A series of flights from Boeing's new software testing simulator reveals the flaw, according to one source.
The latest versions of the popular Boeing jet were grounded in March after two crashes – Lion Air 610 Flight 302 of Ethiopian Airlines – which killed 346 people.
While the catastrophes are still being investigated, preliminary reports show that a new stabilization system pushes the two planes into steep carriers from which pilots can not recover. The issue is known in aviation as a beacon stabilizer.
Boeing said he could break the chain of events that led to the two crashes by developing a software solution that would limit the effectiveness of this stabilization system.
In simulator tests, government pilots have found that denial by a microprocessor can push the nose of the plane to the ground. It is not known whether the microprocessor played a role in both cases.
When testing the potential microprocessor failure in the simulators, "test pilots were hard to recover for a few seconds," one of the sources said. "And if you can not recover in seconds, that's an unreasonable risk.
Boeing engineers try to solve the problem
"The safety of our aircraft is Boeing's highest priority, we work closely with the FAA to safely return MAX service," Boeing said in a statement.
Sources claim that Boeing engineers are trying to determine if the microprocessor problem can be solved through reprogramming software or if the physical microprocessor replacement of each 737 Max aircraft might be required.
A FAA spokesman would not confirm the specific problem, but told CNN that "the FAA process is designed to identify and highlight potential risks." The FAA recently found a potential risk that Boeing needs to mitigate. Pilot training is also updated
In preparation for the return of the aircraft into operation, Boeing and FAA also develop details for additional training for 737 MAX pilots, which may include extra time for the simulator,
Boeing and FAA work with European, Brazilian and Canadian civil aviation authorities.
The FAA is still actively considering whether longer and more costly training will be required for a simulator, according to
Gregory Martin, a spokesman for the FAA, said on Wednesday that the regulator "follows an in-depth process rather than a prescribed schedule for return of the Boeing 737 Max passenger services ". "The FAA will lift the order to ban the plane when we think it's safe to do so," the spokesman said. "We continue to evaluate the modification of Boeing's software and we are still developing the necessary training requirements."