The operator of three Mullboon's restaurants and the private club Studebaker's has placed the enterprises under Chapter 11 of the federal bankruptcy code.

Brentley Mahaffey filed separate petitions for Mullboon's Inc.; Mullboon's of Ogden; Bojo Inc., representing the Midvale restaurant; Concept Clubs Inc., doing business as Studebaker's; and Allen Hospitality Corp., a restaurant management firm.Niether Mahaffey nor his attorney could be reached for comment.

According to the petitions, as of July 31, 1988 Allen Hospitality had liabilities of $672,500 and assets of $22,500; Concept Clubs had liabilities $257,445 and assets of $281,650; Mullboon's Inc. had liabilities of $338,561 and assets of $427,326; Mullboon's of Ogden had liabilities of $189,139 and assets of $153,227; and Bojo Inc. listed liabilities of $142,905 and assets of $219,372.

Under Chapter 11, the companies are shielded from lawsuits and allowed to work out a court approved plan to pay back debts.