Grumman Aerospace Corp. which employs 116 workers and is one of Loudoun County's biggest taxpayers, has decided to close its plant near Sterling and move the operation to Baltimore.

The Loudoun Board of Supervisors which has been attemping to attract new industry to the county, plans to send a delegation to Grumman's Sethpage, N.Y., headquarters next week to attempt to reverse the decision.

A Grumman spokesman said yesterday, however, that "We feel we have made a sound business decision and have no plans to reconsider. But we will be happy to listen to anyone."

Grumman paid $15.658 to the county in real estate tax last year and $71.772 in personal property tax on its 22-acre Sully Road facility. This total of $87.430 made Grumman one of the five largest taxpayers in Loudoun> excluding utilities, according to County Treasurer George Titus.

The Gumman spokesman said about 50 of the 116 employees at the plant will be offered jobs at a Glen Arm. Md., facility north of Baltimore. the company will seek to place the other workers, mostly skilled blue collar employees, before shutting down prior to the end of this year, ha said.

The spokesman said the Sterling plant has been making parts for the F 14 Tomcat and that an Iranian order for 80 of the supersonic fighters is nearing completion. Grumman will continue to produce three planes a month for the U.S. Navy, enough to keep the Sterling and Maryland plants working at half capacity.

The company had sought government approval to produce 60 planes a year instead of 36 but had been turned down, the spokesman said.

Loudoun County Administrator Philip A. Bolen said the loss would have "a serious fiscal impact on the county. They have been a good employer here and are a substantial part of the county tax base," he said.