On April 22, 2019, about 2020 mountain daylight time, a Piper PA-18, N727WW, was substantially damaged when it was involved in an accident near McCall, Idaho. The private pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he departed about 1900 with 14.5 gallons of fuel on board. About 10 miles east of the destination, he began a cruise descent for landing at a reduced power setting. Shortly after the power reduction, the engine continued to run but did not respond to throttle input. The pilot began to troubleshoot the issue, but the airplane continued to descend. The pilot stated that he slowed the airplane as much as possible before impacting trees. The airplane came to rest suspended in a tree about 4 miles from the destination airport. During recovery of the airplane, about 1.5 gallons of fuel was drained from the right fuel tank. There was no fuel drained from the left fuel tank. Both wing fuel tank caps were securely installed. The fuel selector was found in the left tank position. No fuel was found in the gascolator bowl. Disassembly of the carburetor revealed no anomalies or evidence of contaminants. About 1 tablespoon of clear blue liquid consistent with 100 low lead aviation fuel was drained from the carburetor bowl. The oil filter was cut open and found free of metallic debris. The spark plugs and magnetos displayed no anomalies. Examination of the cylinders with a borescope revealed normal operating signatures. The atmospheric conditions at the time of the accident were conducive to the development of carburetor icing at glide power settings.