At the time the planes were grounded , 50 787s were flying worldwide . The test is part of Boeing 's work on an improved commercial lithium - ion battery system . Boeing Dreamliner ##s have been grounded since January after two battery fires . Boeing said it will analyze the data from the test and submit material to the FAA .
The test is part of Boeing 's work on an improved commercial lithium - ion battery system . Boeing Dreamliner ##s have been grounded since January after two battery fires . Boeing said it will analyze the data from the test and submit material to the FAA .