On May 19, 2012, about 1500 eastern daylight time, a Piper PA-28R-201, N6236C, was substantially damaged when it struck an unknown object while flying near Kingston, New York. The certificated commercial pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight, which originated from Kingston-Ulster Airport (20N), Kingston, New York. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. According to the pilot, he departed from 20N and after a brief local flight, was returning to the airport. While flying straight and level at an altitude "not lower than 2,500 feet", the pilot briefly observed a "dark mass" out of the corner of his eye, and then felt the airplane shaking. Upon further inspection, he noted that the left wing was damaged and that fuel was being released from the left wing fuel tank. The pilot continued to 20N, where he subsequently landed the airplane uneventfully. The pilot stated that he was uncertain what the airplane struck, and that following the accident he did not note any evidence of a bird strike. He also stated that he, “definitely did not hit trees.” According to a lineman who worked at 20N, the accident pilot approached him shortly after returning from the accident flight and asked if he wanted to see what a “bird strike” looked like. The lineman then examined the airplane and observed that the left wing of the airplane was covered with a green substance that did not appear to be bird entrails or bile. In looking more closely at the wing, the lineman observed some bark in the jagged metal edges of the damaged wing skin and observed tree bark within the exposed fuel tank. The green residue the lineman initially observed on the left wing turned brown on the day following the accident. The lineman also provided photographs the left wing he had taken following the accident, which were consistent with his stated observations. Federal Aviation Administration inspectors performed an examination of the airplane following the accident, and provided photographs of the damage they observed. The leading edge of the left wing was damaged at two locations, each displaying concave breaches of the wing structure that were oriented perpendicular to the wing chord. The inboard-most breach was about 8 inches wide and the outboard-most breach was about 13 inches wide. The inboard breach was co-located with the left wing fuel tank, and the tank was found absent of fuel. The outboard section of the wing, just inboard of the wing tip, was also crushed and dented aft. The wing skin was covered with brown discolorations of unknown origin. The inspectors cut away portions of the wrinkled wing skin in the vicinity of the fuel tank and found a piece of wood lodged in the bent folds of the skin. The inspectors also found another piece of wood that was previously hidden from view within the fuel tank.