CEN12LA513

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.

On August 1, 2012, about 0920 mountain daylight time, a Grumman Aircraft Engineering Corporation G-164A airplane, N9822, was substantially damaged during a forced landing to a field after experiencing a loss of power near La Salle, Colorado. The pilot suffered minor injuries. The airplane was registered to and operated by Low Level Dusting Company, Inc., under the provisions of 14 Code of Federal Regulations Part 137, as an agricultural application flight. Day visual meteorological conditions prevailed and no flight plan was filed. At the time of the accident the airplane was departing from a private agricultural strip for a local flight. The pilot stated that shortly after takeoff he heard and felt the engine “pop and bang.” The pilot elected to return to the strip, at which time the engine experienced a complete loss of power. During the forced landing to a field of tall alfalfa, the ground roll was faster than desired and the airplane was approaching a ditch and obstacles at the end of the field. The pilot applied heavy braking and the airplane stopped abruptly and nosed over, coming to rest inverted. The outboard portion of the upper left wing separated, the engine separated from the airframe, and the vertical stabilizer was crushed. An examination of the engine revealed that a screw securing the distributor rotor to the brass gear had come out. The rotor had separated and was loose inside of the magneto. Internal damage to the rotor and magneto was consistent with the rotor rubbing inside of the magneto. Further examination of the engine and airframe revealed no anomalies.