A group of Washington area investors, including restaurateur Ulysses G. "Blackie" Auger, plans to acquire Metropolitan Federal Savings and Loan of Bethesda for $20.8 million.

Metropolitan made the announcement yesterday after its board had approved the sale. It now must be approved by stockholders and the Federal Home Loan Bank Board.

The investors will form a private holding company that will offer current stockholders $38 a share, consisting of $15 cash and $23 in the form of a 10-year convertible subordinated debenture paying 10 percent interest. The debentures are secured up to 75 percent by U.S. government securities, with the remainder secured by Metropolitan stock.

Metropolitan, which became a stock association in 1976, has 1,500 stockholders. The current market value of its stock, which is not traded widely, is estimated at between $28 and $31 a share. The principal stockholder, with a 10 percent interest, is Maryland restaurateur William G. Scaggs. He also serves as chairman of the board. The chief executive officer, President Robert J. McCarthy Jr., is expected to remain under the new ownership.

The other investors are attorney Robert Comstock, developer and restaurant owner Joel S. Meisel, and Washington Fish Exchange owner William C. Eacho Jr., plus eight others who declined to be identified. The group has been involved in previous financial investments of various types. Comstock said they decided to buy Metropolitan to keep it from being sold to an out-of-state company. Metropolitan operates 20 branch offices in Montgomery County. As of the end of June, it had assets of $402 million, net worth of $16.3 million and a healthy reserves-to-deposits ratio of more than 5.6 percent.

The investors will continue to operate Metropolitan as a mortgage lender, but also will also take advantage of some of the additional expansion opportunities recently granted savings and loans, Comstock added.