Aviation giant Boeing announced last year plans to reboot a Macon plant from a military facility into a commercial aerospace factory making fuselage pieces for a new cargo variant of the company’s iconic 747 jumbo jet.

State and city leaders hailed the move, which they said would preserve jobs at the facility and create up to 200 more positions over the next few years. But Boeing has reversed course, saying in a statement this week it will close the facility at Middle Georgia Regional Airport once its defense mission is complete at the end of the year.

Boeing placed the blame on a softening market for large cargo jets amid a slump in the cargo hauling market.

The announcement is a blow to Middle Georgia, which put high hopes on what was said to be Boeing’s first-ever conversion of a factory from a defense plant to a commercial aviation facility. The plant employs about 120 people.

The Macon plant makes components for the A-10 close air support fighter-bomber and the CH-47 helicopter. It previously was involved in the C-17 Globemaster freighter program.

The plan to convert the facility, announced in September 2015, called for work to begin on components for 747-8 fuselage panels to begin in 2018.

Boeing said it has halted plans to increase production of the 747-8 aircraft, from half a plane a month to one plane per month in 2019.

“(Boeing Commercial Airplanes) has determined that it does not have a business case at this time for taking on the Macon site,” the company said in a statement.

“Following the completion of defense work in December, site operations will conclude with no planned restart,” the statement said. “We are continuing to assist employees who are interested in employment opportunities at other Boeing locations. As well, we continue to work with state agencies to identify employment opportunities outside of Boeing for employees.”

At the time of last September’s announced change in mission, the state’s economic development chief, Chris Carr, said the conversion plan “is the result of progressive and persistent teamwork between the public and private sector.”

But it appears that teamwork couldn’t overcome global economic pressures.

“Naturally, we are disappointed that market demand will not support Boeing moving forward with these commercial activities,” the state’s Deputy Commissioner of Global Commerce, Tom Croteau, said in a statement. “No state funds were expended for the project. We remain optimistic, and we will be here to support Boeing as they continue to explore new opportunities.”

The site opened in 1980, according to Boeing, and originally made cargo deck equipment for the 747.

“For more than 35 years Boeing has been proud to be a member of the Macon-Bibb community,” Boeing said in a statement. “During that time, the men and women on the Boeing Macon team have performed with unmatched professionalism and delivered products with outstanding quality to those who serve our nation around the globe.”

Macon-Bibb County Industrial Authority Chairman Cliffard Whitby said his organization owns the facility and will retain control of it once Boeing exits. He said the plan is to market it to other potential industrial users, and that the recruitment of future firms might be aided by plans to expand runways at the airport if voters approve a special purpose local option sales tax vote in November.

“Our focus today and for the next several months will be to assist the displaced workforce and their families,” he said. “That’s our top priority right now.’