On April 26, 2021, about 1711 central daylight time, a Piper J3C-65 airplane, N26783, was substantially damaged when it was involved in an accident near Slaughter, Louisiana. The pilot was seriously injured, and the pilot-rated passenger was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he and the owner of the airplane examined the airplane about 6 months before the accident. They started the engine, but it did not sound normal, so they shut it down. Upon further examination, the owner found a mud dauber nest in the throat of the carburetor and removed the nest. No flight was conducted that day. The pilot and a friend (the pilot-rated passenger) returned to look at the airplane again and fly it on the day of the accident. They examined the engine and found two more mud dauber nests in the engine compartment, one of which was inside the scat tube that ran from the exhaust to the carburetor heat. The pilot stated the fuel tanks were full, the engine was started, and a full run-up was performed. The pilot did not note any problems with the engine. He cycled the carburetor heat as part of the before takeoff checklist. Before takeoff, the pilot noted some movement to the treetops nearby, but the windsock indicated no wind. The pilot elected to take off to the north. He completed a pre-takeoff check and another engine run-up before takeoff. The pilot recalled a normal takeoff initially. During the climbout, the pilot looked over the left shoulder of the pilot-rated passenger (who was in the front seat) and noted that the airplane’s airspeed was about 50 knots and that the tachometer indicated about 2,500 rpm; at that time, he felt the airplane “surge.” The pilot recalled attributing the surge to the wind and started a small left turn toward some trees with lower treetops. That was the pilot’s last memory of the accident flight. A witness saw the airplane flying from south to north at a low altitude and thought that the airplane was “drifting” and about to crash. The airplane started a turn, its nose “went up sharply,” and the airplane then descended nose first into the ground. The witness thought that the engine was not running at the time of the crash. A postaccident examination revealed substantial damage to the fuselage and left wing. The engine was pushed up and aft into the forward cabin. The propeller remained attached to the engine; one propeller blade was straight, the other blade was bent aft about 20°, and neither blade exhibited chordwise scraping or leading edge nicks. The airframe, engine, and magnetos were examined, and no anomalies were noted. Weather conditions at the time of the accident were conducive to carburetor icing at glide power.