On December 15, 2021, about 0920 Alaska Standard Time, an experimental amateur built LB-1, N555LB, was substantially damaged when it was involved in an accident near Haines, Alaska. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, after preheating the airplane, performing a preflight, and doing a successful run-up of the engine, which included checking the carburetor heat, he initiated a takeoff. During the initial climb he “went to one notch of flaps and immediately the engine faltered.” He “pushed the nose over and re-set to two notches of flaps.” He confirmed the throttle was in the full power position, but the airplane continued to descend. The pilot made a precautionary landing in the snow between tree stump piles. During the landing, the airplane touched down and bounced; on the second touchdown, the tires sunk into the snow, and the airplane nosed over, coming to rest inverted. The pilot and passenger were able to egress without further incident. The airplane sustained substantial damage to the wings, fuselage, and empennage. The pilot reported that he cut the fuel lines while removing the wings from the airplane for postaccident recovery. He reported the fuel color was blue with no contamination or abnormalities. According to the pilot, there were 30 gallons of 100LL fuel onboard the airplane before he took off. He also reported that he did not believe there was any type of internal engine failure. A postaccident examination and engine run revealed no evidence of any preaccident mechanical malfunctions or failures that would have precluded normal operation. A Global Data Assimilation System (GDAS) model sounding was created for 0900 for the accident location and had a modeled surface elevation at 3,143 ft mean sea level (msl). At an elevation of 3,143 ft msl, the GDAS sounding indicated the wind was from 023° at 6 kts, the temperature was 2.3° F, and the dewpoint was -2.2° F, with a relative humidity of 81 percent. According to Federal Aviation Special Airworthiness Information Bulletin CE-09-35, the temperature and dewpoint were not conducive for carburetor ice. Additional data indicated light rime icing. The pilot reported that the weather observation facility at the Haines Airport (PAHN) from 0700 local up to the time of the flight reported a temperature of 0° F.