Boeing has asked airlines to inspect all 737 Max planes for a possible loose screw in the rudder control system after an international airline discovered a screw with a missing nut during routine maintenance, the Federal Aviation Administration said 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 urged that all planes be inspected for possible loose parts. The company said it is also reviewing its undelivered 737 Max aircraft.
“The issue identified with the specific 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 report any findings to us.”
The FAA said it is closely monitoring inspections and will consider further action if additional cases of loose or missing hardware are discovered.
Boeing said there were no “operational incidents” caused by potentially loose hardware and that flight crews routinely performed checks before pushing back from the gate to warn them if the rudder was not functioning properly.
Such inspections include removing an access panel and visually confirming that the screw in the rudder control system has been properly installed, Boeing said. The company added that inspections would take about two hours per aircraft.
Several major American air travel companies, including United Airlines, Southwest Airlines, American Airlines and Alaska Airlines, use the 737 Max, a short- and medium-haul single-aisle work aircraft.
United, American, Southwest and Alaska each said they did not expect the inspections to impact their operations. Alaska said it would begin inspections on Thursday and expected to complete them in the first half of January. Southwest said it performed the work during routine overnight maintenance.
The 737 Max has a deeply turbulent history.
In 2018, one of the planes, named Lion Air Flight 610, crashed into the sea 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 was behind the crashes. The company announced in late 2019 that it had fired its chief executive and agreed to a $2.5 billion settlement with the Justice Department in 2021.
Last year, Boeing agreed to a $200 million settlement with U.S. securities regulators, concluding an investigation into allegations that the company and its former CEO misled investors about problems with the 737 Max that led to the would have led to fatal crashes.