What was supposed to be a weekend of fun at the Oceano Dunes turned tragic yesterday afternoon. State Park rangers say a sand car traveling at about 40-to-50 miles an hour had equipment failure, causing the vehicle to flip several time end over end. The driver, 24-year-old Kristopher Mancebo of Tulare was ejected from the vehicle. He would be pronounced dead at the scene. His passenger suffered moderate injuries and was transported to an area hospital. Officials say it was the second accident of the weekend.