The controversial plane model has finished its software overhaul.

Boeing has announced that the software updates to their fleet of Boeing 737 MAX aircraft is now complete. The updates were focused on the flight control software that was implicated in the two deadly crashes which involved 737 MAX planes.

Regulators in aviation will likely still have many more questions and challenges for Boeing at this point. It is not fully clear how pilots will interact with the plane’s controls under different circumstances, though Boeing claims it is currently providing this information to regulators. The US Federal Aviation Administration is also currently reviewing Boeing’s software updates and plans for additional pilot training, alongside other foreign aviation regulators. A certification flight with Federal Aviation Administration representatives will be necessary before things can move forward.

The two previous crashes in Indonesia and Ethiopia were attributed to failures in the automated system known as MCAS. MCAS is believed to have mistakenly turned the planes’ noses downward due to mistakes in a sensor. The result was two plane crashes which left a total of 346 people dead. All 370 MAX jets in the world have since been grounded as the cause and potential solution to the mechanical errors has been investigated.

Boeing’s engineers have been working on this software update for about six months now, which is far longer than they’d expected. The changes will link an anti-stall feature to the aircraft’s flight control systems to two sensors, as opposed to one. These changes will push the nose down less often and with far less power. Boeing has run 207 test flights with the new software so far.