{"id":"F2006B04756","name":"AD/BN-2/45 Amdt 1 - Main Undercarriage Leg","slug":"ad-bn-2-45-amdt-1-main-undercarriage-leg","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44520,"registerId":"commonwealth-F2006B04756-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BN-2/45 Amdt 1 - Main Undercarriage Leg","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-2/45\n\nAmdt 1\n\n  \nMain Undercarriage Leg 8/85\n\nApplicability: All model BN-2 referred to in Requirement Documents. Requirement: Action in accordance with:\n\n    Britten Norman SB No. BN-2/SB.135 issue 2., and\n\n    2. AP Precision Hydraulics S.B. No. 32-278 Rev. 1, and\n\n    3. AP Precision Hydraulics S.B. 32-307.\n\nCompliance: 1. Unless already accomplished inspect in accordance with Requirement document 2 within 100 hours time in service after 31 August 1985 or at the next scheduled inspection for Maintenance Release issue after 31 August 1985, whichever is the later.\n\n    2. Repeat inspections in accordance with checks detailed in Requirement document 2 every 100 hours time in service or every 150 landings, whichever is the soonest.\n\n    3. After incorporation of modification detailed in Requirement document 3 inspect for wear every 500 hours time in service as detailed in Requirement document 2.\n\nBackground: The manufacturer is aware of fractures of the centre torque link pin caused by bending of the pin resulting from excessive accumulated wear clearances between the axle bracket, plunger tube and gland bearing. Two local operators have experienced recent torque link pin failures.\n\nThe CAA has classified Requirement documents 1 and 2 as “MANDATORY”.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The instrument continues to require inspection and modification actions for BN‑2 main undercarriage legs as set out in the referenced Requirement Documents. The text provided does not indicate an expansion or narrowing of the AD's applicability or obligations beyond those stated."},"complexity_factors":["Technical specificity: focuses on torque‑link pin wear and fracture mechanics (Background).","Multiple external Requirement Documents must be consulted and followed (Britten Norman SB BN-2/SB.135 issue 2; AP Precision Hydraulics S.B. No. 32-278 Rev. 1; S.B. 32-307).","Mixed compliance metrics and timelines — hours-in-service and number-of-landings with 'whichever is the sooner/later' triggers (Compliance 1–3).","Recurring inspection regime plus altered interval after modification increases scheduling and recordkeeping complexity (Compliance 2–3).","Wide applicability requires operators to check applicability in Requirement Documents ('All model BN-2 referred to in Requirement Documents').","Mandatory classification by the Civil Aviation Authority creates enforceable compliance obligations (last sentence).","Compliance cost and operational impact fall on aircraft operators (inspection, possible modification, downtime).","Interpretive ambiguity risk over terms like 'next scheduled inspection for Maintenance Release issue' and implementation timing."],"plain_english_summary":"Requires operators of Pilatus Britten‑Norman BN‑2 series aeroplanes to inspect the main undercarriage torque‑link pin per three referenced service bulletins, with an initial check within 100 flight hours (or next scheduled maintenance), repeat checks every 100 hours or 150 landings, and extended 500‑hour checks after a specified modification. CASA classifies the referenced documents as mandatory. Operators bear inspection and modification costs; the rule raises recurring maintenance obligations intended to reduce reported torque‑link pin fracture risk."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a narrow, targeted safety directive addressing a specific mechanical failure mode in a single aircraft type. It has not expanded beyond its original purpose of mandating inspections for the main undercarriage leg torque link pin issue."},"complexity_factors":["Short, single-purpose directive focused on one mechanical component","Only 3 defined compliance pathways (initial, recurring, and post-modification)","Cross-references to 3 external manufacturer service bulletins rather than embedding technical details","Simple conditional logic ('whichever is the later/soonest')","No nested exceptions or complex definitions section","Total length under 300 words"],"plain_english_summary":"This AD requires operators of Pilatus Britten-Norman BN-2 aircraft to inspect the main undercarriage centre torque link pin for excessive wear and cracking, following occurrences of pin failure. Inspections must start within 100 flight hours after 31 August 1985 (or at the next maintenance check) and be repeated every 100 flight hours or every 150 landings; aircraft with the approved modification may extend intervals to 500 flight hours.\n\nIt’s mandatory to prevent landing-gear collapse and potential loss of the aircraft and occupants."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bn-2-45-amdt-1-main-undercarriage-leg","history":"/api/acts/ad-bn-2-45-amdt-1-main-undercarriage-leg/history","analysis":"/api/acts/ad-bn-2-45-amdt-1-main-undercarriage-leg/analysis","conflicts":"/api/acts/ad-bn-2-45-amdt-1-main-undercarriage-leg/conflicts","importantCases":"/api/acts/ad-bn-2-45-amdt-1-main-undercarriage-leg/important-cases","documents":"/api/acts/ad-bn-2-45-amdt-1-main-undercarriage-leg/documents"}}