Another issue with Boeing 737 Max, Fuselage flaw grounds nearly 50 planes

Boeing has uncovered another quality issue with its 737 aircraft, this time involving improperly drilled holes in fuselages supplied by Spirit AeroSystems. The defect could delay deliveries of around 50 new planes, the company said on Monday.

In a letter to employees, Stan Deal, CEO of Boeing's commercial airplane division, said the drilling error was detected by Spirit, which manufactures fuselages for the 737.

"While this potential condition is not an immediate safety issue and all 737s can continue operating safely, we currently believe we will have to perform rework on about 50 undelivered planes," Deal wrote.

The disclosure comes as Boeing and Spirit face heightened scrutiny over manufacturing defects after a panel blew out of a 737 MAX 9 jet during an Alaska Airlines flight on January 5. That plane made an emergency landing in Portland shortly after takeoff.

The new fuselage issue adds to quality troubles that have plagued Boeing and strained relations with some major customers. United Airlines' CEO Scott Kirby said last month the carrier may look at other models in the future. Alaska Airlines' CEO Ben Minicucci said he was "angry" over the recent defects.

The U.S. Federal Aviation Administration grounded all 737 MAX 9s after the Alaska Airlines incident. Two weeks later, the agency approved an inspection process to allow the jets to resume service. Alaska and United, the only other U.S. operator, have started returning some MAX 9s to their fleets.

Meanwhile, Boeing last week withdrew a request for regulators to certify a new smaller version of the 737 MAX without meeting a key safety standard. The company's shares fell 3% on Monday amid the ongoing quality concerns.