G-164A N9822 accident near La Salle, Colorado

Probable cause

The loss of engine power due to the detached distributor rotor.

NTSB analysis

The pilot stated that shortly after takeoff for the aerial application flight, the airplane’s engine ”popped and banged.” The pilot decided to jettison the airplane’s load and return to land at the departure airport. However, while returning to the airport, the engine began to surge repeatedly between full power and a total loss of power, and the pilot decided to land in a nearby alfalfa field, where the airplane nosed over during the forced landing. Examination of the engine revealed that a screw that secured the distributor rotor to the brass gear had come out, which resulted in the detached rotor moving loosely inside the magneto. Internal damage to the rotor and magneto was consistent with the rotor rubbing inside of the magneto. This distributor rotor separation and subsequent movement most likely resulted in the rough running engine and the subsequent loss of engine power.

Text from the NTSB. Open the NTSB docket for CEN12LA513 for the full record.