While lean principles (developed by Womack and Jones) have been applied successfully to manufacturing and operations processes in many companies their application to engineering or new product introduction processes has been lacking. This paper introduces the principles of ‘lean engineering’ through some simple definitions, based on the original lean principles, and by describing applications of those principles in the aerospace industry via three case studies. The three case studies demonstrated the application of lean at three different levels of ‘process’ hierarchy, a detailed design activity level, a project management level and a design strategy level. The study concluded that while the application of lean principles in aerospace engineering processes (within new product introduction) is feasible for both large and small companies, the presence of a coherent and sustainable methodology was missing, as well as proper application of supporting management tools and technology.