On July 30, 1996, about 0950 eastern daylight time, a Bell 47D1G, N1200Z, registered to a private individual, was substantially damaged during a forced landing in a residential area near West Boca Raton, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 aerial photography flight. The airline transport-rated pilot and one passenger were not injured. The flight originated about 0920 from the Antiquers Aerodrome Airport, Delray Beach, Florida. The pilot stated that while orbiting near the passenger's home about 550 feet mean sea level, the engine abruptly lost power. He initiated an autorotative landing to a residential area and while descending to land the helicopter on a road, the main rotor blades collided with trees. The helicopter then landed hard causing substantial damage. He further stated that following the loss of power he did not apply carburetor heat or check the magnetos. The passenger who is a private-rated pilot stated that the pilot was orbiting at an altitude between 150 and 200 feet above the ground. The helicopter was recovered and examination revealed sufficient fuel quantity to sustain engine operation; no contaminants were noted. Examination of the engine by an FAA airworthiness inspector revealed crankshaft, camshaft, and valve train continuity. The engine that was semi-attached to the airframe was rotated using the starter and each ignition lead was observed to spark and each magneto was observed to be properly timed to the engine. Review of a carburetor icing probability chart revealed that the conditions were favorable for light icing at cruise or descent power.