On February 12, 2009, at 0815 Pacific standard time, a Schweizer G-164B, N3626T, performed an emergency landing on a dirt road and nosed over, near Buttonwillow, California. Vince Crop Dusters, Inc., operated the airplane under the provisions of title 14 Code of Federal Regulations Part 137. The commercial pilot was not injured, and the airplane was substantially damaged. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight originated at the Vince Crop Dusters home air strip, Buttonwillow. The pilot reported to the National Transportation Safety Board investigator that while en route to a agriculture application job, the engine exhaust started shaking, then smoke started coming off the engine. The pilot landed on a farm road. During the landing his visibility was limited from the smoke, and the right wheel went off the road into soft mud. The airplane swerved to the right and nosed over. The operator reported that upon examination of the engine it was determined that the number 4 cylinder base nuts had backed off allowing the cylinder to separate from the engine case.