Accident Overview
A helicopter pilot reported a normal takeoff to the south. Approximately 30 seconds into the flight, a control paddle separated from the helicopter, resulting in loss of control. The helicopter subsequently crashed into a cornfield and came to rest inverted. The pilot was able to exit the wreckage after the accident.
Post-Crash Findings
Examination of the wreckage revealed that a flight control rotor blade had detached from the helicopter in flight. The blade's spar had separated due to a fatigue crack. According to the NTSB materials laboratory, the fatigue crack originated from corrosion pitting on the spar. The crack propagated nearly all the way around the spar on both sides, leading to the separation.
Inspection Requirements
At the time of the accident, the FAA had issued Airworthiness Directives (ADs) requiring inspection of the spar tube, cuff, and bolt holes every 100 hours, in accordance with a Hiller service bulletin. The service bulletin called for a visual inspection of the inside surface of the cuff and both surfaces of the spar tube for corrosion, followed by a dye-penetrant inspection of the spar and cuff to detect cracks.
Maintenance Records and Evidence
Logbook entries from less than four months and 70 hours of time in service before the accident indicated compliance with the relevant AD and service bulletin. However, during the NTSB materials laboratory testing, no evidence was found of dye penetrant residue, zinc chromate primer, or the required sealant material on the inspected components.
Conclusion
No further details were provided regarding the helicopter type, registration, operator, location, or injuries. The investigation focused on the structural failure and the apparent lack of proper inspection despite logbook claims.