On February 15, 1994, at 2240 Atlantic standard time, a Cessna 172K, N79401, registered to Sugarbush Air Services, Inc., crashed into a house near the Culebra Airport, Culebra, Puerto Rico, while on a 14 CFR Part 91, instructional flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft was destroyed and the commercial- rated pilot flight instructor received minor injuries. The dual student received serious injuries. The flight originated at Culebra, Puerto Rico, on February 15, 1994, at 2030. The flight instructor stated that he was flying the aircraft at the time of the accident. Enroute from Isla Grande Airport, where they had performed takeoffs and landings, he obtained the current San Juan weather and the St. Thomas weather. The winds were reported to be easterly at 10 knots. He elected to perform a downwind landing on runway 31, due to rising terrain northwest of the airport. As they flared for landing they encountered "two successive severe blasts" from the right. They regained control and continued the landing flare. They again encountered a "blast" of air from the right. The aircraft was lifted 60 to 80 feet into the air and moved to the left over buildings, wires, and across a road where it collided with a house. As the aircraft flew out of control he raised the flaps and moved the throttle to the idle position.