The layoffs may include management, engineers and information technology workers, said Ray Goforth, executive director of the Society of Professional Engineering Employees in Aerospace (SPEEA), which represents employees at Spirit.
Spirit, based in Wichita, Kansas, declined to comment. "We have no announcement to make at this time," said spokesman Ken Evans.
Airbus and Boeing are increasing production of jets to fill record orders for new planes. But the job cuts were considered unlikely to affect production at Spirit, which supplies full fuselages for Boeing 737s, the center fuselage section for Airbus A350s, wing sections for the Airbus A320 and other parts.
"Spirit managers are telling us informally that the company is about to engage in mass layoffs," said Goforth. He said some specialties, such as stress and structure engineers, were exempted from the layoffs.
Boeing declined to comment. Airbus could not immediately be reached for comment.
In March, Spirit named Larry Lawson as its new CEO, succeeding Jeff Turner. Spirit had cost overruns last year that led to a $134 million loss in the third quarter. The charges related to Boeing's 787 jet and to Gulfstream business jets.
The company has been performing a strategic and financial review of its development programs in Wichita; Tulsa, Oklahoma; Kinston, North Carolina; and St. Nazaire, France.
Spirit was spun off from Boeing in 2005 and employs about 16,000 in the U.S., Europe and Asia.
Reporting by Alwyn Scott; Editing by David Gregorio