The Boeing 787 Dreamliner will be returning to the air — but only so Boeing can gather information about the battery fires that led the Federal Aviation Administration to ground its new planes in January. In a statement, Boeing said the FAA has approved flights by one of the Dreamliners, something that will allow investigators to collect data about the plane's battery and electrical systems and hopefully lead to answers that could let Boeing fix the problem. As part of the approval, the crew must check for battery damage before the flight, monitor it while in the air, and take aboard only the most essential personnel in case problems do arise.

The 787 Dreamliner made its first US flight last year, but a pair of fires started by batteries have called its safety into question, and their causes are still unclear. In a meeting this morning, the NTSB said that preliminary reports on one plane indicate a single cell in the lithium-ion battery short-circuited, starting the fire. Investigators have ruled out external mechanical damage or an external short-circuit, but the failure remains a mystery: they're currently looking at whether it's possible wrinkles in the assembly or problems with how the eight cells were packaged together could have led to the short-circuit. While the FAA certification process for the 787 apparently involved testing whether a battery short-circuit could cascade through other cells and cause a fire, it clearly didn't catch the defect that showed up during January.

The fire has been tracked down to a single battery cell, but the cause is still unknown

The National Transportation Safety Board has said before that there's no deadline on getting the Dreamliners back in the sky for commercial flights, indicating that an investigation could take years to complete, but the FAA was already expected to allow these test flights. For now, we're seeing the first few steps towards at least figuring out what's gone wrong.