Boeing Whistleblower: Production Line Has “Enormous Volume Of Defects” Bolts On MAX 9 Weren’t Installed::A reader at respected airline industry site Leeham News offered a comment that suggests they have access to Boeing’s internal quality control systems, and shares details of what they saw regarding the Boeing 737 MAX 9 flown by Alaska Airlines that had a door plug detach inflight, causing rapid decompression of the aircraft. The takeaway appears to be that outsourced plane components have so many problems when they show up at the production line that Boeing’s quality control staff can’t keep up with them all.
In a commercial production line, there are part defects, engineering defects, assembly defects, testing defects, tool defects, etc.
Tens of thousands of parts. Thousands of employees (some new hires). Hundreds of vendors.
You will never prevent all defects, but you should be able to discover them before finishing production.
A lot of these wont even be discovered until they are assembled and it fails a test or inspection point.