NTSB uncertain Boeing 737 MAX cabin panel properly bolted

The National Transportation Safety Board said on Monday it is uncertain if a recovered cabin panel that blew off an Alaska Airlines Boeing 737 MAX 9 plane was properly attached or if bolts had been installed.

The NTSB said it will be able to determine if the bolts had been installed through testing. Earlier Monday, United Airlines and Alaska Air both said they had found loose parts on multiple grounded MAX 9 aircraft, raising new concerns among industry experts about how Boeing's best-selling jet family is manufactured.