Boeing said Tuesday that it expected deliveries of its popular 787 Dreamliner to be delayed as it and the Federal Aviation Administration look into quality control concerns with the plane, a widebody jet capable of carrying hundreds of passengers long distances.

Last month, the company said it had grounded eight planes already in service for inspection and repair after finding that it had fallen short of its manufacturing standards. On Tuesday, Boeing said it had identified another failure to abide by its own guidelines during production of a horizontal stabilizer, though it said there was no immediate safety risk.

“We are taking time to thoroughly inspect completed 787s to ensure that they are free of the issues and meet all engineering specifications prior to delivery,” the company said in a statement. “We expect these inspections to affect the timing of 787 deliveries in the near-term.”

Boeing said the new problem stemmed from excess force in assembling components of the stabilizer at its Salt Lake City facility and could affect the part’s life span. A total of 893 airplanes are believed to be affected, the company said, and it is examining whether repairs are needed on any jets now in service.

The Federal Aviation Administration is also investigating the company for manufacturing flaws related to the plane.

“The agency continues to engage with Boeing,” the agency said on Monday. “It is too early to speculate about the nature or extent of any proposed airworthiness directives that might arise.”

Boeing shares fell nearly 6% on Tuesday after The Wall Street Journal, citing agency documents, reported that the FAA was considering requiring deeper inspections of most of the approximately 1,000 Dreamliners delivered since 2011.

The Dreamliner is a star of Boeing’s lineup, a relatively fuel-efficient twin-aisle airplane suited to international service. The jet’s biggest customers include All Nippon Airways, United Airlines, Japan Airlines, American Airlines, Etihad Airways, Qatar Airways and Air Canada.

Production concerns with the plane are long-standing. More than a year ago, a review by The New York Times of hundreds of internal and federal records and interviews with current and former staff members found a culture that emphasized speed over quality at Boeing’s plant in North Charleston, South Carolina, one of two where the Dreamliner is produced. The other is in Everett, Washington.

In some cases, employee concerns were brushed aside as the company sought to cut long manufacturing delays, the investigation of the South Carolina plant found. In addition, Boeing’s practices had attracted the scrutiny of regulators and its own airline customers. Qatar Airways, for example, had stopped accepting planes from the factory. Nearly a dozen workers had filed complaints with federal regulators. And last month, the FAA proposed fining Boeing $1.25 million for failing to protect the independence of the agency’s representatives at the plant.

The concerns over Dreamliner production follow those raised about the Boeing 737 Max, which has been grounded since March 2019 after 346 people were killed in a pair of fatal crashes in Indonesia and Ethiopia. This year, the House Transportation Committee’s Democratic majority accused Boeing of overlooking safety in the interest of meeting manufacturing goals for the Max and said the FAA too willingly yielded to Boeing’s influence.

After a long review, the agency said last month that Boeing had “effectively mitigated” defects in the Max, potentially clearing the way for the plane to fly again this winter.

Many of the Boeing Dreamliners are grounded as air travel remains deeply depressed. Worldwide, domestic traffic fell 58% in July compared with the same month last year, according to the International Air Transport Association, an industry group. International demand was down 92%.

That month, Boeing said it was slashing production of the jet as its airline customers struggled to deal with the deep decline in travel. It also announced that it would study consolidating work on the plane at one plant, a move that the machinists union in Washington has criticized as a smoke screen to move operations to South Carolina, where workers are not unionized.

The study “may simply be masking a decision that is already made,” Jon Holden, president of the union, District 751 of the International Association of Machinists and Aerospace Workers, said in a recent newsletter to members. The editorial board of The Seattle Times called on Washington’s governor to prevent such a move.

Between the Max crisis and the pandemic, Boeing’s business has been buffeted this year. Through August, the company lost a net 378 orders, the company said Tuesday. It gained a net 54 orders last year and 893 in 2018.