{"id":"F2006B04780","name":"AD/BN-2/68 - Rudder Lower Hinge Doubler","slug":"ad-bn-2-68-rudder-lower-hinge-doubler","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44556,"registerId":"commonwealth-F2006B04780-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BN-2/68 - Rudder Lower Hinge Doubler","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-2/68 Rudder Lower Hinge Doubler 6/99\n\nApplicability: Model BN2, BN2A, BN2B, and BN2T Islander aircraft.\n\n \n\nRequirement: Action in accordance with Britten Norman Mandatory Service Bulletin BN2/SB.240. Compliance:              Before 17 July 1999.\n\nThis Airworthiness Directive becomes effective on 17 June 1999.\n\n \n\nBackground: The manufacturer received reports of damage to the rudder lower hinge. This Directive requires installation of a doubler at the left and right side of the rudder lower hinge bracket.\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, one-off airworthiness directive with a narrow, specific scope (rudder hinge reinforcement on four specific aircraft models). It has not expanded beyond its original safety purpose."},"complexity_factors":["Single, specific technical requirement (install doubler per manufacturer's bulletin)","Only 4 aircraft models affected, clearly listed","No conditional logic, exceptions, or nested provisions","No defined terms section — uses plain technical language","Single compliance deadline with no alternative methods or phased implementation","Background explanation included but not legally operative"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially 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 certain **Pilatus Britten-Norman Islander aircraft** (models BN2, BN2A, BN2B, and BN2T) to install a reinforcing metal plate called a \"doubler\" on both the left and right sides of the rudder's lower hinge bracket.\n\n**Why it matters:**\n- The manufacturer received reports of **damage to the rudder lower hinge** — a critical flight control component. If this hinge fails, the pilot could lose control of the aircraft's yaw (side-to-side movement), potentially causing a crash.\n- The \"doubler\" strengthens the hinge bracket to prevent structural failure.\n\n**Who must comply:**\n- Anyone operating the affected Islander aircraft models.\n- **Deadline:** The repair had to be completed before 17 July 1999.\n\n**In short:** This was an urgent safety fix to prevent rudder failure on a specific type of small aircraft commonly used for regional transport and island hopping."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD’s scope is limited to the specified BN2 family models and mandates a single structural modification per the manufacturer’s service bulletin. Nothing in the text indicates an expansion or narrowing of that scope from its stated purpose: it requires installation of the doubler on left and right sides of the rudder lower hinge bracket for the listed models, to be completed by the compliance date. (Applicability; Requirement; Background; Compliance)"},"complexity_factors":["Narrow applicability to four specific aircraft models (Applicability)","Single, discrete technical modification required: installation of a doubler on each side of the rudder lower hinge bracket (Requirement; Background)","Mandatory reliance on an external technical document (Britten Norman Mandatory Service Bulletin BN2/SB.240) for how to perform the work (Requirement)","Short, fixed compliance window between effective date and compliance date (Effective date; Compliance)"],"plain_english_summary":"What this directive does (mechanically)\n\n- This Airworthiness Directive (AD/BN-2/68) requires that operators of certain Pilatus Britten‑Norman Islander aeroplanes install a metal reinforcing plate (a \"doubler\") on both the left and right sides of the rudder lower hinge bracket. (Requirement)\n- The work must be carried out in accordance with Britten Norman Mandatory Service Bulletin BN2/SB.240. (Requirement)\n- The AD applied to Model BN2, BN2A, BN2B and BN2T Islander aircraft. (Applicability)\n- The AD was effective from 17 June 1999 and required compliance before 17 July 1999. (Effective date / Compliance)\n\nWhy the directive was issued (official rationale, attributed)\n\n- The background provided states the manufacturer received reports of damage to the rudder lower hinge. The AD sets the mandatory action of installing the doubler on each side of the rudder lower hinge bracket to address that reported damage. (Background; Requirement)\n\nWho decides, who pays, and what changes\n\n- Decision and instruction: The Civil Aviation Safety Authority issued the directive; the required technical method is the manufacturer’s Mandatory Service Bulletin BN2/SB.240. (Requirement)\n- Who is affected: Owners/operators of the specified BN2 series aircraft are required to comply. (Applicability)\n- Who pays: The text requires operators to carry out the installation, so the direct costs of parts and labour for installing the doubler fall to those operators. (Requirement; Applicability)\n- Behavioural change: Operators must schedule and complete the mandated modification within the compliance window and use the specified service bulletin as the method. (Requirement; Compliance)\n\nImplementation, incentives and trade-offs (source‑grounded observations)\n\n- Compliance method: The AD delegates the technical details to the manufacturer’s Mandatory Service Bulletin, so compliance depends on following that external document rather than specifying installation steps in the AD itself. This concentrates the AD’s technical discretion in the referenced service bulletin. (Requirement)\n- Timing constraint: The AD sets a short compliance window (effective 17 June 1999; comply before 17 July 1999). Operators needed to allocate resources and schedule the work within that timeframe. (Effective date; Compliance)\n- Scope and concentration of effect: The mandate applies only to four BN‑2 family models listed, so the costs and work are concentrated on operators of those models. (Applicability)\n- Compliance burden: The obligation to install the doubler creates an immediate maintenance task that operators must arrange and pay for; the AD does not itself state who performs the work, but requires adherence to the manufacturer’s mandatory instructions. (Requirement)\n\nRisks and practical considerations (implementation risk, substitution effects)\n\n- The AD addresses a specific structural issue reported by the manufacturer; successful mitigation depends on correct installation as specified in the service bulletin. (Background; Requirement)\n- Because the AD references the manufacturer’s service bulletin for the required action, improper or incomplete application of that bulletin would leave the directive’s purpose unmet; the AD does not set out enforcement or inspection detail beyond the compliance date. (Requirement)\n\nSource citations\n\n- Applicability: \"Model BN2, BN2A, BN2B, and BN2T Islander aircraft.\" (Applicability)\n- Requirement: \"Action in accordance with Britten Norman Mandatory Service Bulletin BN2/SB.240.\" (Requirement)\n- Compliance: \"Before 17 July 1999.\" (Compliance)\n- Effective date: \"This Airworthiness Directive becomes effective on 17 June 1999.\" (Effective date)\n- Background: \"The manufacturer received reports of damage to the rudder lower hinge. This Directive requires installation of a doubler at the left and right side of the rudder lower hinge bracket.\" (Background)\n"}},"importantCases":[],"_links":{"self":"/api/acts/ad-bn-2-68-rudder-lower-hinge-doubler","history":"/api/acts/ad-bn-2-68-rudder-lower-hinge-doubler/history","analysis":"/api/acts/ad-bn-2-68-rudder-lower-hinge-doubler/analysis","conflicts":"/api/acts/ad-bn-2-68-rudder-lower-hinge-doubler/conflicts","importantCases":"/api/acts/ad-bn-2-68-rudder-lower-hinge-doubler/important-cases","documents":"/api/acts/ad-bn-2-68-rudder-lower-hinge-doubler/documents"}}