Bell 47G 5 N6203N accident near Laureles, Texas

Probable cause

The pilot's failure to apply additional engine power when he applied collective input, which led to a loss of rotor speed and the exceedance of the helicopter’s performance capability.

NTSB analysis

The commercial pilot reported that, while conducting a spray pass, he pulled on the helicopter's collective, and the rotor speed dropped. He lowered the collective, applied maximum throttle, and pulled on the collective again, but the rotor speed continued to drop. He then attempted to land in a nearby yard, but the tailboom struck a tree, and the helicopter then flipped on its right side.

A witness, who was an experienced agricultural helicopter pilot, reported that he had flown with the accident pilot for about 12 hours in the accident helicopter, which was a piston engine-powered helicopter that did not have a throttle governor, to familiarize him with managing the throttle. He stated that the accident pilot's previous experience was in turbine-powered helicopters that had a throttle governor. The witness stated that he was in the field watching the accident pilot perform spraying operations. The pilot made a downwind pass in the field in a tight area. He said that, when the pilot pulled up to climb above the trees at the end of the pass, he heard the engine "bog down" and that he thought that the pilot had pulled the collective without adding throttle.

A postaccident examination of the helicopter and a test run of the engine revealed no preaccident mechanical malfunctions or failures that would have prevented normal operation. Based on this evidence, it is likely that the pilot failed to apply engine power when he applied collective input, which resulted in a loss of rotor speed and an exceedance of the helicopter's performance capability.

Text from the NTSB. Open the NTSB docket for CEN16LA213 for the full record.