In the multidisciplinary production systems engineering (PSE) process, software engineers depend on requirements and design rationales coming from product and production process planning, summarized as product/ion knowledge. Unfortunately, the engineering artifacts coming from product/ion planning often represent important product/ion knowledge incompletely and not well integrated, leading to risks regarding software engineering quality. In this paper, we report on a case study at a large industrial PSE organization, investigating Technical Debt (TD) effects, items, and causes in PSE process documentation and configuration management according to the VDI guideline 3695 Part 2. We focus on requirements for and issues in the representation of product/ion knowledge in the engineering data provided to software engineers. Based on data elicited from PSE domain experts, we model TD concepts based on the Quality Function Deployment method as foundation for TD analysis and risk management. The initial validation with domain experts revealed how software engineers could benefit from improved product/ion knowledge modeling as foundation for better understanding the rationale of engineering design decisions.