The style of an engineering report is a function of the change intended. For less routine work the report writer should clearly identify the intended result and select an appropriate writing style. On the other hand, a report intended to keep General Motors as a customer even after your company's parts have caused GM to consider a major recall, might be much more formal with overwhelming detail and written from a stance of responsible competence. The second best engineering idea, properly and enthusiastically implemented, will routinely knock the socks off the best engineering idea that is not understood. If the report reader does not understand the report it is the writer that has failed, not the reader.
Different readers process information in different ways.
The effective report writer will appeal to those different processes through the inclusion of narratives, analogies, examples, charts, tables, flow diagrams and perhaps even graphic representations. An engineering report writer gives the several readers their choice of which level to read. He also needs to know that those colors were chosen by the president's wife so he does not want to suggest changes. The Detailed Reader - The thorough and picky reader. This does not mean that you have to overwhelm the readers of the report with ALL the details of what you did, step by step.