A large amount of design information from different areas has become common in most organizations, this knowledge is dispersed in different formats and locations, and shared among different members of the design team; this fact hinders a synergic knowledge management and prevents its proper use by design engineers. Therefore, it is imperative that companies worry about the organization and adequate availability of this knowledge, by creating collaborative environments. In this sense, it is possible to associate the Knowledge-Based Engineering (KBE) approach. Through the concepts of KBE, this study proposes an expert system based on an ontology model to assist the decision-making process, from the storage and adequate availability of knowledge at the right time. Based on a literature review and a diagnosis made in a company of the agricultural machinery sector, the present work presents a solution able to meet the needs of its users (i.e. designers), as well as to improve the quality of decisions taken at the detailed design phase of a New Product Development (NPD) process. For that, a case of hydraulic hose design is explored. The application of the present proposal aims to facilitate the access to information, significantly reduce the appearance of failures along the NPD, as well as allow acquired knowledge to be used in subsequent projects (e.g., lessons learned).