On August 20, 1982, a Bell 47G-4A (registration N4090G) operated by Bonanza Valley Aviation was involved in an aviation accident near Near Brooten, MN. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 3 related events involving the same aircraft type or operator are linked below.
A helicopter engaged in spraying operations lost power and yawed left after lift-off from a flat bed trailer. The pilot attempted a cushioned landing but the gear collapsed and the main rotor struck a fence. Investigation found only severely worn spark plugs.
Accident Details
A pilot had been conducting aerial spraying operations for approximately 2.5 hours before returning to a flat bed type trailer for servicing. After landing on the trailer, the hopper was refilled with 60 gallons of herbicide. The pilot then began a takeoff from the trailer. According to the pilot, immediately after lift-off, the helicopter experienced a loss of power and yawed to the left. The pilot attempted to cushion the landing by raising the collective, but the landing gear collapsed upon contact, and the main rotor blades struck a nearby fence.
Investigation Findings
Post-accident examination of the helicopter's transmission and engine revealed no discrepancies. However, the spark plugs were found to be severely worn. An engine run-up was performed after the accident, and the engine operated satisfactorily. No other mechanical issues were identified.