Bell 47G N3755Z accident near Belen, New Mexico

Probable cause

The pilot's failure to maintain adequate main rotor speed while the helicopter was in an out-of-ground effect hover.

NTSB analysis

The pilot was on a personal flight when he decided to bring the helicopter into an out-of-ground effect hover about 50 ft above the ground. The pilot stated that he "got complacent about maintaining main rotor speed" while in the hover and observed an unsafe main rotor speed. He lowered collective for an immediate landing and engaged the carburetor heat. He attempted to reduce the helicopter's descent rate before impact by increasing the collective control, but the helicopter landed hard on the soft terrain. The main rotor blades subsequently impacted the tailboom and tail rotor. The pilot reported that, after impact, the engine continued to run at about 1,500 rpm. The pilot reported no preimpact mechanical malfunctions or failures with the helicopter that would have precluded normal operation. The pilot postulated that an insufficient main rotor speed had precluded him from making a normal flare and landing. He stated that the engine might have encountered carburetor icing as he maneuvered the helicopter into the out-of-ground effect hover at a decreased engine power setting, which might have contributed to his failure to maintain adequate main rotor speed while hovering. Regardless of if the helicopter had a partial loss of engine power during the out-of-ground effect hover, which the investigation was unable to determine, the pilot should have been able to maintain proper main rotor speed by lowering collective and discontinuing the hover maneuver before the main rotor decreased to an unsafe speed.

Text from the NTSB. Open the NTSB docket for CEN19LA067 for the full record.