Integrated sustainability assessment of scarf repair for aeronautical composite panels: A total efficiency index approach

The implementation of circular economy strategies in the aeronautical sector presents new challenges for improving the sustainability of its value chains, particularly for composite materials. This study introduces an integrated sustainability assessment of a circular repair strategy – bonded patch repair (scarf repair) – to extend the service life of structural composite panels. Considering a functional unit of one square meter of intact panel area, the Total Efficiency Index Framework was applied to compare two scenarios for handling a damaged panel: full panel replacement and local scarf repair. The efficiency index was measured by integrating life cycle assessment, eco-efficiency and process efficiency, providing a unified placement between current and potential performances. Results show that in situ scarf repair is 29 % more eco-efficient than total replacement, generating 17 % more service value and 6 % less environmental impact. However, the replacement showed a higher total efficiency index overall due to its proximity to the target process and eco-efficiency values. These findings suggest that the scarf repair process has greater potential for optimization, particularly in reducing operation time and resource consumption. A sensitivity analysis of increasing panel sizes with the same damaged area concluded that the damaged-to-total area ratio is key in deciding whether repair or replacement should be preferred. Ultimately, the total efficiency index increases with the size of the panel. This study contributes to the limited body of literature on composite repair sustainability, demonstrating the potential of scarf repair strategies and supporting a more circular and sustainable approach to aircraft maintenance.