Investors Financial Corp., the parent of Richmond's Investors Savings Bank, said yesterday that it lost $18.8 million in 1990, more than double its loss of $8.9 million in 1989.

The savings and loan, which operates 50 branches in Virginia, said it lost $4.7 million in the fourth quarter of 1990, an improvement over the loss of $13.8 million in the fourth quarter of 1989.

Investors, which recently underwent a management shake-up following a review by the Office of Thrift Supervision, said the 1990 results reflected increased problems with real estate loans.

As of Dec. 31, the S&L had $182.7 million of troubled loans -- those either in default or not paying interest. Two-thirds of those loans were made in Virginia for land acquisition and construction of homes, hotels, office buildings, apartments and shopping centers.

Steven C. DeLaney, who recently took over as president and chief administrative office, called the 1990 results disappointing, although he said they were expected, "given the breadth and depth of the real estate recession which is gripping most of the nation."

Investors no longer is in compliance with the federal standards for capital, the financial cushion that thrift owners must provide to protect against losses. DeLaney said Investors has filed a capital plan with regulators as required by law and is awaiting its approval.

Assets for Investors totaled $2.1 billion, down 6 percent from the $2.2 billion recorded in 1989.

UNC Inc. of Annapolis, which specializes in aircraft engine repair, reported a dramatic improvement in its sales and profit in 1990.

After a five-year restructuring effort, during which the company exited the submarine propulsion and environmental businesses, UNC has focused on the aviation business.

Profit for 1990 was $5.1 million (30 cents a share), compared with $11,000 a year earlier. Profit in 1989 was eaten up by write-downs associated with the closing of a defense-oriented facility in Connecticut. UNC reported that sales for 1990 were $356.3 million, up 17 percent from $305.2 million in 1989.

The company's turnaround was particularly evident in the fourth quarter, when profit moved up to $1.8 (10 cents) million from a loss of $5.5 million. Sales rose to $91.6 million from $80.7 million in the same quarter a year ago.

UNC Chairman Dan A. Cloussy said, "Despite current softness, the long-term trends of the commercial aviation industry hold promise for strong growth, and UNC expects to be an important part of that industry going forward, and to have increased earnings for 1991."