The Department of Transportation's watchdog has started auditing how the Federal Aviation Administration approved Boeing's 737 Max plane, following two fatal crashes of the popular aircraft within five months.
"While FAA has maintained an excellent safety record, two recent accidents involving Boeing 737 MAX 8 aircraft have raised significant safety concerns," the DOT's inspector general's office said Wednesday.
Transportation Secretary Elaine Chao requested the audit last week.
Boeing and the FAA are facing increasing scrutiny over the plane, the company's fastest-selling aircraft ever. Investigators will examine Boeing's role in getting the plane to market. The FAA approved the aircraft in March and Boeing has orders for some 4,600 of the planes.
The U.S. government on March 13 joined dozens of nations in grounding the planes after the crash of an Ethiopian Airlines Boeing 737 Max 8, which killed all 157 people on board. That followed the crash of the same type of plane that was operated by Indonesian airline Lion Air in October. Investigators say the two crashes, which both occurred shortly after takeoff after the planes struggled to gain altitude, have shown "clear similarities."
A key focus will be an automatic stall prevention system that Boeing added to the planes. Pilots said they didn't know the system was added to the jets until after the Lion Air crash. The FAA did not mandate additional simulator training for the system, the Maneuvering Characteristics Augmentation System, known as MCAS. Investigators of the Lion Air crash have indicated the pilots were battling that system, which repeatedly pushes the nose of the plane downward to avoid a stall.
Boeing has developed a software fix for the system that it's detailing for pilots, airlines and regulators on Wednesday, which would give pilots more control of the plane and take more data into account to activate the system.