ON 8/28/03 APPROX 7:30 PM, EE WAS DOING A P.M. SERVICE ON A 777D ROCK TRUCK. HE THREW A SMALL OIL FILTER FROM THE GROUND UP TO THE DECK OF THE ROCK TRUCK. THE FILTER ROLLED OFF THE TRUCK, HIT A STEP & BOUNCED INTO HIS FOREHEAD. HIS HEAD WAS CUT APPROX 3/4"". HE HAD STITCHES IN FOREHEAD.