Boeing redesigning flight-control system of grounded 737 Max

The latest update to improve aircraft reliability is in addition to the planned software fix

A Boeing 737 Max 8 plane is shown on the assembly line in March at the company's factory in Renton, Washington. The US planemaker is aiming to present an updated software package to regulators by September. Photo: APShow less

Boeing is redesigning the flight-control system of the grounded 737 Max to rely on data from both of the jetliner’s flight-control computers instead of just one, said a person familiar with the plans.

The US plane maker is still aiming to present a final software package to regulators by September, though the timeline could slip, said the person, who asked not to be named because the plans are private. The latest approach is more comprehensive than a software update Boeing has been preparing to address a system linked to two fatal crashes.

The change to the software architecture for the grounded jetliner was reported earlier by the Seattle Times, which detailed Boeing's response to a fault flagged by US regulators in June. The Federal Aviation Administration, under fire for certifying the Max, uncovered the issue while testing theoretical failures in a new system-safety analysis of the Max's flight controls.

Under the changes now being planned for the configuration, the flight-control system will read inputs and outputs from both of a jet's computers for a range of sensors monitoring airspeed, altitude and the angle of the aircraft's wings against the air stream. It will check for any disagreements in the sensor readings, the Seattle Times said.

The new approach, meant to make the Max more reliable, also guards against the risk that a processing error or chip failure could send an erroneous reading to the flight controls, according to the report.

Boeing previously had proposed redesigning a system known as MCAS so that it compared readings from two angle-of-attack sensors vanes and wasn’t triggered by a single, faulty sensor. In both deadly accidents, erroneous data tripped the flight-control software that repeatedly pushed down the aircraft’s nose until pilots lost control.

The October crash of a Lion Air 737 Max 8 and the March disaster involving an Ethiopian Airlines plane of the same model killed 346 people.