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.
Major airline customers for Boeing's 737 Max model include Southwest, United, American Airlines, Ryanair, flydubai, Air Canada, Turkish Airlines and some Chinese carriers.
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.
Meanwhile, analysts don't expect any order cancellations for the Max, according to Addison Schonland, partner as US-baed AirInsight.
"That is because Boeing will stand by the Max and ensure everything gets fixed," he said.
"The impact on Boeing is less a financial hit unless the problem is found on lots of aircraft and Boeing will have to compensate with repair costs. Possibly even inspection costs, too. But the size of this impact is not clear at all for now."
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.
The Arlington, Virginia-based company now expects to deliver 375 to 400 of its 737 aircraft this year, down from a previous target of 400 to 450 jets, as a result of the repair work required.
Boeing expects to complete the transition to producing 38 of the 737 jets per month by year-end, with plans to increase to 50 per month in the 2025-2026 time frame, it said in October.
The company reported a net loss of $1.6 billion in the third quarter on the back of higher costs at its defence unit and fewer deliveries of its 737 aircraft due to supplier problems, marking its ninth consecutive money-losing quarter.
Boeing narrowed its losses from $3.3 billion in the same quarter last year.
The timing of the latest technical snag is "most unfortunate", according to Mr Schonland.
"It comes just as China is taking Max deliveries again. China was the first to ground the Max and the last to retake deliveries," he said.
The timing is also "awkward because load factors are high for the holiday period", Mr Schonland added.
