Originally Posted by
tdracer
As aeromech notes, something was holding that door in place prior to the failure. The ability to detect that it wasn't properly installed is a direct function of what was holding it in place. If, as aeromech suspects, it's something like 'short bolts', then it would be next to impossible to detect without a detailed inspection. OTOH, if bolts were completely missing, and it was being held in place by something like sealant - then yes, I'd expect a competent mechanic to notice the defect prior to installing the interior panels. Problem is we don't know - condemnation of the Renton workforce is premature.
We'll only know the answer to that until the investigation is done (or, if another improperly installed is detected during the mandated inspections).
I can't post pictures, but you can see the problem area in reply 199 (from reddit r/aviation) on the upper left and right where there are fittings that trap the silver pins on the frames that are visible in the indicent photos we've seen. Those capture-fittings didn't work, they seem to be 2-piece fittings with a piece that's attached with a (pin?) after plug installation to prevent upward movement of the plug. 99% sure those are the fittings that are being looked at with magnifying glasses all over the country tonight.