On April 21, 2016, about 1140 central daylight time, a Mooney M20C, N6870N, was destroyed when it impacted trees and terrain after the engine lost power shortly after takeoff from William R. Pogue Municipal Airport (OWP), Sand Springs, Oklahoma. The pilot sustained minor injuries. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions (VMC) prevailed and no flight plan had been filed. The airplane departed OWP and was en route to Ponca City Regional Airport (PNC), Ponca City, Oklahoma, when the accident occurred. During the preflight inspection, the pilot noted there was no contamination or water in the fuel, and the fuel was blue in color, similar to 100LL. He did not dip-stick the fuel tanks, but the [fuel gauges] "indicated fuel on board was ¼ tank on left and 1/3 on right, for a total of 15-16 gallons." According to the pilot's accident report, there was complete loss of engine power during initial climb. The pilot made a "mayday" emergency radio call and attempted to turn back towards the airport. The airplane descended and impacted trees less than a mile northeast of OWP and came to rest inverted. Both wings, ailerons, fuselage, empennage, and tail surfaces were extensively damaged. Several witnesses heard the pilot's radio call and responded to the scene. Emergency medical personnel arrived shortly thereafter and extricated the pilot from the wreckage. Federal Aviation Administration (FAA) inspectors from the Oklahoma City, Oklahoma, Flight Standards District Office (FSDO) went to the scene and examined the airplane. According to a conversation with the airworthiness inspector, the fuel tanks had not been compromised. Although the airplane had just received an annual inspection, it had not been flown for nearly a year and the fuel was at least that old. Examination of the fuel in the fuel pump and gascolator revealed only a few drops of fuel and no evidence of water or other contamination. No visible fuel was observed in the left fuel tank, and 10 to 12 ounces of fuel was drained from that sump. The right fuel tank contained a few gallons of fuel, but he was unable to drain/measure due to the wing resting on the hangar floor. The fuel selector was positioned on the left fuel tank. In an e-mail dated May 12, 2016, the pilot said he thought the cause of the loss of engine power was due to fuel starvation because he was operating on bad information from the fuel gauges and overestimated the amount of fuel available in the left tank.