What happened
Approximately one hour after landing in an open field at 6,200 feet MSL in the Bighorn National Forest near Parkman, Wyoming, the pilot initiated a practice takeoff. The purpose of the flight was to test the aircraft's performance without the passenger on board.
The helicopter achieved effective translational lift and maintained a normal hover before climbing out at 40 knots. Shortly after clearing a 75-foot ridge located between 100 and 150 yards from the takeoff area, the aircraft entered a zone just outside of ground effect where it encountered a downdraft. This caused the aircraft to lose altitude.
The aircraft impacted the ground after passing through 60 to 80 feet of trees and came to rest in an inverted position. The pilot was not injured.
Findings
Calculations performed during the investigation determined the density altitude at the time of the accident was 7,578 feet. The aircraft's gross weight at departure was approximately 1,232 lbs. Data indicated that at an indicated airspeed of 35 knots, the maximum obstacle clearance height was 75 feet with a maximum distance of 800 feet. The pilot reported no mechanical issues, and the engine remained running upon impact.