Accident Details
On March 16, 2025, at about 1415 Alaska daylight time, a Cessna 172A airplane, registration N7274T, was substantially damaged during a forced landing on a frozen river south of Fairbanks, Alaska. The pilot reported minor injuries, and the pilot-rated passenger was uninjured. The flight was operated as a personal flight under Title 14 Code of Federal Regulations Part 91.
Pilot Actions
The pilot, who owned the airplane, was conducting a familiarization flight with a prospective buyer. During the engine run-up, the engine speed did not decrease when the pilot pulled the carburetor heat knob. After shutting down the engine, the pilot observed the passenger actuating the carb heat control knob while he inspected the mechanism on the air box, which appeared to move normally. The pilot then decided to continue the flight.
During the initial climb, the pilot pulled the carburetor heat knob to recheck its functionality. Immediately, the engine speed decreased significantly. The pilot kept the carburetor heat engaged, expecting the condition to clear quickly if it was ice, as had occurred in previous flights. When power did not return, he turned back toward the airport. The engine continued running at low power, but the airplane could not maintain altitude. The pilot elected to land on a frozen river, and during the landing, the airplane nosed over, resulting in substantial damage to the wings.
Postaccident Findings
Examination of the engine after the accident revealed that the carburetor heat cable did not provide the required travel to properly engage the carburetor heat control mechanism in either the fully open or closed position. The carburetor heat was difficult to operate from the cockpit, requiring excessive force to move the control mechanism. The result was that the carburetor heat was always partially on, and this condition could not be changed by actuating the control knob. A visible kink was observed in the carburetor heat control cable where it attached to the mechanism. Additionally, the clamp securing the carburetor heat control cable sheath to the carburetor airbox was installed about 180° from the position indicated in the Cessna 172 & 175 Parts Catalog (1956-1962).
At the time of the accident, the temperature was -12°C (10°F) with a dewpoint of -18°C (0°F). A review of the carburetor icing probability chart in FAA Special Airworthiness Information Bulletin CE-09-35 indicated that the conditions were not conducive to carburetor icing.
Maintenance Background
The airplane’s maintenance logs showed no flight hours logged since 2021. The pilot reported having flown the airplane for a total of 35 hours after the engine had been removed, disassembled, and reinstalled just over three years before the accident. However, the airframe and engine logbooks recorded no flight hours since the reinstallation. The engine was removed, disassembled, and reinstalled in November 2021 due to the engine running without oil.