On August 20, 1998, about 1328 eastern daylight time, a Piper PA-30, N7298Y, collapsed the landing gear on touchdown at the Pitt-Greenville Airport, Greenville, North Carolina. The airplane was operated by Carolina Aerial Mapping Service, Inc., under the provisions of Title 14 CFR Part 91, and visual flight rules. Visual meteorological conditions prevailed at the time of the accident. A flight plan was not filed for the aerial photographic flight. There were no injuries to the airline transport pilot or the photographer, and the airplane was substantially damaged. Origination of the flight was Greenville, North Carolina, about 1105, on the same day. The pilot reported that at 1300, they had completed the photo mission and were returning to Greenville. When the flight was within 10 miles of the airport, the pilot initiated a descend from 8000 feet. To facilitate the descent, the pilot elected to lowered the landing gear. When he placed the landing gear handle in the down position, there was no response, and there were no indicators that confirmed that the landing gear had extended. After several attempts to lower the landing gear, the pilot rechecked the procedures by using the normal and the emergency checklist. Throughout the emergency, the pilot was in radio contact with the Fixed Base Operator (FBO). The FBO provide technical assistance to the pilot. Once the pilot realized that his efforts, to lower the landing gear, were not yielding positive results, he elected to execute a gear-up landing. The pilot established an approach for a gear-up landing on runway 07. The airplane touched down and stopped on the runway. Emergency equipment was also available for the landing. Examination of the landing gear assembly revealed that the efforts of the pilot had achieved a partial extension of the main landing gear. Further examination of the airplane disclosed that the landing gear motor solenoid control wire had an intermittent terminal connection under the rubber insulation boot on the solenoid. According to the maintenance manual, this condition would not allow the solenoid to close and run the landing gear motor.