Randy Tinseth, vice president, marketing for Boeing Commercial Airplanes, said six of the eight airlines with 787s in their fleets have now returned the jetliners to passenger service. The others are expected to follow in a matter of a few days.
To complete the retrofitting work, Boeing sent special teams across the globe.
Ethiopian Airlines was the first to return its 787 aircraft to the skies. Air India and Qatar Airways restarted flights soon after.
United Airlines, the only U.S. company with the 787 in its fleet, put its planes back in air on May 20. The airline, based in Chicago, said it will use 787s on shorter domestic flights before resuming international flying June 10 with new Denver-to-Tokyo service as well as temporary Houston-to-London flights. It's adding flights to Tokyo, Shanghai, and Lagos, Nigeria, in August.
Poland's LOT Airlines plans to return its 787s back into service on Saturday.
Smoldering batteries on two 787s owned by Japan-based airlines prompted authorities to ground the planes in January. The failure of Boeing's newest, flashiest and most important plane embarrassed the company and its customers.
The two battery incidents in January included an emergency landing of one plane, and a fire on another. Federal authorities lifted the grounding order on April 19 but it has taken Boeing and the airlines a few more weeks to fix most of them.
The incidents never caused any serious injuries. But the January grounding embarrassed Boeing and disrupted schedules at the eight airlines that were flying the planes. The company had delivered 50 of the planes worldwide.
The 787 uses more electricity than any other jet. And it makes more use of lithium-ion batteries than other jets to provide power for things like flight controls and a backup generator when its engines are shut down. Each 787 has two of the batteries.
Boeing Co. never did figure out the root cause of the battery incidents. Instead, it redesigned the battery and its charger. The idea was to eliminate all of the possible causes, 787 chief engineer Mike Sinnett said.
The changes include more heat insulation between each cell and charging the battery to a lower maximum voltage.
Boeing never stopped making 787s, but deliveries were halted. They resumed in mid-May, and Boeing has since delivered two planes, both with the new battery system.