Bell 407 N361SF accident near Lawton, Oklahoma

Probable cause

The pilot's loss of helicopter control during landing, which resulted in a hard landing and collision with a wall.

NTSB analysis

The commercial pilot of the helicopter was approaching to land on a helipad. It was his first landing to this helipad, though he had departed from the helipad the day before. Due to trees and transmission lines near the helipad, the pilot flew a slight right-turning, steep approach. When the helicopter was about 125 ft above the pad and 150 ft to the southwest of it, the pilot commanded left cyclic to stop the right turn. He estimated the helicopter to be 40 knots above effective transitional lift, and in a stable 500 ft per minute descent; there was a headwind. The helicopter did not respond to his control input, and the pilot announced to the crew his intention to go around. He increased left cyclic until the cyclic was against his left leg and the helicopter still did not respond. The pilot lost control of the helicopter and it landed hard, colliding with a wall.

Data extracted from the engine control unit (ECU) was consistent with the engine producing the required power and responding to collective control inputs; however, the data indicated that the main rotor speed and torque were exceeded. These exceedances suggested that a large demand for power was commanded by the pilot, likely during the go-around. Examination of the helicopter did not reveal any mechanical anomalies that would have precluded normal operation. The helicopter was in a right bank with 3 crewmembers seated on the right side of the helicopter, one crewmember seated on the left side, and was carrying a near-full fuel load. The distribution of crew members and a high torque setting may have contributed to the pilot's inability to maintain helicopter control; however, the extent to which these factors may have contributed could not be determined.

Text from the NTSB. Open the NTSB docket for CEN16LA386 for the full record.