At about 21:12 EST, a Cessna Cardinal was substantially damaged during a forced landing. The pilot, who was not injured, was en route from Reading, Pa., to Ocean City, N.J. While climbing through 5,000 feet, the engine started to shake violently and lost power. The controller told the pilot that Pottstown Municipal Airport, was 5 miles southwest. The pilot turned toward the airport and began a descent. About 1 mile from the airport the pilot decided that he would not be able to make the runway and maneuvered for a forced landing. The airplane touched down on a two-lane highway and struck an overpass with the left wing. An inspection revealed the No. 1 cylinder had separated from the 1,700-hour engine and was lodged in the cowling.