N8576YPiper PA-18-150

The instructor pilot was giving dual instruction to a pilot-rated student. He reported that soon after departure, the airplane engine RPM reduced to idle. The pilot verified the throttle was at full power, adequate fuel was in both tanks and subsequently applied carburetor heat, which restored the engine to full power. After 10 seconds the RPM began surging and the pilot then turned the carburetor heat off. He turned the carburetor heat on again and pumped the throttle repeatedly while the power continued to surge until the engine quit and he lost all power. They were unable to restart the engine and landed the airplane in a nearby agricultural field. The airplane came to rest inverted, which resulted in substantial damage to the vertical stabilizer.

The engine ran normally on the ground after the airplane was returned to its upright position following the accident. When the temperature and the dewpoint near the time of the accident were plotted on a carburetor icing probability graph, it was revealed that the airplane was likely operating in meteorological conditions conducive to the formation of carburetor icing (for glide power settings). The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.

According to the written statement submitted by the pilot, he was landing on runway 8 when the airplane encountered a gust of wind. The pilot corrected for the gust of wind and the airplane became airborne again. When the airplane touched down again, the airplane began to rotate to the left. The right main landing gear collapsed and the right wing impacted the ground, resulting in substantial damage to the right wing spar. The pilot stated that there were no mechanical anomalies with the airplane at the time of the accident. An examination of the airplane and its related systems, conducted by a Federal Aviation Administration Inspector, revealed no anomalies.