Boeing completed what it called an uneventful flight of a test 787 Dreamliner, its first since the airplanes were grounded more than three weeks ago after a series of battery-related problems.

The test flight on Saturday, designed to gather detailed information on the airplane's lithium-ion batteries, lasted slightly more than two hours, taking off from and returning to Boeing Field in Seattle, the company said.

"The crew reports that the flight was uneventful," Boeing said in a statement.

The 50 Dreamliners in commercial service were grounded worldwide on January 16 after a series of battery-related incidents, including a fire on a parked 787 at Boston's Logan International Airport and an in-flight problem on another airplane in Japan.

The groundings have cost airlines tens of millions of dollars, with no solution yet in sight.

The US Federal Aviation Administration said on Thursday it would allow 787 test flights, under more stringent rules, to monitor the batteries while in flight. Boeing said the information gathered was part of its investigation into the battery events, and that additional details could not be shared.

The airplane is Boeing's fifth 787 flight test airplane, marked as ZA005, and the only member of the test fleet still in service. The flight had a crew of 13, including pilots and testing personnel, Boeing said.

Boeing said no flights of the airplane were planned on Sunday, but that it plans to resume flights early in the coming week. Boeing does not provide advance flight schedules.