This report describes the results of the project "Concept development of jet engine inspection plugs" carried out in the spring of 2008. The work was done at the department of product definition at the company Volvo Aero in Trollhättan. The objective of the work was to develop concepts for a "Volvo-unique" inspection plug. The work is part of Volvo Aero's focus on proprietary (self-developed) technologies. Inspection plugs can be found on virtually all aircraft engines and gas turbines. They are used during inspections with fiber optics done at regular intervals during engine operation. Since the inspection plugs are screwed in and out many times during the life of an engine, it is important that the handling (the assembly and disassembly) is simple. It is also very important that the plugs are properly fixed in position to prevent them from coming off during operation. The focus of the work was to develop proposals on how the assembly and fixing of plugs could be designed to simplify the handling and have adequate and simple function. The procedure during the work was to first study relevant theory and methods that could be used. Then development was carried out according to the first steps of the systematic design methods. These steps include product specifications, concept generation, evaluation and selection of concepts, and development of selected concept. During the implementation, a number of tools and methods, including QFD, FMEA and decision matrices were used. Out of 14 developed concepts, two were chosen for comparison with a leading rival. Both developed concepts turned out to outscore the competitor and the main difference was the cost of production. One of the concepts was considered to have advantages over the other and was consequently chosen for further development. Geometry, manufacturing, materials, sealing and misalignment were the focus areas of the development. CAD models were made of the various design ideas that were identified and one principal inspection plug was recommended for further development.