Boeing bosses have said that commercial flights of its grounded 787 jets would resume "within weeks, not months".
They said they had not pinpointed the causes of the two battery problems that resulted in the world grounding of the technologically-advanced Dreamliner planes.
But Boeing chief project engineer Michael Sinnett said a new design had many layers of safeguards to prevent battery fires and overheating.
It has measures to contain the problem from spreading and to keep the aircraft safe, even if batteries malfunction again, he said.
The executives made the comments in Japan, where All Nippon Airways was the launch customer for the 787.
"We could be back up and going in weeks and not months," Sinnett said.
The 787 fleet was grounded worldwide by the US Federal Aviation Administration, its counterparts in Japan and other nations in January, following a battery fire in a Dreamliner parked in Boston and an overheated battery that led to an emergency landing of another 787 in Japan.
With Japan Airlines another customer alongside All Nippon Airways, about half the 787 jets in use were with Japanese carriers.
The Boeing executives sought to allay fears about the 787 by repeatedly stressing their commitment to safety.
They said it would take too long to work out what had specifically caused the problems in Boston and south-western Japan but the new design would ensure 787s were safe.
Boeing came up with 80 possible causes for the battery problems, categorised them into four groups, and came up with design adjustments such as better insulation between each battery cell so any malfunctions would not spread.
That was to allow the 787 to be back in the air more promptly, they said.
There were also changes to wiring for the battery, aimed at preventing overheating, and a new enclosure for the battery that would eliminate fire risk.
While executives acknowledged that final approval would have to come from the FAA, and did not rule out further delays to ensure safety, they said they were in close contact with the US government authority and did not foresee any long delays.
"It's a safe airplane. We have no concerns at all about that," Sinnett said.
Boeing executive vice president Ray Conner also offered his apologies to the Japanese people for the problems.
He said he was in Japan to meet with aviation authorities and airlines and the company had picked Japan as the place to outline the battery fix.
About a third of the plane is made by Japanese manufacturers, including GS Yuasa, which supplies the lithium-ion batteries.
Despite assurances from Boeing, it is unclear if travellers will have enough confidence in the 787 to book flights on them. Both ANA and JAL have announced cancellations of hundreds of 787 flights through the end of May. Still, once the FAA clears the jet, approval from Japanese aviation regulators is likely to be instant.
Transport Ministry official Yasuo Ishii said Japanese were part of the tests and certification in the US, and planned to go along with and be part of the FAA decision. He said it was even possible commercial flights could resume as early as next month.
JAL spokesman Jian Yang said the airline saw the 787 tests going "to a new stage" and was ready to co-operate with others in the effort. ANA also welcomed Boeing's plan.
"As the launch customer for the 787, ANA hopes for a resumption of flights as soon as possible, while putting safety as a top priority," it said.
Boeing executives played down fire risks, stressing that there was no fire in the Japan failure and that there was no major damage to the aircraft.
They said they would not hesitate to fly on the 787 or have their families fly on them. They declined comment on questions about monetary compensations for the carriers, which are suffering losses because of flight cancellations.