Boeing is seeking regulatory approval on battery fixes for its 787 Dreamliner, which could put the troubled new jetliner back in the skies by April. The Dreamliner has been marred by a slew of problems in recent months, which led to the global grounding of all 50 active Dreamliners and raised doubts about the plane's future.

"Boeing executives briefed key members of Congress in Washington, D.C., on Wednesday, telling them the company has developed a permanent fix" to the battery problems that have plagued its new flagship plane, says Dominic Gates at the Seattle Times.

The company is expected to lay out a plan to the Federal Aviation Administration on Friday, hoping that the FAA will clear engineers' proposed fixes. The changes will reportedly include a stronger outer containment box, a system of high-pressure tubes that vent gases directly out of the airplane, and better insulation between the battery’s eight cells.

A congressional aide reportedly said that Boeing hopes to have its planes cleared for takeoff by April.

Investigators for the National Transportation Safety Board are still probing the cause of two incidents that led to the grounding, including a battery fire aboard a 787 in Boston in early January.

The other incident involved a smoldering battery aboard a Dreamliner in Japan, which led to an emergency landing and a separate investigation by Japanese regulators. They were initially stymied, but announced today that they had identified the causes of issues including oil leaks, cracks in cockpit glass, and braking problems, the Associated Press reported.

Boeing, meanwhile, has remained quiet. CEO Jim McNerney — who reportedly "sent handwritten apologies to the chairmen of airlines whose 787 batteries went up in smoke," according to the Wall Street Journal — has been laying low and working closely with engineers.

"I'm the one who has to stand up with absolute confidence when Boeing proposes a solution to enable this technology for the world," McNerney said. “And the only way I know how is to dive in deeply with the people doing the scientific and technical work.”

Despite the problems, Boeing has declined to change its production schedule and continues to build five Dreamliners each month. But the company can't deliver or get paid for the plans until it's cleared to fly.

"We'll have a lot of 787s stacking up around here if we don't get this done sooner rather than later," McNerney said.