NTSB Factual Report

On July 4, 2016, about 0930 Pacific daylight time, a Bert N. Norris RV-6, experimental amateur-built conventional gear airplane, was substantially damaged during a forced landing following a loss of engine power near St. Maries Municipal Airport (S72), St. Maries, Idaho. The airplane was registered to a private individual and operated by the pilot as a 14 Code of Federal Regulations Part 91 personal flight. The private pilot and one passenger were not injured. Visual meteorological conditions (VMC) prevailed and a flight plan was not filed. The flight originated from Homeport Airport (11WA), Cheney, Washington, about 0910.

During a telephone interview with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on the day following the accident, the pilot stated that while on short final approach to runway 28 at S72, the engine experienced a partial loss of power. He believed the power loss was due to carburetor icing, as he may not have activated the carburetor heat. He then switched fuel tanks, activated the boost pump, pumped the throttle, but was unable to restore power. The pilot reported that he subsequently landed the airplane in a field about 100 yards from the approach end of runway 28. during the landing roll, the airplane nosed over, which resulted in substantial damage to the rudder.

In a written report submitted to the NTSB IIC on July 14, 2016, the pilot reported that as he approached S72 he visually confirmed that the weather was still VMC. He entered the [traffic] pattern for runway 28, began to reduce power on the engine, and while in the turn from base leg to final approach the engine completely quit. The pilot stated that he verified that the carburetor heat and the fuel boost pump were on, after which he changed the fuel selector to the opposite tank. He then looked for a place to land, but most of the fields were filled with hay bales, which prompted him to continue his turn to the airport. The pilot stated that the airplane touched down about 500 ft short of runway 28 and nosed over. The airplane sustained damage to both wings, the rudder and the elevator.

According to a Federal Aviation Administration aviation safety inspector who performed an onsite postaccident examination of the airplane, the inspector reported that he was able to rotate the propeller by hand, that the engine appeared to be in good shape, and the examination revealed no general indication of engine failure that would have been causal to the accident. Additionally, the inspector reported that the pilot relayed to him that carburetor heat might not have been applied during the flight, which may have caused the engine to lose power during the approach to the airport.

According to a carburetor icing probability chart, the reported temperature and dew point at the time of the accident were in a range for moderate carburetor icing at cruise power settings and serious carburetor icing at descent power settings.

NTSB Probable Cause

A partial loss of engine power due to carburetor icing, which resulted from the pilot’s failure to apply carburetor heat.