On September 12, 2007, a Bell 47G-3B-1 (registration N360SS) was involved in an aviation accident near Avondale, CO. Investigators recorded the probable cause as: The pilot's failure to attain translational lift and his improper flare. A contributing factor in this accident was the sudden wind shift. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter pilot took off downhill in no wind, then encountered a 10-12 knot tailwind. Unable to gain translational lift, he attempted to land at 5-6 mph, but the tail skid struck the ground, causing the main rotor to contact and sever the tail boom.
Incident Overview
According to the pilot's account, the helicopter took off downhill in calm wind conditions. Shortly after departure, the wind shifted to a westerly direction, resulting in a tailwind of 10 to 12 knots. The pilot reported being unable to gain effective translational lift under the tailwind condition.
Landing Attempt and Sequence of Events
In response, the pilot initiated a landing with a forward speed of 5 to 6 mph. As he attempted to stop the helicopter, the tail skid struck the ground simultaneously with the main skids. The aircraft then lurched forward, causing the main rotor blades to contact the tail boom.
Damage
The impact severed the tail boom from the airframe. Additionally, the helicopter's skids were broken torsionally from the airframe.