(Bloomberg) -- Ryanair Holdings Plc said it faces broad delivery delays of the 737 Max aircraft as Boeing Co. deals with the latest supplier glitch afflicting the workhorse jet, with the disruptions forcing the airline to pare back its winter flight schedule.

Boeing advised the Irish discount specialist at a meeting this week that it will only be able to deliver 14 of the 27 aircraft due by late December, Ryanair Chief Executive Officer Michael O’Leary said in an interview Wednesday in London. The setback is the result of quality lapses at Spirit AeroSystems Holdings Inc., which builds the jet’s frame, he said.

The delays will result in schedule cuts during winter, Ryanair said in a separate statement Thursday. Flight cancellations will take effect from the end of October, and Ryanair cautioned that the delays could affect its full-year traffic target should they worsen or extend into 2024.

The timing of deliveries of the remaining 43 aircraft scheduled to arrive by next April is “in the lap of the gods”, O’Leary said Wednesday. Boeing aims to push back some of the handovers into the peak summer period next year, while Ryanair wants the planes sooner. The disruption is particularly vexing for Ryanair as it needs all the capacity it can get to benefit from the post-pandemic travel boom, the CEO said. 

“We’re really getting worried,” O’Leary said of Boeing. “Most of the delays here are production failures, quality control failures in Wichita or Seattle and they have to eliminate those. They build great aircraft but quality control and production problems have really become a feature of the last couple years.”

Ryanair fell as much as 2% to €15.61 in Dublin. The stock has gained 27% so far this year.

The carrier already lowered its full-year traffic estimate in July to about 183.5 million passengers, down from a previous prediction of 185 million, also citing Boeing delays.

The disruptions at one of Boeing’s most important and loyal customers highlight the obstacles that the US manufacturer faces as it addresses supplier defects while trying to speed up work in its factories to meet soaring demand for fuel-efficient new jetliners. 

“We value our partnership with Ryanair and are committed to supporting them,” a Boeing representative said.

Spirit AeroSystems recently discovered a drilling irregularity in the aft pressure bulkheads that helps maintain cabin pressure, affecting some Max 7, 8 and -8200 models — the high-density version ordered by Ryanair. The inspections are more complicated than for a separate issue found earlier this year, requiring X-ray probes of hundreds of holes per plane, Brian West, Boeing’s chief financial officer, said this month.

Ryanair placed a landmark order this year for 150 of Boeing’s largest 737 Max models, with an additional 150 options. Still, O’Leary has never been shy of calling out the planemaker publicly over delays or pricing. In July, the airline cut its passenger growth forecast after deliveries were disrupted by a separate Spirit issue involving brackets that join the jet’s vertical fin to its fuselage. 

(Updates with Ryanair statement from second paragraph.)

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