In order to improve efficiencies and minimise costs, maintenance, repair and overhaul (MRO) services in the aviation sector are increasingly embracing lean philosophy and technologies advances. The central tenet of lean philosophy is to eliminate non-value adding activities from value streams. While the take-up of lean philosophy is increasing, there are indications that aviation MRO services are facing challenges in implementing lean and this inevitably impacts on the effectiveness of such continuous improvement programmes. This paper presents findings from a study on aspects of lean philosophy in aviation MRO organisations. The focus of the study is on critical success factors that can impact the effectiveness of continuous improvement and lean waste reduction programmes in aviation MRO organisations. Findings from the study showed that emphasis needs to be placed on technical, non-technical and managerial considerations when implementing lean in aviation MRO organisations. In addition, also observed is a shift of emphasis in critical success factors when operating cloud-based aviation MRO systems in comparison to traditional aviation MRO systems.