Boeing Co. told U.S regulators on Friday that it didn’t see the need to undertake a potentially costly fix for a wiring issue on the company’s grounded 737 Max, according to two people familiar with the briefing.
The planemaker found in an audit last year of the 737 Max that wires were bundled improperly in a way that could trigger a failure similar to what happened in two crashes of the plane in which a total of 346 people died.
U.S. law requires wiring that could cause a hazardous condition in a failure to be separated from other wires.
The wiring issue is one of the remaining hurdles that must be resolved before the plane can be approved for flight. While Boeing has projected that it wouldn’t delay the effort, regulators could require costly and time-consuming repairs.
Other regulators, including the European Aviation Safety Agency, must also approve any fix.
A representative of Boeing declined to comment.
“We will rigorously evaluate Boeing’s proposal to address a recently discovered wiring issue with the 737 Max,” the U.S. Federal Aviation Administration said in an emailed statement. “The manufacturer must demonstrate compliance with all certification standards.”
The plane won’t be approved for passenger service until the agency is “satisfied that all safety-related issues are addressed,” the agency said in the statement.
The Max was grounded last March, three days after the second crash in less than five months. Boeing announced last month it was extending its projected time for resuming service on the jetliner to June or July, pushing the date back by months to ease tensions with regulators.
Boeing has argued that the wiring layout on the Max is similar or identical to previous models of the 737 known as the Next-Generation and there haven’t been any safety problems on those aircraft, one person said.
However, the Maneuvering Augmentation Characteristics System -- the automated flight-control feature that was automatically diving the planes in the two crashes -- wasn’t on the Next-Generation models.
The wiring issues have been found in more than a dozen locations on the 737 Max.
Aircraft wiring was suspected to have triggered several major accidents in recent decades and regulators have taken scores of actions to guard against short circuit and other failures.
But one of the lessons airlines, manufacturers and regulators have learned is that working on wire bundles can create unintended hazards, potentially complicating how the issue will be addressed on the 737 Max.