BY JOAN LOWY and JOSHUA FREED

Associated Press

WASHINGTON — Boeing has developed a plan that it intends to propose to federal regulators to temporarily fix problems with the 787 Dreamliner’s batteries that have kept the planes on the ground for more than a month, a congressional official told the Associated Press on Wednesday.

Boeing Commercial Airplanes CEO Ray Conner is expected to present the plan to Michael Huerta, head of the Federal Aviation Administration, in a meeting on Friday, the official said. The official spoke on condition of anonymity because he wasn’t authorized to speak publicly.

Boeing Co. spokesman Marc Birtel said the company doesn’t talk in advance about meetings with federal officials.

“Everyone is working to get to the answer as quickly as possible, and good progress is being made,” Birtel said.

The FAA and overseas aviation authorities grounded all 50 of the planes in service worldwide after a lithium ion battery caught fire on a plane parked in Boston and a smoking battery led to an emergency landing by another plane in Japan.

Japan’s Transport Ministry said Wednesday its investigation has uncovered a new problem: The aircraft’s auxiliary power unit, which contains a lithium ion battery, was improperly connected to the main battery that overheated.

Among the measures being discussed to make the batteries safe enough to return the 787 to the skies are adding more ceramic spacers between battery cells to contain any short-circuiting and fire within that cell.

More ceramic spacers would make the battery larger, which would require a bigger box to contain the battery cells. A more robust box lined with material to prevent any fire from spreading is also under discussion.

Boeing hasn’t said how much the 787 grounding will cost it. Imperial Capital analyst Ken Herbert estimated last week that it could cost Boeing $25 million a month in direct costs, with the total price tag climbing past $1 billion, including spending to fix the problem and expenses for delayed deliveries.

Boeing is still building five 787s each month, and has said it still wants to speed up to 10 a month by the end of the year. The company had orders for 800 of the planes at the time they were grounded.

It would take a delay of more than a couple of months for Boeing to back away from its speed-up plan, UBS analyst David Strauss wrote in a note on Wednesday.

Eight airlines in seven countries have 787s in their fleets. United Airlines, the only U.S. carrier with 787s, has cut its five 787s out of its schedule through the end of March.