A lingering fog of uncertainty at the Boeing Co. campus in North Charleston lifted Friday when the Federal Aviation Administration agreed to clear the company’s 787 Dreamliners to fly again.

The revolutionary jet has been grounded since January because of batteries that overheated on two of the planes.

Flights could resume within a week, The Associated Press reported.

Boeing assembles the 787 in North Charleston and Everett, Wash. Its local campus has more than 6,000 employees.

FAA officials said Friday they have accepted the company’s revamped battery system, though the exact cause of the problem that sparked a fire on one 787 and smoke on another has not been identified.

The agency said that next week it will send airlines instructions and publish a notice formally lifting the grounding order.

The move will give Boeing the go-ahead to begin retrofitting the planes.

“FAA approval clears the way for us and the airlines to begin the process of returning the 787 to flight with continued confidence in the safety and reliability of this game-changing new airplane,” said Boeing CEO Jim McNerney.

The FAA conducted a month-long series of certification tests. Boeing said its new battery system “performed as expected during normal operation and under failure conditions.”

The grounding order had no discernible impact on production at Boeing’s two 787 factories.

This week, Boeing South Carolina rolled out a new 787 at its factory at Charleston International Airport, bringing to six the number of jets parked on the flight line.