On July 25, 1996, at 1540 central daylight time, a Rockwell International Thrush S2R, N4886X, registered to Riddell Flying Service Inc., of West Helena, Arkansas, and operated by Air Ag Inc., of Greeley, Nebraska, under Title 14 CFR Part 91, impacted terrain during a forced landing following a loss of engine power near Tahlequah, Oklahoma. Visual meteorological conditions prevailed for the cross country flight and a flight plan was not filed. The commercial pilot was not injured and the airplane sustained substantial damage. The flight originated from West Helena 1 hour and 50 minutes before the accident. During a telephone interview, conducted by the investigator-in-charge, the pilot reported that the flight departed with 104 gallons of fuel (94 usable) en route to Plains, Kansas, with the first refueling stop planned for Tahlequah. Approximately 10 miles from Tahlequah while in cruise flight at 6,500 feet MSL, a total loss of engine power occurred. During the forced landing approach to a rough field approximately 7 miles from Tahlequah, the airplane landed hard, collapsing the gear, damaging the lower fuselage, propeller, left wing and spraying system. The owner reported, during a telephone interview conducted by the investigator-in-charge, that the operator had leased the airplane and was ferrying the airplane to Kansas. The owner further stated that the engine had accumulated about 3 hours since a major overhaul. Fuel consumption rate had not been determined for this engine since the overhaul; however, the previous fuel consumption rate was 45 gph and the airplane "ran out of fuel." The Pilot/Operator report states that the engine quit "due to fuel starvation."