THE DRIVER WAS GOING DOWN THE HILL ON HAUL ROAD, THE TRUCK BEGAN TO GAIN SPEED. THE BRAKES WERE APPLIED ALONG W/ENGINE BRAKE. THE TRUCK WASN'T SLOWING DOWN FOR THE CORNER AT BOTTOM OF HILL. TH E AIR PRESSURE WAS LOW & THE DRIVER ENTERED THE CORNER TOO FAST. TRUCK LAID OVER ON LEFT SIDE. DRIVER WAS PINNED BETWEEN SEAT & DOOR, RECEIVED CUT ON LEFT CALF & HEAD.