GRUMMAN ACFT ENG COR G-164A

Full Narrative

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.