On November 3, 1999, at about 1815 eastern standard time, a Piper PA-28-235, N8515W, registered to a private owner experienced an on-ground collision with a fixed object at the Raleigh-Durham International Airport, Raleigh, North Carolina. Visual meteorological conditions prevailed and no flight plan was filed. The airplane sustained substantial damage. The private-rated pilot and private-rated pilot/passenger reported no injuries. The flight originated from Concord, North Carolina, about 1 hour before the accident. The pilot stated he made a visual approach to runway 23 right, and backed the approach up with the ILS. On touchdown the airplane veered to the left. He stated he had not applied any brakes. The airplane departed the runway into the grass. He applied brakes, regained directional control, and maneuvered the airplane back on the runway. He contacted the tower and informed them that he did not know what had happened. He stated the tower asked him if he had a bird strike. He stated he did not know. He exited the runway onto the taxiway and contacted ground. He looked out the window to his left and saw a dent in the wing. He informed ground control that he knew he had hit something. He taxied to the ramp without further incident. An operational check of the airplane brake system by an FAA aviation safety inspector revealed no deficiencies.