The 30,000 hour commercial rated pilot was flying downwind at approximately 50 feet on an agricultural application pass at the end of the field when the engine quit. The pilot landed straight ahead and hit two levees and a canal bank before coming to rest upside down. There was substantial damage to both wings, the empennage, and the tail surfaces, but only minor injuries to the pilot, who was the only occupant. The FAA inspector who responded to the accident scene said his visual check of the fuel in the airplane and in the operator’s supply facilities showed fuel that was clean and uncontaminated. The loss of engine power was undetermined. Weather reported at the time of the accident was 10 miles visibility, with few clouds at 3,700 feet, southerly winds at 14 knots, gusting to 21 knots with a temperature of 90 degrees and dew point of 72 degrees.