{"id":"F2006B04767","name":"AD/BN-2/56 - Elevator Trim Cable","slug":"ad-bn-2-56-elevator-trim-cable","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44531,"registerId":"commonwealth-F2006B04767-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BN-2/56 - Elevator Trim Cable","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nPilatus Britten-Norman BN-2 Series Aeroplanes\n\nAD/BN-2/56 Elevator Trim Cable 1/95 DM\n\nApplicability: Model BN2A and 2B Series Islander, and BN2T Turbine Islander aircraft, including those styled Defender; having the Century 31 Autopilot System fitted to Modification NB/M/1271 or Century 2000 Autopilot System fitted to Modification NB/M/1488.\n\nRequirement: Action in accordance with Pilatus Britten-Norman Mandatory Service Bulletin BN- 2/SB 217 Issue 1.\n\nNote: UK CAA AD 007-09-94 refers.\n\nCompliance: Within 50 hours time in service after 9 November 1994, and thereafter at intervals not to exceed 100 hours time in service.\n\nBackground: Reports have been received of wear and eventual fraying of the elevator trim cable splice. Investigation has shown that the positions of the wear and fraying areas on the cable correspond with the positions of the fairleads at frame stations 352.4, 383.45, and 390.6.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope is limited to the listed BN2A/BN2B/BN2T aircraft fitted with the two specified autopilot modifications and requires actions in accordance with the named mandatory service bulletin. The source text does not indicate any expansion or narrowing of that scope beyond these explicit applicability criteria (Applicability; Requirement)."},"complexity_factors":["Narrow technical scope: focuses on elevator trim cable splice wear at specified fairlead/frame stations (Background).","Specific applicability tied to aircraft models and two named autopilot modifications (Applicability).","Mandates compliance with an external document (Pilatus Britten‑Norman Mandatory Service Bulletin BN‑2/SB 217 Issue 1) rather than setting detailed remedial steps in the directive itself (Requirement).","Regular, short compliance intervals with an initial retroactive deadline (within 50 hours after 9 Nov 1994, then every 100 hours) increasing operational scheduling needs (Compliance).","Cross-reference to a foreign regulator’s AD (UK CAA) that may require checking additional material (Note)."],"plain_english_summary":"# What this directive does\n\nThis Airworthiness Directive requires owners/operators of certain Pilatus Britten‑Norman Islander aeroplanes to carry out the maintenance actions set out in Pilatus Britten‑Norman Mandatory Service Bulletin BN‑2/SB 217 Issue 1. The stated aim of those actions is to address wear and eventual fraying of the elevator trim cable splice that has been reported on affected aeroplanes (Requirement; Background).\n\n# Which aircraft are affected\n\nThe directive applies only to: Model BN2A and BN2B Series Islander, and BN2T Turbine Islander aircraft (including those styled Defender) that have either the Century 31 Autopilot fitted under Modification NB/M/1271 or the Century 2000 Autopilot fitted under Modification NB/M/1488 (Applicability).\n\n# What owners/operators must do and when\n\nOperators must perform the actions described in the manufacturer’s mandatory service bulletin referenced in the directive (Requirement). The first action must be completed within 50 hours time in service after 9 November 1994, and then repeated at intervals not exceeding 100 hours time in service thereafter (Compliance).\n\n# Why the directive was issued\n\nInvestigations found wear and fraying of the elevator trim cable splice at locations that line up with fairleads at frame stations 352.4, 383.45 and 390.6. The service bulletin is intended to address those wear locations (Background). A related United Kingdom CAA directive is also referenced (Note).\n\n# Who pays and what changes in behaviour\n\nOwners/operators bear the cost and time to perform inspections, repairs or replacements required by the service bulletin (Requirement; Compliance). They must schedule recurring maintenance at the 50‑hour/100‑hour intervals specified (Compliance). Aircraft without the listed autopilot modifications are outside the directive’s scope (Applicability), so operators may change configuration or choose different equipment to alter applicability if that is operationally and legally feasible.\n\n# Implementation and risk considerations\n\nThe directive is prescriptive: it requires compliance with a specified service bulletin rather than leaving remedial method open (Requirement). That creates a clear compliance path but requires access to the service bulletin, appropriate parts and qualified maintenance personnel (Requirement). The directive identifies precise physical wear locations on the aircraft structure (Background), which narrows the technical focus of inspections and repairs.\n\n# Trade-offs and costs to consider\n\nPerforming the mandated actions incurs maintenance costs and aircraft downtime (Requirement; Compliance). Those costs are incurred to reduce the risk of elevator trim cable failure that has been observed in service (Background). The directive is limited in scope to specific models and autopilot installations, so its costs will fall unevenly on operators who own the affected combinations of airframe and autopilot (Applicability)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific aircraft configurations. It has not expanded beyond its original purpose of mandating inspections for elevator trim cable wear."},"complexity_factors":["Single, specific mechanical issue addressed","Clear applicability criteria (specific aircraft models with specific modifications)","Simple compliance timeline (50 hours initially, then 100-hour intervals)","No defined terms section or complex cross-referencing","References only one external document (manufacturer's service bulletin)","Straightforward conditional logic: if you have this aircraft with this equipment, you must do this inspection"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**Which planes are affected:** Pilatus Britten-Norman BN-2 series aircraft (Islander and Turbine Islander models, including the Defender variant), but **only** those fitted with specific autopilot systems (Century 31 or Century 2000).\n\n**What the problem is:** The elevator trim cable (a control cable that adjusts the plane's pitch trim) has been wearing and fraying where it passes through guide holes (fairleads) at specific points in the aircraft structure. This is a safety risk because if the cable fails, the pilot could lose control of the aircraft's trim.\n\n**What must be done:** Aircraft operators must follow the manufacturer's mandatory service bulletin (BN-2/SB 217 Issue 1) to inspect and address this issue.\n\n**When it must be done:**\n- First inspection: Within 50 hours of flying time after 9 November 1994\n- Ongoing: Every 100 hours of flying time thereafter\n\n**Why it matters:** This is a recurring inspection requirement designed to catch cable wear before it causes a failure. It reflects a known defect pattern discovered through incident reports."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bn-2-56-elevator-trim-cable","history":"/api/acts/ad-bn-2-56-elevator-trim-cable/history","analysis":"/api/acts/ad-bn-2-56-elevator-trim-cable/analysis","conflicts":"/api/acts/ad-bn-2-56-elevator-trim-cable/conflicts","importantCases":"/api/acts/ad-bn-2-56-elevator-trim-cable/important-cases","documents":"/api/acts/ad-bn-2-56-elevator-trim-cable/documents"}}