Labor Department has sued the Carpenters Pension Fund Trust-Detroit and Vicinity, Troy, Mich., claiming the fund used plan assets to make mortgage loans to participants. Such loans are not allowed by the plan. Under the lawsuit, the Labor Department seeks to require the plan and its trustees to undo the loans and repay the plan, as well as make up for any losses it incurred in undoing the loans. According to the lawsuit, the plans trustees authorized AAA Mortgage to make mortgage loans since September 1995, and let participants pledge their vested accrued retirement benefits as collateral for the mortgage loans, even though the plan expressly forbids such pledges. As of July 30, the outstanding principal of the mortgage loans exceeded $14.7 million, according to the suit. The plan, established as a result of collective bargaining by the Michigan Regional Council of Carpenters and five employer associations, had $1.04 billion in assets as of April 30, 1998, according to the suit.