There is nothing inherently wrong with changing from batch to lean manufacturing. I've been involved with many lean implementation efforts, in an ISO 9001 compliant environment, from small (one part moving from machined to cast, similar to this one, but the size of your fist, and no lives on the line), to entire production lines.
You need to do your homework, use rigorous techniques and processes, and at the end of it, test final parts and assemblies as rigorously as the original. A complex, utterly critical part like this one would need a herculean effort to get right. I'm not full of the warm fuzzies about Boeing's ability to execute an effort like this in the last 20 years, from what I've read here and elsewhere about Boeing's strategic realignments.