An employee had just finished a repair on a tilt hoist. He climbed a 9-foot A-frame ladder to ensure that a nut on the chain tensioner was tight. He then climbed down the ladder, which had been leaned against the frame of the tilt hoist. When he was at the second rung from the bottom, the ladder slid down. He did not fall from the ladder but struck his right hip on the ladder as it slid down, breaking it.