WASHINGTON, April 4 (Reuters) - Boeing Co may carry out a certification test flight of its grounded 787 Dreamliner with a revamped battery system on Friday, a key step toward returning the state-of-the-art aircraft to flight, a U.S. government official said on Thursday.
The official, who was not authorized to speak on the record, said the certification test could be carried out on Friday if all remaining ground-based tests were completed on Thursday.
"They're not quite there yet," said the official, adding that it might not be clear until early Friday if the certification flight could take place.
Boeing declined to confirm the timing of the flight. "As a matter of long-standing policy Boeing does not provide advance notice of flight test activities until we have filed flight test plans," Boeing spokesman Marc Birtel told Reuters when asked about a possible test flight on Friday. Boeing typically files a flight plan a few hours before the plane takes off.
All 50 787s in service worldwide were grounded in January after the airplane's lithium-ion batteries overheated on two separate aircraft, one on the ground in Boston and a second during a flight in Japan.
The certification flight is part of a series of tests to show whether measures Boeing has devised to fix the battery problems work as intended. A preparation flight on March 25 "went according to plan," Boeing said.
It's still unknown what caused the two batteries to overheat, and the National Transportation Safety Boad is investigating. But Boeing came up with measures it says make the battery safe. It encased the battery in a steel box, changed the circuitry of the battery charger and added a titanium venting tube to expel heat and fumes outside the plane.
Once Boeing completes its testing, the Federal Aviation Administration will review the test data and decide whether to certify the fix and return the plane to service.
Airlines have been barred from using the plane since it was grounded in January, and Boeing has been barred from delivering 787s, though it continues to build the plane.