealth-F2006B04758-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BN-2/47 - Wing Tip Tank Selector Switches - 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-2/47 Wing Tip Tank Selector Switches - Modification 5/83\n\nApplicability: All models fitted with wing tip tanks. Document: Britten Norman SB No. BN-2/SB 157. Compliance:              Before further flight after 31st Dec. 1983.\n\nBackground: Arising from recommendations contained in the reports of two accidents, the wing tip fuel tank selector switches, system placarding, and selection indicator lamps have been changed by the aircraft manufacturer.\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 issued in response to specific accidents. It has not expanded beyond its original purpose of mandating a specific hardware modification to address identified safety risks."},"complexity_factors":["Very short document (approximately 150 words)","Only 4 defined elements: applicability, document reference, compliance deadline, and background","No cross-references to other legislation or regulations","Single, unambiguous compliance requirement with fixed deadline","No conditional logic, exceptions, or nested provisions","Straightforward mandatory action with clear scope (specific aircraft model + specific equipment)"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\n- Requires owners and operators of **Pilatus Britten-Norman BN-2 series aeroplanes** (small twin-engine aircraft commonly used for regional transport and island hopping) to modify their **wing tip fuel tank selector switches**.\n- The changes also cover related **system placards** (warning/instruction labels) and **selection indicator lamps** (lights showing which tank is selected).\n\n**Who it affects:**\n- Anyone who owns or operates a BN-2 aircraft fitted with **wing tip tanks** — extra fuel tanks mounted at the wing tips.\n\n**Why it matters:**\n- This directive was triggered by **two accidents** where the existing fuel selector switch design may have contributed to the incidents.\n- The manufacturer (Britten-Norman) redesigned the system to prevent confusion about which fuel tank is being used.\n- **Compliance is mandatory** — the work must be done before any further flight after 31 December 1983.\n\n**In short:** If you fly one of these planes with tip tanks, you must get the fuel selector switches upgraded by the deadline or the aircraft cannot legally fly."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD's scope, as stated in the source text, aligns with its stated purpose: it mandates modification of wing tip tank selector switches, system placarding and selection indicator lamps on all BN‑2 models fitted with wing tip tanks. It does not expand beyond those parts or aircraft; it requires implementation per the manufacturer’s service bulletin and sets a firm compliance deadline (Applicability, Document, Compliance, Background)."},"complexity_factors":["Narrow technical scope limited to wing tip tank selector switches, placarding and indicator lamps.","Clear, single compliance deadline: \"Before further flight after 31st Dec. 1983.\"","Applicability plainly limited to BN-2 models fitted with wing tip tanks.","Relies on an external manufacturer service bulletin (Britten Norman SB No. BN-2/SB 157) for technical implementation—AD does not contain the step-by-step technical detail.","Safety rationale referenced (two accident reports) but no quantitative cost/benefit or implementation details in the AD text.","Regulatory form is prescriptive (mandatory before-flight compliance) which reduces interpretive complexity but increases operational impact for owners/operators."],"plain_english_summary":"What this instrument does (mechanics)\n\n- Requires modification of the wing tip fuel-tank selector switches, the system placarding, and the selection indicator lamps on Pilatus Britten‑Norman BN‑2 series aeroplanes that have wing tip tanks (see \"Background\" and \"Document: Britten Norman SB No. BN-2/SB 157\").\n- The technical method for the change is set out by the aircraft manufacturer in the referenced service bulletin (Document: Britten Norman SB No. BN-2/SB 157).\n\nWho it affects and when it must happen\n\n- Applicability: all BN‑2 models fitted with wing tip tanks (\"Applicability\").\n- Compliance timing: the modification must be carried out before the aeroplane is next flown after 31 December 1983 (\"Compliance\").\n- The directive is issued under the Civil Aviation Safety Authority airworthiness-directive regime (header: \"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 ... SCHEDULE OF AIRWORTHINESS DIRECTIVES\").\n\nWhy it was issued (the source claim)\n\n- The directive cites recommendations arising from the reports of two accidents as the reason for the manufacturer changing the selector switches, placarding and indicator lamps (\"Background\"). The AD makes those manufacturer changes mandatory for affected aircraft.\n\nPractical effects, who pays, and what changes in behaviour\n\n- Who pays: aircraft owners/operators of BN‑2 series aeroplanes fitted with wing tip tanks must arrange and pay for the modification (inferred from the Applicability and Compliance requirements). The AD makes the modification a precondition of further flight.\n- What operators must do: locate the service bulletin cited (Britten Norman SB No. BN-2/SB 157) and implement the changes specified there to the switches, placards and lamps before next flight after the stated date (\"Document\" and \"Compliance\").\n- Behavioural effect: operators will have to schedule maintenance or retrofit work (causing aircraft downtime) and use the parts/procedures specified by the manufacturer; until the modification is completed the affected aeroplanes cannot lawfully be flown (per the \"before further flight\" requirement).\n\nCosts, incentives and implementation trade-offs (source-grounded)\n\n- Direct cost and downtime fall on owners/operators because compliance is required before flight (see \"Applicability\" and \"Compliance\").\n- The AD delegates the technical specification to the manufacturer’s service bulletin (\"Document\"), concentrating dependence on the manufacturer for parts and procedures. That concentrates decision-making about how to implement the change with the manufacturer and the maintenance provider.\n- The AD states its safety rationale (recourse to two accident reports) but does not set out quantified benefits or cost estimates in the text provided (\"Background\").\n- Implementation risk and opportunity cost arise from the need to obtain parts, schedule maintenance and temporarily remove aircraft from service; those are implied by the compliance requirement and the reliance on a service bulletin for technical detail (\"Compliance\" and \"Document\").\n\nAdministrative and discretion points\n\n- The directive is prescriptive and time‑bound: compliance is mandatory before further flight after the stated date, which leaves limited operational discretion to delay or phase-in the change for affected aircraft (\"Compliance\").\n- The AD itself provides the mandate but refers to the manufacturer’s service bulletin for the technical method, so regulators and operators will look to that SB for the detailed implementation steps (\"Document\").\n\nSource citations\n\n- Issuing regime: \"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 ... SCHEDULE OF AIRWORTHINESS DIRECTIVES\".\n- Applicability: \"All models fitted with wing tip tanks.\" (Applicability).\n- Technical document: \"Britten Norman SB No. BN-2/SB 157.\" (Document).\n- Compliance deadline: \"Before further flight after 31st Dec. 1983.\" (Compliance).\n- Stated reason: \"Arising from recommendations contained in the reports of two accidents...\" (Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bn-2-47-wing-tip-tank-selector-switches-modification","history":"/api/acts/ad-bn-2-47-wing-tip-tank-selector-switches-modification/history","analysis":"/api/acts/ad-bn-2-47-wing-tip-tank-selector-switches-modification/analysis","conflicts":"/api/acts/ad-bn-2-47-wing-tip-tank-selector-switches-modification/conflicts","importantCases":"/api/acts/ad-bn-2-47-wing-tip-tank-selector-switches-modification/important-cases","documents":"/api/acts/ad-bn-2-47-wing-tip-tank-selector-switches-modification/documents"}}