On November 19, 2006, at 1715 Pacific standard time, a Cessna 172RG airplane, N28RJ, was substantially damaged when the landing gear collapsed during the landing roll on runway 28R at the Montgomery Field Airport (MYF), San Diego, California. The commercial pilot and three passengers were not injured. The airplane was operated by the pilot through the Golden Wings Flying Club, El Cajon, California, under the provisions of 14 CFR Part 91. The personal flight departed MYF at 1600. Night visual meteorological conditions prevailed and a flight plan had not been filed. According to a report obtained from the MYF airport manager, the airplane experienced a complete electrical failure during the flight. The pilot elected to return and land at MYF. After receiving a clearance to land from the tower (via light gun signal), the pilot prepared for landing and moved the landing gear handle to the down position. The landing gear dropped from their bays, but did not extend and lock into place. The pilot did not pump the emergency landing gear extension handle to lock the landing gear in the down position. As the aircraft touched down on the runway, the main landing gear legs folded back into their retracted position. The left wing and horizontal stabilizer contacted the runway as the aircraft came to a stop in an upright position. The airplane sustained substantial damage to its left horizontal stabilizer. The reason for the electrical failure was not determined.