On February 28, 2000, at about 1512 eastern standard time, a Cessna 150L, N717NC, registered to Nosworthy Corporation, operating as a 14 CFR Part 91 personal flight, crashed on approach to landing at Pilot Country Airport (X05), Brooksville, Florida. Visual meteorological conditions prevailed and no flight plan was filed. The airplane sustained substantial damage. The private pilot reported minor injures. The private pilot passenger sustained serious injuries. The flight originated from Pilot Country Airport about 5 minutes before the accident. The pilot stated he had landed at X05 and taxied back for takeoff. He remained in left closed traffic for runway 36. Upon reaching his abeam point for his intended point of landing, he applied carburetor heat, reduced power, turned left base, applied flaps 40 degrees, and pushed the throttle in to clear the engine. The engine did not clear. He added power with no response. He pushed the throttle all the way in with negative results, turned final and lined up so as to land over the lowest part of an earth berm running perpendicular to the end of the runway. He lined up with a grass strip alongside the runway flying just above stall speed. He realized the berm was coming closer. He applied aft pressure on the control yoke and hit the berm with all 3 landing gear, and the airplane came to rest inverted. Examination of the airplane wreckage revealed the carburetor heat was found in the off position. Damage at the bottom of the carburetor air box revealed that the air valve was in the open position, no carburetor heat applied. Examination of the engine revealed no mechanical reason for the engine failing to maintain power. For additional information see FAA Inspector statement and Continental Motors Accident Investigation Report. The engine assembly was removed and transported to Certified Engines Unlimited, Inc., an authorized FAA approved repair station. The engine was placed in a test cell. The engine developed rated power and achieved takeoff power. Review of the probability carburetor icing chart revealed the engine would encounter serious icing at descent power based on the weather observation at the time of the accident.