US regulators have found a potential risk in Boeing’s troubled 737 Max aircraft during simulator trials, which is likely to delay test flights.

According to Boeing release, during the FAA’s review of the 737 MAX software update and recent simulator sessions: “The Federal Aviation Administration (FAA) identified an additional requirement that it has asked the company to address through the software changes that the company has been developing for the past eight months.”

In March, this top-selling aircraft was grounded following two crashes within six months.

Boeing is focusing on upgrading the plane’s flight control system to prevent it from stalling. Failure of this system was considered to be the reason for these crashes by investigators.

Once fixed, the software is intended to cut pilot workload by accounting for a potential source of un-commanded stabiliser motion.

Boeing stated that will not offer the 737 MAX for certification by the FAA until all requirements for certification of the plane are complete.

In May, the FAA indicated that the approval of the changed 737 Max could come this month, which would enable test flights next month.

In October 2018, a Lion Air plane crashed in Indonesia. Pilots on this aircraft were believed to have had trouble with stall prevention system that pulled the plane’s nose down.

In March this year, another plane crashed in Ethiopia. This crash was also blamed on the stall prevention system. These two crashes killed a combined 346 people.

In the same month, Boeing announced a fix for 737 Max aircraft. However, earlier this month, Boeing announced that some of its 737 planes, including many 737 Max aircraft, may have faulty parts on their wings.

Working with the US Federal Aviation Administration (FAA), it contacted 737 operators, advising them to inspect the slat track assemblies on some planes.