Boeing supply chain is 500 miles long. Multiple suppliers for every part, and practically none of them are made by Boeing. I started my career in aerospace manufacturing. The whole supply chain is designed to track and shift liability down into the smaller suppliers, who can be easily replaced. That panel blew off your plane? Well who made it?!?! Where are the certs?!?! That vendor must've done something wrong! It surely wasn't us not tightening the bolts all the way.