The efficient and effective management of knowledge is becoming increasingly important within the aerospace design engineering sector due to the complexity of product development. Semantic technology is becoming mainstream technology and is being applied by many disciplines for the management of complex knowledge. However, there is a lack of a semantic knowledge life cycle to support the semantic knowledge management discipline. This paper presents a systematic knowledge life cycle (KLC) for supporting the semantic knowledge management discipline with a particular emphasis on the importance of structuring knowledge. The semantic KLC comprises eight stages namely: (1) Understand the domain (2) Structure (3) Enrich vocabulary (4) Capture (5) Represent (6) Interpret the 'know how' (7) Share (8) KBE system. This research project adopts a qualitative approach and a five-phased research methodology. An illustrative scenario within the aerospace engineering industry for producing gas turbine systems is used to demonstrate the practicality and applicability of the proposed approach. The semantic KLC supports a shared agreement of meaning and understanding between design and manufacturing engineers.