Accident Overview
On April 27, 2018, at 1800 central daylight time, a Grumman G-164A airplane nosed over during an off-airport forced landing in Garwood, Texas. The pilot reported no injuries. The aircraft, registered to and operated by Aero Ag Services Inc., was conducting a Title 14 Code of Federal Regulations Part 137 aerial application flight. Day visual meteorological conditions prevailed, and the flight was not operated on a flight plan. The local flight originated from a private airstrip in Garwood.
Pilot Report
According to the pilot, this was the 28th flight of the day, and the airplane was taking off with a full load of fertilizer. The ground run and lift off were normal. After lifting off, the pilot began a turn and reduced engine power to 32 inches of manifold pressure. He then felt a "slight shudder" and a further reduction in engine power, without sputtering or backfiring. Although the manifold pressure remained at 32 inches and the propeller was at full rpm, the pilot decided to return to the airstrip. While turning, he perceived that the engine was not producing power, so he leveled the wings, lowered the nose, and dumped some of the fertilizer load.
Forced Landing and Damage
During the forced landing, the airplane contacted a levee, which separated the landing gear and caused the airplane to become airborne again. It touched down a second time and nosed over. The aircraft sustained substantial damage. One propeller blade was bent rearward about 70 degrees, and the other was slightly bent rearward. The carburetor was broken off the engine.
Postaccident Engine Examination
On September 12, 2018, an examination of the engine was conducted at Air Salvage of Dallas in Lancaster, Texas. Both magnetos produced spark when rotated by hand. Engine continuity was established, and compression was achieved on all cylinders except the No. 5 cylinder, which sustained impact damage. The spark plugs were removed and found to be slightly dark in color with normal wear signatures. The blower impeller appeared normal but had excessive backlash of about 0.750 inches; however, there was no end play and no signs of contact between the impeller and the case. No metal was detected in the oil sump or inlet screen. The air box and air filter were clear of debris. The carburetor heat door was wired in the open/off position. The examination revealed no anomalies that would have precluded normal operation.
Weather Information
The temperature and dewpoint recorded at Wharton Regional Airport (ARM), located 23 miles southeast of the accident site, at 1815 were 77°F and 48°F, respectively. According to the Federal Aviation Administration SAIB CE-09-35 Carburetor Icing Probability Chart, these conditions were favorable for serious carburetor icing at glide power.