Three “levels” of Engineering Drawing were defined by the now-defunct DOD-D-1000 “Drawings, Engineering and Associated Lists”. Even though the standard is no longer in use, and has not (to my knowledge) been functionally replaced by an industry standard, the “levels” concept is of some use in establishing a mental organization of how design progresses. It will, therefore, be quoted extensively here:
Levels 1, 2 and 3 provide for a natural progression of a design from its inception to production. Levels may be [contractually] ordered to define a conceptual or developmental design, a production prototype or limited production design, or the highest type of engineering drawings required for quantity production of the item or system by the developer and other than the original developer. Combinations of Levels may be specified in the contract or order.
Level 1, Conceptual and developmental design. Engineering drawings and associated lists…shall, as a minimum, disclose engineering design information sufficient to assess an engineering concept and may provide information sufficient to fabricate developmental hardware…layout drawings and combinations of types of engineering drawings may be used to convey the engineering concept…such [that] the engineering information is understandable…or enable fabrication…or developmental hardware for test or experimentation.
Level 2, Production prototype and limited production…shall disclose a design approach suitable to support the manufacture of a production prototype and limited production models…shall include, as applicable, parts list, detail and assembly drawings, interface control data, diagram, performance characteristics, critical manufacturing limits, and details of new materials and processes. Special inspection and test requirements necessary to determine compliance with requirements for the item shall be defined…or referenced…
Level 3, Production…shall provide engineering definition sufficiently complete to enable a competent manufacturer to produce and maintain quality control of item(s) to the degree that physical and performance characteristics interchangeable with those of the original design are obtained without resorting to additional product design effort, additional design data, or recourse to the original design activity1…shall provide the necessary data to permit competitive procurement of items substantially identical to the original item(s)2.
Footnotes- That is, the intent of a Level 3 drawing set is to be able to shoot the original Engineering staff without endangering production capability.[↩]
- That is, sufficient that the acquisition customer can take production away from the developer and place it with a cheaper manufacturer without loss of interchangeability amongst the manufactured parts. It’s a dog-eat-dog world out there, and has been for a long, long time![↩]