Boeing Co (BA.N) is working on a series of battery design changes designed to minimize fire risks on its grounded 787 passenger jet and get the plane flying again as soon as March, the Wall Street Journal reported on Wednesday.
Regulators grounded the 787 on January 16 after a battery fire in Boston and a second incident involving a battery on a flight in Japan.
The newspaper, citing government and industry officials, said Boeing was looking at changes within the battery to keep heat or fire from spreading. Technical details have not yet been finalized or approved, though, the paper's sources noted.
One source added that under a best-case scenario, passenger flights could resume next month.
Boeing declined to comment on the report.
Some 50 Dreamliners have been grounded while investigators try to solve the battery mystery, costing airlines tens of millions of dollars already.
Earlier on Wednesday, the head of the U.S. National Transportation Safety Board said it was "probably weeks away" from completing its probe.
The NTSB is conducting the U.S. probe with help from Boeing, battery maker GS Yuasa Corp (6674.T) of Japan, the Federal Aviation Administration and battery experts from other U.S. federal agencies. None of the agencies have identified what caused the battery failures on the 250-passenger airliner.
Boeing this week asked the FAA for permission to conduct new test flights of the 787, suggesting it is making progress in finding a solution to the battery problems, but the government agency has not yet announced a decision.
Earlier this week Japan Airlines Co Ltd (9201.T) said it will talk to Boeing about compensation for the grounding of the 787 Dreamliner, adding that the idling of its jets would cost it nearly $8 million from its earnings through to the end of March.
Rival All Nippon Airways (9202.T), which has more 787s than JAL, said last week it would seek compensation from Boeing once the amount of damages was clearer.
(Reporting by Ben Berkowitz; Editing by Gary Hill, Bernard Orr and Eric Walsh)