While Boeing's 787 Dreamliner remains grounded by the Federal Aviation Administration, investigators from the National Transportation Safety Board continue to dig into the question of why batteries onboard the new airliner overheated in two separate incidents. So far there are no definitive answers, NTSB Chairman Deborah Hersman told reporters yesterday [a PDF of her presentation is here]. And, she said, "This is not something that we are expecting will be solved overnight." Boeing said in a statement, "The company has formed teams consisting of hundreds of engineering and technical experts who are working around the clock with the sole focus of resolving the issue and returning the 787 fleet to flight status." Pictured: NTSB Materials Engineer Matt Fox scrutinizes the JAL Boeing 787 battery that caught fire in Boston.