CEN12LA228

After an uneventful flight, the pilot slowed the helicopter into a stable hover about 15 feet above the landing point. Although the engine continued to operate, the main rotor rpm suddenly decayed and the helicopter landed hard. The pilot, who had over 5,600 flight hours in helicopters, stated that there was no warning before the loss of main rotor drive. The helicopter was in a position whereby power to the rotor system was essential to conducting a safe landing. Examination of the helicopter revealed that the bolt that retains the clutch drive rod end in the clutch pivot fork had sheared, resulting in the clutch disengaging. Once the clutch disengaged, there was no drive to the rotor system, and the helicopter's descent could not be arrested. With the exception of the failed bolt, examination of the entire drive system did not show any preexisting mechanical malfunction or abnormalities that would have precluded normal operation. The helicopter had operated about 1,350 hours since it was new, and the retaining bolt was the original installation. The reason for the failure of the bolt could not be determined.

On April 3, 2012, approximately 1555 central daylight time, an Enstrom 280FX helicopter, N3042D, registered to Travland Helicopters Intl INC., of Alpine, Texas, was substantially damaged during a hard landing after a loss of power at the Corpus Christie Airport (CRP), Corpus Christie, Texas. The commercial pilot received minor injuries and his passenger was not injured. Visual meteorological conditions prevailed and a flight plan was not filed for the flight. The business flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. The flight originated from Edinburg, Texas, and Corpus Christie was its intended destination. After an uneventful flight from Edinburg, Texas, and set up for landing at CRP, the pilot slowed the helicopter into a stable hover about 15 feet above the landing point, the rotor RPM suddenly decayed and the helicopter landed hard, resulting in substantial damage to the tailboom. The pilot, who had over 5,600 flight hours in helicopters, stated that there was no warning prior to the loss of main rotor drive. The helicopter was in a position whereby power to the rotor system was essential to effect a safe landing. Examination of the helicopter by an FAA inspector revealed that the bolt that retains the clutch drive rod end in the clutch pivot fork had sheared. The ears of the pivot fork were worn on the inside, but not bent. The rod end to the clutch drive was not bent. The bolt was elongated and the pivot fork bushing was worn. The head of the bolt was not found. Examination of the entire drive system did not show any preexisting mechanical malfunction or abnormalities. The bolt was the proper hardware for the installation. The helicopter had about 1,350 hours since it was new, and the retaining bolt was the original installation.