On April 22, 1999, about 1925 eastern daylight time, a Piper PA-24-180, N7059P, registered to McGill Aircraft Corporation, was landed gear up at the Fernandina Beach Municipal Airport, Fernandina Beach, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 maintenance test flight. The airplane was substantially damaged and the private-rated pilot, the sole occupant, was not injured. The flight originated about 10 minutes earlier from the St. Mary's Airport, St. Mary's, Georgia. The pilot stated that the flight entered the traffic pattern on a left midfield downwind at a 45-degree entry and turned base then final and used a "mental" checklist but did not use the printed checklist in his lap. He further stated that he was wearing his headset and could not recall hearing the gear warning horn. He landed with the landing gear retracted. Postaccident, he reentered the airplane which was on the runway, turned on the master switch, and noted the landing gear "up" light illuminated. He determined that the airplane came to rest approximately 375 feet from the point of touchdown. With the airplane on the runway, an FAA certificated airframe and powerplant mechanic entered the airplane, turned on the master switch, and heard the gear warning horn. He advanced the throttle which silenced the horn. The airplane was raised from the runway, and the landing gear was extended using the normal extension method; the gear locked into place. Following recovery of the airplane, the landing gear system was examined in the presence of an FAA Airworthiness Inspector. The landing gear warning horn did not operate but an aural "click" sound was heard. The landing gear lights operated during the test.