***This report was modified on October 29, 2012. Please see the docket for this accident to view the original report.*** The pilot stated that he was in the airport traffic pattern prior to landing at the private airstrip. Aware of the unmarked power lines at the runway threshold, he used the top of the tower as a reference for altitude. After clearing the top of the tower, the pilot steepened his descent in order to land, but realized that additional power lines were still in the airplane’s flight path. The pilot applied full engine power in an attempt to clear the power lines, but the airplane’s landing gear struck the lines, and the airplane pitched downward. The airplane impacted the ground resulting in substantial damage to the right wing, and fuselage. The pilot reported there were no mechanical malfunctions or failures with the airplane that would have precluded normal operation.