Cold spray is a solid-state deposition technology with great potential for coating and repair applications. This study examines the compliance of the cold spray repair process with a qualification and testing framework based on the requirements set by the European Union Aviation Safety Agency (EASA). As part of this effort, the case study of a repair of a Main Landing Gear (MLG) aluminium component is investigated to demonstrate the applicability of the proposed framework. This framework integrates mechanical and microstructural evaluations, including bond strength, hardness profiling and microstructural characterisation according to relevant ASTM and ISO standards. Experimental results from post-repair testing indicated promising performance, while ongoing testing is aligning reasonably with expected benchmarks and showing compliance with the EASA requirements.

Continuous monitoring of spray velocity during the cold spray process would be desirable to support quality control, as spray velocity is the key process parameter determining the deposit quality. This study explores the feasibility of utilising Airborne Acoustic Emission (AAE) for real-time monitoring of spray velocity. Six spray tests were conducted, varying pressure and temperature to achieve different velocities. Optical means were used to measure velocity; while, the signal from the AAE was captured during deposition via a microphone. Features demonstrating a strong correlation with velocity were extracted from the acoustic signals. Both rule-based and machine learning models were employed to identify the moments where the nozzle was engaged with the substrate and diagnose the velocity. The results indicate that monitoring the spray velocity of the cold spray process using AAE is feasible.