Boeing Co. said Monday it conducted a successful test flight of its troubled 787 Dreamliner jet equipped with a new, enhanced battery system.

A 787 jet flew for two hours mostly around Washington state, in a step toward resuming operations after Dreamliners were grounded worldwide for two months due to a series of battery-related incidents.

The U.S. Federal Aviation Administration will analyze data from the test flight and, if no problems are detected, is expected to give the green light for commercial 787 flights in April at the earliest.

The move, however, could spark criticism, given that Japanese and U.S. authorities are still investigating the cause of the battery trouble.

The test flight was conducted using a 787 that is scheduled to be delivered to LOT Polish Airlines S.A.