On October 23, 2004, at approximately 1105 mountain daylight time, a Cessna 170A, N9176A, piloted by a private pilot, was substantially damaged when it impacted the roof of a townhouse while maneuvering near Glenwood Springs, Colorado. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under the provisions of Title 14 CFR Part 91 without a flight plan. The pilot sustained serious injuries. The local flight originated at approximately 1000. Prior to the accident, the pilot had been flying for approximately 1 hour. He stated that he descended from approximately 8,500 feet msl at an engine power setting of 2,200 rpm, without carburetor heat. This descent lasted approximately 20 to 30 minutes as he flew from west to east, approximately 60 miles. The pilot entered the traffic pattern at approximately 7,000 feet msl. He applied carburetor heat, enrichened the mixture "somewhat," and reduced power to approximately 1,500 to 1,700 rpm, "prepatory for landing." According to the accident report submitted by the pilot, he was on final approach for runway 32 when he "decided [the] aircraft [was] too high" and added throttle to initiate a go-around. The engine did not respond to the application of throttle. In a phone conversation with the pilot, he stated that the engine did not cough or sputter and the propeller was still spinning. According to a witness who observed the airplane prior to the accident, the engine sounded as if it was running with "landing power." The pilot reversed course to avoid flying over the city of Glenwood Springs. He was unable to maintain altitude and the airplane impacted the roof of a townhouse, slid down the roof and subsequently impacted the side of an adjacent townhouse. The airplane came to rest on the ground between the two town homes. The engine, propeller and cowling were crushed aft and the left wing was crushed aft. On November 4, 2004, the engine was inspected and run by a representative of Teledyne Continental Motors under the auspices of the National Transportation Safety Board. No anomalies were noted that would have precluded the engine from producing power. The aviation routine weather report (METAR) at Rifle, Colorado, reported the temperature as 34 degrees Fahrenheit (F) and the dewpoint as 31 degrees F. According to the carburetor icing chart, conditions were conducive for "serious icing at cruise power."