ST. LOUIS (AP) _ The structural engineers found responsible for design flaws that caused two skywalks to collapse at a Hyatt Regency hotel in 1981 have appealed a state board's decision to revoke their licenses.

The walkways overhanging the lobby of the Kansas City Hyatt fell during a crowded tea dance on July 17, 1981, killing 114 people and injuring more than 200 others.

The petition, filed Thursday in St. Louis Circuit Court, contends that the Missouri Board for Architects, Professional Engineers and Land Surveyors acted unconstitutionally and beyond its authority when it revoked the engineering licenses of Jack D. Gillum and Daniel M. Duncan on Jan. 22.

The eight-member board made its unanimous decision two months after Administrative Law Judge James Deutsch recommended that Gillum and Duncan be disciplined by the board because of gross negligence on the Hyatt project.

The appeal says the board's action denied the two their constitutional rights to equal protection and due process of law. It contends that several provisions of the state law regulating architects and engineers are ''vague, indefinite and uncertain.''

The decision and order of the board was ''arbitrary, capricious, and unreasonable and involves an abuse of discretion,'' the appeal claims.