A Maine-based investment fund that was designed to help small businesses in rural areas has gone into receivership after operating for 15 years as part of a failed experiment by the U.S. Small Business Administration. A federal judge has turned over management of the fund, operated by Brunswick-based Coastal Enterprises Inc., to the SBA for the purpose of liquidating it. The deeply indebted fund, known as CEI Community Ventures Fund LLC, is one of the last remnants of an SBA program launched in 2002 to infuse long-term capital into small businesses in underserved areas through equity investing. While Community Ventures met its goal of creating rural jobs, it was ultimately hamstrung by factors including a recession in the early 2000s, restrictions on where it was allowed to invest, and a requirement that investment capital provided by the SBA must be repaid with interest, according to those involved. “It was really a social experiment, so that made it very challenging,” said Tim Agnew, principal of Massachusetts-based Masthead Venture Partners, who did volunteer work for the fund. Community Ventures was licensed by the SBA in August 2002 as a New Markets Venture Capital Company, according to a complaint filed in September by the SBA in U.S.