The Japanese transportation minister, Akihiro Ota, said Friday that regulators there were in the final stages of evaluating the safety of the battery system changes. Analysts said Japanese regulators could require a few additional safeguards before approving the modified planes for flight.

Mr. Loftis said he could not predict how long it might take to obtain approval from regulators in Japan and elsewhere. The F.A.A. has primary authority to regulate and certify the safety of Boeing aircraft and, typically, its decisions are validated by other countries with few changes. “I am not expecting anything out of the ordinary” in the recertification of the 787 by foreign regulators, Mr. Loftis said. “They have the documentation and the analysis we have done. I would expect them to grant their approvals in the near future.”

It was not immediately clear when or where the first 787s would return to the skies. Once Boeing’s technicians have made the modifications, the planes will be turned back over to the airlines, which will follow their own procedures to prepare them for service. All Nippon, which operates 17 Dreamliners, is planning to make 100 to 200 test flights next month before resuming passenger service in June, Reuters reported last week.

Analysts predicted that it would be months before the entire 787 fleet was back in the air but said it would probably not be long before the first passenger flights resumed.

“It would be unwise to believe that the process of rectification will be fully complete before the end of the summer,” said Howard Wheeldon, an independent investment strategist in London, adding, “It seems to me that we can expect the first 787 to resume flying in airline service within a matter of weeks.”

With the F.A.A.’s approval of the battery modifications, Boeing said it was also beginning discussions with airlines about rescheduling deliveries of jets on order. The company has continued to build planes over the past three months, and Boeing has more than a dozen finished planes parked at its factories in Washington State and South Carolina.

Before the battery problems in January, Boeing had hoped to double its production of 787s to 10 per month by the end of this year, from 5 per month at present. Mr. Loftis declined to say Monday when Boeing would be in a position to begin ramping up production.

Boeing was expected to give an update on the situation Wednesday, when it reports first-quarter results.