Boeing plans 787 battery test flights for end of week - sources

SEATTLE/WASHINGTON (Reuters) - Boeing Co plans to conduct two flight tests of its revamped 787 battery system, possibly as soon as the end of the week, according to three sources familiar with the matter.

The 787 flights, the first since February, would mark another step toward Boeing's recently announced goal of returning the grounded jet to service in a matter of weeks, not months.

Regulators banned the plane from the skies in January after lithium-ion batteries burned on two 787s in quick succession that month. The Federal Aviation Administration gave Boeing permission for a single "ferry" flight on February 7 to move a jet to Washington state from Texas, carrying minimal crew and no passengers.

Boeing declined to comment.

The FAA on March 12 approved Boeing's plan to test a redesigned battery system, to prove it is safe. The FAA-approved plan includes a rigorous battery testing standard Boeing helped develop but did not previously use.

Boeing said last week that it was one-third of the way through the testing, and expected to finish in a week or two. Boeing's prediction drew scepticism from some regulators and industry experts, who said it was too early to say when the Dreamliner would fly again with the root cause of the battery overheating still unknown.

A senior official at Boeing's biggest 787 customer, All Nippon Airways , told Reuters this week that the timetable was a best-case scenario and was too uncertain for it use in planning.

The testing regimen set by the FAA requires one flight test. But Boeing plans to conduct two flights: One for its own purposes and a second to gather data to submit for FAA approval, according to the sources, who spoke on condition that they not be named.

The flights could still be delayed by weather or other factors. Flight plans for the events had not yet been filed with the FAA.

The flights would depart from and return to Paine Field, an airport adjacent to the factory in Everett, Washington, where the 787 Dreamliner is made.

(Reporting by Alwyn Scott in Seattle and Andrea Shala-Esa in Washington; Editing by Chris Gallagher)