People performing production work must have a product sample or clear description of an acceptable product to use as the basis for guiding their work. When the quality of work can only be verified by destructive testing or prolonged use of the product, then special attention must be paid to how the work is carried out. Keep records of how the work is carried out, what equipment was used and who did the work. This typically applies to soldering, welding, painting, gluing or heat treating operations. Identify your special processes and qualify the operators of these special processes to prevent problems.
Software development is also a special process.