WPR16LA122

The student pilot reported that, during cruise flight in the experimental light sport airplane, he encountered moderate turbulence. Shortly thereafter, the engine experienced a total loss of power. Following an uneventful landing in an open field, the pilot found that a fuel line was pinched between his seat and the fuselage. After repositioning the fuel line, he was able to start the engine and took off to return to the airport. While in the airport traffic pattern, his seat shifted, and the engine lost power a second time. The pilot initiated a forced landing to a nearby road; however, just before touchdown, the pilot "banked hard left" to avoid hitting a vehicle on the road. The airplane subsequently experienced an aerodynamic stall and impacted the ground. Postaccident examination of the airplane revealed that the fuel line located behind the pilot's seat could be compressed by hand. Movement of the seat allowed for the fuel line to be pinched, resulting in an interruption of fuel flow to the engine. After installing a new propeller, a test run of the engine was completed with no anomalies observed.

On May 23, 2016, about 0945 Pacific daylight time, a Rans S-5, N481TJ, sustained substantial damage to the fuselage when it impacted the ground near Lodi Airport (1O3), Lodi, California following a loss of engine power. The student pilot, the sole occupant, sustained minor injuries. The airplane was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight that originated from 1O3 at 0930. In the written statement, the pilot reported that during the flight, he encountered a moderate turbulence that was accompanied by 4 bumps. Seconds later, the engine lost power. The pilot executed an emergency landing to a nearby field. After he landed, he observed that the fuel line was pinched between the airframe and the seat. The pilot repositioned the fuel line, and ran the engine for 10 minutes to ensure there were no abnormalities and took off to return to the airport. On the downwind leg, the seat shifted to the left, and the engine stopped producing power. The pilot elected to land on a nearby road; however, a vehicle approached his direction. The pilot made a hard left turn to avoid landing on the road and the airplane stalled at about 50 feet above ground level and subsequently impacted terrain. According to the Federal Aviation Administration inspector, it was apparent that the movement of the seat pinched the fuel line which resulted in the starvation of the fuel to the engine and, therefore, caused the engine to stop producing power. The inspector stated that the pilot and a mechanic replaced the propeller and started the engine with no issues. On June 9, 2016, a National Transportation Safety Board investigator conducted the engine and airframe examination. He observed that the fuel line from the engine remained connected to the fuel pump, and from the fuel pump, the fuel line extended into the right side of the fuselage. The fuel line was manually cut forward of the fuel shut off valve, located on the right side of the airframe, just behind the seat. No abrasions or chafing were observed on the fuel line. The fuel line about 3 inches from the area it was cut could be compressed by hand. The seat remained partially attached to the airframe. The seat featured a rigid mount via two tubes on the left and right sides of the seat, that attached to the airplane structure forward of the seat. The rear of the seat frame was suspended by seat belt type webbing attached to the left and right side of the seat frame assembly. The right side seat frame tube exhibited a wear mark on the lower right side, which corresponded to another wear mark on an aluminum tube that spanned the airplane crosswise. No evidence of any preexisting mechanical malfunction was found.