On March 13, 2000, at 1530 central standard time, a Grumman G-164A agricultural airplane, N6637, was substantially damaged when it impacted a fence during an aborted takeoff from a private grass airstrip near Garwood, Texas. The airplane was registered to and operated by Aero Ag Services, Inc., of Garwood. The commercial pilot, sole occupant, was not injured. Visual meteorological conditions prevailed and a flight plan was not filed for the 14 Code of Federal Regulations Part 137 aerial application flight. The local flight was originating at the time of the accident. During a telephone interview, conducted by the NTSB investigator-in-charge, the pilot stated that this was his 15th application load of the day. During the takeoff roll, approximately 3/4 of the way down the runway, the engine lost power. The pilot stated that "the engine kept cutting in and out." He elected to abort the takeoff; however, he could not stop the airplane prior to the end of the runway. The airplane rolled through a fence and came to rest on its nose in a ditch. The pilot and the FAA inspector, who visited the accident site, started the engine and conducted a magneto check. The engine operated "normally" on the right magneto; however, the engine would not operate with the left magneto selected. The FAA inspector stated that both of the bottom wing spars were structurally damaged.