On June 20, 1997, at 1515 central daylight time (cdt), a Grumman- Schweizer G-164A, N48FS, operated by a commercial pilot, sustained substantial damage when during its takeoff run the flight controls locked up. During the subsequent abort, the airplane nosed over. Visual meteorological conditions prevailed at the time of the accident. The aerial application flight was being conducted under 14 CFR Part 137. No flight plan was on file. The pilot reported no injuries. The local flight was originating from a private airstrip 5 miles northeast of Benton, Missouri, when the accident occurred. In his written statement, the pilot said that he was departing to the south from the mid-point of a private dirt strip. The airplane accelerated normally. Just after the pilot moved the stick full forward to lift the tail wheel off of the ground, he realized that the control lock was hung up on the control stick. The pilot could not pull back on the stick. The pilot said that he "throttled back too late. The propeller struck the ground. The airplane did a somersault, landing on its back." A Federal Aviation Administration (FAA) inspector examined the wreckage at the site. The airplane's empennage was broken downward and aft. The upper half of the airplane's vertical stabilizer and top half of the rudder were crushed downward. The top surfaces of the upper wings were bent and wrinkled. The forward leading edges of the lower wings were crushed downward and aft. The forward main spar and ribs near the wing roots were bent aft. The propeller exhibited torsional bending, chordwise scratching and tip curling. The engine was restarted and ran normally. A secondary ground control lock was found hooked onto the pin of the control stick making it impossible to move the airplane's ailerons or elevator. No other anomalies were found with the airplane. The airplane manufacturer stated that the control lock which is manufactured for the airplane consists of a "Y-shaped" bar which comes up from under the airplane's control panel with a small tab affixed to it. The tab has 3/8 inch hole in it. The hole fits over a pin mounted on the upper front side of the control stick. The manufacturer's control lock is designed to lock all of the airplane's flight controls. The secondary control lock found hooked on the control stick was installed by the pilot/owner of the airplane. It consisted of a small tab of metal with a 3/8 inch hole in it, mounted to a metal "A-frame" brace on the center floor of the cockpit. It was designed to lock the airplane's ailerons and elevator, leaving the rudder and tailwheel free to move. This allowed for better ground handling of the airplane.