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.
For anyone interested what happened (according to some anonymous whistle-blower):
They had to remove the door plug to replace damaged pressure seal but didn't want to run QA on the plug after installing it back so they didn't mark it as 'removed' in the tracking system, they simply treated it as door that were "opened". Parts were missed when inserting the plug, QA didn't check because it wasn't in the system, plane was delivered to the client. The rest is history.
There' s a lot of backstory to it but that's the direct cause. Supposedly.
yep: https://lemmy.nowsci.com/comment/4930362