This book is both a short introduction to the recent developments, challenges and opportunities in Aviation Maintenance, Repair and Overhaul(MRO), and at the same time, a presentation of the research focal areas and the key waypoints towards smarter and more sustainable MRO. Innovation and integration have always been key aspects of Aviation. Currently, evolutions in aircraft design, materials and production techniques are ahead of the MRO practices in use.This gap is creating demand for new knowledge to develop and operationalise adaptive, digital and sustainable MRO tools, applicable or integrated in modern aircraft systems and components.