On July 2, 1984, a Bell 47G-3B-1 (registration N501FH) was involved in an aviation accident near Shelley, ID. Investigators recorded the probable cause as: The pilot's failure to maintain control of the aircraft due to unpredictable winds and the turbocharged engine's slow response to throttle inputs. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During an agricultural flight, the aircraft collided with the ground after a wind gust caught the plane. The pilot reported unpredictable winds at the mountain base and noted the turbocharged engine was slow to respond.
What happened
The aircraft was engaged in an agricultural flight when it ultimately collided with the terrain. According to the pilot's report, the ambient wind conditions were relatively light at the time of the accident, with speeds ranging from 3 to 5 knots and no significant gusts initially present. However, the pilot noted that wind patterns are highly unpredictable near the base of nearby mountains. A sudden gust of wind caught the aircraft during the operation, contributing to the loss of control or situational awareness that led to the impact.
The investigation
The pilot provided specific details regarding the mechanical and environmental factors present during the flight. It was stated that the aircraft was equipped with a turbocharged engine. During the critical phase of the accident, the pilot observed that this engine was slow to respond to throttle inputs. This delayed response may have hindered the pilot's ability to compensate for the sudden wind gust or maintain necessary altitude and airspeed during the agricultural operation.
Findings
The primary factors contributing to the accident include the unpredictable nature of the winds at the base of the mountains and the specific performance characteristics of the aircraft's powerplant. The combination of a sudden wind gust and the turbocharged engine's slow response to throttle adjustments created a challenging environment for the pilot, leading to the ground collision.
Probable cause
The pilot's failure to maintain control of the aircraft due to unpredictable winds and the turbocharged engine's slow response to throttle inputs.