On September 9, 1997, approximately 1030 mountain daylight time, a Bellanca 7GCBC, N5500L, was substantially damaged when it collided with a power line about a mile west of Columbus, Montana while engaged in low flying. The two pilots on board were not injured. They performed a precautionary landing in a wheat field adjacent to the power lines. Visual meteorological conditions prevailed at the time of the accident. The airplane was being delivered to the owner's home in Snohomish, Washington. There was no report of the ELT actuating. The pilot in the rear seat stated that he was flying the airplane, which had just been purchased by the pilot in the front seat. The rear seat pilot, who was also an aircraft mechanic, did not meet flight currency requirements and had not had a medical exam since 1992. The front seat pilot was the new owner of the airplane. She stated that she was not aware of the other pilot's medical status or lack of currency.