Boeing discovers new 737 Max software flaw that may delay jet comeback

US planemaker working with the aviation regulator to address glitch and updating airlines and suppliers

FILE - In this Dec. 16, 2019, file photo, a worker looks up underneath a Boeing 737 MAX jet, in Renton, Wash. Boeing has found a new software problem on its grounded 737 Max jetliner. The aircraft maker said, Friday, Jan. 17, 2020, it is making the necessary changes and working with the Federal Aviation Administration. (AP Photo/Elaine Thompson, File)
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Boeing discovered a new flaw in the software of its troubled 737 Max during a technical review of the grounded plane, adding to the problems plaguing the jet and potentially further delaying its return to commercial service.

The US planemaker is working to fix the glitch, Boeing said in a statement on Friday. Boeing's share price dropped 2.36 per cent to $324.15 at the close of trading in New York on Friday, making it the day’s biggest loser on the Dow Jones Industrial Average.

“We are making necessary updates and working with the FAA on submission of this change, and keeping our customers and suppliers informed," Boeing said in an emailed statement. "Our highest priority is ensuring the 737 Max is safe and meets all regulatory requirements before it returns to service.”

Boeing's best-selling plane has been grounded since March 2019 following two deadly crashes, in which its flight-control system was implicated. Ethiopian Airlines and Lion Air's 737 Max plane crashes, which killed 346 people, occurred after the Maneuvering Characteristics Augmentation System (MCAS), a flight-control system, repeatedly pushed the planes to dive nose downwards. Pilots in both tragic incidents were able to maintain control temporarily, but eventually the aircraft dived steeply and crashed.

The issue surfaced during a technical review that happens towards the end of the formal development process of the software updates being installed on the aircraft. The review is required to specifically identify and address such issues.

The glitch revolves around a software power-up monitoring function. This function verifies that certain system monitors are operating correctly, ensuring there are no latent faults.

The monitor check is initiated by a software command when the aircraft or system power ups, and will set the appropriate indication if maintenance action is required.

The issue is that one of the monitors was not being initiated correctly by the software at power-up.

It is unclear how long it will take to fix the problem. Boeing did not provide a timeline when The National asked for comment.

The US aviation regulator has not publicly commented on the software issue.

Boeing is freezing production of the 737 Max in January. The crisis has cost the jet maker billions of dollars in losses, hurt airlines' operations and disrupted plane parts suppliers. The return of the 737 Max to commercial service has been postponed several times, leading to costly flight cancellations for airlines.

Southwest Airlines, GECAS, Flydubai, American Airlines, Air Canada, Norwegian Air Shuttle, Air Lease Corporation and Air China are the biggest customers of the 737 Max jet.