Grumman Acft Eng Cor-Schweizer G-164B N8422K accident near Amana, Iowa

Probable cause

The loss of engine power for reasons that could not be determined.

NTSB analysis

The pilot of the agricultural airplane reported that the airplane’s engine lost power shortly after takeoff. The airplane settled into the corn field off the departure end of the runway and nosed over. The airplane sustained substantial damage to its left wing and fuselage.

All three propeller blades exhibited aft bending, bending opposite rotation, twisting toward low pitch and chordwise/rotational scoring predominately on the camber side which was consistent with impact at low power. Examination of the engine revealed a discontinuity in the drive system consisting of a broken torsion shaft. The broken torsion shaft is indicative of the engine operating at the time of impact. Examination of the fuel control unit and the propeller governor did not reveal any anomalies. No anomalies were found with respect to the engine, propeller, fuel control unit, or propeller governor that would explain the reported loss of engine power.

Based on the results of testing and examination, the reason for the reported loss of engine power could not be determined.

Text from the NTSB. Open the NTSB docket for CEN21LA329 for the full record.