A series of simulator flights to test new software has uncovered a previously unknown flaw in the Boeing 737 Max computer system. Government pilots found that a microprocessor failure could push the plane downward, two sources familiar with the testing told CNN. The airliner has been grounded since March after two crashes killed 346 people, and the new development could add to the delay before the plane is put back in service. Preliminary reports from the investigation of those crashes showed that a new stabilization system pushed the planes into steep nosedives from which the pilots could not recover. Boeing has said it can come up with a software fix to limit the stabilization system.
Boeing acknowledged Wednesday that the FAA "identified an additional requirement" for software changes and said that it agreed with the decision. No date has been given for the plane's return to service. Many carriers have taken them off their flight schedules into October, USA Today notes. Nearly 500 of the 737 Max planes are grounded around the world, and about 100 of those are parked at Boeing's factory in Renton, Washington. The company has run out of room to park the 90,000-pound planes, some of which are newly built and haven't yet been delivered to their owners, and is putting them in the employee parking lot. (Read more Boeing 737 stories.)