On August 7, 2005, at 1245 mountain standard time, a Mooney M20C, N6330Q, collided with terrain while executing an emergency landing after a loss of engine power at La Cholla Air Park, Oro Valley, Arizona. The commercial pilot operated the airplane under the provisions of 14 CFR Part 91. The pilot and passenger were not injured, and the airplane was substantially damaged. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight originated at Novato, California, at 0735. The pilot reported to the National Transportation Safety Board investigator that they had been airborne for about 5 hours 10 minutes. She had been using standard fuel management procedures by switching tanks about every hour. She made the final switch to the right tank at 1230. At 1240, she overflew the La Cholla Air Park and executed a standard entry. While in a left-hand turn to enter the downwind leg, and at 1,500 feet above ground level (agl), the engine began to run abnormally and then quit producing power. She diverted to the crosswind runway, and landed short of the runway threshold in desert vegetation. An examination of the airplane revealed that neither the left wing fuel tank or the right wing fuel tank contained fuel. In this unfueled condition both left and right cockpit fuel gages read 1/4. The airplane was fueled with 1 gallon avgas in the left tank. The engine was started and run for approximately 30 seconds before it was shutdown. The propeller was bent, causing the airplane to vibrate severely during the engine test run.