New York (CNN Business) Boeing's largest supplier is laying off a significant number of its employees because of the 737 Max production suspension.

Spirit AeroSystems SPR , which makes fuselages for the Max as well as other items for Boeing, announced Friday that it is furloughing approximately 2,800 workers. Shares of the Wichita, Kansas-based company fell more than 1% in trading.

"The difficult decision announced today is a necessary step given the uncertainty related to both the timing for resuming 737 Max production and the overall production levels that can be expected following the production suspension," Spirit AeroSystems CEO Tom Gentile said in a press release.

Boeing BA said in December that it was suspending 737 max production for an indefinite period, due to continued uncertainty about when the plane will be allowed to fly again. The company hasn't said how long the production halt will last or at what rate it might resume once the Federal Aviation Administration certifies the jets to fly again.

Spirit believes production will be "lower than previously expected" whenever it resumes. Boeing accounts for 79% of the manufacturer's revenue, according to Spirit's 2019 annual report to the Securities and Exchange Commission. The Max alone represents more than 50% of Spirit's revenue.

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