On July 10, 2013, about 1430 central daylight time, an Ayres Corporation S2R-T41 airplane, N2239B, was substantially damaged while landing near Coy, Arkansas. The commercial pilot was not injured. The airplane was registered to and operated by Bells Ag Service Inc., under the provisions of 14 Code of Federal Regulations Part 91 as maintenance flight. Visual meteorological conditions prevailed for the flight, which operated without a flight plan. The local flight originated approximately 1420. During the maintenance flight, the pilot was troubleshooting the spray system on the airplane in order to prepare the airplane for the coming agricultural season. During the landing flare, the airplane's propeller went into reverse thrust and the airplane settled to the grass runway and landed hard. The airplane bounced during the landing, departed the runway environment, and hit a stationary tank with the left wing. The airplane continued across two ditches and came to rest on its nose. A postaccident examination of the airplane revealed that the left wing spar was bent. An examination of the engine, propeller, and related systems revealed that the linkage to the propeller governor had not been rigged properly. An examination of the remaining engine and airplane systems revealed no anomalies.