Boeing has urged airlines to inspect 737 Max aircraft for a possible loose bolt in the rudder control system, according to the US Federal Aviation Administration.
The US plane maker has issued a multi-operator message, urging operators of newer single-aisle planes to inspect specific tie rods that control rudder movement for possible loose hardware, the US regulatory body said on Thursday.
The FAA said it is closely monitoring targeted inspections.
“The FAA will remain in contact with Boeing and the airlines while the inspections are under way,” the agency said.
Boeing recommended the inspections after an international operator discovered a bolt with a missing nut while performing routine maintenance on a mechanism in the rudder-control linkage, said the FAA.
The company discovered an additional undelivered aircraft with a nut that was not properly tightened, it said.
The inspections will take about two hours per aircraft, with all new 737 Max planes to undergo the check before they are handed over to customers.
The agency said it is asking the airlines to work through their approved safety management systems to identify whether any loose hardware has been detected previously and to provide the FAA with details on how quickly the inspections can be completed.
“The FAA will consider additional action based on any further discovery of loose or missing hardware,” it said.
Boeing shares were down 1.2 per cent at midday on Thursday, before closing down 0.67 per cent.
This is the latest quality issue to affect the company’s best-selling jet, which was grounded for two years, in March 2019, after a defect in its flight stabilising system was involved in two fatal crashes.
In October, Boeing cut its 737 delivery target for this year, citing production quality problems at its biggest supplier Spirit AeroSystems, which makes fuselages for the narrow-body jets.