Boeing put its 787 battery fix through a “final” flight test on Friday and will soon submit the data to regulators, who the aircraft maker hopes will sign off on the new battery system and allow the 787 back in the air.

The 787 Dreamliner has been grounded since mid-January because of smoldering batteries that, in one case, caused a serious fire on the tarmac in Boston. Boeing’s fix includes more heat insulation and a battery box designed so that any meltdown of the lithium-ion battery will vent hot gases outside of the plane.