The Federal Aviation Administration said Friday it received a formal proposal from Boeing to fix the 787 Dreamliner's battery problems and "will analyze it closely."
But the agency indicated it won't rush to get the Dreamliners back in the air despite the crisis that the grounding of the planes has brought to Boeing and its customers.
"The safety of the flying public is our top priority, and we won't allow the 787 to return to commercial service until we're confident that any proposed solution has addressed the battery failure risks," an FAA statement said.
The Dreamliners have been grounded since mid-January after two battery failures caused a battery fire in a jet on the ground in Boston and then a smoldering battery on a flight in Japan.
A Boeing team led by Commercial Airplanes chief Ray Conner presented the proposal in Washington, D.C., on Friday afternoon to FAA head Michael Huerta, Deputy Transportation Secretary John Porcari and other FAA officials.
Boeing issued a short statement saying the two sides had "a productive meeting," providing no further detail.
The plan — a long-term solution, rather than a temporary fix — calls for revamping the aircraft's two lithium ion batteries to ensure that any short-circuiting that could lead to a fire won't spread from one battery cell to the others, officials said. That would be achieved by placing more robust ceramic insulation around each of the battery's eight cells. The aim is to contain not only the short-circuiting, but any thermal runaway, a chemical reaction that leads to progressively hotter temperatures.
The additional spacers will enlarge the battery, requiring a bigger battery box to hold the eight cells. That new box would also be more robust, with greater insulation along its sides to prevent any fire from escaping and damaging the rest of the plane, officials said.
The plan will require testing and partially recertifying the safety of the plane's batteries, said the officials, who spoke on condition of anonymity because they weren't authorized to speak publicly.
The testing and recertification will take time, with engineers currently estimating completion sometime in April at the soonest, they said. Even after the batteries are recertified, it could take some more time to get the planes back into the air. Boeing will have to send teams to eight airlines in seven countries to retrofit their planes.