Horace Evans Slone, 70, a retired engineer and official, died Sunday at his home in Bethesda after a heart attack.

He was a member of the FCC review board from the time it was established in 1962 until he retired in 1971.

Mr. Slone joined the FCC in Philadelphia in 1940. He transferred here in 1946, and worked in the broadcast engineering department.

Three years later, he was appointed to the office of formal hearing assistants and later became chief of that office.

Born in Lee Center, N.W., Mr. Slone received a degree in electrical engineering from Syracuse University and took graduate work at Cornell University.

He worked as a radio engineer for the General Electric Co. in Schenectady, N.Y., and as a broadcasting engineer in Newport News, Va. From 1937 to 1939, Mr. Slone was assistant professor of electrical engineering at Clemson College.

He was a member of Silver Spring Lodge No. 215 of the Masons and of the Scottish Rite. He also was a past patron of Chapter No. 66 of the Eastern Star.

Mr. Slone belonged to the Concord-St. Andrew's United Methodist Church in Bethesda.

He is survived by his wife, Janet, of the home; a son, Joseph H. Fitzgerald, of Rockville, and a sister, Mrs. John E. Christopher, of Syracuse.

The family suggests that expressions of sympathy be in the formof contributions to the American Heart Association.