OLATHE, CO, USA
N92HA
Bell 47-GB31
While on its third aerial application pass, to dispense a rinse load, the helicopter flew into its own wake turbulence and had insufficient power to overcome the settling which ensued. The helicopter struck the ground in a nose low attitude and the main rotor blades severed the tail boom. Density altitude at the time was computed to be approximately 8,900 feet.
On July 17, 1998, at 1230 mountain daylight time, a Bell 47-GB31 helicopter, N92HA, settled to a hard landing while maneuvering near Olathe, Colorado, during an aerial application flight. The commercial pilot and sole occupant was not injured and the helicopter sustained substantial damage. The flight was being operated as an aerial application flight under Title 14 CFR Part 137, and no flight plan was filed. Visual meteorological conditions prevailed. According to the pilot, he was dispensing a rinse load and had made three passes over the same path. He said the wind came up as he turned the helicopter for another pass and he flew into his own wake turbulence. The pilot said he had insufficient power to overcome the ensuing descent and the helicopter settled onto the ground in a nose low attitude. This caused the main rotor blades to strike the tail boom and sever it from the aircraft. Density altitude at the time was computed to be approximately 8,900 feet.
The pilot's inadequate in-flight planning which resulted in an encounter with his own wake turbulence. Related factors were high density altitude and wake turbulence.
Source: NTSB Aviation Accident Database
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