On July 19, 1994, at 2100 eastern daylight time, a Piper PA-23-160, N4482P, landed hard at the Columbus Metropolitan Airport, in Columbus, Georgia. The commercial flight instructor and his student were not injured. The aircraft was substantially damaged. The aircraft was operated under 14 CFR Part 91 by Corporate Air Transport of Columbus. Visual meteorological conditions existed at the time, and no flight plan was filed for the local, instructional flight. The flight originated at 2030. The flight instructor reported that after practicing some touch and go landings, his student was at the controls during the final landing. The approach proceeded normally, but the last landing was "firm." During a post-flight inspection of the aircraft, fuel was observed leaking from the aircraft. An internal inspection revealed that both main wing spars were bent. The flight instructor reported to the operator that the landing was "hard." A mechanic inspected the aircraft the following morning, and found both wing spars damaged beyond repair. All landing gear down lock switches were hanging from their wires, and fuel was leaking from the gascolators of both engines. The emergency locator transmitter was thrown from its position in the tail, and had activated. The landing gear warning horn activated when the electrical master switch was turned on. Several rivets were sheared, and the skin was wrinkled on both wings. The dual student had logged about 2,453 hours in single engine airplanes, and about 6 hours in multi-engine airplanes.