The Boeing Co. announced today that it plans to reduce the workforce of its Renton-based Commercial Airplanes division by 4,500 workers this spring, a 6.6 percent cut.

In making the reductions – which could include layoffs – the company will focus on overhead and support positions not directly related to airplane production, according to company spokesman Tim Healy.

Boeing’s production plant for 737 jetliner is in Renton, where it employs thousands of workers. Healy said the process is in its early stages and he can’t say how many workers would be affected in Renton or any production site or office.

Boeing also has its massive production plant in Everett.

It’s the second major announcement about job reductions affecting large Renton employers.

Kenworth Truck Co. announced in November that it will lay off up to 430 workers at its plant in north Renton in mid-January because of a significant downturn in truck sales caused by a worsening economy.

Most of Boeing’s reductions will happen in April, May and June. Employees who will lose their jobs will receive 60-day WARN notices beginning in late February. Boeing will offer laid-off employees layoff benefits and services to switch to a new career.

The cutbacks will return the division to its employment level at the beginning of 2008, when it employed more than 63,000 people. Employment now stands at about 68,000.

“We are taking prudent actions to make sure Boeing remains well positioned in today’s difficult economic environment,” Scott Carson, president and CEO of Boeing Commercial Airplanes, said in a press release.

According to the press release, Commercial Airplanes has begun a program to reduce overhead costs and discretionary spending. Although normal attrition and a reduction in contract labor will account for some of the job reductions, layoffs of Boeing employees also are necessary.

The reductions, according to the press released, “will enable Boeing to continue focusing on successfully executing new airplane development programs, delivering airplanes to customers, continuously improving productivity and quality, and supporting customer airplanes in the fleet.”