On May 29, 2003, at 1200 central daylight time, a Grumman G-164A, N29SK, operated by Nemaha Valley Aerial Inc., sustained substantial damage during a loss of directional control while landing at a private airstrip near Seneca, Kansas. Visual meteorological conditions prevailed at the time of the accident. The commercial pilot reported no injuries. The 14 CFR Part 137 aerial application flight was not operating on a flight plan. The local flight departed at an unconfirmed time. The pilot reported he applied brakes after touching down and the airplane made an "unwarranted and abrupt 90-degree turn to the right." The pilot stated he applied left rudder to gain control of the airplane and the airplane slid sideways down the runway. The left main landing gear strut collapsed and the wing impacted the runway. The airplane subsequently impacted a ditch and came to a stop. A Federal Aviation Administration airworthiness inspector conducted an on-scene examination of the airplane. The examination showed no anomalies in the main landing gear brakes or brake assemblies. The right main landing gear strut was intact.