(CNN) - There's no serious problems, according to aviation authorities looking into the Japanese company that makes the lithium ion batteries linked to problems that have led to the grounding of Boeing 787 Dreamliners.
U.S. and Japanese officials carried out a joint inspection at the facility in Kyoto where GS Yuasa makes the batteries.
While investigators found several issues in quality control at the company, they didn't uncover any serious problems that can be linked to recent incidents involving Dreamliners, Yasuo Ishii, Director of Air Worthiness Standards at the Japanese transport ministry, said Tuesday.
Two recent incidents, a fire aboard the Japan Airlines aircraft in Boston's Logan International Airport on January 7, and a smoke alarm aboard a plane flying over Japan on January 16, prompted the Federal Aviation Administration to ground all Dreamliners in the United States, and other nations quickly followed suit.
The investigation has now shifted from the battery maker to the manufacturer of the system that monitors the battery's voltage and temperature, Ishii said.