Airbus has identified and contained a quality issue in the fuselage structure of its A321neo aircraft, the European planemaker said, adding that the affected jets could continue operating as the defect does not pose a safety risk.

The problem affects around 500 aircraft—roughly 250 already in service and another 250 in production, according to a source familiar with the matter who was not authorised to speak publicly.

The A321neo is Airbus' largest and best-selling single-aisle jet, seating up to 244 passengers and designed for routes of up to 4,000 nautical miles (7,400 kilometres). The source said the defect does not affect the longer-range A321XLR variant.

This is the second fuselage-related industrial problem to hit Airbus' top-selling model in nine months, after the manufacturer reported defects in fuselage panels last December. That earlier issue was also a quality problem with no safety implications, but resolving it caused several months of delivery delays.

Airbus said the latest issue involves a "deviation" in the surface protection, or coating, applied to stringers—the skeletal components that run lengthways along a fuselage. The company said the flaw was discovered while parts were already undergoing rework on the production line.

The source said Airbus first identified the problem over the summer, with detailed analysis results coming back more recently. The affected fuselage sections are manufactured by Stelia Aerospace, Airbus' in-house aerostructures unit, which was not immediately available for comment outside business hours.

Airbus said it has identified and contained the source of the defect and that a remedy is available. Customers are continuing to take deliveries without requiring extra pre-delivery work, and Airbus has told them there is no immediate requirement for repairs, the source said.

European aviation regulators may still issue a directive that requires fixing the defects within a set timeframe. US carrier Delta Air Lines, which operates A321neo aircraft, said it remains in continual contact with manufacturers and would "always take action to meet or exceed operator recommendations and regulator directives."

The latest setback comes as Airbus works to raise narrow-body production to 75 aircraft a month from about 60 currently.

Source: Reuters