Boeing's Dreamliner battery fix approved by US regulators
US aircraft regulators have approved a revamped battery design for Boeing's 787 Dreamliner, paving the way for the fleet to return to the skies, after problems grounded it for months.
The Federal Aviation Administration (FAA) said airlines needed to replace the batteries to return to service.
It said it will publish a final directive next week.
Other international regulators are likely to follow but it will still be a couple of weeks before flights resume.
Boeing's chairman and chief executive 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."
Transportation Secretary Ray LaHood said: "Safety of the travelling public is our number one priority. These changes to the 787 battery will ensure the safety of the aircraft and its passengers."
The FAA said it would "closely monitor" modifications of the aircraft and teams of inspectors would be sent.
Boeing said the regulator had set a "high bar for our team and our solution".
Planes 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.
"This is a comprehensive and permanent solution with multiple layers of protection," said Boeing's head of commercial aircraft Ray Conner.
"The ultimate layer of protection is the new enclosure, which will ensure that even if a battery fails, there is no impact to the airplane and no possibility of fire.
"We have the right solution in hand, and we are ready to go," he added.
All of the 50 Boeing 787 planes in service were grounded in mid-January after their lithium-ion batteries emitted smoke on several separate occasions.
The problems sparked a battery fire on a parked Japan Airlines 787 at Boston's Logan International Airport and another incident in which battery smoke forced an emergency landing of an All Nippon Airways (ANA) 787 in Japan.
The 787 is said to be one of the most fuel-efficient in the industry, and Boeing delivered 46 Dreamliners to customers in 2012.
The plane is the first in the world to use the lithium-ion batteries, which are lighter, hold more power and recharge more quickly.
But the grounding has cost Boeing an estimated $600m (£393m). Japanese carrier ANA lost some 1.4bn yen ($15m; £9.5m) in revenue through January's disruption alone.