On August 11, 1994, a Bell 47G3B1 (registration N64292) was involved in an aviation accident near Sargeant, MN. Investigators recorded the probable cause as: The pilot's inadvertent failure to maintain clearance from a transmission wire while maneuvering to avoid a guy wire, which resulted in main rotor blade contact and subsequent loss of control. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter pilot lost control after main rotor blades struck a transmission wire while maneuvering to avoid a guy wire during an aerial application spray run.
What happened
The pilot was conducting agricultural operations, having just completed one aerial application spray run. While maneuvering the helicopter to begin a subsequent pass, he attempted to avoid a guy wire. During this evasive action, the main rotor blades inadvertently struck a transmission wire. Despite the impact, the pilot retained partial control of the aircraft and executed a forced landing in a nearby field.
The investigation
The investigation focused on the mechanical interaction between the helicopter's rotor system and the overhead utility infrastructure. Examination confirmed that the main rotor blades made contact with a transmission wire during the maneuver to avoid a guy wire.
Probable cause
The pilot's inadvertent failure to maintain clearance from a transmission wire while maneuvering to avoid a guy wire, which resulted in main rotor blade contact and subsequent loss of control.