On May 24, 1995, about 1248 eastern daylight time, a Boeing 727-232, N489DA, registered to Delta Air Lines, Inc., and operating as Delta flight 1522, scheduled domestic passenger service from West Palm Beach, Florida, to Atlanta, Georgia, sustained damage when it collided with a tug during pushback at West Palm Beach. Visual meteorological conditions prevailed at the time and an instrument flight rules flight plan was filed. The aircraft sustained substantial damage. The airline transport-rated pilot, first officer, flight engineer, 3 flight attendants, and 130 passengers were not injured. The flight was originating at the time of the accident. The tug driver who was pushing N489DA from the gate stated that two of the aircraft's engines had been started before pushback due to the aircraft's power unit being inoperative. During the pushback there were two wing walkers. There was not a signal man in front of the aircraft in view of the captain, as required by Delta Air Lines pushback procedures, due to manpower shortages. He pushed the aircraft straight back and then turned the aircraft's tail to the left. The aircraft and tug made a "U" shape at this time with the tug on the aircraft's right front. As he moved the tug to straighten the aircraft's nose gear, the safety pin on the tug end of the tow bar sheered. He did not believe he turned the nose gear beyond the normal limits; however, it was a "sharp" turn. The aircraft became disconnected from the tug and rolled forward at which time the right front side of the aircraft struck the tug. As the aircraft rolled forward the tug driver's headset cord became disconnected from the aircraft and he lost communication with the cockpit crew. The left wingman arrived at the front of the aircraft at this time and signaled the captain to brake the aircraft and stop it.