Boeing is investigating a new quality issue with its 787 Dreamliner after finding hundreds of incorrectly installed fasteners on some undelivered jets. The problem involves improper "torquing" of over 900 fasteners per plane. While there is no immediate safety concern, Boeing is assessing the cause and potential rework needed. The company confirmed checks are being conducted and stated the in-service fleet remains safe. This investigation follows previous scrutiny and production slowdowns, though 787 deliveries continue, albeit at a reduced rate.