On May 18, 1996, at about 1530 eastern daylight time, a Cessna 205A, N5261G, lost total engine power while towing a banner near Sommerville, Virginia. The pilot, the sole occupant, was not injured. The airplane sustained substantial damage when it impacted a tree during the emergency landing roll. Visual meteorological conditions prevailed, and no flight plan was filed. The local flight was conducted under 14 CFR Part 91, and departed from the Hartwood Airport, in Somerville, Virginia, at about 1150. The pilot stated that he was returning to the departure airport with a long (50 letter) banner in tow. He indicated that the airplane was approximately two miles from the airfield, at an altitude of about 900 feet above ground level, when the engine started to sputter and then quit. The pilot unsuccessfully attempted to release the banner over a wooded area, then turned the aircraft to a heading of approximately 160 degrees to land. The airplane touched down on the edge of a local farmers hayfield and struck a tree during the landing roll. The pilot reported that he examined the banner tow attach ring, and found that it had fouled on the tow hitch, "...preventing [the banner's] release." He said that he had leaned the mixture during the banner tow operation, but about two minutes before the engine stopped he enriched the fuel mixture and turned on the fuel boost pump. He stated that, according to his figures and fuel quantity gauges, he had approximately 30 minutes of fuel remaining on board the airplane. Postaccident examination revealed approximately seven gallons of fuel remained in the wing fuel tanks. Due to the damage to the engine mounts, the engine could not be run. However, examination of the engine and it's accessories revealed no evidence of preimpact mechanical malfunction.