Boeing has urged airlines to inspect all 737 Max planes for a possible loose bolt in the rudder control system after an international airline discovered a bolt with a missing nut during a scheduled maintenance routine, the Federal Aviation Administration announced Thursday.
After the international airline, which the agency did not name, noticed the missing nut, Boeing discovered that an undelivered 737 Max also had a nut that was not properly tightened, the FAA said .
Boeing said it had delivered more than 1,370 planes worldwide since 2017 and requested that all be inspected for possible loose hardware. The company said it was also inspecting its undelivered 737 Max planes.
“The issue identified on this particular aircraft has been resolved,” Boeing said in a statement. “Out of an abundance of caution, we recommend that operators inspect their 737 Max aircraft and notify us of any findings.”
The FAA said it is closely monitoring the inspections and will consider further action if additional cases of loose or missing hardware are discovered.
Boeing said there had been no “in-service incidents” caused by possible loose hardware and that, before backing out of the gate, flight crews routinely performed checks that would alert them if the rudder was not working properly.
Such inspections involve removing an access panel and visually confirming that the rudder control system bolt has been properly installed, Boeing said. The company added that inspections would take about two hours by plane.
Several major U.S. airlines, including United Airlines, Southwest Airlines, American Airlines and Alaska Airlines, use the 737 Max, a high-performance single-aisle aircraft designed for short and intermediate distances.
United, American and Alaska each said they did not expect the inspections to affect their operations. Alaska said it would begin inspections Thursday and expected to finish them in the first half of January. Southwest did not immediately respond to a request for comment.
The 737 Max has a deeply troubled history.
In 2018, one of the planes, operating as Lion Air Flight 610, crashed into the ocean off the coast of Indonesia, killing all 189 passengers and crew on board. Less than five months later, in 2019, another flight, operating as Ethiopian Airlines Flight 302, crashed shortly after leaving the Ethiopian capital, Addis Ababa, killing all 157 people on board.
Regulators around the world grounded the Max after the second crash. The FAA cleared it to fly again in late 2020 after Boeing made changes to the plane, including to MCAS, the flight control system that caused the crashes. The company announced in late 2019 that it had fired its chief executive officer and agreed to a $2.5 billion settlement with the Justice Department in 2021.
Last year, Boeing reached a $200 million settlement with U.S. securities regulators, resolving an investigation into allegations that the company and its former chief executive misled investors about 737 Max problems that had leads to fatal accidents.
Gn En bus