New York (CNN) — The launch of Boeing’s long-delayed 777X aircraft has encountered another problem, forcing the company to pause testing and dealing yet another blow to Boeing’s reputation for quality.

Boeing discovered problems in a structural component between the engine and the plane’s wings in a test flight. Boeing said in a statement that it “identified a component that did not perform as designed” and it’s replacing the part to record “any learnings from the component.” The Air Current was first to report on the problems.

The 777X, billed by Boeing as the “world’s largest and most efficient twin-engine jet,” was supposed to enter service in 2020. It had expected to have delivered several hundred of the planes by now. But it has been plagued by delays and cost overruns.

Another stumbling block could further delay its revised 2025 launch date. Test flights of its four-aircraft fleet will resume “when ready,” Boeing added.

The 777 has been a big success for Boeing since it began service in 1995, and it remains the best selling wide-body aircraft. The 777X would provide airlines with another version of the plane, in addition to the popular but aging 777-300ER.

It’s another setback for Boeing, which is already embroiled in safety crisis following the mid-air blowout of one of its door plugs on a 737 Max flight operated by Alaska Airlines earlier this year. Boeing said that a lack of paperwork resulted in the four bolts needed to hold the door plug in place never being installed before the plane left the factory last year.

The 777X problems were just the latest in a host of safety and quality concerns related to Boeing assembly lines. Those problems have become the focus of multiple federal investigations and whistleblower revelations, and the cause of delays in jet deliveries that are causing headaches for airlines and passengers around the globe.

Last week, Boeing posted a rare win over Airbus in July orders for new planes. However, it still badly trails its rival in orders so far this year, as safety concerns continue to dent the company’s reputation.

Boeing has lost $33 billion since 2019 — an eye-popping number that underscores how far the company has fallen from the days when its name was a byword for American quality.

Shares of Boeing (BA) fell 2% in premarket trading Tuesday. The stock is down nearly 30% for the year.

–CNN’s Chris Isidore and Tamara Hardingham-Gill contributed to this report.

The-CNN-Wire

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