TOKYO — Boeing on Thursday presented the Japanese government with its plan to address battery problems on its new 787 Dreamliner, stressing that added protections against possible battery fires and overheating are more than enough to allow its planes back in the air.
Japanese investigators, however, have maintained that there is still not enough evidence to show that the batteries themselves are the cause of fires, and that a shock could have caused them to overheat. That could complicate Boeing’s efforts to get regulators around the world to approve their fixes, because they focus only on containing any problems that might arise in the batteries.
The Japanese assertions have put Japan’s transport safety board at odds with American investigators, who have said publicly that there was no such surge in electrical current from outside the battery. The lithium-ion batteries on the 787 are made by GS Yuasa of Japan.
Raymond L. Conner, the chief executive of Boeing’s commercial airplane division, who is in Tokyo for talks with Japanese government officials, airliners and suppliers, gave a public apology for the problems with the 787 and said that he was confident that the battery fixes were a “permanent” solution that ensured the batteries would not be a danger going forward.
“What we did today was to discuss these solutions that we are looking at that could be final solutions,” Mr. Connor told reporters after meeting with the Japanese transport minister, Akihiro Ota.
“We feel this solution takes into account any possible event that could occur,” he said, “any causal factor that could cause an event, and we are very confident that we have a fix that will be permanent and allow us to continue to use the technology.”
He denied that there was any disagreement between the American and Japanese positions on the needed fixes. He said that Boeing continued to have a “great relationship” with GS Yuasa, the battery maker.
Boeing has delivered 50 787s so far to eight airlines, and it expects to sell thousands of the fuel-efficient jets. But a battery caught fire on one Japan Airlines plane parked in Boston on Jan. 7, and smoke forced another 787 operated by All Nippon Airways to make an emergency landing in Japan.
Boeing has proposed separating the battery cells with insulation to keep heat from spreading from one to another. It also would build a fireproof container around the batteries and add tubes to vent smoke or hazardous gases out of the plane.
Japanese officials would like to Boeing to add a voltage monitor to detect any electric surges from outside the battery. Boeing officials said they did not think they needed this.