ERA21LA144

The student pilot was performing ground reference maneuvers at 1,000 ft when the flight instructor noticed that the airplane had descended “about 100 ft.” He advised the student pilot to climb the airplane back to the desired altitude, but the airplane did not respond to the student’s control inputs. The instructor took control of the airplane and his remedial actions failed to restore engine power, so he performed a forced landing to a dirt road between cultivated fields, which resulted in substantial damage to the airplane. A detailed examination of the airplane and a successful postaccident engine run failed to reveal any preimpact mechanical anomalies. Although atmospheric conditions at the time of the accident were conducive to serious icing at glide power, the reason for the loss of engine power could not be determined based on the available information.

On February 26, 2021, about 1445 eastern standard time, a Cessna 172N, N5631E, was substantially damaged when it was involved in an accident near Boynton Beach, Florida. The flight instructor and student pilot were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The instructor and the student pilot provided written statements that were consistent throughout. About 10 minutes after departure, the student was performing ground reference maneuvers at 1,000 ft when the flight instructor noticed the airplane had descended “about 100 ft.” He advised the student to climb the airplane back to the desired altitude, but the airplane did not respond to the student’s control inputs. The instructor assumed control of the airplane and performed remedial actions to restore engine power, which were unsuccessful. He then selected a dirt road that bisected cultivated fields for a forced landing. After landing, the airplane’s right wing, right main landing gear, and right wing strut impacted a gate post along the road, which separated the gear and strut, collapsed the wing at its root, and rotated the airplane 180° before it came to rest on its right side. Review of maintenance information revealed that the airplane’s most recent 100-hour inspection was completed on February 13, 2021, at 15,942 total aircraft hours. The airplane was recovered, and a detailed examination of the airplane was performed by a Federal Aviation Administration (FAA) aviation safety inspector. The examination revealed no preimpact mechanical anomalies, and a fuel can was plumbed into the fuel system at the wing root, as the wings were removed during recovery. The engine started immediately, accelerated smoothly, and ran continuously without interruption. A magneto check was performed satisfactorily, and an inspection of the carburetor heat system revealed that the system operated as designed with no anomalies or blockages noted. According to the New Carburetor Icing-Probability chart published by the Australian Transport Safety Bureau (ATSB) and cited in the FAA report, atmospheric conditions at the time of the accident were conducive to "serious icing at descent power.” Review of the icing probability chart contained within the FAA Special Airworthiness Information Bulletin CE-09-35 revealed the atmospheric conditions at the time of the accident were “conducive to serious icing at glide power.”