Aeronca 7AC N82383 accident near Brighton, Michigan

Probable cause

The pilot’s failure to maintain airspeed following a partial loss of engine power for reasons that could not be determined during postaccident examination, which resulted in an aerodynamic stall and loss of airplane control. Contributing to the severity of the pilot’s head injuries was the failure of the shoulder harness assembly.

NTSB analysis

Witnesses observed the airplane make a normal engine run-up before takeoff followed by a normal takeoff from the runway. Shortly after takeoff, the engine did not sound like it was developing full power, and the airplane was struggling to climb. Subsequently, the airplane made a 180-degree turn and then descended toward terrain in a nose-down attitude. Postaccident examination of the airplane revealed no evidence of any preimpact mechanical failures or anomalies that would have precluded normal operation. Although the weather conditions at the time of takeoff were conducive to the formation of carburetor ice at glide and cruise power, it could not be determined whether carburetor ice was a factor in the loss of engine power. It is likely that the pilot failed to maintain airspeed during the turn back to the airport, which resulted in a stall.

Postaccident examination of the airframe revealed that the pilot's shoulder harness failed during the accident. Material examination of the shoulder harness webbing and stitching showed that they failed due to an overload event. The occupants' injuries suggest that both occupants were using the four-point shoulder harnesses at the time of the accident and were exposed to strong deceleration forces. If the pilot's shoulder harness had not failed, he likely would not have suffered the brain injury he received, which caused permanent disability. However, it is possible that an intact shoulder harness could have led to more severe chest, abdominal, or cervical injuries. The investigation could not determine whether the pilot would have died or sustained a permanent disability from some other injury if the shoulder harness had remained intact.

Text from the NTSB. Open the NTSB docket for CEN12FA601 for the full record.