On July 6, 2009, about 1115 mountain standard time, a Piper PA-28-140, N5957U, sustained substantial damage when it struck a tree during a precautionary landing near Taylor, Arizona. The airplane was registered to, and operated by, the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The commercial pilot and his passenger were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight. The cross-country flight was originating at the time, with an intended destination of Payson, Arizona. The pilot reported that after conducting a short field takeoff from runway 21 (a 7,000-foot long asphalt runway), "the aircraft was not getting enough lift from the engine." The pilot stated that he "could not find a mixture setting that would give additional power" and that the airplane was unable to hold altitude. The pilot observed power lines ahead and to the left and right of the airplane simultaneously with the stall warning light "flickering on," the pilot decided to initiate an off airport landing in an open field as he was "uncertain if I had enough power to turn around." The pilot stated that "the engine was not producing enough power and there was a little sputtering." During the landing roll, the right wing of the airplane struck a juniper bush. Examination of the airplane by the pilot revealed that the right wing was partially separated at the wing root. The engine was examined by the NTSB investigator-in-charge (IIC). The engine remained attached to the airframe via all its mounts. The left and right wings were removed by wreckage recovery personnel to facilitate wreckage transport. An external fuel tank was attached to the left wing fuel lines to facilitate an engine run. The engine was started and ran uneventfully at various power settings for about two minutes before it was shut off using the mixture control lever. A magneto check was performed at 1,700 rpm and a 100 rpm drop was noted for both the right and left magnetos. Examination of the engine revealed no mechanical anomalies that would have precluded normal operation. The closest weather reporting station was located at the Show Low Regional Airport (SOW), Show Low, Arizona, about 12 nautical miles southeast of the accident site. At 1130, the automated weather observing system reported wind from 250 degrees at 12 knots, visibility 10 statute miles, clear sky, temperature 28 degrees Celsius, dew point 3 degrees Celsius, and an altimeter setting of 30.25 inches of Mercury. Using recorded weather conditions, an airport elevation of 5,823 feet mean sea level (msl), the IIC calculated the density altitude to be 8,429 feet and a pressure altitude of 5,519 feet.