On January 13, 2018, at 1639 mountain standard time, a Beech K35 Bonanza, N803R, experienced a loss of engine power after departure from Vance Brand Airport, (LMO), Longmont, Colorado. The pilot sustained serious injuries, the passenger sustained minor injuries, and the airplane sustained substantial damage. The airplane was registered to and operated by a private individual under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident and no flight plan had been filed. The local flight originally departed LMO at 1551. A witness reported that he was near taxiway A3 when heard "a popping noise" coming from the airplane during takeoff. A few seconds later he heard the engine "shut off" as the airplane was in a nose up attitude. The airplane rolled to the right and then descended in a "steep dive" toward the ground. When he arrived at the accident site (figure 1) he observed smoke and smelled fuel near the airplane. He stated that the ground near the airplane was wet and fuel was leaking from the left wing where it had partially separated from the fuselage. Figure 1 – Accident site After the accident the pilot stated that he planned to operate in the local area as an orientation flight for his son. Before the flight he taxied to the local fixed base operator (FBO) and added 21.7 gallons of fuel. He added that for local flights he did not fill the tanks completely; he estimated there were 22 to 24 gallons in the left and right main tanks respectively and 15 gallons in the auxiliary tank. He also estimated that the engine's fuel burn rate would have been about 15 to 16 gallons per hour for the accident flight. Before takeoff the fuel selector was positioned to the left fuel tank. After performing maneuvers in the local area, they returned to LMO with the right fuel tank selected. They entered the traffic pattern and performed one uneventful touch-and-go landing. They flew around the traffic pattern and landed again for a second touch-and-go landing. During the takeoff, with about 500 ft of runway remaining, he retracted the landing gear and continued to climb out. About 3 seconds later the engine began running rough but the instruments did not reveal anything unusual to the pilot. The engine experienced a total loss of power about 300 ft above ground level (agl). He pitched the nose down to maintain airspeed, flared the airplane near the ground, then landed hard in a field. The pilot estimated that at the time of the accident there were 12 gallons of fuel in the left tank, 18 gallons in the right tank, and 15 gallons in the auxiliary tank. After the accident the airplane owner stated that he had never experienced any engine issues in the past. The responding Federal Aviation Administration (FAA) inspector stated that fuel was present on the ground and leaking from the airplane. After the accident the fuel selector was positioned to OFF by first responders and the original position was unknown. Fuel recovered from the fuel tanks was tested for water using a water detecting paste and no water was detected. A postaccident examination of the airplane and engine revealed no mechanical malfunctions or anomalies which would have precluded normal operation. The airplane was equipped with an engine data monitor (EDM) that recorded the basic engine parameters, which included cylinder head temperatures and exhaust gas temperatures. A review of the EDM data did not reveal any anomalies.