On February 15, 2019, about 1600 central standard time, an experimental, amateur-built Vans RV-8, N737MC, was substantially damaged when it was involved in an accident near Horseshoe Bay, Texas. The airline transport pilot and passenger sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that the purpose of the flight was to travel to Northwest Regional Airport (52F), Roanoke, Texas, for lunch with friends. The airplane departed from Lakeway Airpark (3R9), Lakeway, Texas, with both tanks full of fuel, for a total of 43 gallons. The airplane consumed about "11-12" gallons of fuel on the leg to 52F. The pilot switched fuel tanks just before landing at 52F, and, when the airplane landed, he reported the fuel tank levels were "both about even" at 10 gallons based on the fuel gauges. The pilot reported that this indication was not quite accurate with the tailwheel on the ground, as the fuel gauges read about 1.5 to 2.5 gallons high from an inflight reading with the fuselage level. The pilot then departed 52F to Horseshoe Bay Resort Airport (DZB), Horseshoe Bay, Texas. The airplane consumed about 11 gallons of fuel during the flight. The pilot subsequently departed and, after reaching about 1,800 ft above mean sea level, the pilot adjusted the throttle for climb power. As the pilot reached for the fuel/air mixture control and fuel boost pump switch, the engine lost total power. The pilot performed a forced landing, during which the airplane sustained substantial damage to the fuselage, wings, and empennage. The passenger reported that about 30 to 40 seconds after takeoff, he heard a "chugging" sound from the engine and observed the propeller "turning less than normal." The passenger estimated that the airplane was less than 1,000 ft above ground level when the loss of engine power occurred. The passenger reported that the airplane "started to turn around," but then the pilot realized the airplane would not make it back to the airport. Several witnesses heard the engine "sputtering" after the takeoff. One witness, who was a pilot, saw the airplane "turn to the left" as if it attempted to return to the departure airport. A Federal Aviation Administration (FAA) inspector responded to the accident site to examine the airplane. The inspector reported there was no fuel present in the two breached fuel tanks, there were no signs of fuel on the ground at the accident site, and there were no signs of vegetation at the accident site affected by fuel. First responders reported that they did not notice fuel present at the accident site, nor was there a postimpact fire. A postaccident examination of the airframe and engine revealed no mechanical anomalies. A Shadin Fuel Flow Indicator was installed in the airplane. The unit, which displayed fuel quantity remaining based upon the pilot’s total fuel amount input prior to flight, powered on with a “GOOD” indicator showing. The unit displayed 17.8 gallons of fuel remaining and 23.2 gallons of fuel used.