Raytheon Aircraft Company B36TC N471BB accident near Sugar Grove, Illinois

Probable cause

The partial loss of engine power for reasons that could not be determined because postaccident testing and examination did not reveal any anomalies that would have precluded normal operation.

NTSB analysis

The pilot reported that shortly after takeoff, the airplane’s engine lost partial power and shook violently. The pilot elected to land the airplane in a cornfield off the end of the runway, where the it sustained substantial damage to both wings. A postaccident engine run performed with the engine still mounted on the airframe revealed no anomalies, but full-power testing could not be performed due to shortening of the propeller blades to facilitate the test. A mechanic who performed work on the engine after the accident reported that the turbocharger was full of oil and that the shaft appeared to be loose. As a result, the turbocharger was replaced with an overhauled unit. The mechanic also reported that the mechanical fuel pump was replaced after the accident but prior to arrival at the engine repair facility. It was reportedly replaced to correct a lean mixture condition, but the mechanic could not verify the reason. Based on the available information, the reason for the engine's partial loss of power could not be determined during the course of the investigation.

Text from the NTSB. Open the NTSB docket for CEN12LA481 for the full record.