Fluor Gives a Boost to Performing Arts Center : Donation: The $500,000 gift will help cover what Center officials call the inevitable gap between operating expenses and income.

In a significant boost to the Orange County Performing Arts Center’s drive to increase its relatively cash-poor endowment fund, the Fluor Foundation has awarded a $500,000 grant to the fund.

Fluor’s gift, announced Thursday, raises the fund to $3.5 million in cash and investments. Center officials said they hope to have $15 million in cash assets in the fund by the end of 1996.

The contribution is the foundation’s fourth award to the Center in 11 years, bringing its total Center support to $2.5 million. The foundation is the philanthropic arm of the Irvine-based Fluor Corp., one of the nation’s largest construction companies.

Center officials say that interest and dividends from the endowment are used to help cover what they call the inevitable gap between annual operating expenses and earned income, and therefore ease the burden of annual fund raising.

In 1991, approximately $230,000 will be realized through the endowment for Center programming and operations. The Center’s operating shortfall for the year is projected at $5.1 million, most of which will have to be raised through private fund raising.

While Center founders were collecting cash gifts for the construction of Segerstrom Hall, which opened in 1986, they gathered more than $50 million in pledges to the endowment fund. But most of the pledges are estate bequests and other deferred gifts, are not legally binding and in any case would not be received until as many as 40 years from now.

Though some performing arts centers operate without endowments, a number of major centers have cash endowments that equal or exceed their annual operating budgets (the Center’s 1991 budget is more than $17 million). The Lincoln Center for the Performing Arts in New York City, for example, has an endowment of $70 million against an annual budget of about $40 million. The Los Angeles Music Center has an endowment of $49 million against an annual operating budget of $76 million.

Last year, Center officials announced a drive to raise more cash for the endowment. The drive was launched by a $1 million award from the W. M. Keck Foundation. The Fluor Foundation award is the first major gift since then.

“We made a commitment to the Center long ago,” Bob Fluor said Thursday. Fluor is president of the Fluor Foundation and Fluor Corp.’s vice president of corporate affairs.

Henry T. Segerstrom, Center vice chairman for endowment, said in a prepared statement that increasing the cash level of the endowment fund is crucial to both the current and long-term stability of the Center.