N1915N

On March 19, 2017, at 0955 central daylight time, a Cessna 120 airplane, N1915N, was substantially damaged during a runway excursion at Sackman Field Airport (H49), Columbia, Illinois. The pilot receiving instruction and the flight instructor were not injured. The airplane was registered to Aeronca Champ Club LLC and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed for the flight that operated without a flight plan. The local flight was originating at the time of the accident.According to information provided by the flight instructor, the purpose of the flight was to complete a tail-wheel endorsement for the pilot. The accident occurred on the fourth full-length runway departure, after about one hour of total flight time. While taking off from runway 21, the airplane was 2/3 down the length of the runway when the flight instructor assessed that the engine was not developing enough power for a successful takeoff, so he took control of the airplane and began braking. With full brake application and about 700 ft remaining, the airplane slowed down but not enough to remain on the runway. The airplane exited the end of the runway and collided with a drainage ditch, entered a cultivated field and nosed over.

Inspectors from the Federal Aviation Administration responded to the accident site and visually examined the airplane. No anomalies were detected.

On the NTSB Form 6120, the flight instructor suspected carburetor icing as the reason of the loss of engine power. The flight instructor reported that carburetor heat was applied on each landing and after each landing, the carburetor heat was turned off as they taxied for departure.

A review of the Carburetor Icing Probability Chart located in the FAA's Special Airworthiness Information Bulletin CE-09-35, Carburetor Icing Prevention found that the airplane was operating in an area conducive to the formation of serious icing at cruise power.