On May 23, 1996, at 1800 mountain daylight time, a Navion NA1, N2530T, collided with trees and terrain during the forced landing following a loss of engine power near Los Lunas, New Mexico. The flight was operated by Southwest Aviation, Inc., of Fairacres, New Mexico, under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the personal cross country flight and a flight plan was not filed. The private pilot received serious injuries, and the airplane sustained substantial damage. The flight originated from Albuquerque, New Mexico, at 1730. Witnesses reported to the local authorities that there was "no power on the engine." Maneuvering to clear houses, the airplane landed in the "only open area"; however, during the landing roll the airplane struck trees. The integrity of the left fuel tip tank was compromised; however, the integrity of the right fuel tip tank was not compromised and was 1/2 full. The FAA inspector responding to the accident site found the fuel selector on the main (center) tank, with an estimated 10 gallons of fuel in that tank. The left wing was separated from the airframe with additional structural damage to the right wing, firewall, engine, and engine mounts. During telephone interviews, conducted by the investigator-in-charge, and on the Pilot/Operator Report, the information in this paragraph was revealed. The pilot flew between Albuquerque, New Mexico, and Los Cruces, New Mexico, on a regular basis. During this flight, as the pilot leveled the airplane at 10,500 feet MSL for cruise and moved the fuel selector from the main tank to the right fuel tank the engine "sputtered and died." He selected the main fuel tank and turned the fuel boost pump to the "HIGH" position (which had restarted the engine during a loss of power on a previous flight); however, this time the engine did not restart and a forced landing was initiated. Congested areas of trailer houses and trees gave no suitable place for the landing. The pilot stated that during the final approach, he extended the landing gear and upon maneuvering to cleared a 70 foot tree he "stalled the airplane [and] drop[p]ed approximately 75 feet to the ground." During a telephone interview, conducted by the investigator-in-charge, the owner/operator reported that the pilot had been flying this Navion for about 2 years and had originally received a renter check out from a flight instructor; however, the owner did not recall the extent of the check out. The owner stated that he often flew the airplane and that "air would collect in the fuel lines if the tip tank was run dry." Subsequently, after refilling the tank, when the tank was selected, the engine "might quit for a few seconds especially if the fuel boost pump was not turned on prior to selecting the tip tank." However, once the engine was running, "the boost pump needed to be turned off to prevent too much fuel flow to the engine." Fueling records for the aircraft did not reveal if a fuel tank was run dry prior to this flight. The owner recalled the pilot having mentioned the previous loss of engine power; however, no discrepancies were found with the airplane. A review of the maintenance records by the investigator-in-charge revealed that following a major overhaul, on October 10, 1989, engine S/N 121662-8-B was installed on the airframe. The last annual inspection was November 9, 1995, with no open discrepancies noted in the maintenance records and the airplane was "determined airworthy." On October 15, 1996, engine model IO-520-B, S/N 121662-8-B, was examined by the NTSB at Mobile, Alabama. An engine test run in the factory test cell (Teledyne Continental Motors) did not reveal any discrepancies that would have contributed to a loss of engine power. See the enclosed report for additional details.