The FAA lifted the 3-month-old grounding order for Boeing 787 aircrafts Friday after approving a fix for the plane's lithium batteries.
Airlines grounded their Dreamliner fleets in January due to battery overheating issues.
During the investigation, investigators disassembled and examined the battery from a Dreamliner that caught fire. The charred insides of the plane's lithium ion battery showed the battery had received voltage in excess of its design limits
Although the exact root of the fire remains unknown, airlines will be able to begin flying the planes as soon as the new systems are installed. The revamped system includes additional insulation around each of the battery's eight cells to prevent a short circuit or fire in one of the cells from spreading to the others.
The new system also includes enhanced venting of smoke and gas from inside the battery to outside the plane. A strengthened box to hold the battery is an effort to ensure that if a fire were to occur, it wouldn't escape to the rest of the plane.
United Airlines is currently the only U.S. airline operating the 787, with six airplanes in service. The lone U.S. carrier operating Boeing's newest and most technologically advanced airliner says it's on schedule for 787 domestic flights starting May 31.
A Japanese airline is discussing plans to request more monitoring and protections, which could cause more delays.
The Associated Press contributed to this report.