Incident Summary
After the pilot had dispensed a load of chemicals, he was returning to land when he felt a vibration in the tail boom. This was followed by a loud noise, and the helicopter began turning. In response, the pilot lowered the collective and reduced the power. The helicopter then landed hard, and the tail rotor blades severed the tail boom. During the accident sequence, the tail rotor gear box also separated.
Investigation Results
An investigation later revealed that the tail rotor boom center support fitting, part number 269A2324-7, had failed after 511 hours of flight time. The failure of this component was determined to be the cause of the accident.