Salina ? Airplane maker Hawker Beechcraft Corp. announced Monday that it will close its Salina operation.

The company, one of the nation’s leading business jet manufacturers, said in a news release that it informed its Salina employees and the International Association of Machinists leadership Monday morning.

The release said the union has been asked to make a “business case” for moving jobs to Wichita, where Hawker Beechcraft is headquartered.

No timeline for the closure has been set.

Its lease with the the Salina Airport Authority, where it occupies 484,000 square feet and 10 buildings, doesn’t expire until February 2012.

“We are continuing to work with them for a smooth transition as they close down their Salina operation between now and 2012,” said Melissa McCoy, a spokeswoman for the authority.

About 240 people work at the Salina operation, down from about 500 a year ago. The plant builds wings, spar assemblies and other subassemblies.

Local union negotiator Pat Maxey said workers were prepared for the news.

Hawker Beechcraft CEO Bill Boisture had said in October the company likely would close the Salina plant and move the work to Wichita.

“Now it’s getting down to how long it’s going to be open. Whether these jobs are going to Wichita or not is what is up in the air,” Maxey said.

Salina Airport Authority Executive Director Tim Rogers said it was disappointing news coming from a company that has been in Salina since 1966. Beechcraft was an anchor tenant when the military closed Schilling Air Force Base.

Officials including Salina City Manager Jason Gage and Salina Area Chamber of Commerce President and CEO Dennis Lauver expressed dismay with the company at a news conference Monday afternoon. Multiple local entities had been working to put together a proposal to keep the company in Salina.