On August 18, 2011, at 0936 central daylight time, a Grumman G-164A, N6567, registered to and operated by Aero Ag Services, Inc., impacted a rice field shortly after taking off from a grass airstrip near El Campo, Texas. The commercial pilot was not injured. The airplane sustained substantial damage to its top wing, vertical stabilizer, and rudder. The airplane was being operated under the provisions of 14 Code of Federal Regulations Part 137 as an aerial application flight. Visual meteorological conditions prevailed for the flight, which was operating without a flight plan. The local flight originated from El Campo moments before the accident. According to the pilot-operator's accident report, he had just taken off and was about 2 miles from the airstrip when the engine lost power. The pilot started dumping his fertilizer load and landed straight ahead in a flooded rice field. Upon touchdown, the airplane nosed over. Post-accident examination revealed a crack radiating from the exhaust valve rocker box on the number 3 cylinder where the rocker arm bolt attaches the rocker arm. The top of the rocker box separated, causing the rocker arm to fail. An examination of the remaining systems revealed no preimpact failures or anomalies.