Aircraft regulators in the United States have approved a revamped battery design for the Boeing 787 Dreamliner.
The decision paves the way for the fleet to return to the skies, after problems grounded it for months.
The Federal Aviation Administration said airlines needed to replace the batteries to return to service.
Boeing chairman Jim McNerney said: “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.”
Planes will now need to be fitted with a “containment and venting” system for both the lithium-ion batteries.
That includes a stainless-steel enclosure to prevent heat, fumes or fire from spreading if a battery overheats in flight, said the FAA.
There are presently 50 Boeing Dreamliners in service around the world.