Aeronca 7BCM N2558E accident near Mahnomen, Minnesota

Probable cause

The pilot’s failure to abort the takeoff after recognizing a partial loss of engine power during the takeoff roll and his subsequent inability to maintain adequate airspeed during a turn to avoid power lines, which resulted in an aerodynamic stall. The reasons for the loss of engine power could not be determined because postaccident examination of the engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.

NTSB analysis

The sport pilot reported that the initial takeoff roll was normal but that he then noted that the airplane was not gaining airspeed and that the engine was not developing full power; however, he decided to continue the takeoff. He stated that, once he was committed to the takeoff, there seemed to be an even "greater loss of power." The airplane only reached 150 ft, and he decided to turn right to avoid a highway and power lines. He initiated a 20° bank, and subsequently the airplane stalled and then impacted a bean field adjacent to the airport.

Postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Although weather conditions at the time of the accident were conducive to moderate icing at cruise power or serious carburetor icing at descent power, given the airplane was at takeoff power, it is unlikely that carburetor ice accumulated and caused the power loss. The pilot's decision to not abort the takeoff at the first sign of a loss of engine power resulted in a slow airspeed during the initial climb during a turn, which resulted in the aerodynamic stall.

Text from the NTSB. Open the NTSB docket for CEN17LA238 for the full record.