WPR20LA040

The pilot reported that, while the airplane was traveling westbound at 1,100 ft above the ground, the engine stopped producing power without warning. The propeller continued to windmill. The pilot initiated a 180° turn back toward the airport and attempted to restart the engine but was unable to do so. The pilot decided to land the airplane onto a nearby cotton field. When the airplane touched down, the landing gear sunk into the soft dirt, and nosed over. During a postaccident examination, the engine was able to be started, but it operated poorly and was smoking before it stopped producing power. Disassembly of the engine revealed that the two rotors and five of the six apex seals remained intact. The remaining apex seal was fractured in half. It was not possible to determine whether the apex seal fractured before or during the accident sequence. No other anomalies were revealed. The available evidence for this accident precluded a determination of whether the fractured apex seal caused the total loss of engine power.

On December 5, 2019, about 1520 mountain standard time, a Vans RV-6 airplane, N616RV, sustained substantial damage when it was involved in an accident near Pima, Arizona. The pilot and passenger sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, while the airplane was traveling westbound at 1,100 ft above the ground, the engine stopped producing power without warning. The propeller continued to windmill. The pilot initiated a 180° turn back toward the airport and attempted to restart the engine but was unable to do so. He decided to land the airplane onto a nearby cotton field. When the airplane touched down, the landing gear sunk into the soft dirt, and the airplane flipped onto its back. The vertical stabilizer and rudder sustained substantial damage. The airplane was equipped with a 150 hp Mazda 13B engine. A postaccident examination found that ignition and fuel were still available to the engine. The engine started normally but operated poorly, and smoke was emanating from it. Shortly afterward, the engine stopped producing power. Disassembly of the engine revealed that the two rotors and five of the six apex seals remained intact. The remaining apex seal was fractured in half; no other anomalies were noted.