Investigators on both sides of the Pacific are going over Boeing's batteries and electrical systems again Tuesday to try and find the cause of the problems on the 787.
All 50 of the 787 Dreamliners that Boeing has delivered to airlines were grounded after an overheated battery forced the emergency landing of an All Nippon Airways 787 flight last week in western Japan. Boeing has halted deliveries of new planes until it can address the electrical problems.
Japanese investigators have been inside the Kyoto plant that makes the high-capacity, lithium-ion batteries. They are looking at how the batteries are produced and how they are tested before they leave.
Some analysts are wondering if the problem could be as simple as a bad batch of batteries.
Meanwhile, U.S. investigators will be inspecting two plants in Arizona. One makes the auxiliary power controller. The other makes the battery chargers for the Dreamliner.
Many aviation analysts believe it's possible the problems with the electrical system could be coming from different sources. If that's the case, that could mean the grounding of the entire Dreamliner fleet could last a long time.
The Associated Press contributed to this report.