Robinson R44 N459TA accident near Ida Grove, Iowa

Probable cause

A total loss of engine power during an aerial application flight for undetermined reasons.

NTSB analysis

The commercial pilot of the helicopter was performing an aerial application flight when he noted the engine rpm below "half" and dropping along with the main rotor rpm. The pilot reduced the collective and attempted a high hovering autorotation. Due to the lack of airspeed and altitude, the helicopter impacted a bean field "very hard." The pilot reported that the engine was not operating when the helicopter came to rest on its left side.

The pilot reported that he was paying close attention to the carburetor heat temperature during the flight, as he had the carburetor heat lever pulled out "a little over half" and he kept the needle out of the yellow arc depicted on the carburetor temperature gauge. A postaccident examination of the airframe and engine found no preimpact mechanical malfunctions or failures that would have precluded normal operation, and the helicopter had adequate fuel onboard at the time of the accident. The temperature and dew point at the time of the accident were conducive to the formation of serious carburetor icing at glide power settings. However, given that the pilot was monitoring the carburetor temperature gauge, it is unlikely that the loss of engine power was due to carburetor ice. The reason for the loss of engine power could not be determined based on the available information.

Text from the NTSB. Open the NTSB docket for CEN19LA230 for the full record.