A Boeing 787 conducted a 109-minute flight on Friday, with the US aerospace giant saying the test was the final measure to assess the safety of its proposed fix to prevent the plane's lithium-ion batteries from overheating.

"The crew reported that the certification demonstration plan was straightforward and the flight was uneventful," Boeing wrote in a statement, saying the flight sought to "demonstrate that the new battery system performs as intended during normal and non-normal flight conditions."

The flight took off from and landed at Paine Field in Everett, Washington, home to Boeing's largest plane-building factory. A similar test flight was conducted on March 25, a jet built for Polish airline LOT was used for both tests.

Overheating batteries

The US Federal Aviation Authority (FAA) regulator grounded all Boeing 787's on January 17, following two problems with the batteries on board. One plane's battery caught fire on the ground at Boston's Logan International Airport, while another 787 was forced into an emergency landing in Japan after a battery overheated. The cause of these problems has not been identified.

Boeing has since put more insulation in the battery, encased it in a steel box, changed the battery charger's circuitry and added a titanium venting tube designed to expel heat and fumes outside the plane.

Two FAA officials were among the 11 crew members on board for Friday's flight. The FAA must certify the plane as fit to fly.

"They're doing the tests now, and we've agreed with the tests that they're doing," US Transportation Secretary Ray LaHood, who oversees the FAA, said on Friday. "When they complete the tests, they'll give us the information and we'll make a decision."

Boeing previously said it hoped the process would now take weeks, not months, though the FAA has not laid out a timetable.

The 787, which Boeing calls the Dreamliner, entered commercial service in October 2011. Globally, 50 Dreamliners are already in service; Boeing is continuing to manufacture the new airliner for fresh orders, although it cannot deliver any new models until the flight ban is lifted.

msh/mr (AFP, AP, Reuters)