SEATTLE -- The Federal Aviation Administration said Friday it received a formal proposal from Boeing to fix the lithium-ion battery problems in the 787 Dreamliners 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," said an FAA statement.

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.

Though no one was seriously hurt in either incident, the 787 grounding has already lasted a day longer than the 1979 grounding of the DC-10 fleet, which was prompted by an air crash that killed 273 people.

A Boeing team led by Commercial Airplanes chief Ray Conner presented the company's proposed fix in Washington, D.C., on Friday afternoon to FAA head Michael Huerta, Deputy Transportation Secretary John Porcari and other FAA officials.

Boeing issued only a short statement saying the two sides had "a productive meeting," providing no further detail.

Boeing remains tight-lipped about its proposed fix, but according to multiple sources, it includes:

--A stronger, sealed containment box enclosing the eight battery cells;

--A system of venting tubes that in case of an incident would channel any flammable vapors or liquids directly out of the airplane;

...continued