"On the most recent issue, the FAA's process is designed to discover and highlight potential risks. The FAA recently found a potential risk that Boeing must mitigate," the FAA told the news agency. "The safety of our airplanes is Boeing's highest priority," a Boeing spokesperson told Engadget in a statement. "We are working closely with the FAA to safely return the MAX to service."

While the FAA and Boeing didn't disclose the exact nature of the flaw, CNN reports government pilots found an issue with the microprocessor that may lead to the plane pointing downwards if the chip fails. According to one of the outlet's sources, during the simulator tests, "it was difficult for the test pilots to recover in a matter of seconds. And if you can't recover in a matter of seconds, that's an unreasonable risk." It's not clear if the microprocessor played a role in the crashes.

The 737 Max has been out of service since earlier this year after two crashes killed 346 people. Last month, Boeing said it completed an update to resolve software flaws that contributed to the incidents.

Boeing statement via a spokesperson: