Hughes 269C N7482F accident near Tallulah, Louisiana

Probable cause

The pilot's failure to reset the cyclic trim before takeoff, which resulted in ground resonance.

NTSB analysis

The commercial pilot reported that the helicopter's engine start and run-up were normal. At full power for takeoff, the helicopter began to vibrate. The pilot "rolled the throttle off" and lowered the collective; however, the vibrations became worse and the helicopter "began to destroy itself." He reported that he had not re-centered before the cyclic trim before takeoff as noted on the checklist, and it remained at a nearly full-forward position from the previous flight. He noted that if the cyclic had been centered, the vibrations would have stopped. However, with the trim full forward, the rotor blades began hitting the stops, causing the vibrations. The pilot added that there were no malfunctions or failures with the helicopter before the accident.

Text from the NTSB. Open the NTSB docket for CEN17LA229 for the full record.