Engineering covers numerous industries and disciplines. The very process of attempting to solve a technical problem by the application of engineering principles has the potential to qualify for the relief. Attempting to make something better, stronger, faster or even cheaper will necessitate development.
This is because there will normally be a fundamental aim of the development, e.g. 50% better durability, or 100% availability, which would be seen as a step change in performance over the original.
Attempting to achieve the increases in performance will entail overcoming technological challenges, e.g. the melting temperature of the alloy in turbine blades, if the blades can be produced to perform at higher temperatures, the turbine engine will be more efficient and use less fuel.
Similarly, the manufacturing process development, or the development of a new design for manufacture, or for repair could also be qualifying activity.
Virtual design development, e.g. the engineering design for Oil & Gas installations, or chemical processes can also be potentially qualifying. The design is really only a proposed solution. It is applied research in many instances. It is thought of as the best on paper solution and viable. Often when the design is in construction and installation, anomalies are found and new solutions have to be developed.
Any group of engineers in any industry will face similar challenges and the finding of the potential solutions is likely to fall into the definition of R&D-for-tax-purposes.