Boeing has confirmed that it will deploy a flight control software upgrade for the 737 Max “in the coming weeks”.
In a statement, the manufacturer says it has been developing the software enhancement in the aftermath of the Lion Air flight JT610 crash, but did not link it to the Ethiopian Airlines 737 Max 8 crash on 10 March.
“This includes updates to the Maneuvering Characteristics Augmentation System (MCAS) flight control law, pilot displays, operation manuals and crew training. The enhanced flight control law incorporates angle of attack (AOA) inputs, limits stabiliser trim commands in response to an erroneous angle of attack reading, and provides a limit to the stabiliser command in order to retain elevator authority,” it details, adding that the upgrade is designed “to make an already safe aircraft safer”.
Boeing adds it has been working closely with the US Federal Aviation Administration (FAA) on the “development, planning and certification” of the software upgrade, which also incorporates feedback from customers. It will deploy the upgrade across the 737 Max fleet in the coming weeks.
The FAA has said that it anticipates mandating the software enhancement through an airworthiness directive no later than April.
“It is important to note that the FAA is not mandating any further action at this time,” adds Boeing.
The FAA said on 11 March that it has not received enough evidence to warrant a grounding of the US fleet of Max aircraft, even as a growing number of aviation regulators around the world ordered a grounding of the type. It disclosed however that it was overseeing Boeing’s changes to the MCAS.
In the Boeing statement, the manufacturer also said that the MCAS was implemented on the Max to improve aircraft handling characteristics and decrease pitch-up tendency at elevated angles of attack, adding that the system does not control the aircraft in normal flight but rather improves its behavior in a non-normal part of the operating envelope.
It reiterated that the Max’s flight operations manual already outlines existing procedures to safely handle a situation where there is erroneous data from an AOA sensor. “The pilot will always be able to override the flight control law using electric trim or manual trim,” it adds.
Flight ET302 crashed six minutes after takeoff from Addis Ababa enroute to Nairobi on 10 March. The airline has revealed that the pilot “mentioned that he had difficulty” and asked to return to the airport shortly after takeoff. This raised concern about similarities to the JT610 crash on 29 October 2018, which occurred shortly after takeoff from Jakarta.