The Digi_MRO project, funded by the European Commission under grant 20X1718B, ran from 1 January 2018 to 30 September 2022 and was led by MTU Maintenance Hannover GmbH. The consortium comprised MTU Maintenance Hannover, MTU München, Richard Wolf GmbH, and the Institute for Measurement and Control Engineering at Leibniz University Hannover. Project leaders were Oktay Halman and Dr. Manuel Voit for work package 1.1, Nils Budziszewski for work package 1.2, and Dr. Gerald Reitz for work package 1.4. The programme aimed to advance digital, predictive maintenance for civil turbofan engines and to support the European “Flight Path 2050” sustainability strategy.
In work package 1.1, On‑Wing Repair 4.0, the team developed a stripe‑light projection measurement head in collaboration with Leibniz University Hannover, enabling precise damage assessment on engine components. Crack inspection focused on Fluorescent Penetrant Inspection (FPI). By adapting the existing Richard Wolf FPI boroscope, the consortium introduced a directly washable process that proved most suitable for aviation use. New spray, wash‑nozzle, and compressed‑air systems were designed, and a telescopic head was created to reach difficult locations; these were validated in MTU Maintenance Hannover’s facilities. For blade‑edge inspection, specialized blenders were engineered with a milling geometry that preserves cracks for subsequent FPI, and process capability was demonstrated by MTU experts. The robot‑assisted boroscope work, also part of AP 1.1, yielded a continuum‑robot concept driven by cable‑tensioned segments. A prototype scaled 2.5 times larger than the target engine geometry was built and refined, showing that continuous, repeatable motion can be achieved within the tight confines of an engine core. These results lay the groundwork for future miniaturisation and reach extension, enabling real‑time in‑service inspection.
Work package 1.2 focused on digitalised workscoping to optimise consumption. Key performance‑relevant features of fan, booster, high‑pressure turbine (HDT), and non‑destructive testing (NDT) components were catalogued and measured. A geometry‑scan analysis tool was created to evaluate fan and compressor blade shapes. Applying the tool to a dataset of fan blades revealed measurable geometry changes caused by maintenance operations compared with new parts. Although aerodynamic assessment via CFD was not completed within the project period, the team developed a procedure to synthesize realistic geometry‑deviation datasets for parametric CFD studies, which will continue after the project’s end. These tools will support ongoing evaluation of geometry variations in the MRO process, forming the basis for predictive, life‑cycle‑optimised maintenance.
The combined outcomes of AP 1.1, AP 1.2, and AP 1.4 are expected to reduce unscheduled shop visits by 2 %, thereby lowering maintenance effort and enhancing sustainability in engine refurbishment. The project’s technological advances—advanced damage detection, FPI‑compatible inspection tools, continuum‑robotic inspection, and digital workscoping—provide a foundation for a shift from standardised to digitally personalised maintenance. This aligns with the broader industry trend toward “Flight Hour Agreements” and supports MTU’s strategy to integrate production and maintenance functions, ultimately strengthening competitiveness in the European aerospace market.