CEN22LA156

The flight instructor and student pilot were conducting an instructional flight. The instructor stated that, about 7 minutes after departure and while the airplane was in level flight at 3,500 ft mean sea level, the engine sputtered and the airplane was unable to maintain altitude. The instructor assumed control of the airplane from the student pilot at that time. She performed several troubleshooting steps; however, engine power was not restored. During the descent, the propeller windmilled and, according to the instructor, “the engine would catch” randomly and “operate for a few moments,” but the engine would lose power each time. The instructor also stated that, during a discussion with the student pilot, he indicated that, when he pulled the throttle to idle, the engine “would smooth out somewhat, but would start missing” when the throttle was pushed forward. The instructor executed a forced landing to a field, and the airplane nosed over. The airplane sustained substantial damage to the fuselage, empennage, and both wings The atmospheric conditions at the time of the accident were not conducive to the development of carburetor icing. A postaccident examination of the airplane revealed that there was uncontaminated fuel available in the engine and that there was no evidence of mechanical malfunctions or failures that would have precluded normal operation. As a result, the reason for the total loss of engine power could not be determined.

On March 24, 2022, about 1730 central daylight time, a Cessna 172N airplane, N733KP, was substantially damaged when it was involved in an accident near Springtown, Texas. The flight instructor was not injured, and the student pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. Airport fuel transaction records showed that, at 1657:45, the flight instructor purchased 7.5 gallons of 100 low-lead fuel from the self-serve fuel pump at Bridgeport Municipal Airport (XBP), Bridgeport, Texas. The flight instructor stated that the fuel tanks were already “pretty full” when she added the fuel. About 7 minutes after the flight departed XBP to the south and while the airplane was in cruise flight at an altitude of about 3,500 ft mean sea level, the engine sputtered and the airplane was unable to maintain altitude. The flight instructor assumed control of the airplane from the student pilot at that time. She performed several troubleshooting steps, but engine power was not restored. Automatic dependent surveillance-broadcast (ADS-B) data showed that that airplane made a right descending turn and then continued to descend on a straight path. The flight instructor stated that, during the descent, the propeller windmilled and “randomly the engine would catch and operate for a few moments before dying again, so this wasn't something that could be remedied in the air.” During the forced landing, the airplane nosed over and came to rest inverted. The instructor added that the fuel selector valve was positioned to BOTH and that she did not manipulate the fuel selector during the event. Also, the instructor stated that she did not remember the rpm on the tachometer during the event and that she did not apply carburetor heat while troubleshooting the loss of power. The student pilot stated that during the event, when they would pull the throttle to idle, the engine “would smooth out somewhat, but would start missing” when the throttle was pushed forward. During the forced landing, the airplane nosed over and came to rest inverted in a field, which resulted in substantial damage to the fuselage, empennage, and both wings. Fuel was leaking from the wings after the accident. The XBP airport manager reported that the fuel source was checked for contaminants and that none were found. Also, two other airplanes were fueled from the same source about the same time, and the pilot of those airplanes did not report any issues with the fuel. The atmospheric conditions at the time of the accident were not conducive to the development of carburetor icing. A postaccident examination revealed uncontaminated blue fuel inside the carburetor and fuel strainer bowl. The propeller was manually rotated to confirm engine continuity. The propeller rotated with no binding or abnormalities noted with the engine. All pistons moved through each respective cylinder, and all rocker arms moved normally. Suction andcompression were both obtained from each cylinder during the engine rotation. Each of the top ignition wires produced a spark during engine rotation. Examination of the airplane revealed no mechanical malfunctions or failures that would have precluded normal operation.