The airplane was being used to haul skydivers. According to the pilot, after about the third or fourth flight, there was a partial loss of power, due to a fuel tank vent that had been blocked by a mud dauber nest. The pilot noted that when a fuel cap was removed, he heard a 'hiss' as differential air pressure was relieved. Maintenance was performed to clear the vent, then the pilot continued hauling skydivers. After skydivers egressed at 10,500 feet during the ninth flight, the pilot entered a spiralling descent to return to the airport. He reported that during an approach to land on the runway, he attempted to add power to arrest his descent, but the engine did not respond. The pilot changed fuel tanks and attempted to restart the engine, but to no avail. He managed to fly over a pond, but the airplane touched down short of the threshold. The pilot steered the airplane to the left to avoid a fence; however, while maneuvering between the fence and a hangar, the airplane's left wingtip hit the hangar. The airplane then pivoted into the hangar and was further damaged. After impact, the pilot noted that the left fuel tank had ruptured and 'fuel was running' onto his neck and left side. The temperature and dew point were reported to be 64 and 37 degrees, respectively; according to icing probability charts, conditions were not conducive for carburetor icing. No reason was found for the loss of engine power.