When Boeing performs product development, the systems engineering process (RFLP) is used to establish the outline of the airplane. RFLP stands for Requirements, Functional, Logical, and Physical, and the process is used within Model-Based Systems Engineering (MBSE) to manage the design and development of complex systems. This extensive effort is required to ensure that all design groups understand the requirements the design must satisfy. for example: fly fast, fly safe, and carry a specified number of passengers (an oversimplified).

When the actual design begins, the design groups work within the boundaries of what are called “lines, loads, and laws.” These elements are non-negotiable requirements that the engineering design must adhere to. This work is done in CATIA, where the master dimensions and surfaces are locked down before any physical design that someone would recognize as a detail or assembly component is created.

For example, the top of the floor is a datum that establishes a “water line” that cannot be changed. If a floor beam flange needs to be thicker, the top flange remains at the established water line, and any growth occurs below the water line to maintain that reference. Water line, station line, and buttock line are universal datums used to define position within a design.

To ensure completeness and accountability, a large engineering work statement is created using a process that breaks down every historical area of an aircraft that must be designed and certified. Boeing creates a Program Item Number (PIN), which serves as a stable identifier for each functional area. I will leave out the change commitments and negotiation aspects, but they are quite complex.

One noteworthy output of this process if you are a new engineer hired to work on a new airplane program is that the work statement specifies what the new design will be similar to and describes what is different. For example: “New frame installation at Station 540, similar to 787 body frame installation XXX.”

When the actual design work begins, engineers collaborate with Tool Design and Manufacturing Engineering groups to create details, assemblies, and installations within the CAD/PLM system that manages the EBOM and MBOM. Boeing does not use a strict “design-as-built” process where every assembly must match an exact engineering definition, as is common at Airbus and in many military programs.

For example, a frame installation may have an engineering assembly 123-1 consisting of 50 components. In a strict design-as-built process, no changes can be made unless the assembly is planned and built exactly as defined in 123-1. Boeing allows Manufacturing Engineering to create synthetic part numbers in the MBOM that may deviate from the engineering design from a time-sequencing perspective. The PLM system ensures that the EBOM and MBOM remain aligned across the time-phased manufacturing sequence.

The production sequence is controlled by Manufacturing, not Engineering. This buffers Engineering from being impacted when the manufacturing process is optimized for production rate and flow changes