On March 5, 2002, approximately 1855 mountain standard time, an Unander Velocity 173RG experimental-category amateur-built airplane, N278GJ, was substantially damaged in a gear-up landing at Salt Lake City Municipal Airport #2 (Salt Lake #2), West Jordan, Utah. The private pilot-in-command and one passenger were not injured in the accident. Visual meteorological conditions were reported at Salt Lake #2 at 1855, and no flight plan was filed for the 14 CFR 91 personal flight from Wendover, Utah. The pilot reported that he was attempting a landing after dark on runway 16 at the non-towered airport. The accident pilot reported that as he was turning base for runway 16, another aircraft (registration number not reported or determined), which he had passed on the way into Salt Lake #2, announced that he was entering downwind for runway 34. The pilot reported that he attempted to talk to the pilot of the other aircraft on the radio, but got no response (NOTE: According to the U.S. Government Airport/Facility Directory (A/FD), Salt Lake #2's Common Traffic Advisory Frequency [CTAF] frequency is 122.7 MHz.) The pilot stated that he put the gear switch down, but forgot to check for three green lights since his attention was diverted to the other aircraft. The pilot stated that he saw the other aircraft turning final as he (the accident pilot) was about to flare. The pilot reported that he then attempted to initiate a go-around, but the aircraft's propeller struck the runway and the engine stopped. The aircraft touched down on the sod on the side of the runway and subsequently struck an object on the ground and slid partially back onto the runway. The pilot stated that the other aircraft subsequently landed on runway 34 and went past the accident aircraft. An FAA inspector who was at the airport at the time reported that the landing gear handle was in the "down" position at the accident scene, but that the gear appeared to have never come out of the wells. The pilot of the other aircraft was not identified to the NTSB and was not contacted. The pilot reported that a hydraulic down pressure switch (part number 0166-41604-3-064) had failed, disabling normal landing gear extension. The pilot reported the total time on the part as 3 hours, and stated that he had just replaced this switch after a previous switch had failed. The pilot indicated in his NTSB accident report that the aircraft kit maker, Velocity Aircraft of Sebastian, Florida, had been made aware of this problem. Salt Lake #2 is equipped with an AWOS-3 automated weather observation system (AWOS) that broadcasts automated weather observations on 134.425 MHz. Winds at the airport were reported as being calm at 1755, then from 240 degrees true at 8 knots at 1855 and from 250 degrees true at 7 knots at 1955. The A/FD does not specify a calm-wind or preferred runway for the airport.