On March 17, 2015, about 1430 central standard time, a Grumman G-164A airplane, N9755, performed a forced landing following a partial loss of engine power near New Roads, Louisiana. The commercial pilot, the sole occupant, received minor injuries. The airplane was substantially damaged. The aircraft was registered to a private individual and operated by Old River Applicators LLC, under the provisions of 14 Code of Federal Regulations Part 137 as an aerial application flight. Visual meteorological conditions prevailed for the flight, which operated without a flight plan.According to information provided by the responding Federal Aviation Administration (FAA) inspector, as the pilot was maneuvering to commence an aerial application run, smoke from the engine entered the cockpit followed by a loss of engine power. The pilot conducted a forced landing to a field when the airplane nosed over on landing resulting in damage to the vertical stabilizer. An examination of the airplane's engine by the FAA found three cylinders with stuck exhaust valves and zero to low compression values.