IEC TS 61400-28:2025 sets out minimum requirements for actions, investigations and assessments to ensure the continued structural integrity of wind farm assets, particularly wind turbines, aimed at verifying that they remain safe for personnel to operate. The document describes how to maintain those assets and collect suitable evidence to demonstrate to third parties that risks are minimised, particularly where risks are related to collateral damage or injury, such as could be suffered by personnel or structures neighbouring the wind farm. Covered in this document are assessments of current condition and remaining useful life, resulting in the technical basis for justifying extended operation beyond the design life (defined in 3.1.3) and also beyond the site-specific assessed lifetime, whichever is shorter, for structural or major components and systems contributing to primary layer of the safety system.